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Users of GNU ld (BFD) from binutils 2.39+ will observe multiple
instances of a new warning when linking kernels in the form:
ld: warning: vmlinux: missing .note.GNU-stack section implies executable stack
ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
ld: warning: vmlinux has a LOAD segment with RWX permissions
Generally, we would like to avoid the stack being executable. Because
there could be a need for the stack to be executable, assembler sources
have to opt-in to this security feature via explicit creation of the
.note.GNU-stack feature (which compilers create by default) or command
line flag --noexecstack. Or we can simply tell the linker the
production of such sections is irrelevant and to link the stack as
--noexecstack.
LLVM's LLD linker defaults to -z noexecstack, so this flag isn't
strictly necessary when linking with LLD, only BFD, but it doesn't hurt
to be explicit here for all linkers IMO. --no-warn-rwx-segments is
currently BFD specific and only available in the current latest release,
so it's wrapped in an ld-option check.
While the kernel makes extensive usage of ELF sections, it doesn't use
permissions from ELF segments.
Link: https://lore.kernel.org/linux-block/3af4127a-f453-4cf7-f133-a181cce06f73@kernel.dk/
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107
Link: https://github.com/llvm/llvm-project/issues/57009
Reported-and-tested-by: Jens Axboe <axboe@kernel.dk>
Suggested-by: Fangrui Song <maskray@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Pull Kbuild updates from Masahiro Yamada:
- Remove the support for -O3 (CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3)
- Fix error of rpm-pkg cross-builds
- Support riscv for checkstack tool
- Re-enable -Wformwat warnings for Clang
- Clean up modpost, Makefiles, and misc scripts
* tag 'kbuild-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
modpost: remove .symbol_white_list field entirely
modpost: remove unneeded .symbol_white_list initializers
modpost: add PATTERNS() helper macro
modpost: shorten warning messages in report_sec_mismatch()
Revert "Kbuild, lto, workaround: Don't warn for initcall_reference in modpost"
modpost: use more reliable way to get fromsec in section_rel(a)()
modpost: add array range check to sec_name()
modpost: refactor get_secindex()
kbuild: set EXIT trap before creating temporary directory
modpost: remove unused Elf_Sword macro
Makefile.extrawarn: re-enable -Wformat for clang
kbuild: add dtbs_prepare target
kconfig: Qt5: tell the user which packages are required
modpost: use sym_get_data() to get module device_table data
modpost: drop executable ELF support
checkstack: add riscv support for scripts/checkstack.pl
kconfig: shorten the temporary directory name for cc-option
scripts: headers_install.sh: Update config leak ignore entries
kbuild: error out if $(INSTALL_MOD_PATH) contains % or :
kbuild: error out if $(KBUILD_EXTMOD) contains % or :
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Pull Kselftest updates from Shuah Khan:
- timers test build fixes and cleanups for new tool chains
- removing khdr from kselftest framework and main Makefile
- changes to test output messages to improve reports
* tag 'linux-kselftest-next-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (24 commits)
Makefile: replace headers_install with headers for kselftest
selftests/landlock: drop deprecated headers dependency
selftests: timers: clocksource-switch: adapt to kselftest framework
selftests: timers: clocksource-switch: add 'runtime' command line parameter
selftests: timers: clocksource-switch: add command line switch to skip sanity check
selftests: timers: clocksource-switch: sort includes
selftests: timers: clocksource-switch: fix passing errors from child
selftests: timers: inconsistency-check: adapt to kselftest framework
selftests: timers: nanosleep: adapt to kselftest framework
selftests: timers: fix declarations of main()
selftests: timers: valid-adjtimex: build fix for newer toolchains
Makefile: add headers_install to kselftest targets
selftests: drop KSFT_KHDR_INSTALL make target
selftests: stop using KSFT_KHDR_INSTALL
selftests: drop khdr make target
selftests: drivers/dma-buf: Improve message in selftest summary
selftests/kcmp: Make the test output consistent and clear
selftests:timers: globals don't need initialization to 0
selftests/drivers/gpu: Add error messages to drm_mm.sh
selftests/tpm2: increase timeout for kselftests
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Pull io_uring updates from Jens Axboe:
- As per (valid) complaint in the last merge window, fs/io_uring.c has
grown quite large these days. io_uring isn't really tied to fs
either, as it supports a wide variety of functionality outside of
that.
Move the code to io_uring/ and split it into files that either
implement a specific request type, and split some code into helpers
as well. The code is organized a lot better like this, and io_uring.c
is now < 4K LOC (me).
- Deprecate the epoll_ctl opcode. It'll still work, just trigger a
warning once if used. If we don't get any complaints on this, and I
don't expect any, then we can fully remove it in a future release
(me).
- Improve the cancel hash locking (Hao)
- kbuf cleanups (Hao)
- Efficiency improvements to the task_work handling (Dylan, Pavel)
- Provided buffer improvements (Dylan)
- Add support for recv/recvmsg multishot support. This is similar to
the accept (or poll) support for have for multishot, where a single
SQE can trigger everytime data is received. For applications that
expect to do more than a few receives on an instantiated socket, this
greatly improves efficiency (Dylan).
- Efficiency improvements for poll handling (Pavel)
- Poll cancelation improvements (Pavel)
- Allow specifiying a range for direct descriptor allocations (Pavel)
- Cleanup the cqe32 handling (Pavel)
- Move io_uring types to greatly cleanup the tracing (Pavel)
- Tons of great code cleanups and improvements (Pavel)
- Add a way to do sync cancelations rather than through the sqe -> cqe
interface, as that's a lot easier to use for some use cases (me).
- Add support to IORING_OP_MSG_RING for sending direct descriptors to a
different ring. This avoids the usually problematic SCM case, as we
disallow those. (me)
- Make the per-command alloc cache we use for apoll generic, place
limits on it, and use it for netmsg as well (me).
- Various cleanups (me, Michal, Gustavo, Uros)
* tag 'for-5.20/io_uring-2022-07-29' of git://git.kernel.dk/linux-block: (172 commits)
io_uring: ensure REQ_F_ISREG is set async offload
net: fix compat pointer in get_compat_msghdr()
io_uring: Don't require reinitable percpu_ref
io_uring: fix types in io_recvmsg_multishot_overflow
io_uring: Use atomic_long_try_cmpxchg in __io_account_mem
io_uring: support multishot in recvmsg
net: copy from user before calling __get_compat_msghdr
net: copy from user before calling __copy_msghdr
io_uring: support 0 length iov in buffer select in compat
io_uring: fix multishot ending when not polled
io_uring: add netmsg cache
io_uring: impose max limit on apoll cache
io_uring: add abstraction around apoll cache
io_uring: move apoll cache to poll.c
io_uring: consolidate hash_locked io-wq handling
io_uring: clear REQ_F_HASH_LOCKED on hash removal
io_uring: don't race double poll setting REQ_F_ASYNC_DATA
io_uring: don't miss setting REQ_F_DOUBLE_POLL
io_uring: disable multishot recvmsg
io_uring: only trace one of complete or overflow
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Factor out the common prerequisites for DT compilation into the new
target, dtbs_prepare.
Add comments to explain why include/config/kernel.release is the
prerequisite. Our policy is that installation targets must not rebuild
anything in the tree. If 'make modules_install' is executed as root,
include/config/kernel.release may be owned by root.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
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If the directory path given to KBUILD_EXTMOD (or M=) contains % or :,
the module fails to build.
% is used in pattern rules, and : as the separator of dependencies.
Bail out with a clearer error message.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
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The difference in most compilers between `-O3` and `-O2` is mostly down
to whether loops with statically determinable trip counts are fully
unrolled vs unrolled to a multiple of SIMD width.
This patch is effectively a revert of
commit 15f5db60a137 ("kbuild,arc: add
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC") without re-adding
ARCH_CFLAGS
Ever since
commit cfdbc2e16e65 ("ARC: Build system: Makefiles, Kconfig, Linker
script")
ARC has been built with -O3, though the reason for doing so was not
specified in inline comments or the commit message. This commit does not
re-add -O3 to arch/arc/Makefile.
Folks looking to experiment with `-O3` (or any compiler flag for that
matter) may pass them along to the command line invocation of make:
$ make KCFLAGS=-O3
Code that looks to re-add an explicit Kconfig option for `-O3` should
provide:
1. A rigorous and reproducible performance profile of a reasonable
userspace workload that demonstrates a hot loop in the kernel that
would benefit from `-O3` over `-O2`.
2. Disassembly of said loop body before and after.
3. Provides stats on terms of increase in file size.
Link: https://lore.kernel.org/linux-kbuild/CA+55aFz2sNBbZyg-_i8_Ldr2e8o9dfvdSfHHuRzVtP2VMAUWPg@mail.gmail.com/
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Replace headers_install with headers as kselftest uses the header
files from within the kernel tree rather than from a system-wide
installation.
We can still run this directly:
$ make O=build kselftest-all
and when building from the selftests directory:
$ make O=build headers
$ make O=build -C tools/testing/selftests all
Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Reported-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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In preparation for splitting io_uring up a bit, move it into its own
top level directory. It didn't really belong in fs/ anyway, as it's
not a file system only API.
This adds io_uring/ and moves the core files in there, and updates the
MAINTAINERS file for the new location.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add headers_install as a dependency to kselftest targets so that they
can be run directly from the top of the tree. The kselftest Makefile
used to try to call headers_install "backwards" but failed due to the
relative path not being consistent.
Now we can either run this directly:
$ make O=build kselftest-all
or this:
$ make O=build headers_install
$ make O=build -C tools/testing/selftest all
The same commands work as well when building directly in the source
tree (no O=) or any arbitrary path (relative or absolute).
Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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If CONFIG_TRIM_UNUSED_KSYMS is enabled and the kernel is built from
a pristine state, the vmlinux is linked twice.
Commit 3fdc7d3fe4c0 ("kbuild: link vmlinux only once for
CONFIG_TRIM_UNUSED_KSYMS") explains why this happens, but it did not fix
the issue at all.
Now I realized I had applied a wrong patch.
In v1 patch [1], the autoksyms_recursive target correctly recurses to
"$(MAKE) -f $(srctree)/Makefile autoksyms_recursive".
In v2 patch [2], I accidentally dropped the diff line, and it recurses to
"$(MAKE) -f $(srctree)/Makefile vmlinux".
Restore the code I intended in v1.
[1]: https://lore.kernel.org/linux-kbuild/1521045861-22418-8-git-send-email-yamada.masahiro@socionext.com/
[2]: https://lore.kernel.org/linux-kbuild/1521166725-24157-8-git-send-email-yamada.masahiro@socionext.com/
Fixes: 3fdc7d3fe4c0 ("kbuild: link vmlinux only once for CONFIG_TRIM_UNUSED_KSYMS")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
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In commit 8b202ee21839 ("s390: disable -Warray-bounds") the s390 people
disabled the '-Warray-bounds' warning for gcc-12, because the new logic
in gcc would cause warnings for their use of the S390_lowcore macro,
which accesses absolute pointers.
It turns out gcc-12 has many other issues in this area, so this takes
that s390 warning disable logic, and turns it into a kernel build config
entry instead.
Part of the intent is that we can make this all much more targeted, and
use this conflig flag to disable it in only particular configurations
that cause problems, with the s390 case as an example:
select GCC12_NO_ARRAY_BOUNDS
and we could do that for other configuration cases that cause issues.
Or we could possibly use the CONFIG_CC_NO_ARRAY_BOUNDS thing in a more
targeted way, and disable the warning only for particular uses: again
the s390 case as an example:
KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_NO_ARRAY_BOUNDS),-Wno-array-bounds)
but this ends up just doing it globally in the top-level Makefile, since
the current issues are spread fairly widely all over:
KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
We'll try to limit this later, since the gcc-12 problems are rare enough
that *much* of the kernel can be built with it without disabling this
warning.
Cc: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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While the concept of checking for dangling pointers to local variables
at function exit is really interesting, the gcc-12 implementation is not
compatible with reality, and results in false positives.
For example, gcc sees us putting things on a local list head allocated
on the stack, which involves exactly those kinds of pointers to the
local stack entry:
In function ‘__list_add’,
inlined from ‘list_add_tail’ at include/linux/list.h:102:2,
inlined from ‘rebuild_snap_realms’ at fs/ceph/snap.c:434:2:
include/linux/list.h:74:19: warning: storing the address of local variable ‘realm_queue’ in ‘*&realm_27(D)->rebuild_item.prev’ [-Wdangling-pointer=]
74 | new->prev = prev;
| ~~~~~~~~~~^~~~~~
But then gcc - understandably - doesn't really understand the big
picture how the doubly linked list works, so doesn't see how we then end
up emptying said list head in a loop and the pointer we added has been
removed.
Gcc also complains about us (intentionally) using this as a way to store
a kind of fake stack trace, eg
drivers/acpi/acpica/utdebug.c:40:38: warning: storing the address of local variable ‘current_sp’ in ‘acpi_gbl_entry_stack_pointer’ [-Wdangling-pointer=]
40 | acpi_gbl_entry_stack_pointer = ¤t_sp;
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
which is entirely reasonable from a compiler standpoint, and we may want
to change those kinds of patterns, but not not.
So this is one of those "it would be lovely if the compiler were to
complain about us leaving dangling pointers to the stack", but not this
way.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Change the "make clean" rule to remove all the .tmp_* files.
.tmp_objdiff is the only exception, which should be removed by
"make mrproper".
Rename the record directory of objdiff, .tmp_objdiff to .objdiff to
avoid the removal by "make clean".
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
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Pull Kbuild updates from Masahiro Yamada:
- Add HOSTPKG_CONFIG env variable to allow users to override pkg-config
- Support W=e as a shorthand for KCFLAGS=-Werror
- Fix CONFIG_IKHEADERS build to support toybox cpio
- Add scripts/dummy-tools/pahole to ease distro packagers' life
- Suppress false-positive warnings from checksyscalls.sh for W=2 build
- Factor out the common code of arch/*/boot/install.sh into
scripts/install.sh
- Support 'kernel-install' tool in scripts/prune-kernel
- Refactor module-versioning to link the symbol versions at the final
link of vmlinux and modules
- Remove CONFIG_MODULE_REL_CRCS because module-versioning now works in
an arch-agnostic way
- Refactor modpost, Makefiles
* tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (56 commits)
genksyms: adjust the output format to modpost
kbuild: stop merging *.symversions
kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS
modpost: extract symbol versions from *.cmd files
modpost: add sym_find_with_module() helper
modpost: change the license of EXPORT_SYMBOL to bool type
modpost: remove left-over cross_compile declaration
kbuild: record symbol versions in *.cmd files
kbuild: generate a list of objects in vmlinux
modpost: move *.mod.c generation to write_mod_c_files()
modpost: merge add_{intree_flag,retpoline,staging_flag} to add_header
scripts/prune-kernel: Use kernel-install if available
kbuild: factor out the common installation code into scripts/install.sh
modpost: split new_symbol() to symbol allocation and hash table addition
modpost: make sym_add_exported() always allocate a new symbol
modpost: make multiple export error
modpost: dump Module.symvers in the same order of modules.order
modpost: traverse the namespace_list in order
modpost: use doubly linked list for dump_lists
modpost: traverse unresolved symbols in order
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Pull kernel hardening updates from Kees Cook:
- usercopy hardening expanded to check other allocation types (Matthew
Wilcox, Yuanzheng Song)
- arm64 stackleak behavioral improvements (Mark Rutland)
- arm64 CFI code gen improvement (Sami Tolvanen)
- LoadPin LSM block dev API adjustment (Christoph Hellwig)
- Clang randstruct support (Bill Wendling, Kees Cook)
* tag 'kernel-hardening-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (34 commits)
loadpin: stop using bdevname
mm: usercopy: move the virt_addr_valid() below the is_vmalloc_addr()
gcc-plugins: randstruct: Remove cast exception handling
af_unix: Silence randstruct GCC plugin warning
niu: Silence randstruct warnings
big_keys: Use struct for internal payload
gcc-plugins: Change all version strings match kernel
randomize_kstack: Improve docs on requirements/rationale
lkdtm/stackleak: fix CONFIG_GCC_PLUGIN_STACKLEAK=n
arm64: entry: use stackleak_erase_on_task_stack()
stackleak: add on/off stack variants
lkdtm/stackleak: check stack boundaries
lkdtm/stackleak: prevent unexpected stack usage
lkdtm/stackleak: rework boundary management
lkdtm/stackleak: avoid spurious failure
stackleak: rework poison scanning
stackleak: rework stack high bound handling
stackleak: clarify variable names
stackleak: rework stack low bound handling
stackleak: remove redundant check
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Pull objtool updates from Ingo Molnar:
- Comprehensive interface overhaul:
=================================
Objtool's interface has some issues:
- Several features are done unconditionally, without any way to
turn them off. Some of them might be surprising. This makes
objtool tricky to use, and prevents porting individual features
to other arches.
- The config dependencies are too coarse-grained. Objtool
enablement is tied to CONFIG_STACK_VALIDATION, but it has several
other features independent of that.
- The objtool subcmds ("check" and "orc") are clumsy: "check" is
really a subset of "orc", so it has all the same options.
The subcmd model has never really worked for objtool, as it only
has a single purpose: "do some combination of things on an object
file".
- The '--lto' and '--vmlinux' options are nonsensical and have
surprising behavior.
Overhaul the interface:
- get rid of subcmds
- make all features individually selectable
- remove and/or clarify confusing/obsolete options
- update the documentation
- fix some bugs found along the way
- Fix x32 regression
- Fix Kbuild cleanup bugs
- Add scripts/objdump-func helper script to disassemble a single
function from an object file.
- Rewrite scripts/faddr2line to be section-aware, by basing it on
'readelf', moving it away from 'nm', which doesn't handle multiple
sections well, which can result in decoding failure.
- Rewrite & fix symbol handling - which had a number of bugs wrt.
object files that don't have global symbols - which is rare but
possible. Also fix a bunch of symbol handling bugs found along the
way.
* tag 'objtool-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
objtool: Fix objtool regression on x32 systems
objtool: Fix symbol creation
scripts/faddr2line: Fix overlapping text section failures
scripts: Create objdump-func helper script
objtool: Remove libsubcmd.a when make clean
objtool: Remove inat-tables.c when make clean
objtool: Update documentation
objtool: Remove --lto and --vmlinux in favor of --link
objtool: Add HAVE_NOINSTR_VALIDATION
objtool: Rename "VMLINUX_VALIDATION" -> "NOINSTR_VALIDATION"
objtool: Make noinstr hacks optional
objtool: Make jump label hack optional
objtool: Make static call annotation optional
objtool: Make stack validation frame-pointer-specific
objtool: Add CONFIG_OBJTOOL
objtool: Extricate sls from stack validation
objtool: Rework ibt and extricate from stack validation
objtool: Make stack validation optional
objtool: Add option to print section addresses
objtool: Don't print parentheses in function addresses
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Many architectures have similar install.sh scripts.
The first half is really generic; it verifies that the kernel image
and System.map exist, then executes ~/bin/${INSTALLKERNEL} or
/sbin/${INSTALLKERNEL} if available.
The second half is kind of arch-specific; it copies the kernel image
and System.map to the destination, but the code is slightly different.
Factor out the generic part into scripts/install.sh.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
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To enable the new Clang randstruct implementation[1], move
randstruct into its own Makefile and split the CFLAGS from
GCC_PLUGINS_CFLAGS into RANDSTRUCT_CFLAGS.
[1] https://reviews.llvm.org/D121556
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220503205503.3054173-5-keescook@chromium.org
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Fix typos in comments so that they make sense.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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When developing new code/feature, CONFIG_WERROR is most
often turned off, especially for people using make W=12 to
get more warnings.
In such case, turning on -Werror temporarily would require
switching on CONFIG_WERROR in the configuration, building,
then switching off CONFIG_WERROR.
For this use case, this patch introduces a new 'e' modifier
to W= as a short hand for KCFLAGS+=-Werror" so that -Werror
got added to the kernel (built-in) and modules' CFLAGS.
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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The dependency
$(obj)/%.mod: $(obj)/%$(mod-prelink-ext).o
... exists because *.mod files previously contained undefined symbols,
which are computed from *.o files when CONFIG_TRIM_UNUSED_KSYMS=y.
Now that the undefined symbols are put into separate *.usyms files,
there is no reason to make *.mod depend on *.o files.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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The *.mod files have two lines; the first line lists the member objects
of the module, and the second line, if CONFIG_TRIM_UNUSED_KSYMS=y, lists
the undefined symbols.
Currently, we generate *.mod after constructing composite modules,
otherwise, we cannot compute the second line. No prerequisite is
required to print the first line.
They are orthogonal. Splitting them into separate commands will ease
further cleanups.
This commit splits the list of undefined symbols out to *.usyms files.
Previously, the list of undefined symbols ended up with a very long
line, but now it has one symbol per line.
Use sed like we did before commit 7d32358be8ac ("kbuild: avoid split
lines in .mod files").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
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Now that stack validation is an optional feature of objtool, add
CONFIG_OBJTOOL and replace most usages of CONFIG_STACK_VALIDATION with
it.
CONFIG_STACK_VALIDATION can now be considered to be frame-pointer
specific. CONFIG_UNWINDER_ORC is already inherently valid for live
patching, so no need to "validate" it.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/939bf3d85604b2a126412bf11af6e3bd3b872bcb.1650300597.git.jpoimboe@redhat.com
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Add HOSTPKG_CONFIG to allow tooling that builds the kernel to override
what pkg-config and parameters are used.
Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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This flag is specific to clang, where it is only used by the 32-bit and
64-bit ARM backends. In certain situations, the presence of this flag
will cause a warning, as shown by commit 6580c5c18fb3 ("um: clang: Strip
out -mno-global-merge from USER_CFLAGS").
Since commit 61163efae020 ("kbuild: LLVMLinux: Add Kbuild support for
building kernel with Clang") that added this flag back in 2014, there
have been quite a few changes to the GlobalMerge pass in LLVM. Building
several different ARCH=arm and ARCH=arm64 configurations with LLVM 11
(minimum) and 15 (current main version) with this flag removed (i.e.,
with the default of '-mglobal-merge') reveals no modpost warnings, so it
is likely that the issue noted in the comment is no longer relevant due
to changes in LLVM or modpost, meaning this flag can be removed.
If any new warnings show up that are a result of the removal of this
flag, it can be added back under arch/arm{,64}/Makefile to avoid
warnings on other architectures.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: David Gow <davidgow@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Pull Kbuild updates from Masahiro Yamada:
- Add new environment variables, USERCFLAGS and USERLDFLAGS to allow
additional flags to be passed to user-space programs.
- Fix missing fflush() bugs in Kconfig and fixdep
- Fix a minor bug in the comment format of the .config file
- Make kallsyms ignore llvm's local labels, .L*
- Fix UAPI compile-test for cross-compiling with Clang
- Extend the LLVM= syntax to support LLVM=<suffix> form for using a
particular version of LLVm, and LLVM=<prefix> form for using custom
LLVM in a particular directory path.
- Clean up Makefiles
* tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: Make $(LLVM) more flexible
kbuild: add --target to correctly cross-compile UAPI headers with Clang
fixdep: use fflush() and ferror() to ensure successful write to files
arch: syscalls: simplify uapi/kapi directory creation
usr/include: replace extra-y with always-y
certs: simplify empty certs creation in certs/Makefile
certs: include certs/signing_key.x509 unconditionally
kallsyms: ignore all local labels prefixed by '.L'
kconfig: fix missing '# end of' for empty menu
kconfig: add fflush() before ferror() check
kbuild: replace $(if A,A,B) with $(or A,B)
kbuild: Add environment variables for userprogs flags
kbuild: unify cmd_copy and cmd_shipped
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The LLVM make variable allows a developer to quickly switch between the
GNU and LLVM tools. However, it does not handle versioned binaries, such
as the ones shipped by Debian, as LLVM=1 just defines the tool variables
with the unversioned binaries.
There was some discussion during the review of the patch that introduces
LLVM=1 around versioned binaries, ultimately coming to the conclusion
that developers can just add the folder that contains the unversioned
binaries to their PATH, as Debian's versioned suffixed binaries are
really just symlinks to the unversioned binaries in /usr/lib/llvm-#/bin:
$ realpath /usr/bin/clang-14
/usr/lib/llvm-14/bin/clang
$ PATH=/usr/lib/llvm-14/bin:$PATH make ... LLVM=1
However, that can be cumbersome to developers who are constantly testing
series with different toolchains and versions. It is simple enough to
support these versioned binaries directly in the Kbuild system by
allowing the developer to specify the version suffix with LLVM=, which
is shorter than the above suggestion:
$ make ... LLVM=-14
It does not change the meaning of LLVM=1 (which will continue to use
unversioned binaries) and it does not add too much additional complexity
to the existing $(LLVM) code, while allowing developers to quickly test
their series with different versions of the whole LLVM suite of tools.
Some developers may build LLVM from source but not add the binaries to
their PATH, as they may not want to use that toolchain systemwide.
Support those developers by allowing them to supply the directory that
the LLVM tools are available in, as it is no more complex to support
than the version suffix change above.
$ make ... LLVM=/path/to/llvm/
Update and reorder the documentation to reflect these new additions.
At the same time, notate that LLVM=0 is not the same as just omitting it
altogether, which has confused people in the past.
Link: https://lore.kernel.org/r/20200317215515.226917-1-ndesaulniers@google.com/
Link: https://lore.kernel.org/r/20220224151322.072632223@infradead.org/
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Pull array-bounds updates from Kees Cook:
"This enables -Warray-bounds and -Wzero-length-bounds, now that the
many bug fixes have landed all over the place in the kernel, and in
GCC itself[1].
A couple fixes[2] for known corner-case issues currently live in my
"pending-fixes" tree which I'm expecting to send next week if other
maintainers still haven't picked them up.
I'm also expecting we can enable -Wstringop-overflow next cycle, as
there are only a few stragglers[3], but it might even be possible for
this release"
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578
[2] https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?h=for-next/pending-fixes&id=2d253138910eec553fc706379914243d71de9b85
[3] https://github.com/KSPP/linux/issues/181
* tag 'array-bounds-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
Makefile: Enable -Wzero-length-bounds
Makefile: Enable -Warray-bounds
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Pull Kbuild update for C11 language base from Masahiro Yamada:
"Kbuild -std=gnu11 updates for v5.18
Linus pointed out the benefits of C99 some years ago, especially
variable declarations in loops [1]. At that time, we were not ready
for the migration due to old compilers.
Recently, Jakob Koschel reported a bug in list_for_each_entry(), which
leaks the invalid pointer out of the loop [2]. In the discussion, we
agreed that the time had come. Now that GCC 5.1 is the minimum
compiler version, there is nothing to prevent us from going to
-std=gnu99, or even straight to -std=gnu11.
Discussions for a better list iterator implementation are ongoing, but
this patch set must land first"
[1] https://lore.kernel.org/all/CAHk-=wgr12JkKmRd21qh-se-_Gs69kbPgR9x4C+Es-yJV2GLkA@mail.gmail.com/
[2] https://lore.kernel.org/lkml/86C4CE7D-6D93-456B-AA82-F8ADEACA40B7@gmail.com/
* tag 'kbuild-gnu11-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
Kbuild: use -std=gnu11 for KBUILD_USERCFLAGS
Kbuild: move to -std=gnu11
Kbuild: use -Wdeclaration-after-statement
Kbuild: add -Wno-shift-negative-value where -Wextra is used
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Linus Torvalds
Nick Desaulniers
Masahiro Yamada
Guillaume Tucker
Jens Axboe
Kees Cook
Randy Dunlap
Yann Droneaud
Josh Poimboeuf
Chun-Tse Shao
Nathan Chancellor