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Pull rseq updates from Thomas Gleixner:
"A large overhaul of the restartable sequences and CID management:
The recent enablement of RSEQ in glibc resulted in regressions which
are caused by the related overhead. It turned out that the decision to
invoke the exit to user work was not really a decision. More or less
each context switch caused that. There is a long list of small issues
which sums up nicely and results in a 3-4% regression in I/O
benchmarks.
The other detail which caused issues due to extra work in context
switch and task migration is the CID (memory context ID) management.
It also requires to use a task work to consolidate the CID space,
which is executed in the context of an arbitrary task and results in
sporadic uncontrolled exit latencies.
The rewrite addresses this by:
- Removing deprecated and long unsupported functionality
- Moving the related data into dedicated data structures which are
optimized for fast path processing.
- Caching values so actual decisions can be made
- Replacing the current implementation with a optimized inlined
variant.
- Separating fast and slow path for architectures which use the
generic entry code, so that only fault and error handling goes into
the TIF_NOTIFY_RESUME handler.
- Rewriting the CID management so that it becomes mostly invisible in
the context switch path. That moves the work of switching modes
into the fork/exit path, which is a reasonable tradeoff. That work
is only required when a process creates more threads than the
cpuset it is allowed to run on or when enough threads exit after
that. An artificial thread pool benchmarks which triggers this did
not degrade, it actually improved significantly.
The main effect in migration heavy scenarios is that runqueue lock
held time and therefore contention goes down significantly"
* tag 'core-rseq-2025-11-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/mmcid: Switch over to the new mechanism
sched/mmcid: Implement deferred mode change
irqwork: Move data struct to a types header
sched/mmcid: Provide CID ownership mode fixup functions
sched/mmcid: Provide new scheduler CID mechanism
sched/mmcid: Introduce per task/CPU ownership infrastructure
sched/mmcid: Serialize sched_mm_cid_fork()/exit() with a mutex
sched/mmcid: Provide precomputed maximal value
sched/mmcid: Move initialization out of line
signal: Move MMCID exit out of sighand lock
sched/mmcid: Convert mm CID mask to a bitmap
cpumask: Cache num_possible_cpus()
sched/mmcid: Use cpumask_weighted_or()
cpumask: Introduce cpumask_weighted_or()
sched/mmcid: Prevent pointless work in mm_update_cpus_allowed()
sched/mmcid: Move scheduler code out of global header
sched: Fixup whitespace damage
sched/mmcid: Cacheline align MM CID storage
sched/mmcid: Use proper data structures
sched/mmcid: Revert the complex CID management
...
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Pull bug handling infrastructure updates from Ingo Molnar:
"Core updates:
- Improve WARN(), which has vararg printf like arguments, to work
with the x86 #UD based WARN-optimizing infrastructure by hiding the
format in the bug_table and replacing this first argument with the
address of the bug-table entry, while making the actual function
that's called a UD1 instruction (Peter Zijlstra)
- Introduce the CONFIG_DEBUG_BUGVERBOSE_DETAILED Kconfig switch (Ingo
Molnar, s390 support by Heiko Carstens)
Fixes and cleanups:
- bugs/s390: Remove private WARN_ON() implementation (Heiko Carstens)
- <asm/bugs.h>: Make i386 use GENERIC_BUG_RELATIVE_POINTERS (Peter
Zijlstra)"
* tag 'core-bugs-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (31 commits)
x86/bugs: Make i386 use GENERIC_BUG_RELATIVE_POINTERS
x86/bug: Fix BUG_FORMAT vs KASLR
x86_64/bug: Inline the UD1
x86/bug: Implement WARN_ONCE()
x86_64/bug: Implement __WARN_printf()
x86/bug: Use BUG_FORMAT for DEBUG_BUGVERBOSE_DETAILED
x86/bug: Add BUG_FORMAT basics
bug: Allow architectures to provide __WARN_printf()
bug: Implement WARN_ON() using __WARN_FLAGS()
bug: Add report_bug_entry()
bug: Add BUG_FORMAT_ARGS infrastructure
bug: Clean up CONFIG_GENERIC_BUG_RELATIVE_POINTERS
bug: Add BUG_FORMAT infrastructure
x86: Rework __bug_table helpers
bugs/s390: Remove private WARN_ON() implementation
bugs/core: Reorganize fields in the first line of WARNING output, add ->comm[] output
bugs/sh: Concatenate 'cond_str' with '__FILE__' in __WARN_FLAGS(), to extend WARN_ON/BUG_ON output
bugs/parisc: Concatenate 'cond_str' with '__FILE__' in __WARN_FLAGS(), to extend WARN_ON/BUG_ON output
bugs/riscv: Concatenate 'cond_str' with '__FILE__' in __BUG_FLAGS(), to extend WARN_ON/BUG_ON output
bugs/riscv: Pass in 'cond_str' to __BUG_FLAGS()
...
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Pull objtool updates from Ingo Molnar:
- klp-build livepatch module generation (Josh Poimboeuf)
Introduce new objtool features and a klp-build script to generate
livepatch modules using a source .patch as input.
This builds on concepts from the longstanding out-of-tree kpatch
project which began in 2012 and has been used for many years to
generate livepatch modules for production kernels. However, this is a
complete rewrite which incorporates hard-earned lessons from 12+
years of maintaining kpatch.
Key improvements compared to kpatch-build:
- Integrated with objtool: Leverages objtool's existing control-flow
graph analysis to help detect changed functions.
- Works on vmlinux.o: Supports late-linked objects, making it
compatible with LTO, IBT, and similar.
- Simplified code base: ~3k fewer lines of code.
- Upstream: No more out-of-tree #ifdef hacks, far less cruft.
- Cleaner internals: Vastly simplified logic for
symbol/section/reloc inclusion and special section extraction.
- Robust __LINE__ macro handling: Avoids false positive binary diffs
caused by the __LINE__ macro by introducing a fix-patch-lines
script which injects #line directives into the source .patch to
preserve the original line numbers at compile time.
- Disassemble code with libopcodes instead of running objdump
(Alexandre Chartre)
- Disassemble support (-d option to objtool) by Alexandre Chartre,
which supports the decoding of various Linux kernel code generation
specials such as alternatives:
17ef: sched_balance_find_dst_group+0x62f mov 0x34(%r9),%edx
17f3: sched_balance_find_dst_group+0x633 | <alternative.17f3> | X86_FEATURE_POPCNT
17f3: sched_balance_find_dst_group+0x633 | call 0x17f8 <__sw_hweight64> | popcnt %rdi,%rax
17f8: sched_balance_find_dst_group+0x638 cmp %eax,%edx
... jump table alternatives:
1895: sched_use_asym_prio+0x5 test $0x8,%ch
1898: sched_use_asym_prio+0x8 je 0x18a9 <sched_use_asym_prio+0x19>
189a: sched_use_asym_prio+0xa | <jump_table.189a> | JUMP
189a: sched_use_asym_prio+0xa | jmp 0x18ae <sched_use_asym_prio+0x1e> | nop2
189c: sched_use_asym_prio+0xc mov $0x1,%eax
18a1: sched_use_asym_prio+0x11 and $0x80,%ecx
... exception table alternatives:
native_read_msr:
5b80: native_read_msr+0x0 mov %edi,%ecx
5b82: native_read_msr+0x2 | <ex_table.5b82> | EXCEPTION
5b82: native_read_msr+0x2 | rdmsr | resume at 0x5b84 <native_read_msr+0x4>
5b84: native_read_msr+0x4 shl $0x20,%rdx
.... x86 feature flag decoding (also see the X86_FEATURE_POPCNT
example in sched_balance_find_dst_group() above):
2faaf: start_thread_common.constprop.0+0x1f jne 0x2fba4 <start_thread_common.constprop.0+0x114>
2fab5: start_thread_common.constprop.0+0x25 | <alternative.2fab5> | X86_FEATURE_ALWAYS | X86_BUG_NULL_SEG
2fab5: start_thread_common.constprop.0+0x25 | jmp 0x2faba <.altinstr_aux+0x2f4> | jmp 0x4b0 <start_thread_common.constprop.0+0x3f> | nop5
2faba: start_thread_common.constprop.0+0x2a mov $0x2b,%eax
... NOP sequence shortening:
1048e2: snapshot_write_finalize+0xc2 je 0x104917 <snapshot_write_finalize+0xf7>
1048e4: snapshot_write_finalize+0xc4 nop6
1048ea: snapshot_write_finalize+0xca nop11
1048f5: snapshot_write_finalize+0xd5 nop11
104900: snapshot_write_finalize+0xe0 mov %rax,%rcx
104903: snapshot_write_finalize+0xe3 mov 0x10(%rdx),%rax
... and much more.
- Function validation tracing support (Alexandre Chartre)
- Various -ffunction-sections fixes (Josh Poimboeuf)
- Clang AutoFDO (Automated Feedback-Directed Optimizations) support
(Josh Poimboeuf)
- Misc fixes and cleanups (Borislav Petkov, Chen Ni, Dylan Hatch, Ingo
Molnar, John Wang, Josh Poimboeuf, Pankaj Raghav, Peter Zijlstra,
Thorsten Blum)
* tag 'objtool-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
objtool: Fix segfault on unknown alternatives
objtool: Build with disassembly can fail when including bdf.h
objtool: Trim trailing NOPs in alternative
objtool: Add wide output for disassembly
objtool: Compact output for alternatives with one instruction
objtool: Improve naming of group alternatives
objtool: Add Function to get the name of a CPU feature
objtool: Provide access to feature and flags of group alternatives
objtool: Fix address references in alternatives
objtool: Disassemble jump table alternatives
objtool: Disassemble exception table alternatives
objtool: Print addresses with alternative instructions
objtool: Disassemble group alternatives
objtool: Print headers for alternatives
objtool: Preserve alternatives order
objtool: Add the --disas=<function-pattern> action
objtool: Do not validate IBT for .return_sites and .call_sites
objtool: Improve tracing of alternative instructions
objtool: Add functions to better name alternatives
objtool: Identify the different types of alternatives
...
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Pull misc vfs updates from Christian Brauner:
"Features:
- Cheaper MAY_EXEC handling for path lookup. This elides MAY_WRITE
permission checks during path lookup and adds the
IOP_FASTPERM_MAY_EXEC flag so filesystems like btrfs can avoid
expensive permission work.
- Hide dentry_cache behind runtime const machinery.
- Add German Maglione as virtiofs co-maintainer.
Cleanups:
- Tidy up and inline step_into() and walk_component() for improved
code generation.
- Re-enable IOCB_NOWAIT writes to files. This refactors file
timestamp update logic, fixing a layering bypass in btrfs when
updating timestamps on device files and improving FMODE_NOCMTIME
handling in VFS now that nfsd started using it.
- Path lookup optimizations extracting slowpaths into dedicated
routines and adding branch prediction hints for mntput_no_expire(),
fd_install(), lookup_slow(), and various other hot paths.
- Enable clang's -fms-extensions flag, requiring a JFS rename to
avoid conflicts.
- Remove spurious exports in fs/file_attr.c.
- Stop duplicating union pipe_index declaration. This depends on the
shared kbuild branch that brings in -fms-extensions support which
is merged into this branch.
- Use MD5 library instead of crypto_shash in ecryptfs.
- Use largest_zero_folio() in iomap_dio_zero().
- Replace simple_strtol/strtoul with kstrtoint/kstrtouint in init and
initrd code.
- Various typo fixes.
Fixes:
- Fix emergency sync for btrfs. Btrfs requires an explicit sync_fs()
call with wait == 1 to commit super blocks. The emergency sync path
never passed this, leaving btrfs data uncommitted during emergency
sync.
- Use local kmap in watch_queue's post_one_notification().
- Add hint prints in sb_set_blocksize() for LBS dependency on THP"
* tag 'vfs-6.19-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
MAINTAINERS: add German Maglione as virtiofs co-maintainer
fs: inline step_into() and walk_component()
fs: tidy up step_into() & friends before inlining
orangefs: use inode_update_timestamps directly
btrfs: fix the comment on btrfs_update_time
btrfs: use vfs_utimes to update file timestamps
fs: export vfs_utimes
fs: lift the FMODE_NOCMTIME check into file_update_time_flags
fs: refactor file timestamp update logic
include/linux/fs.h: trivial fix: regualr -> regular
fs/splice.c: trivial fix: pipes -> pipe's
fs: mark lookup_slow() as noinline
fs: add predicts based on nd->depth
fs: move mntput_no_expire() slowpath into a dedicated routine
fs: remove spurious exports in fs/file_attr.c
watch_queue: Use local kmap in post_one_notification()
fs: touch up predicts in path lookup
fs: move fd_install() slowpath into a dedicated routine and provide commentary
fs: hide dentry_cache behind runtime const machinery
fs: touch predicts in do_dentry_open()
...
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Implement WARN_ONCE like WARN using BUGFLAG_ONCE.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115758.339309119@infradead.org
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Since we have an explicit format string, use it for the condition string
instead of frobbing it in the file string.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115758.097401406@infradead.org
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In addition to providing __WARN_FLAGS(), allow an architecture to also
provide __WARN_printf().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115757.807154591@infradead.org
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This completes 3bc3c9c3ab6d ("bugs/core: Pass down the condition
string of WARN_ON_ONCE(cond) warnings to __WARN_FLAGS()") and makes
WARN_ON() and WARN_ON_ONCE() behaviour consistent.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115757.690999560@infradead.org
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Add BUG_FORMAT_ARGS; when an architecture is able to provide a va_list
given pt_regs, use this to print format arguments.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115757.457339417@infradead.org
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Three repeated CONFIG_GENERIC_BUG_RELATIVE_POINTERS #ifdefs right
after one another yields unreadable code. Add a helper.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115757.341703850@infradead.org
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Add BUG_FORMAT; an architecture opt-in feature that allows adding the
WARN_printf() format string to the bug_entry table.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251110115757.223371452@infradead.org
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Bring in the UDB and objtool data annotations to avoid conflicts while further extending the bug exceptions.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
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Commit 9c7dc1dd897a ("objtool: Warn on functions with ambiguous
-ffunction-sections section names") only works for drivers which are
compiled on architectures supported by objtool.
Make a script to perform the same check for all architectures.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/a6a49644a34964f7e02f3a8ce43af03e72817180.1763669451.git.jpoimboe@kernel.org
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When compiled with -ffunction-sections, a function named startup() will
be placed in .text.startup. However, .text.startup is also used by the
compiler for functions with __attribute__((constructor)).
That creates an ambiguity for the vmlinux linker script, which needs to
differentiate those two cases.
Similar naming conflicts exist for functions named exit(), split(),
unlikely(), hot() and unknown().
One potential solution would be to use '#ifdef CC_USING_FUNCTION_SECTIONS'
to create two distinct implementations of the TEXT_MAIN macro. However,
-ffunction-sections can be (and is) enabled or disabled on a per-object
basis (for example via ccflags-y or AUTOFDO_PROFILE).
So the recently unified TEXT_MAIN macro (commit 1ba9f8979426
("vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros")) is
necessary. This means there's no way for the linker script to
disambiguate things.
Instead, use objtool to warn on any function names whose resulting
section names might create ambiguity when the kernel is compiled (in
whole or in part) with -ffunction-sections.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: live-patching@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://patch.msgid.link/65fedea974fe14be487c8867a0b8d0e4a294ce1e.1762991150.git.jpoimboe@kernel.org
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Since:
6568f14cb5ae ("vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN")
the TEXT_MAIN macro uses a series of patterns to prevent the
.text.startup[.*] and .text.exit[.*] sections from getting
linked into the vmlinux runtime .text.
That commit is a tad too aggressive: it also inadvertently filters out
valid runtime text sections like .text.start and
.text.start.constprop.0, which can be generated for a function named
start() when -ffunction-sections is enabled.
As a result, those sections become orphans when building with
CONFIG_LD_DEAD_CODE_DATA_ELIMINATION for arm:
arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/usb/host/sl811-hcd.o' being placed in section `.text.start.constprop.0'
arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/media/dvb-frontends/drxk_hard.o' being placed in section `.text.start.constprop.0'
arm-linux-gnueabi-ld: warning: orphan section `.text.start' from `drivers/media/dvb-frontends/stv0910.o' being placed in section `.text.start'
arm-linux-gnueabi-ld: warning: orphan section `.text.start.constprop.0' from `drivers/media/pci/ddbridge/ddbridge-sx8.o' being placed in section `.text.start.constprop.0'
Fix that by explicitly adding the partial "substring" sections (.text.s,
.text.st, .text.sta, etc) and their cloned derivatives.
While this unfortunately means that TEXT_MAIN continues to grow,
these changes are ultimately necessary for proper support of
-ffunction-sections.
Fixes: 6568f14cb5ae ("vmlinux.lds: Exclude .text.startup and .text.exit from TEXT_MAIN")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: live-patching@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://patch.msgid.link/cd588144e63df901a656b06b566855019c4a931d.1762991150.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202511040812.DFGedJiy-lkp@intel.com/
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://patch.msgid.link/20251105153622.758836-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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TIF_NOTIFY_RESUME is a multiplexing TIF bit, which is suboptimal especially
with the RSEQ fast path depending on it, but not really handling it.
Define a separate TIF_RSEQ in the generic TIF space and enable the full
separation of fast and slow path for architectures which utilize that.
That avoids the hassle with invocations of resume_user_mode_work() from
hypervisors, which clear TIF_NOTIFY_RESUME. It makes the therefore required
re-evaluation at the end of vcpu_run() a NOOP on architectures which
utilize the generic TIF space and have a separate TIF_RSEQ.
The hypervisor TIF handling does not include the separate TIF_RSEQ as there
is no point in doing so. The guest does neither know nor care about the VMM
host applications RSEQ state. That state is only relevant when the ioctl()
returns to user space.
The fastpath implementation still utilizes TIF_NOTIFY_RESUME for failure
handling, but this only happens within exit_to_user_mode_loop(), so
arguably the hypervisor ioctl() code is long done when this happens.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027084307.903622031@linutronix.de
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An ftrace warning was reported in ftrace_init_ool_stub():
WARNING: arch/powerpc/kernel/trace/ftrace.c:234 at ftrace_init_ool_stub+0x188/0x3f4, CPU#0: swapper/0
The problem is that the linker script is placing .text.startup in .text
rather than in .init.text, due to an inadvertent match of the TEXT_MAIN
'.text.[0-9a-zA-Z_]*' pattern.
This bug existed for some configurations before, but is only now coming
to light due to the TEXT_MAIN macro unification in commit 1ba9f8979426
("vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros").
The .text.startup section consists of constructors which are used by
KASAN, KCSAN, and GCOV. The constructors are only called during boot,
so .text.startup is supposed to match the INIT_TEXT pattern so it can be
placed in .init.text and freed after init. But since INIT_TEXT comes
*after* TEXT_MAIN in the linker script, TEXT_MAIN needs to manually
exclude .text.startup.
Update TEXT_MAIN to exclude .text.startup (and its .text.startup.*
variant from -ffunction-sections), along with .text.exit and
.text.exit.* which should match EXIT_TEXT.
Specifically, use a series of more specific glob patterns to match
generic .text.* sections (for -ffunction-sections) while explicitly
excluding .text.startup[.*] and .text.exit[.*].
Also update INIT_TEXT and EXIT_TEXT to explicitly match their
-ffunction-sections variants (.text.startup.* and .text.exit.*).
Fixes: 1ba9f8979426 ("vmlinux.lds: Unify TEXT_MAIN, DATA_MAIN, and related macros")
Closes: https://lore.kernel.org/72469502-ca37-4287-90b9-a751cecc498c@linux.ibm.com
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Debugged-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Link: https://patch.msgid.link/07f74b4e5c43872572b7def30f2eac45f28675d9.1761872421.git.jpoimboe@kernel.org
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Previously linker scripts would always generate vmlinuz that has sections
aligned. And thus padded (correct Authenticode calculation) and unpadded
calculation would be same. As in https://github.com/rhboot/pesign userspace
tool would produce the same authenticode digest for both of the following
commands:
pesign --padding --hash --in ./arch/x86_64/boot/bzImage
pesign --nopadding --hash --in ./arch/x86_64/boot/bzImage
The commit 3e86e4d74c04 ("kbuild: keep .modinfo section in
vmlinux.unstripped") added .modinfo section of variable length. Depending
on kernel configuration it may or may not be aligned.
All userspace signing tooling correctly pads such section to calculation
spec compliant authenticode digest.
However, if bzImage is not further processed and is attempted to be loaded
directly by EDK2 firmware, it calculates unpadded Authenticode digest and
fails to correct accept/reject such kernel builds even when propoer
Authenticode values are enrolled in db/dbx. One can say EDK2 requires
aligned/padded kernels in Secureboot.
Thus add ALIGN(8) to the .modinfo section, to esure kernels irrespective of
modinfo contents can be loaded by all existing EDK2 firmware builds.
Fixes: 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped")
Cc: stable@vger.kernel.org
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@surgut.co.uk>
Link: https://patch.msgid.link/20251026202100.679989-1-dimitri.ledkov@surgut.co.uk
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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TEXT_MAIN, DATA_MAIN and friends are defined differently depending on
whether certain config options enable -ffunction-sections and/or
-fdata-sections.
There's no technical reason for that beyond voodoo coding. Keeping the
separate implementations adds unnecessary complexity, fragments the
logic, and increases the risk of subtle bugs.
Unify the macros by using the same input section patterns across all
configs.
This is a prerequisite for the upcoming livepatch klp-build tooling
which will manually enable -ffunction-sections and -fdata-sections via
KCFLAGS.
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
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Pull hyperv updates from Wei Liu:
- Unify guest entry code for KVM and MSHV (Sean Christopherson)
- Switch Hyper-V MSI domain to use msi_create_parent_irq_domain()
(Nam Cao)
- Add CONFIG_HYPERV_VMBUS and limit the semantics of CONFIG_HYPERV
(Mukesh Rathor)
- Add kexec/kdump support on Azure CVMs (Vitaly Kuznetsov)
- Deprecate hyperv_fb in favor of Hyper-V DRM driver (Prasanna
Kumar T S M)
- Miscellaneous enhancements, fixes and cleanups (Abhishek Tiwari,
Alok Tiwari, Nuno Das Neves, Wei Liu, Roman Kisel, Michael Kelley)
* tag 'hyperv-next-signed-20251006' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
hyperv: Remove the spurious null directive line
MAINTAINERS: Mark hyperv_fb driver Obsolete
fbdev/hyperv_fb: deprecate this in favor of Hyper-V DRM driver
Drivers: hv: Make CONFIG_HYPERV bool
Drivers: hv: Add CONFIG_HYPERV_VMBUS option
Drivers: hv: vmbus: Fix typos in vmbus_drv.c
Drivers: hv: vmbus: Fix sysfs output format for ring buffer index
Drivers: hv: vmbus: Clean up sscanf format specifier in target_cpu_store()
x86/hyperv: Switch to msi_create_parent_irq_domain()
mshv: Use common "entry virt" APIs to do work in root before running guest
entry: Rename "kvm" entry code assets to "virt" to genericize APIs
entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM proper
mshv: Handle NEED_RESCHED_LAZY before transferring to guest
x86/hyperv: Add kexec/kdump support on Azure CVMs
Drivers: hv: Simplify data structures for VMBus channel close message
Drivers: hv: util: Cosmetic changes for hv_utils_transport.c
mshv: Add support for a new parent partition configuration
clocksource: hyper-v: Skip unnecessary checks for the root partition
hyperv: Add missing field to hv_output_map_device_interrupt
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Pull MM updates from Andrew Morton:
- "mm, swap: improve cluster scan strategy" from Kairui Song improves
performance and reduces the failure rate of swap cluster allocation
- "support large align and nid in Rust allocators" from Vitaly Wool
permits Rust allocators to set NUMA node and large alignment when
perforning slub and vmalloc reallocs
- "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend
DAMOS_STAT's handling of the DAMON operations sets for virtual
address spaces for ops-level DAMOS filters
- "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren
Baghdasaryan reduces mmap_lock contention during reads of
/proc/pid/maps
- "mm/mincore: minor clean up for swap cache checking" from Kairui Song
performs some cleanup in the swap code
- "mm: vm_normal_page*() improvements" from David Hildenbrand provides
code cleanup in the pagemap code
- "add persistent huge zero folio support" from Pankaj Raghav provides
a block layer speedup by optionalls making the
huge_zero_pagepersistent, instead of releasing it when its refcount
falls to zero
- "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to
the recently added Kexec Handover feature
- "mm: make mm->flags a bitmap and 64-bit on all arches" from Lorenzo
Stoakes turns mm_struct.flags into a bitmap. To end the constant
struggle with space shortage on 32-bit conflicting with 64-bit's
needs
- "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap
code
- "selftests/mm: Fix false positives and skip unsupported tests" from
Donet Tom fixes a few things in our selftests code
- "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised"
from David Hildenbrand "allows individual processes to opt-out of
THP=always into THP=madvise, without affecting other workloads on the
system".
It's a long story - the [1/N] changelog spells out the considerations
- "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on
the memdesc project. Please see
https://kernelnewbies.org/MatthewWilcox/Memdescs and
https://blogs.oracle.com/linux/post/introducing-memdesc
- "Tiny optimization for large read operations" from Chi Zhiling
improves the efficiency of the pagecache read path
- "Better split_huge_page_test result check" from Zi Yan improves our
folio splitting selftest code
- "test that rmap behaves as expected" from Wei Yang adds some rmap
selftests
- "remove write_cache_pages()" from Christoph Hellwig removes that
function and converts its two remaining callers
- "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD
selftests issues
- "introduce kernel file mapped folios" from Boris Burkov introduces
the concept of "kernel file pages". Using these permits btrfs to
account its metadata pages to the root cgroup, rather than to the
cgroups of random inappropriate tasks
- "mm/pageblock: improve readability of some pageblock handling" from
Wei Yang provides some readability improvements to the page allocator
code
- "mm/damon: support ARM32 with LPAE" from SeongJae Park teaches DAMON
to understand arm32 highmem
- "tools: testing: Use existing atomic.h for vma/maple tests" from
Brendan Jackman performs some code cleanups and deduplication under
tools/testing/
- "maple_tree: Fix testing for 32bit compiles" from Liam Howlett fixes
a couple of 32-bit issues in tools/testing/radix-tree.c
- "kasan: unify kasan_enabled() and remove arch-specific
implementations" from Sabyrzhan Tasbolatov moves KASAN arch-specific
initialization code into a common arch-neutral implementation
- "mm: remove zpool" from Johannes Weiner removes zspool - an
indirection layer which now only redirects to a single thing
(zsmalloc)
- "mm: task_stack: Stack handling cleanups" from Pasha Tatashin makes a
couple of cleanups in the fork code
- "mm: remove nth_page()" from David Hildenbrand makes rather a lot of
adjustments at various nth_page() callsites, eventually permitting
the removal of that undesirable helper function
- "introduce kasan.write_only option in hw-tags" from Yeoreum Yun
creates a KASAN read-only mode for ARM, using that architecture's
memory tagging feature. It is felt that a read-only mode KASAN is
suitable for use in production systems rather than debug-only
- "mm: hugetlb: cleanup hugetlb folio allocation" from Kefeng Wang does
some tidying in the hugetlb folio allocation code
- "mm: establish const-correctness for pointer parameters" from Max
Kellermann makes quite a number of the MM API functions more accurate
about the constness of their arguments. This was getting in the way
of subsystems (in this case CEPH) when they attempt to improving
their own const/non-const accuracy
- "Cleanup free_pages() misuse" from Vishal Moola fixes a number of
code sites which were confused over when to use free_pages() vs
__free_pages()
- "Add Rust abstraction for Maple Trees" from Alice Ryhl makes the
mapletree code accessible to Rust. Required by nouveau and by its
forthcoming successor: the new Rust Nova driver
- "selftests/mm: split_huge_page_test: split_pte_mapped_thp
improvements" from David Hildenbrand adds a fix and some cleanups to
the thp selftesting code
- "mm, swap: introduce swap table as swap cache (phase I)" from Chris
Li and Kairui Song is the first step along the path to implementing
"swap tables" - a new approach to swap allocation and state tracking
which is expected to yield speed and space improvements. This
patchset itself yields a 5-20% performance benefit in some situations
- "Some ptdesc cleanups" from Matthew Wilcox utilizes the new memdesc
layer to clean up the ptdesc code a little
- "Fix va_high_addr_switch.sh test failure" from Chunyu Hu fixes some
issues in our 5-level pagetable selftesting code
- "Minor fixes for memory allocation profiling" from Suren Baghdasaryan
addresses a couple of minor issues in relatively new memory
allocation profiling feature
- "Small cleanups" from Matthew Wilcox has a few cleanups in
preparation for more memdesc work
- "mm/damon: add addr_unit for DAMON_LRU_SORT and DAMON_RECLAIM" from
Quanmin Yan makes some changes to DAMON in furtherance of supporting
arm highmem
- "selftests/mm: Add -Wunreachable-code and fix warnings" from Muhammad
Anjum adds that compiler check to selftests code and fixes the
fallout, by removing dead code
- "Improvements to Victim Process Thawing and OOM Reaper Traversal
Order" from zhongjinji makes a number of improvements in the OOM
killer: mainly thawing a more appropriate group of victim threads so
they can release resources
- "mm/damon: misc fixups and improvements for 6.18" from SeongJae Park
is a bunch of small and unrelated fixups for DAMON
- "mm/damon: define and use DAMON initialization check function" from
SeongJae Park implement reliability and maintainability improvements
to a recently-added bug fix
- "mm/damon/stat: expose auto-tuned intervals and non-idle ages" from
SeongJae Park provides additional transparency to userspace clients
of the DAMON_STAT information
- "Expand scope of khugepaged anonymous collapse" from Dev Jain removes
some constraints on khubepaged's collapsing of anon VMAs. It also
increases the success rate of MADV_COLLAPSE against an anon vma
- "mm: do not assume file == vma->vm_file in compat_vma_mmap_prepare()"
from Lorenzo Stoakes moves us further towards removal of
file_operations.mmap(). This patchset concentrates upon clearing up
the treatment of stacked filesystems
- "mm: Improve mlock tracking for large folios" from Kiryl Shutsemau
provides some fixes and improvements to mlock's tracking of large
folios. /proc/meminfo's "Mlocked" field became more accurate
- "mm/ksm: Fix incorrect accounting of KSM counters during fork" from
Donet Tom fixes several user-visible KSM stats inaccuracies across
forks and adds selftest code to verify these counters
- "mm_slot: fix the usage of mm_slot_entry" from Wei Yang addresses
some potential but presently benign issues in KSM's mm_slot handling
* tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (372 commits)
mm: swap: check for stable address space before operating on the VMA
mm: convert folio_page() back to a macro
mm/khugepaged: use start_addr/addr for improved readability
hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list
alloc_tag: fix boot failure due to NULL pointer dereference
mm: silence data-race in update_hiwater_rss
mm/memory-failure: don't select MEMORY_ISOLATION
mm/khugepaged: remove definition of struct khugepaged_mm_slot
mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL
hugetlb: increase number of reserving hugepages via cmdline
selftests/mm: add fork inheritance test for ksm_merging_pages counter
mm/ksm: fix incorrect KSM counter handling in mm_struct during fork
drivers/base/node: fix double free in register_one_node()
mm: remove PMD alignment constraint in execmem_vmalloc()
mm/memory_hotplug: fix typo 'esecially' -> 'especially'
mm/rmap: improve mlock tracking for large folios
mm/filemap: map entire large folio faultaround
mm/fault: try to map the entire file folio in finish_fault()
mm/rmap: mlock large folios in try_to_unmap_one()
mm/rmap: fix a mlock race condition in folio_referenced_one()
...
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Pull Kbuild updates from Nathan Chancellor:
- Extend modules.builtin.modinfo to include module aliases from
MODULE_DEVICE_TABLE for builtin modules so that userspace tools (such
as kmod) can verify that a particular module alias will be handled by
a builtin module
- Bump the minimum version of LLVM for building the kernel to 15.0.0
- Upgrade several userspace API checks in headers_check.pl to errors
- Unify and consolidate CONFIG_WERROR / W=e handling
- Turn assembler and linker warnings into errors with CONFIG_WERROR /
W=e
- Respect CONFIG_WERROR / W=e when building userspace programs
(userprogs)
- Enable -Werror unconditionally when building host programs
(hostprogs)
- Support copy_file_range() and data segment alignment in gen_init_cpio
to improve performance on filesystems that support reflinks such as
btrfs and XFS
- Miscellaneous small changes to scripts and configuration files
* tag 'kbuild-6.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (47 commits)
modpost: Initialize builtin_modname to stop SIGSEGVs
Documentation: kbuild: note CONFIG_DEBUG_EFI in reproducible builds
kbuild: vmlinux.unstripped should always depend on .vmlinux.export.o
modpost: Create modalias for builtin modules
modpost: Add modname to mod_device_table alias
scsi: Always define blogic_pci_tbl structure
kbuild: extract modules.builtin.modinfo from vmlinux.unstripped
kbuild: keep .modinfo section in vmlinux.unstripped
kbuild: always create intermediate vmlinux.unstripped
s390: vmlinux.lds.S: Reorder sections
KMSAN: Remove tautological checks
objtool: Drop noinstr hack for KCSAN_WEAK_MEMORY
lib/Kconfig.debug: Drop CLANG_VERSION check from DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
riscv: Remove ld.lld version checks from many TOOLCHAIN_HAS configs
riscv: Unconditionally use linker relaxation
riscv: Remove version check for LTO_CLANG selects
powerpc: Drop unnecessary initializations in __copy_inst_from_kernel_nofault()
mips: Unconditionally select ARCH_HAS_CURRENT_STACK_POINTER
arm64: Remove tautological LLVM Kconfig conditions
ARM: Clean up definition of ARM_HAS_GROUP_RELOCS
...
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Pull asm-generic updates from Arnd Bergmann:
"Two small patches for the asm-generic header files: Varad Gautam
improves the MMIO tracing to be faster when the tracepoints are built
into the kernel but disabled, while Qi Xi updates the DO_ONCE logic so
that clearing the WARN_ONCE() flags does not change the other DO_ONCE
users"
* tag 'asm-generic-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
once: fix race by moving DO_ONCE to separate section
asm-generic/io.h: Skip trace helpers if rwmmio events are disabled
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At present VMBus driver is hinged off of CONFIG_HYPERV which entails
lot of builtin code and encompasses too much. It's not always clear
what depends on builtin hv code and what depends on VMBus. Setting
CONFIG_HYPERV as a module and fudging the Makefile to switch to builtin
adds even more confusion. VMBus is an independent module and should have
its own config option. Also, there are scenarios like baremetal dom0/root
where support is built in with CONFIG_HYPERV but without VMBus. Lastly,
there are more features coming down that use CONFIG_HYPERV and add more
dependencies on it.
So, create a fine grained HYPERV_VMBUS option and update Kconfigs for
dependency on VMBus.
Signed-off-by: Mukesh Rathor <mrathor@linux.microsoft.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com> # drivers/pci
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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Pull VDSO updates from Thomas Gleixner:
- Further consolidation of the VDSO infrastructure and the common data
store
- Simplification of the related Kconfig logic
- Improve the VDSO selftest suite
* tag 'timers-vdso-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
selftests: vDSO: Drop vdso_test_clock_getres
selftests: vDSO: vdso_test_abi: Add tests for clock_gettime64()
selftests: vDSO: vdso_test_abi: Test CPUTIME clocks
selftests: vDSO: vdso_test_abi: Use explicit indices for name array
selftests: vDSO: vdso_test_abi: Drop clock availability tests
selftests: vDSO: vdso_test_abi: Use ksft_finished()
selftests: vDSO: vdso_test_abi: Correctly skip whole test with missing vDSO
selftests: vDSO: Fix -Wunitialized in powerpc VDSO_CALL() wrapper
vdso: Add struct __kernel_old_timeval forward declaration to gettime.h
vdso: Gate VDSO_GETRANDOM behind HAVE_GENERIC_VDSO
vdso: Drop Kconfig GENERIC_VDSO_TIME_NS
vdso: Drop Kconfig GENERIC_VDSO_DATA_STORE
vdso: Drop kconfig GENERIC_COMPAT_VDSO
vdso: Drop kconfig GENERIC_VDSO_32
riscv: vdso: Untangle Kconfig logic
time: Build generic update_vsyscall() only with generic time vDSO
vdso/gettimeofday: Remove !CONFIG_TIME_NS stubs
vdso: Move ENABLE_COMPAT_VDSO from core to arm64
ARM: VDSO: Remove cntvct_ok global variable
vdso/datastore: Gate time data behind CONFIG_GENERIC_GETTIMEOFDAY
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Pull TIF bit unification updates from Thomas Gleixner:
"A set of changes to consolidate the generic TIF (thread info flag)
bits accross architectures.
All architectures define the same set of generic TIF bits. This makes
it pointlessly hard to add a new generic TIF bit or to change an
existing one.
Provide a generic variant and convert the architectures which utilize
the generic entry code over to use it. The TIF space is divided into
16 generic bits and 16 architecture specific bits, which turned out to
provide enough space on both sides"
* tag 'core-core-2025-09-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
LoongArch: Fix bitflag conflict for TIF_FIXADE
riscv: Use generic TIF bits
loongarch: Use generic TIF bits
s390/entry: Remove unused TIF flags
s390: Use generic TIF bits
x86: Use generic TIF bits
asm-generic: Provide generic TIF infrastructure
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Pull hardening updates from Kees Cook:
"One notable addition is the creation of the 'transitional' keyword for
kconfig so CONFIG renaming can go more smoothly.
This has been a long-standing deficiency, and with the renaming of
CONFIG_CFI_CLANG to CONFIG_CFI (since GCC will soon have KCFI
support), this came up again.
The breadth of the diffstat is mainly this renaming.
- Clean up usage of TRAILING_OVERLAP() (Gustavo A. R. Silva)
- lkdtm: fortify: Fix potential NULL dereference on kmalloc failure
(Junjie Cao)
- Add str_assert_deassert() helper (Lad Prabhakar)
- gcc-plugins: Remove TODO_verify_il for GCC >= 16
- kconfig: Fix BrokenPipeError warnings in selftests
- kconfig: Add transitional symbol attribute for migration support
- kcfi: Rename CONFIG_CFI_CLANG to CONFIG_CFI"
* tag 'hardening-v6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
lib/string_choices: Add str_assert_deassert() helper
kcfi: Rename CONFIG_CFI_CLANG to CONFIG_CFI
kconfig: Add transitional symbol attribute for migration support
kconfig: Fix BrokenPipeError warnings in selftests
gcc-plugins: Remove TODO_verify_il for GCC >= 16
stddef: Introduce __TRAILING_OVERLAP()
stddef: Remove token-pasting in TRAILING_OVERLAP()
lkdtm: fortify: Fix potential NULL dereference on kmalloc failure
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The commit c2c60ea37e5b ("once: use __section(".data.once")") moved
DO_ONCE's ___done variable to .data.once section, which conflicts with
DO_ONCE_LITE() that also uses the same section.
This creates a race condition when clear_warn_once is used:
Thread 1 (DO_ONCE) Thread 2 (DO_ONCE)
__do_once_start
read ___done (false)
acquire once_lock
execute func
__do_once_done
write ___done (true) __do_once_start
release once_lock // Thread 3 clear_warn_once reset ___done
read ___done (false)
acquire once_lock
execute func
schedule once_work __do_once_done
once_deferred: OK write ___done (true)
static_branch_disable release once_lock
schedule once_work
once_deferred:
BUG_ON(!static_key_enabled)
DO_ONCE_LITE() in once_lite.h is used by WARN_ON_ONCE() and other warning
macros. Keep its ___done flag in the .data..once section and allow resetting
by clear_warn_once, as originally intended.
In contrast, DO_ONCE() is used for functions like get_random_once() and
relies on its ___done flag for internal synchronization. We should not reset
DO_ONCE() by clear_warn_once.
Fix it by isolating DO_ONCE's ___done into a separate .data..do_once section,
shielding it from clear_warn_once.
Fixes: c2c60ea37e5b ("once: use __section(".data.once")")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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The kernel's CFI implementation uses the KCFI ABI specifically, and is
not strictly tied to a particular compiler. In preparation for GCC
supporting KCFI, rename CONFIG_CFI_CLANG to CONFIG_CFI (along with
associated options).
Use new "transitional" Kconfig option for old CONFIG_CFI_CLANG that will
enable CONFIG_CFI during olddefconfig.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20250923213422.1105654-3-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
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Keep the .modinfo section during linking, but strip it from the final
vmlinux.
Adjust scripts/mksysmap to exclude modinfo symbols from kallsyms.
This change will allow the next commit to extract the .modinfo section
from the vmlinux.unstripped intermediate.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/aaf67c07447215463300fccaa758904bac42f992.1758182101.git.legion@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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With `CONFIG_TRACE_MMIO_ACCESS=y`, the `{read,write}{b,w,l,q}{_relaxed}()`
mmio accessors unconditionally call `log_{post_}{read,write}_mmio()`
helpers, which in turn call the ftrace ops for `rwmmio` trace events
This adds a performance penalty per mmio accessor call, even when
`rwmmio` events are disabled at runtime (~80% overhead on local
measurement).
Guard these with `tracepoint_enabled()`.
Signed-off-by: Varad Gautam <varadgautam@google.com>
Fixes: 210031971cdd ("asm-generic/io: Add logging support for MMIO accessors")
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Common TIF bits do not have to be defined by every architecture. They can
be defined in a generic header.
That allows adding generic TIF bits without chasing a gazillion of
architecture headers, which is again a unjustified burden on anyone who
works on generic infrastructure as it always needs a boat load of work to
keep existing architecture code working when adding new stuff.
While it is not as horrible as the ignorance of the generic entry
infrastructure, it is a welcome mechanism to make architecture people
rethink their approach of just leaching generic improvements into
architecture code and thereby making it accumulatingly harder to maintain
and improve generic code. It's about time that this changes.
Provide the infrastructure and split the TIF space in half, 16 generic and
16 architecture specific bits.
This could probably be extended by TIF_SINGLESTEP and BLOCKSTEP, but those
are only used in architecture specific code. So leave them alone for now.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
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Pass in the memdesc_flags_t instead of a pointer to the page. This will
allow us to remove a few conversions to struct page in upcoming patches.
Link: https://lkml.kernel.org/r/20250805172307.1302730-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Detect booting as an "L1VH" partition. This is a new scenario very
similar to root partition where the mshv_root driver can be used to
create and manage guest partitions.
It mostly works the same as root partition, but there are some
differences in how various features are handled. hv_l1vh_partition()
is introduced to handle these cases. Add hv_parent_partition()
which returns true for either case, replacing some hv_root_partition()
checks.
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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While tracking down a problem where constant expressions used by
BUILD_BUG_ON() suddenly stopped working[1], we found that an added static
initializer was convincing the compiler that it couldn't track the state
of the prior statically initialized value. Tracing this down found that
ffs() was used in the initializer macro, but since it wasn't marked with
__attribute__const__, the compiler had to assume the function might
change variable states as a side-effect (which is not true for ffs(),
which provides deterministic math results).
Add missing __attribute_const__ annotations to generic implementations of
ffs(), __ffs(), fls(), and __fls() functions. These are pure mathematical
functions that always return the same result for the same input with no
side effects, making them eligible for compiler optimization.
Build tested with x86_64 defconfig using GCC 14.2.0, which should validate
the implementations when used by ARM, ARM64, LoongArch, Microblaze,
NIOS2, and SPARC32 architectures.
Link: https://github.com/KSPP/linux/issues/364 [1]
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250804164417.1612371-2-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
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All users of the generic vDSO library also use the generic vDSO datastore.
Remove the now unnecessary Kconfig symbol.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/all/20250826-vdso-cleanups-v1-9-d9b65750e49f@linutronix.de
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Resolve conflicts with this commit that was developed in parallel
during the merge window:
8c8efa93db68 ("x86/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust")
Conflicts:
arch/riscv/include/asm/bug.h
arch/x86/include/asm/bug.h
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Pull initial deferred unwind infrastructure from Steven Rostedt:
"This is the core infrastructure for the deferred unwinder that is
required for sframes[1]. Several other patch series are based on this
work although those patch series are not dependent on each other. In
order to simplify the development, having this core series upstream
will allow the other series to be worked on in parallel. The other
series are:
- The two patches to implement x86 support [2] [3]
- The s390 work [4]
- The perf work [5]
- The ftrace work [6]
- The sframe work [7]
And more is on the way.
The core infrastructure adds the following in kernel APIs:
- int unwind_user_faultable(struct unwind_stacktrace *trace);
Performs a user space stack trace that may fault user pages in.
- int unwind_deferred_init(struct unwind_work *work, unwind_callback_t func);
Allows a tracer to register with the unwind deferred
infrastructure.
- int unwind_deferred_request(struct unwind_work *work, u64 *cookie);
Used when a tracer request a deferred trace. Can be called from
interrupt or NMI context.
- void unwind_deferred_cancel(struct unwind_work *work);
Called by a tracer to unregister from the deferred unwind
infrastructure.
- void unwind_deferred_task_exit(struct task_struct *task);
Called by task exit code to flush any pending unwind requests.
- void unwind_task_init(struct task_struct *task);
Called by do_fork() to initialize the task struct for the
deferred unwinder.
- void unwind_task_free(struct task_struct *task);
Called by do_exit() to free up any resources used by the
deferred unwinder.
None of the above is actually compiled unless an architecture enables it,
which none currently do"
Link: https://sourceware.org/binutils/wiki/sframe [1]
Link: https://lore.kernel.org/linux-trace-kernel/20250717004958.260781923@kernel.org/ [2]
Link: https://lore.kernel.org/linux-trace-kernel/20250717004958.432327787@kernel.org/ [3]
Link: https://lore.kernel.org/linux-trace-kernel/20250710163522.3195293-1-jremus@linux.ibm.com/ [4]
Link: https://lore.kernel.org/linux-trace-kernel/20250718164119.089692174@kernel.org/ [5]
Link: https://lore.kernel.org/linux-trace-kernel/20250424192612.505622711@goodmis.org/ [6]
Link: https://lore.kernel.org/linux-trace-kernel/20250717012848.927473176@kernel.org/ [7]
* tag 'trace-deferred-unwind-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
unwind: Finish up unwind when a task exits
unwind deferred: Use SRCU unwind_deferred_task_work()
unwind: Add USED bit to only have one conditional on way back to user space
unwind deferred: Add unwind_completed mask to stop spurious callbacks
unwind deferred: Use bitmask to determine which callbacks to call
unwind_user/deferred: Make unwind deferral requests NMI-safe
unwind_user/deferred: Add deferred unwinding interface
unwind_user/deferred: Add unwind cache
unwind_user/deferred: Add unwind_user_faultable()
unwind_user: Add user space unwinding API with frame pointer support
|
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Pull MM updates from Andrew Morton:
"As usual, many cleanups. The below blurbiage describes 42 patchsets.
21 of those are partially or fully cleanup work. "cleans up",
"cleanup", "maintainability", "rationalizes", etc.
I never knew the MM code was so dirty.
"mm: ksm: prevent KSM from breaking merging of new VMAs" (Lorenzo Stoakes)
addresses an issue with KSM's PR_SET_MEMORY_MERGE mode: newly
mapped VMAs were not eligible for merging with existing adjacent
VMAs.
"mm/damon: introduce DAMON_STAT for simple and practical access monitoring" (SeongJae Park)
adds a new kernel module which simplifies the setup and usage of
DAMON in production environments.
"stop passing a writeback_control to swap/shmem writeout" (Christoph Hellwig)
is a cleanup to the writeback code which removes a couple of
pointers from struct writeback_control.
"drivers/base/node.c: optimization and cleanups" (Donet Tom)
contains largely uncorrelated cleanups to the NUMA node setup and
management code.
"mm: userfaultfd: assorted fixes and cleanups" (Tal Zussman)
does some maintenance work on the userfaultfd code.
"Readahead tweaks for larger folios" (Ryan Roberts)
implements some tuneups for pagecache readahead when it is reading
into order>0 folios.
"selftests/mm: Tweaks to the cow test" (Mark Brown)
provides some cleanups and consistency improvements to the
selftests code.
"Optimize mremap() for large folios" (Dev Jain)
does that. A 37% reduction in execution time was measured in a
memset+mremap+munmap microbenchmark.
"Remove zero_user()" (Matthew Wilcox)
expunges zero_user() in favor of the more modern memzero_page().
"mm/huge_memory: vmf_insert_folio_*() and vmf_insert_pfn_pud() fixes" (David Hildenbrand)
addresses some warts which David noticed in the huge page code.
These were not known to be causing any issues at this time.
"mm/damon: use alloc_migrate_target() for DAMOS_MIGRATE_{HOT,COLD" (SeongJae Park)
provides some cleanup and consolidation work in DAMON.
"use vm_flags_t consistently" (Lorenzo Stoakes)
uses vm_flags_t in places where we were inappropriately using other
types.
"mm/memfd: Reserve hugetlb folios before allocation" (Vivek Kasireddy)
increases the reliability of large page allocation in the memfd
code.
"mm: Remove pXX_devmap page table bit and pfn_t type" (Alistair Popple)
removes several now-unneeded PFN_* flags.
"mm/damon: decouple sysfs from core" (SeongJae Park)
implememnts some cleanup and maintainability work in the DAMON
sysfs layer.
"madvise cleanup" (Lorenzo Stoakes)
does quite a lot of cleanup/maintenance work in the madvise() code.
"madvise anon_name cleanups" (Vlastimil Babka)
provides additional cleanups on top or Lorenzo's effort.
"Implement numa node notifier" (Oscar Salvador)
creates a standalone notifier for NUMA node memory state changes.
Previously these were lumped under the more general memory
on/offline notifier.
"Make MIGRATE_ISOLATE a standalone bit" (Zi Yan)
cleans up the pageblock isolation code and fixes a potential issue
which doesn't seem to cause any problems in practice.
"selftests/damon: add python and drgn based DAMON sysfs functionality tests" (SeongJae Park)
adds additional drgn- and python-based DAMON selftests which are
more comprehensive than the existing selftest suite.
"Misc rework on hugetlb faulting path" (Oscar Salvador)
fixes a rather obscure deadlock in the hugetlb fault code and
follows that fix with a series of cleanups.
"cma: factor out allocation logic from __cma_declare_contiguous_nid" (Mike Rapoport)
rationalizes and cleans up the highmem-specific code in the CMA
allocator.
"mm/migration: rework movable_ops page migration (part 1)" (David Hildenbrand)
provides cleanups and future-preparedness to the migration code.
"mm/damon: add trace events for auto-tuned monitoring intervals and DAMOS quota" (SeongJae Park)
adds some tracepoints to some DAMON auto-tuning code.
"mm/damon: fix misc bugs in DAMON modules" (SeongJae Park)
does that.
"mm/damon: misc cleanups" (SeongJae Park)
also does what it claims.
"mm: folio_pte_batch() improvements" (David Hildenbrand)
cleans up the large folio PTE batching code.
"mm/damon/vaddr: Allow interleaving in migrate_{hot,cold} actions" (SeongJae Park)
facilitates dynamic alteration of DAMON's inter-node allocation
policy.
"Remove unmap_and_put_page()" (Vishal Moola)
provides a couple of page->folio conversions.
"mm: per-node proactive reclaim" (Davidlohr Bueso)
implements a per-node control of proactive reclaim - beyond the
current memcg-based implementation.
"mm/damon: remove damon_callback" (SeongJae Park)
replaces the damon_callback interface with a more general and
powerful damon_call()+damos_walk() interface.
"mm/mremap: permit mremap() move of multiple VMAs" (Lorenzo Stoakes)
implements a number of mremap cleanups (of course) in preparation
for adding new mremap() functionality: newly permit the remapping
of multiple VMAs when the user is specifying MREMAP_FIXED. It still
excludes some specialized situations where this cannot be performed
reliably.
"drop hugetlb_free_pgd_range()" (Anthony Yznaga)
switches some sparc hugetlb code over to the generic version and
removes the thus-unneeded hugetlb_free_pgd_range().
"mm/damon/sysfs: support periodic and automated stats update" (SeongJae Park)
augments the present userspace-requested update of DAMON sysfs
monitoring files. Automatic update is now provided, along with a
tunable to control the update interval.
"Some randome fixes and cleanups to swapfile" (Kemeng Shi)
does what is claims.
"mm: introduce snapshot_page" (Luiz Capitulino and David Hildenbrand)
provides (and uses) a means by which debug-style functions can grab
a copy of a pageframe and inspect it locklessly without tripping
over the races inherent in operating on the live pageframe
directly.
"use per-vma locks for /proc/pid/maps reads" (Suren Baghdasaryan)
addresses the large contention issues which can be triggered by
reads from that procfs file. Latencies are reduced by more than
half in some situations. The series also introduces several new
selftests for the /proc/pid/maps interface.
"__folio_split() clean up" (Zi Yan)
cleans up __folio_split()!
"Optimize mprotect() for large folios" (Dev Jain)
provides some quite large (>3x) speedups to mprotect() when dealing
with large folios.
"selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" and some cleanup" (wang lian)
does some cleanup work in the selftests code.
"tools/testing: expand mremap testing" (Lorenzo Stoakes)
extends the mremap() selftest in several ways, including adding
more checking of Lorenzo's recently added "permit mremap() move of
multiple VMAs" feature.
"selftests/damon/sysfs.py: test all parameters" (SeongJae Park)
extends the DAMON sysfs interface selftest so that it tests all
possible user-requested parameters. Rather than the present minimal
subset"
* tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (370 commits)
MAINTAINERS: add missing headers to mempory policy & migration section
MAINTAINERS: add missing file to cgroup section
MAINTAINERS: add MM MISC section, add missing files to MISC and CORE
MAINTAINERS: add missing zsmalloc file
MAINTAINERS: add missing files to page alloc section
MAINTAINERS: add missing shrinker files
MAINTAINERS: move memremap.[ch] to hotplug section
MAINTAINERS: add missing mm_slot.h file THP section
MAINTAINERS: add missing interval_tree.c to memory mapping section
MAINTAINERS: add missing percpu-internal.h file to per-cpu section
mm/page_alloc: remove trace_mm_alloc_contig_migrate_range_info()
selftests/damon: introduce _common.sh to host shared function
selftests/damon/sysfs.py: test runtime reduction of DAMON parameters
selftests/damon/sysfs.py: test non-default parameters runtime commit
selftests/damon/sysfs.py: generalize DAMON context commit assertion
selftests/damon/sysfs.py: generalize monitoring attributes commit assertion
selftests/damon/sysfs.py: generalize DAMOS schemes commit assertion
selftests/damon/sysfs.py: test DAMOS filters commitment
selftests/damon/sysfs.py: generalize DAMOS scheme commit assertion
selftests/damon/sysfs.py: test DAMOS destinations commitment
...
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Pull kvm updates from Paolo Bonzini:
"ARM:
- Host driver for GICv5, the next generation interrupt controller for
arm64, including support for interrupt routing, MSIs, interrupt
translation and wired interrupts
- Use FEAT_GCIE_LEGACY on GICv5 systems to virtualize GICv3 VMs on
GICv5 hardware, leveraging the legacy VGIC interface
- Userspace control of the 'nASSGIcap' GICv3 feature, allowing
userspace to disable support for SGIs w/o an active state on
hardware that previously advertised it unconditionally
- Map supporting endpoints with cacheable memory attributes on
systems with FEAT_S2FWB and DIC where KVM no longer needs to
perform cache maintenance on the address range
- Nested support for FEAT_RAS and FEAT_DoubleFault2, allowing the
guest hypervisor to inject external aborts into an L2 VM and take
traps of masked external aborts to the hypervisor
- Convert more system register sanitization to the config-driven
implementation
- Fixes to the visibility of EL2 registers, namely making VGICv3
system registers accessible through the VGIC device instead of the
ONE_REG vCPU ioctls
- Various cleanups and minor fixes
LoongArch:
- Add stat information for in-kernel irqchip
- Add tracepoints for CPUCFG and CSR emulation exits
- Enhance in-kernel irqchip emulation
- Various cleanups
RISC-V:
- Enable ring-based dirty memory tracking
- Improve perf kvm stat to report interrupt events
- Delegate illegal instruction trap to VS-mode
- MMU improvements related to upcoming nested virtualization
s390x
- Fixes
x86:
- Add CONFIG_KVM_IOAPIC for x86 to allow disabling support for I/O
APIC, PIC, and PIT emulation at compile time
- Share device posted IRQ code between SVM and VMX and harden it
against bugs and runtime errors
- Use vcpu_idx, not vcpu_id, for GA log tag/metadata, to make lookups
O(1) instead of O(n)
- For MMIO stale data mitigation, track whether or not a vCPU has
access to (host) MMIO based on whether the page tables have MMIO
pfns mapped; using VFIO is prone to false negatives
- Rework the MSR interception code so that the SVM and VMX APIs are
more or less identical
- Recalculate all MSR intercepts from scratch on MSR filter changes,
instead of maintaining shadow bitmaps
- Advertise support for LKGS (Load Kernel GS base), a new instruction
that's loosely related to FRED, but is supported and enumerated
independently
- Fix a user-triggerable WARN that syzkaller found by setting the
vCPU in INIT_RECEIVED state (aka wait-for-SIPI), and then putting
the vCPU into VMX Root Mode (post-VMXON). Trying to detect every
possible path leading to architecturally forbidden states is hard
and even risks breaking userspace (if it goes from valid to valid
state but passes through invalid states), so just wait until
KVM_RUN to detect that the vCPU state isn't allowed
- Add KVM_X86_DISABLE_EXITS_APERFMPERF to allow disabling
interception of APERF/MPERF reads, so that a "properly" configured
VM can access APERF/MPERF. This has many caveats (APERF/MPERF
cannot be zeroed on vCPU creation or saved/restored on suspend and
resume, or preserved over thread migration let alone VM migration)
but can be useful whenever you're interested in letting Linux
guests see the effective physical CPU frequency in /proc/cpuinfo
- Reject KVM_SET_TSC_KHZ for vm file descriptors if vCPUs have been
created, as there's no known use case for changing the default
frequency for other VM types and it goes counter to the very reason
why the ioctl was added to the vm file descriptor. And also, there
would be no way to make it work for confidential VMs with a
"secure" TSC, so kill two birds with one stone
- Dynamically allocation the shadow MMU's hashed page list, and defer
allocating the hashed list until it's actually needed (the TDP MMU
doesn't use the list)
- Extract many of KVM's helpers for accessing architectural local
APIC state to common x86 so that they can be shared by guest-side
code for Secure AVIC
- Various cleanups and fixes
x86 (Intel):
- Preserve the host's DEBUGCTL.FREEZE_IN_SMM when running the guest.
Failure to honor FREEZE_IN_SMM can leak host state into guests
- Explicitly check vmcs12.GUEST_DEBUGCTL on nested VM-Enter to
prevent L1 from running L2 with features that KVM doesn't support,
e.g. BTF
x86 (AMD):
- WARN and reject loading kvm-amd.ko instead of panicking the kernel
if the nested SVM MSRPM offsets tracker can't handle an MSR (which
is pretty much a static condition and therefore should never
happen, but still)
- Fix a variety of flaws and bugs in the AVIC device posted IRQ code
- Inhibit AVIC if a vCPU's ID is too big (relative to what hardware
supports) instead of rejecting vCPU creation
- Extend enable_ipiv module param support to SVM, by simply leaving
IsRunning clear in the vCPU's physical ID table entry
- Disable IPI virtualization, via enable_ipiv, if the CPU is affected
by erratum #1235, to allow (safely) enabling AVIC on such CPUs
- Request GA Log interrupts if and only if the target vCPU is
blocking, i.e. only if KVM needs a notification in order to wake
the vCPU
- Intercept SPEC_CTRL on AMD if the MSR shouldn't exist according to
the vCPU's CPUID model
- Accept any SNP policy that is accepted by the firmware with respect
to SMT and single-socket restrictions. An incompatible policy
doesn't put the kernel at risk in any way, so there's no reason for
KVM to care
- Drop a superfluous WBINVD (on all CPUs!) when destroying a VM and
use WBNOINVD instead of WBINVD when possible for SEV cache
maintenance
- When reclaiming memory from an SEV guest, only do cache flushes on
CPUs that have ever run a vCPU for the guest, i.e. don't flush the
caches for CPUs that can't possibly have cache lines with dirty,
encrypted data
Generic:
- Rework irqbypass to track/match producers and consumers via an
xarray instead of a linked list. Using a linked list leads to
O(n^2) insertion times, which is hugely problematic for use cases
that create large numbers of VMs. Such use cases typically don't
actually use irqbypass, but eliminating the pointless registration
is a future problem to solve as it likely requires new uAPI
- Track irqbypass's "token" as "struct eventfd_ctx *" instead of a
"void *", to avoid making a simple concept unnecessarily difficult
to understand
- Decouple device posted IRQs from VFIO device assignment, as binding
a VM to a VFIO group is not a requirement for enabling device
posted IRQs
- Clean up and document/comment the irqfd assignment code
- Disallow binding multiple irqfds to an eventfd with a priority
waiter, i.e. ensure an eventfd is bound to at most one irqfd
through the entire host, and add a selftest to verify eventfd:irqfd
bindings are globally unique
- Add a tracepoint for KVM_SET_MEMORY_ATTRIBUTES to help debug issues
related to private <=> shared memory conversions
- Drop guest_memfd's .getattr() implementation as the VFS layer will
call generic_fillattr() if inode_operations.getattr is NULL
- Fix issues with dirty ring harvesting where KVM doesn't bound the
processing of entries in any way, which allows userspace to keep
KVM in a tight loop indefinitely
- Kill off kvm_arch_{start,end}_assignment() and x86's associated
tracking, now that KVM no longer uses assigned_device_count as a
heuristic for either irqbypass usage or MDS mitigation
Selftests:
- Fix a comment typo
- Verify KVM is loaded when getting any KVM module param so that
attempting to run a selftest without kvm.ko loaded results in a
SKIP message about KVM not being loaded/enabled (versus some random
parameter not existing)
- Skip tests that hit EACCES when attempting to access a file, and
print a "Root required?" help message. In most cases, the test just
needs to be run with elevated permissions"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (340 commits)
Documentation: KVM: Use unordered list for pre-init VGIC registers
RISC-V: KVM: Avoid re-acquiring memslot in kvm_riscv_gstage_map()
RISC-V: KVM: Use find_vma_intersection() to search for intersecting VMAs
RISC-V: perf/kvm: Add reporting of interrupt events
RISC-V: KVM: Enable ring-based dirty memory tracking
RISC-V: KVM: Fix inclusion of Smnpm in the guest ISA bitmap
RISC-V: KVM: Delegate illegal instruction fault to VS mode
RISC-V: KVM: Pass VMID as parameter to kvm_riscv_hfence_xyz() APIs
RISC-V: KVM: Factor-out g-stage page table management
RISC-V: KVM: Add vmid field to struct kvm_riscv_hfence
RISC-V: KVM: Introduce struct kvm_gstage_mapping
RISC-V: KVM: Factor-out MMU related declarations into separate headers
RISC-V: KVM: Use ncsr_xyz() in kvm_riscv_vcpu_trap_redirect()
RISC-V: KVM: Implement kvm_arch_flush_remote_tlbs_range()
RISC-V: KVM: Don't flush TLB when PTE is unchanged
RISC-V: KVM: Replace KVM_REQ_HFENCE_GVMA_VMID_ALL with KVM_REQ_TLB_FLUSH
RISC-V: KVM: Rename and move kvm_riscv_local_tlb_sanitize()
RISC-V: KVM: Drop the return value of kvm_riscv_vcpu_aia_init()
RISC-V: KVM: Check kvm_riscv_vcpu_alloc_vector_context() return value
KVM: arm64: selftests: Add FEAT_RAS EL2 registers to get-reg-list
...
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Pull ftrace updates from Steven Rostedt:
- Keep track of when fgraph_ops are registered or not
Keep accounting of when fgraph_ops are registered as if a fgraph_ops
is registered twice it can mess up the accounting and it will not
work as expected later. Trigger a warning if something registers it
twice as to catch bugs before they are found by things just not
working as expected.
- Make DYNAMIC_FTRACE always enabled for architectures that support it
As static ftrace (where all functions are always traced) is very
expensive and only exists to help architectures support ftrace, do
not make it an option. As soon as an architecture supports
DYNAMIC_FTRACE make it use it. This simplifies the code.
- Remove redundant config HAVE_FTRACE_MCOUNT_RECORD
The CONFIG_HAVE_FTRACE_MCOUNT was added to help simplify the
DYNAMIC_FTRACE work, but now every architecture that implements
DYNAMIC_FTRACE also has HAVE_FTRACE_MCOUNT set too, making it
redundant with the HAVE_DYNAMIC_FTRACE.
- Make pid_ptr string size match the comment
In print_graph_proc() the pid_ptr string is of size 11, but the
comment says /* sign + log10(MAX_INT) + '\0' */ which is actually 12.
* tag 'ftrace-v6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: Remove redundant config HAVE_FTRACE_MCOUNT_RECORD
ftrace: Make DYNAMIC_FTRACE always enabled for architectures that support it
fgraph: Keep track of when fgraph_ops are registered or not
fgraph: Make pid_str size match the comment
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Pull timekeeping and VDSO updates from Thomas Gleixner:
- Introduce support for auxiliary timekeepers
PTP clocks can be disconnected from the universal CLOCK_TAI reality
for various reasons including regularatory requirements for
functional safety redundancy.
The kernel so far only supports a single notion of time, which means
that all clocks are correlated in frequency and only differ by offset
to each other.
Access to non-correlated PTP clocks has been available so far only
through the file descriptor based "POSIX clock IDs", which are
subject to locking and have to go all the way out to the hardware.
The access is not only horribly slow, as it has to go all the way out
to the NIC/PTP hardware, but that also prevents the kernel to read
the time of such clocks e.g. from the network stack, where it is
required for TSN networking both on the transmit and receive side
unless the hardware provides offloading.
The auxiliary clocks provide a mechanism to support arbitrary clocks
which are not correlated to the system clock. This is not restricted
to the PTP use case on purpose as there is no kernel side association
of these clocks to a particular PTP device because that's a pure user
space configuration decision. Having them independent allows to
utilize them for other purposes and also enables them to be tested
without hardware dependencies.
To avoid pointless overhead these clocks have to be enabled
individualy via a new sysfs interface to reduce the overhead to a
single compare in the hotpath if they are enabled at the Kconfig
level at all.
These clocks utilize the existing timekeeping/NTP infrastructures,
which has been made possible over the recent releases by incrementaly
converting these infrastructures over from a single static instance
to a multi-instance pointer based implementation without any
performance regression reported.
The auxiliary clocks provide the same "emulation" of a "correct"
clock as the existing CLOCK_* variants do with an independent
instance of data and provide the same steering mechanism through the
existing sys_clock_adjtime() interface, which has been confirmed to
work by the chronyd(8) maintainer.
That allows to provide lockless kernel internal and VDSO support so
that applications and kernel internal functionalities can access
these clocks without restrictions and at the same performance as the
existing system clocks.
- Avoid double notifications in the adjtimex() syscall. Not a big
issue, but a trivial to avoid latency source.
* tag 'timers-ptp-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
vdso/gettimeofday: Add support for auxiliary clocks
vdso/vsyscall: Update auxiliary clock data in the datapage
vdso: Introduce aux_clock_resolution_ns()
vdso/gettimeofday: Introduce vdso_get_timestamp()
vdso/gettimeofday: Introduce vdso_set_timespec()
vdso/gettimeofday: Introduce vdso_clockid_valid()
vdso/gettimeofday: Return bool from clock_gettime() helpers
vdso/gettimeofday: Return bool from clock_getres() helpers
vdso/helpers: Add helpers for seqlocks of single vdso_clock
vdso/vsyscall: Split up __arch_update_vsyscall() into __arch_update_vdso_clock()
vdso/vsyscall: Introduce a helper to fill clock configurations
timekeeping: Remove the temporary CLOCK_AUX workaround
timekeeping: Provide ktime_get_clock_ts64()
timekeeping: Provide interface to control auxiliary clocks
timekeeping: Provide update for auxiliary timekeepers
timekeeping: Provide adjtimex() for auxiliary clocks
timekeeping: Prepare do_adtimex() for auxiliary clocks
timekeeping: Make do_adjtimex() reusable
timekeeping: Add auxiliary clock support to __timekeeping_inject_offset()
timekeeping: Make timekeeping_inject_offset() reusable
...
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Introduce a generic API for unwinding user stacks.
In order to expand user space unwinding to be able to handle more complex
scenarios, such as deferred unwinding and reading user space information,
create a generic interface that all architectures can use that support the
various unwinding methods.
This is an alternative method for handling user space stack traces from
the simple stack_trace_save_user() API. This does not replace that
interface, but this interface will be used to expand the functionality of
user space stack walking.
None of the structures introduced will be exposed to user space tooling.
Support for frame pointer unwinding is added. For an architecture to
support frame pointer unwinding it needs to enable
CONFIG_HAVE_UNWIND_USER_FP and define ARCH_INIT_USER_FP_FRAME.
By encoding the frame offsets in struct unwind_user_frame, much of this
code can also be reused for future unwinder implementations like sframe.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Indu Bhagat <indu.bhagat@oracle.com>
Cc: "Jose E. Marchesi" <jemarch@gnu.org>
Cc: Beau Belgrave <beaub@linux.microsoft.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Sam James <sam@gentoo.org>
Link: https://lore.kernel.org/20250729182404.975790139@kernel.org
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Co-developed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/all/20250710164301.3094-2-mathieu.desnoyers@efficios.com/
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Co-developed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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There are no longer any callers of hugetlb_free_pgd_range().
Link: https://lkml.kernel.org/r/20250716012611.10369-4-anthony.yznaga@oracle.com
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Ftrace is tightly coupled with architecture specific code because it
requires the use of trampolines written in assembly. This means that when
a new feature or optimization is made, it must be done for all
architectures. To simplify the approach, CONFIG_HAVE_FTRACE_* configs are
added to denote which architecture has the new enhancement so that other
architectures can still function until they too have been updated.
The CONFIG_HAVE_FTRACE_MCOUNT was added to help simplify the
DYNAMIC_FTRACE work, but now every architecture that implements
DYNAMIC_FTRACE also has HAVE_FTRACE_MCOUNT set too, making it redundant
with the HAVE_DYNAMIC_FTRACE.
Remove the HAVE_FTRACE_MCOUNT config and use DYNAMIC_FTRACE directly where
applicable.
Link: https://lore.kernel.org/all/20250703154916.48e3ada7@gandalf.local.home/
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/20250704104838.27a18690@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
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Only mips and loongarch implemented this API, however what it does was
checking against stack overflow for either len or addr. That's already
done in arch's arch_get_unmapped_area*() functions, even though it may not
be 100% identical checks.
For example, for both of the architectures, there will be a trivial
difference on how stack top was defined. The old code uses STACK_TOP
which may be slightly smaller than TASK_SIZE on either of them, but the
hope is that shouldn't be a problem.
It means the whole API is pretty much obsolete at least now, remove it
completely.
Link: https://lkml.kernel.org/r/20250627160707.2124580-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Jann Horn <jannh@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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With CONFIG_MEM_ALLOC_PROFILING=n, vmlinux and all modules unnecessarily
contain the symbols __start_alloc_tags and __stop_alloc_tags, which define
an empty range. In the case of modules, the presence of these symbols
also forces the linker to create an empty .codetag.alloc_tags section.
Update codetag.lds.h to make the data conditional on
CONFIG_MEM_ALLOC_PROFILING.
Link: https://lkml.kernel.org/r/20250618125037.53182-1-petr.pavlu@suse.com
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Reviewed-by: Kent Overstreet <kent.overstreet@linux.dev>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Casey Chen <cachen@purestorage.com>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The empty MOD_CODETAG_SECTIONS() macro added an incomplete .data section
in module linker script, which caused symbol lookup tools like gdb to
misinterpret symbol addresses e.g., __ib_process_cq incorrectly mapping to
unrelated functions like below.
(gdb) disas __ib_process_cq
Dump of assembler code for function trace_event_fields_cq_schedule:
Removing the empty section restores proper symbol resolution and layout,
ensuring .data placement behaves as expected.
Link: https://lkml.kernel.org/r/20250610162258.324645-1-cachen@purestorage.com
Fixes: 0db6f8d7820a ("alloc_tag: load module tags into separate contiguous memory")
22d407b164ff ("lib: add allocation tagging support for memory allocation profiling")
Signed-off-by: Casey Chen <cachen@purestorage.com>
Reviewed-by: Yuanyuan Zhong <yzhong@purestorage.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Linus Torvalds
Peter Zijlstra
Josh Poimboeuf
Ingo Molnar
Mateusz Guzik
Thomas Gleixner
Dimitri John Ledkov
Mukesh Rathor
Qi Xi
Kees Cook
Masahiro Yamada
Varad Gautam
Matthew Wilcox (Oracle)
Nuno Das Neves
Thomas Weißschuh
Anthony Yznaga
Steven Rostedt
Peter Xu
Petr Pavlu
Casey Chen