<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-dev/arch/powerpc/Kconfig, branch linus/master</title>
<subtitle>Linux kernel development work - see feature branches</subtitle>
<id>https://git.zx2c4.com/linux-dev/atom/arch/powerpc/Kconfig?h=linus%2Fmaster</id>
<link rel='self' href='https://git.zx2c4.com/linux-dev/atom/arch/powerpc/Kconfig?h=linus%2Fmaster'/>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/'/>
<updated>2022-06-09T19:17:43Z</updated>
<entry>
<title>Merge tag 'powerpc-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux</title>
<updated>2022-06-09T19:17:43Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-06-09T19:17:43Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=95fc76c81b9270a9ab38f4947fe5cb786c8c79cc'/>
<id>urn:sha1:95fc76c81b9270a9ab38f4947fe5cb786c8c79cc</id>
<content type='text'>
Pull powerpc fixes from Michael Ellerman:

 - On 32-bit fix overread/overwrite of thread_struct via ptrace
   PEEK/POKE.

 - Fix softirqs not switching to the softirq stack since we moved
   irq_exit().

 - Force thread size increase when KASAN is enabled to avoid stack
   overflows.

 - On Book3s 64 mark more code as not to be instrumented by KASAN to
   avoid crashes.

 - Exempt __get_wchan() from KASAN checking, as it's inherently racy.

 - Fix a recently introduced crash in the papr_scm driver in some
   configurations.

 - Remove include of &lt;generated/compile.h&gt; which is forbidden.

Thanks to Ariel Miculas, Chen Jingwen, Christophe Leroy, Erhard Furtner,
He Ying, Kees Cook, Masahiro Yamada, Nageswara R Sastry, Paul Mackerras,
Sachin Sant, Vaibhav Jain, and Wanming Hu.

* tag 'powerpc-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/32: Fix overread/overwrite of thread_struct via ptrace
  powerpc/book3e: get rid of #include &lt;generated/compile.h&gt;
  powerpc/kasan: Force thread size increase with KASAN
  powerpc/papr_scm: don't requests stats with '0' sized stats buffer
  powerpc: Don't select HAVE_IRQ_EXIT_ON_IRQ_STACK
  powerpc/kasan: Silence KASAN warnings in __get_wchan()
  powerpc/kasan: Mark more real-mode code as not to be instrumented
</content>
</entry>
<entry>
<title>powerpc/kasan: Force thread size increase with KASAN</title>
<updated>2022-06-02T12:56:47Z</updated>
<author>
<name>Michael Ellerman</name>
<email>mpe@ellerman.id.au</email>
</author>
<published>2022-06-01T14:31:14Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=3e8635fb2e072672cbc650989ffedf8300ad67fb'/>
<id>urn:sha1:3e8635fb2e072672cbc650989ffedf8300ad67fb</id>
<content type='text'>
KASAN causes increased stack usage, which can lead to stack overflows.

The logic in Kconfig to suggest a larger default doesn't work if a user
has CONFIG_EXPERT enabled and has an existing .config with a smaller
value.

Follow the lead of x86 and arm64, and force the thread size to be
increased when KASAN is enabled.

That also has the effect of enlarging the stack for 64-bit KASAN builds,
which is also desirable.

Fixes: edbadaf06710 ("powerpc/kasan: Fix stack overflow by increasing THREAD_SHIFT")
Reported-by: Erhard Furtner &lt;erhard_f@mailbox.org&gt;
Reported-by: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
[mpe: Use MIN_THREAD_SHIFT as suggested by Christophe]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220601143114.133524-1-mpe@ellerman.id.au
</content>
</entry>
<entry>
<title>Merge tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux</title>
<updated>2022-05-31T21:10:54Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-31T21:10:54Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=35b51afd23c98e2f055ac563aca36173a12588b9'/>
<id>urn:sha1:35b51afd23c98e2f055ac563aca36173a12588b9</id>
<content type='text'>
Pull RISC-V updates from Palmer Dabbelt:

 - Support for the Svpbmt extension, which allows memory attributes to
   be encoded in pages

 - Support for the Allwinner D1's implementation of page-based memory
   attributes

 - Support for running rv32 binaries on rv64 systems, via the compat
   subsystem

 - Support for kexec_file()

 - Support for the new generic ticket-based spinlocks, which allows us
   to also move to qrwlock. These should have already gone in through
   the asm-geneic tree as well

 - A handful of cleanups and fixes, include some larger ones around
   atomics and XIP

* tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits)
  RISC-V: Prepare dropping week attribute from arch_kexec_apply_relocations[_add]
  riscv: compat: Using seperated vdso_maps for compat_vdso_info
  RISC-V: Fix the XIP build
  RISC-V: Split out the XIP fixups into their own file
  RISC-V: ignore xipImage
  RISC-V: Avoid empty create_*_mapping definitions
  riscv: Don't output a bogus mmu-type on a no MMU kernel
  riscv: atomic: Add custom conditional atomic operation implementation
  riscv: atomic: Optimize dec_if_positive functions
  riscv: atomic: Cleanup unnecessary definition
  RISC-V: Load purgatory in kexec_file
  RISC-V: Add purgatory
  RISC-V: Support for kexec_file on panic
  RISC-V: Add kexec_file support
  RISC-V: use memcpy for kexec_file mode
  kexec_file: Fix kexec_file.c build error for riscv platform
  riscv: compat: Add COMPAT Kbuild skeletal support
  riscv: compat: ptrace: Add compat_arch_ptrace implement
  riscv: compat: signal: Add rt_frame implementation
  riscv: add memory-type errata for T-Head
  ...
</content>
</entry>
<entry>
<title>powerpc: Don't select HAVE_IRQ_EXIT_ON_IRQ_STACK</title>
<updated>2022-05-29T00:30:42Z</updated>
<author>
<name>Michael Ellerman</name>
<email>mpe@ellerman.id.au</email>
</author>
<published>2022-05-25T03:26:39Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=1346d00e1bdfd4067f92bc14e8a6131a01de4190'/>
<id>urn:sha1:1346d00e1bdfd4067f92bc14e8a6131a01de4190</id>
<content type='text'>
The HAVE_IRQ_EXIT_ON_IRQ_STACK option tells generic code that irq_exit()
is called while still running on the hard irq stack (hardirq_ctx[] in
the powerpc code).

Selecting the option means the generic code will *not* switch to the
softirq stack before running softirqs, because the code is already
running on the (mostly empty) hard irq stack.

But since commit 1b1b6a6f4cc0 ("powerpc: handle irq_enter/irq_exit in
interrupt handler wrappers"), irq_exit() is now called on the regular task
stack, not the hard irq stack.

That's because previously irq_exit() was called in __do_irq() which is
run on the hard irq stack, but now it is called in
interrupt_async_exit_prepare() which is called from do_irq() constructed
by the wrapper macro, which is after the switch back to the task stack.

So drop HAVE_IRQ_EXIT_ON_IRQ_STACK from the Kconfig. This will mean an
extra stack switch when processing some interrupts, but should
significantly reduce the likelihood of stack overflow.

It also means the softirq stack will be used for running softirqs from
other interrupts that don't use the hard irq stack, eg. timer interrupts.

Fixes: 1b1b6a6f4cc0 ("powerpc: handle irq_enter/irq_exit in interrupt handler wrappers")
Cc: stable@vger.kernel.org # v5.12+
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220525032639.1947280-1-mpe@ellerman.id.au

</content>
</entry>
<entry>
<title>Merge tag 'powerpc-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux</title>
<updated>2022-05-28T18:27:17Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-28T18:27:17Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=6112bd00e84e5dbffebc3c1e908cbe914ca772ee'/>
<id>urn:sha1:6112bd00e84e5dbffebc3c1e908cbe914ca772ee</id>
<content type='text'>
Pull powerpc updates from Michael Ellerman:

 - Convert to the generic mmap support (ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)

 - Add support for outline-only KASAN with 64-bit Radix MMU (P9 or later)

 - Increase SIGSTKSZ and MINSIGSTKSZ and add support for AT_MINSIGSTKSZ

 - Enable the DAWR (Data Address Watchpoint) on POWER9 DD2.3 or later

 - Drop support for system call instruction emulation

 - Many other small features and fixes

Thanks to Alexey Kardashevskiy, Alistair Popple, Andy Shevchenko, Bagas
Sanjaya, Bjorn Helgaas, Bo Liu, Chen Huang, Christophe Leroy, Colin Ian
King, Daniel Axtens, Dwaipayan Ray, Fabiano Rosas, Finn Thain, Frank
Rowand, Fuqian Huang, Guilherme G. Piccoli, Hangyu Hua, Haowen Bai,
Haren Myneni, Hari Bathini, He Ying, Jason Wang, Jiapeng Chong, Jing
Yangyang, Joel Stanley, Julia Lawall, Kajol Jain, Kevin Hao, Krzysztof
Kozlowski, Laurent Dufour, Lv Ruyi, Madhavan Srinivasan, Magali Lemes,
Miaoqian Lin, Minghao Chi, Nathan Chancellor, Naveen N. Rao, Nicholas
Piggin, Oliver O'Halloran, Oscar Salvador, Pali Rohár, Paul Mackerras,
Peng Wu, Qing Wang, Randy Dunlap, Reza Arbab, Russell Currey, Sohaib
Mohamed, Vaibhav Jain, Vasant Hegde, Wang Qing, Wang Wensheng, Xiang
wangx, Xiaomeng Tong, Xu Wang, Yang Guang, Yang Li, Ye Bin, YueHaibing,
Yu Kuai, Zheng Bin, Zou Wei, and Zucheng Zheng.

* tag 'powerpc-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (200 commits)
  powerpc/64: Include cache.h directly in paca.h
  powerpc/64s: Only set HAVE_ARCH_UNMAPPED_AREA when CONFIG_PPC_64S_HASH_MMU is set
  powerpc/xics: Include missing header
  powerpc/powernv/pci: Drop VF MPS fixup
  powerpc/fsl_book3e: Don't set rodata RO too early
  powerpc/microwatt: Add mmu bits to device tree
  powerpc/powernv/flash: Check OPAL flash calls exist before using
  powerpc/powermac: constify device_node in of_irq_parse_oldworld()
  powerpc/powermac: add missing g5_phy_disable_cpu1() declaration
  selftests/powerpc/pmu: fix spelling mistake "mis-match" -&gt; "mismatch"
  powerpc: Enable the DAWR on POWER9 DD2.3 and above
  powerpc/64s: Add CPU_FTRS_POWER10 to ALWAYS mask
  powerpc/64s: Add CPU_FTRS_POWER9_DD2_2 to CPU_FTRS_ALWAYS mask
  powerpc: Fix all occurences of "the the"
  selftests/powerpc/pmu/ebb: remove fixed_instruction.S
  powerpc/platforms/83xx: Use of_device_get_match_data()
  powerpc/eeh: Drop redundant spinlock initialization
  powerpc/iommu: Add missing of_node_put in iommu_init_early_dart
  powerpc/pseries/vas: Call misc_deregister if sysfs init fails
  powerpc/papr_scm: Fix leaking nvdimm_events_map elements
  ...
</content>
</entry>
<entry>
<title>Merge tag 'modules-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux</title>
<updated>2022-05-27T00:13:43Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-27T00:13:43Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=ef98f9cfe20d8ca063365d46d4ab2b85eeeb324f'/>
<id>urn:sha1:ef98f9cfe20d8ca063365d46d4ab2b85eeeb324f</id>
<content type='text'>
Pull modules updates from  Luis Chamberlain:

 - It was time to tidy up kernel/module.c and one way of starting with
   that effort was to split it up into files. At my request Aaron Tomlin
   spearheaded that effort with the goal to not introduce any functional
   at all during that endeavour. The penalty for the split is +1322
   bytes total, +112 bytes in data, +1210 bytes in text while bss is
   unchanged. One of the benefits of this other than helping make the
   code easier to read and review is summoning more help on review for
   changes with livepatching so kernel/module/livepatch.c is now pegged
   as maintained by the live patching folks.

   The before and after with just the move on a defconfig on x86-64:

     $ size kernel/module.o
        text    data     bss     dec     hex filename
       38434    4540     104   43078    a846 kernel/module.o

     $ size -t kernel/module/*.o
        text    data     bss     dec     hex filename
       4785     120       0    4905    1329 kernel/module/kallsyms.o
      28577    4416     104   33097    8149 kernel/module/main.o
       1158       8       0    1166     48e kernel/module/procfs.o
        902     108       0    1010     3f2 kernel/module/strict_rwx.o
       3390       0       0    3390     d3e kernel/module/sysfs.o
        832       0       0     832     340 kernel/module/tree_lookup.o
      39644    4652     104   44400    ad70 (TOTALS)

 - Aaron added module unload taint tracking (MODULE_UNLOAD_TAINT_TRACKING),
   to enable tracking unloaded modules which did taint the kernel.

 - Christophe Leroy added CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
   which lets architectures to request having modules data in vmalloc
   area instead of module area. There are three reasons why an
   architecture might want this:

    a) On some architectures (like book3s/32) it is not possible to
       protect against execution on a page basis. The exec stuff can be
       mapped by different arch segment sizes (on book3s/32 that is 256M
       segments). By default the module area is in an Exec segment while
       vmalloc area is in a NoExec segment. Using vmalloc lets you muck
       with module data as NoExec on those architectures whereas before
       you could not.

    b) By pushing more module data to vmalloc you also increase the
       probability of module text to remain within a closer distance
       from kernel core text and this reduces trampolines, this has been
       reported on arm first and powerpc folks are following that lead.

    c) Free'ing module_alloc() (Exec by default) area leaves this
       exposed as Exec by default, some architectures have some security
       enhancements to set this as NoExec on free, and splitting module
       data with text let's future generic special allocators be added
       to the kernel without having developers try to grok the tribal
       knowledge per arch. Work like Rick Edgecombe's permission vmalloc
       interface [0] becomes easier to address over time.

       [0] https://lore.kernel.org/lkml/20201120202426.18009-1-rick.p.edgecombe@intel.com/#r

 - Masahiro Yamada's symbol search enhancements

* tag 'modules-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (33 commits)
  module: merge check_exported_symbol() into find_exported_symbol_in_section()
  module: do not binary-search in __ksymtab_gpl if fsa-&gt;gplok is false
  module: do not pass opaque pointer for symbol search
  module: show disallowed symbol name for inherit_taint()
  module: fix [e_shstrndx].sh_size=0 OOB access
  module: Introduce module unload taint tracking
  module: Move module_assert_mutex_or_preempt() to internal.h
  module: Make module_flags_taint() accept a module's taints bitmap and usable outside core code
  module.h: simplify MODULE_IMPORT_NS
  powerpc: Select ARCH_WANTS_MODULES_DATA_IN_VMALLOC on book3s/32 and 8xx
  module: Remove module_addr_min and module_addr_max
  module: Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
  module: Introduce data_layout
  module: Prepare for handling several RB trees
  module: Always have struct mod_tree_root
  module: Rename debug_align() as strict_align()
  module: Rework layout alignment to avoid BUG_ON()s
  module: Move module_enable_x() and frob_text() in strict_rwx.c
  module: Make module_enable_x() independent of CONFIG_ARCH_HAS_STRICT_MODULE_RWX
  module: Move version support into a separate file
  ...
</content>
</entry>
<entry>
<title>Merge tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2022-05-26T19:32:41Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-26T19:32:41Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=98931dd95fd489fcbfa97da563505a6f071d7c77'/>
<id>urn:sha1:98931dd95fd489fcbfa97da563505a6f071d7c77</id>
<content type='text'>
Pull MM updates from Andrew Morton:
 "Almost all of MM here. A few things are still getting finished off,
  reviewed, etc.

   - Yang Shi has improved the behaviour of khugepaged collapsing of
     readonly file-backed transparent hugepages.

   - Johannes Weiner has arranged for zswap memory use to be tracked and
     managed on a per-cgroup basis.

   - Munchun Song adds a /proc knob ("hugetlb_optimize_vmemmap") for
     runtime enablement of the recent huge page vmemmap optimization
     feature.

   - Baolin Wang contributes a series to fix some issues around hugetlb
     pagetable invalidation.

   - Zhenwei Pi has fixed some interactions between hwpoisoned pages and
     virtualization.

   - Tong Tiangen has enabled the use of the presently x86-only
     page_table_check debugging feature on arm64 and riscv.

   - David Vernet has done some fixup work on the memcg selftests.

   - Peter Xu has taught userfaultfd to handle write protection faults
     against shmem- and hugetlbfs-backed files.

   - More DAMON development from SeongJae Park - adding online tuning of
     the feature and support for monitoring of fixed virtual address
     ranges. Also easier discovery of which monitoring operations are
     available.

   - Nadav Amit has done some optimization of TLB flushing during
     mprotect().

   - Neil Brown continues to labor away at improving our swap-over-NFS
     support.

   - David Hildenbrand has some fixes to anon page COWing versus
     get_user_pages().

   - Peng Liu fixed some errors in the core hugetlb code.

   - Joao Martins has reduced the amount of memory consumed by
     device-dax's compound devmaps.

   - Some cleanups of the arch-specific pagemap code from Anshuman
     Khandual.

   - Muchun Song has found and fixed some errors in the TLB flushing of
     transparent hugepages.

   - Roman Gushchin has done more work on the memcg selftests.

  ... and, of course, many smaller fixes and cleanups. Notably, the
  customary million cleanup serieses from Miaohe Lin"

* tag 'mm-stable-2022-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (381 commits)
  mm: kfence: use PAGE_ALIGNED helper
  selftests: vm: add the "settings" file with timeout variable
  selftests: vm: add "test_hmm.sh" to TEST_FILES
  selftests: vm: check numa_available() before operating "merge_across_nodes" in ksm_tests
  selftests: vm: add migration to the .gitignore
  selftests/vm/pkeys: fix typo in comment
  ksm: fix typo in comment
  selftests: vm: add process_mrelease tests
  Revert "mm/vmscan: never demote for memcg reclaim"
  mm/kfence: print disabling or re-enabling message
  include/trace/events/percpu.h: cleanup for "percpu: improve percpu_alloc_percpu event trace"
  include/trace/events/mmflags.h: cleanup for "tracing: incorrect gfp_t conversion"
  mm: fix a potential infinite loop in start_isolate_page_range()
  MAINTAINERS: add Muchun as co-maintainer for HugeTLB
  zram: fix Kconfig dependency warning
  mm/shmem: fix shmem folio swapoff hang
  cgroup: fix an error handling path in alloc_pagecache_max_30M()
  mm: damon: use HPAGE_PMD_SIZE
  tracing: incorrect isolate_mote_t cast in mm_vmscan_lru_isolate
  nodemask.h: fix compilation error with GCC12
  ...
</content>
</entry>
<entry>
<title>kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS</title>
<updated>2022-05-24T07:33:20Z</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2022-05-13T11:39:22Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=7b4537199a4a8480b8c3ba37a2d44765ce76cd9b'/>
<id>urn:sha1:7b4537199a4a8480b8c3ba37a2d44765ce76cd9b</id>
<content type='text'>
include/{linux,asm-generic}/export.h defines a weak symbol, __crc_*
as a placeholder.

Genksyms writes the version CRCs into the linker script, which will be
used for filling the __crc_* symbols. The linker script format depends
on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset
to the reference of CRC.

It is time to get rid of this complexity.

Now that modpost parses text files (.*.cmd) to collect all the CRCs,
it can generate C code that will be linked to the vmlinux or modules.

Generate a new C file, .vmlinux.export.c, which contains the CRCs of
symbols exported by vmlinux. It is compiled and linked to vmlinux in
scripts/link-vmlinux.sh.

Put the CRCs of symbols exported by modules into the existing *.mod.c
files. No additional build step is needed for modules. As before,
*.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal.

No linker magic is used here. The new C implementation works in the
same way, whether CONFIG_RELOCATABLE is enabled or not.
CONFIG_MODULE_REL_CRCS is no longer needed.

Previously, Kbuild invoked additional $(LD) to update the CRCs in
objects, but this step is unneeded too.

Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Tested-by: Nathan Chancellor &lt;nathan@kernel.org&gt;
Tested-by: Nicolas Schier &lt;nicolas@fjasle.eu&gt;
Reviewed-by: Nicolas Schier &lt;nicolas@fjasle.eu&gt;
Tested-by: Sedat Dilek &lt;sedat.dilek@gmail.com&gt; # LLVM-14 (x86-64)
</content>
</entry>
<entry>
<title>powerpc: Book3S 64-bit outline-only KASAN support</title>
<updated>2022-05-22T05:58:29Z</updated>
<author>
<name>Daniel Axtens</name>
<email>dja@axtens.net</email>
</author>
<published>2022-05-18T10:05:31Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=41b7a347bf1491e7300563bb224432608b41f62a'/>
<id>urn:sha1:41b7a347bf1491e7300563bb224432608b41f62a</id>
<content type='text'>
Implement a limited form of KASAN for Book3S 64-bit machines running under
the Radix MMU, supporting only outline mode.

 - Enable the compiler instrumentation to check addresses and maintain the
   shadow region. (This is the guts of KASAN which we can easily reuse.)

 - Require kasan-vmalloc support to handle modules and anything else in
   vmalloc space.

 - KASAN needs to be able to validate all pointer accesses, but we can't
   instrument all kernel addresses - only linear map and vmalloc. On boot,
   set up a single page of read-only shadow that marks all iomap and
   vmemmap accesses as valid.

 - Document KASAN in powerpc docs.

Background
----------

KASAN support on Book3S is a bit tricky to get right:

 - It would be good to support inline instrumentation so as to be able to
   catch stack issues that cannot be caught with outline mode.

 - Inline instrumentation requires a fixed offset.

 - Book3S runs code with translations off ("real mode") during boot,
   including a lot of generic device-tree parsing code which is used to
   determine MMU features.

    [ppc64 mm note: The kernel installs a linear mapping at effective
    address c000...-c008.... This is a one-to-one mapping with physical
    memory from 0000... onward. Because of how memory accesses work on
    powerpc 64-bit Book3S, a kernel pointer in the linear map accesses the
    same memory both with translations on (accessing as an 'effective
    address'), and with translations off (accessing as a 'real
    address'). This works in both guests and the hypervisor. For more
    details, see s5.7 of Book III of version 3 of the ISA, in particular
    the Storage Control Overview, s5.7.3, and s5.7.5 - noting that this
    KASAN implementation currently only supports Radix.]

 - Some code - most notably a lot of KVM code - also runs with translations
   off after boot.

 - Therefore any offset has to point to memory that is valid with
   translations on or off.

One approach is just to give up on inline instrumentation. This way
boot-time checks can be delayed until after the MMU is set is up, and we
can just not instrument any code that runs with translations off after
booting. Take this approach for now and require outline instrumentation.

Previous attempts allowed inline instrumentation. However, they came with
some unfortunate restrictions: only physically contiguous memory could be
used and it had to be specified at compile time. Maybe we can do better in
the future.

[paulus@ozlabs.org - Rebased onto 5.17.  Note that a kernel with
 CONFIG_KASAN=y will crash during boot on a machine using HPT
 translation because not all the entry points to the generic
 KASAN code are protected with a call to kasan_arch_is_ready().]

Originally-by: Balbir Singh &lt;bsingharora@gmail.com&gt; # ppc64 out-of-line radix version
Signed-off-by: Daniel Axtens &lt;dja@axtens.net&gt;
Signed-off-by: Paul Mackerras &lt;paulus@ozlabs.org&gt;
[mpe: Update copyright year and comment formatting]
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/YoTE69OQwiG7z+Gu@cleo

</content>
</entry>
<entry>
<title>powerpc: Add generic PAGE_SIZE config symbols</title>
<updated>2022-05-22T05:58:27Z</updated>
<author>
<name>Michael Ellerman</name>
<email>mpe@ellerman.id.au</email>
</author>
<published>2022-05-05T12:51:22Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=d036dc79cccd748e2a101c80c31efada7be8bb7c'/>
<id>urn:sha1:d036dc79cccd748e2a101c80c31efada7be8bb7c</id>
<content type='text'>
Other arches (sh, mips, hexagon) use standard names for PAGE_SIZE
related config symbols.

Add matching symbols for powerpc, which are enabled by default but
depend on our architecture specific PAGE_SIZE symbols.

This allows generic/driver code to express dependencies on the PAGE_SIZE
without needing to refer to architecture specific config symbols.

Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Link: https://lore.kernel.org/r/20220505125123.2088143-1-mpe@ellerman.id.au

</content>
</entry>
</feed>
