linux.git/arch/arm/kernel, branch v6.10-rc6 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git ARM: 9405/1: ftrace: Don't assume stack frames are contiguous in memory 2024-06-10T11:00:27+00:00 Ard Biesheuvel ardb@kernel.org 2024-06-04T21:32:34+00:00 e3cf20e5c68df604315ab30bdbe15dc8a5da556b The frame pointer unwinder relies on a standard layout of the stack frame, consisting of (in downward order) Calling frame: PC <---------+ LR | SP | FP | .. locals .. | Callee frame: | PC | LR | SP | FP ----------+ where after storing its previous value on the stack, FP is made to point at the location of PC in the callee stack frame, using the canonical prologue: mov ip, sp stmdb sp!, {fp, ip, lr, pc} sub fp, ip, #4 The ftrace code assumes that this activation record is pushed first, and that any stack space for locals is allocated below this. Strict adherence to this would imply that the caller's value of SP at the time of the function call can always be obtained by adding 4 to FP (which points to PC in the callee frame). However, recent versions of GCC appear to deviate from this rule, and so the only reliable way to obtain the caller's value of SP is to read it from the activation record. Since this involves a read from memory rather than simple arithmetic, we need to use the uaccess API here which protects against inadvertent data aborts resulting from attempts to dereference bogus FP values. The plain uaccess API is ftrace instrumented itself, so to avoid unbounded recursion, use the __get_kernel_nofault() primitive directly. Closes: https://lore.kernel.org/all/alp44tukzo6mvcwl4ke4ehhmojrqnv6xfcdeuliybxfjfvgd3e@gpjvwj33cc76 Closes: https://lore.kernel.org/all/d870c149-4363-43de-b0ea-7125dec5608e@broadcom.com/ Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Reported-by: Justin Chen <justin.chen@broadcom.com> Tested-by: Thorsten Scherer <t.scherer@eckelmann.de> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> 
The frame pointer unwinder relies on a standard layout of the stack
frame, consisting of (in downward order)

   Calling frame:
     PC   <---------+
     LR             |
     SP             |
     FP             |
     .. locals ..   |
   Callee frame:    |
     PC             |
     LR             |
     SP             |
     FP   ----------+

where after storing its previous value on the stack, FP is made to point
at the location of PC in the callee stack frame, using the canonical
prologue:

   mov     ip, sp
   stmdb   sp!, {fp, ip, lr, pc}
   sub     fp, ip, #4

The ftrace code assumes that this activation record is pushed first, and
that any stack space for locals is allocated below this. Strict
adherence to this would imply that the caller's value of SP at the time
of the function call can always be obtained by adding 4 to FP (which
points to PC in the callee frame).

However, recent versions of GCC appear to deviate from this rule, and so
the only reliable way to obtain the caller's value of SP is to read it
from the activation record. Since this involves a read from memory
rather than simple arithmetic, we need to use the uaccess API here which
protects against inadvertent data aborts resulting from attempts to
dereference bogus FP values.

The plain uaccess API is ftrace instrumented itself, so to avoid
unbounded recursion, use the __get_kernel_nofault() primitive directly.

Closes: https://lore.kernel.org/all/alp44tukzo6mvcwl4ke4ehhmojrqnv6xfcdeuliybxfjfvgd3e@gpjvwj33cc76

Closes: https://lore.kernel.org/all/d870c149-4363-43de-b0ea-7125dec5608e@broadcom.com/

Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reported-by: Justin Chen <justin.chen@broadcom.com>
Tested-by: Thorsten Scherer <t.scherer@eckelmann.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Merge tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2024-05-19T16:21:03+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-05-19T16:21:03+00:00 61307b7be41a1f1039d1d1368810a1d92cb97b44 Pull mm updates from Andrew Morton: "The usual shower of singleton fixes and minor series all over MM, documented (hopefully adequately) in the respective changelogs. Notable series include: - Lucas Stach has provided some page-mapping cleanup/consolidation/ maintainability work in the series "mm/treewide: Remove pXd_huge() API". - In the series "Allow migrate on protnone reference with MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's MPOL_PREFERRED_MANY mode, yielding almost doubled performance in one test. - In their series "Memory allocation profiling" Kent Overstreet and Suren Baghdasaryan have contributed a means of determining (via /proc/allocinfo) whereabouts in the kernel memory is being allocated: number of calls and amount of memory. - Matthew Wilcox has provided the series "Various significant MM patches" which does a number of rather unrelated things, but in largely similar code sites. - In his series "mm: page_alloc: freelist migratetype hygiene" Johannes Weiner has fixed the page allocator's handling of migratetype requests, with resulting improvements in compaction efficiency. - In the series "make the hugetlb migration strategy consistent" Baolin Wang has fixed a hugetlb migration issue, which should improve hugetlb allocation reliability. - Liu Shixin has hit an I/O meltdown caused by readahead in a memory-tight memcg. Addressed in the series "Fix I/O high when memory almost met memcg limit". - In the series "mm/filemap: optimize folio adding and splitting" Kairui Song has optimized pagecache insertion, yielding ~10% performance improvement in one test. - Baoquan He has cleaned up and consolidated the early zone initialization code in the series "mm/mm_init.c: refactor free_area_init_core()". - Baoquan has also redone some MM initializatio code in the series "mm/init: minor clean up and improvement". - MM helper cleanups from Christoph Hellwig in his series "remove follow_pfn". - More cleanups from Matthew Wilcox in the series "Various page->flags cleanups". - Vlastimil Babka has contributed maintainability improvements in the series "memcg_kmem hooks refactoring". - More folio conversions and cleanups in Matthew Wilcox's series: "Convert huge_zero_page to huge_zero_folio" "khugepaged folio conversions" "Remove page_idle and page_young wrappers" "Use folio APIs in procfs" "Clean up __folio_put()" "Some cleanups for memory-failure" "Remove page_mapping()" "More folio compat code removal" - David Hildenbrand chipped in with "fs/proc/task_mmu: convert hugetlb functions to work on folis". - Code consolidation and cleanup work related to GUP's handling of hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2". - Rick Edgecombe has developed some fixes to stack guard gaps in the series "Cover a guard gap corner case". - Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the series "mm/ksm: fix ksm exec support for prctl". - Baolin Wang has implemented NUMA balancing for multi-size THPs. This is a simple first-cut implementation for now. The series is "support multi-size THP numa balancing". - Cleanups to vma handling helper functions from Matthew Wilcox in the series "Unify vma_address and vma_pgoff_address". - Some selftests maintenance work from Dev Jain in the series "selftests/mm: mremap_test: Optimizations and style fixes". - Improvements to the swapping of multi-size THPs from Ryan Roberts in the series "Swap-out mTHP without splitting". - Kefeng Wang has significantly optimized the handling of arm64's permission page faults in the series "arch/mm/fault: accelerate pagefault when badaccess" "mm: remove arch's private VM_FAULT_BADMAP/BADACCESS" - GUP cleanups from David Hildenbrand in "mm/gup: consistently call it GUP-fast". - hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault path to use struct vm_fault". - selftests build fixes from John Hubbard in the series "Fix selftests/mm build without requiring "make headers"". - Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the series "Improved Memory Tier Creation for CPUless NUMA Nodes". Fixes the initialization code so that migration between different memory types works as intended. - David Hildenbrand has improved follow_pte() and fixed an errant driver in the series "mm: follow_pte() improvements and acrn follow_pte() fixes". - David also did some cleanup work on large folio mapcounts in his series "mm: mapcount for large folios + page_mapcount() cleanups". - Folio conversions in KSM in Alex Shi's series "transfer page to folio in KSM". - Barry Song has added some sysfs stats for monitoring multi-size THP's in the series "mm: add per-order mTHP alloc and swpout counters". - Some zswap cleanups from Yosry Ahmed in the series "zswap same-filled and limit checking cleanups". - Matthew Wilcox has been looking at buffer_head code and found the documentation to be lacking. The series is "Improve buffer head documentation". - Multi-size THPs get more work, this time from Lance Yang. His series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free" optimizes the freeing of these things. - Kemeng Shi has added more userspace-visible writeback instrumentation in the series "Improve visibility of writeback". - Kemeng Shi then sent some maintenance work on top in the series "Fix and cleanups to page-writeback". - Matthew Wilcox reduces mmap_lock traffic in the anon vma code in the series "Improve anon_vma scalability for anon VMAs". Intel's test bot reported an improbable 3x improvement in one test. - SeongJae Park adds some DAMON feature work in the series "mm/damon: add a DAMOS filter type for page granularity access recheck" "selftests/damon: add DAMOS quota goal test" - Also some maintenance work in the series "mm/damon/paddr: simplify page level access re-check for pageout" "mm/damon: misc fixes and improvements" - David Hildenbrand has disabled some known-to-fail selftests ni the series "selftests: mm: cow: flag vmsplice() hugetlb tests as XFAIL". - memcg metadata storage optimizations from Shakeel Butt in "memcg: reduce memory consumption by memcg stats". - DAX fixes and maintenance work from Vishal Verma in the series "dax/bus.c: Fixups for dax-bus locking"" * tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits) memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault selftests: cgroup: add tests to verify the zswap writeback path mm: memcg: make alloc_mem_cgroup_per_node_info() return bool mm/damon/core: fix return value from damos_wmark_metric_value mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED selftests: cgroup: remove redundant enabling of memory controller Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT Docs/mm/damon/design: use a list for supported filters Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file selftests/damon: classify tests for functionalities and regressions selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None' selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts selftests/damon/_damon_sysfs: check errors from nr_schemes file reads mm/damon/core: initialize ->esz_bp from damos_quota_init_priv() selftests/damon: add a test for DAMOS quota goal ... 
Pull mm updates from Andrew Morton:
 "The usual shower of singleton fixes and minor series all over MM,
  documented (hopefully adequately) in the respective changelogs.
  Notable series include:

   - Lucas Stach has provided some page-mapping cleanup/consolidation/
     maintainability work in the series "mm/treewide: Remove pXd_huge()
     API".

   - In the series "Allow migrate on protnone reference with
     MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
     MPOL_PREFERRED_MANY mode, yielding almost doubled performance in
     one test.

   - In their series "Memory allocation profiling" Kent Overstreet and
     Suren Baghdasaryan have contributed a means of determining (via
     /proc/allocinfo) whereabouts in the kernel memory is being
     allocated: number of calls and amount of memory.

   - Matthew Wilcox has provided the series "Various significant MM
     patches" which does a number of rather unrelated things, but in
     largely similar code sites.

   - In his series "mm: page_alloc: freelist migratetype hygiene"
     Johannes Weiner has fixed the page allocator's handling of
     migratetype requests, with resulting improvements in compaction
     efficiency.

   - In the series "make the hugetlb migration strategy consistent"
     Baolin Wang has fixed a hugetlb migration issue, which should
     improve hugetlb allocation reliability.

   - Liu Shixin has hit an I/O meltdown caused by readahead in a
     memory-tight memcg. Addressed in the series "Fix I/O high when
     memory almost met memcg limit".

   - In the series "mm/filemap: optimize folio adding and splitting"
     Kairui Song has optimized pagecache insertion, yielding ~10%
     performance improvement in one test.

   - Baoquan He has cleaned up and consolidated the early zone
     initialization code in the series "mm/mm_init.c: refactor
     free_area_init_core()".

   - Baoquan has also redone some MM initializatio code in the series
     "mm/init: minor clean up and improvement".

   - MM helper cleanups from Christoph Hellwig in his series "remove
     follow_pfn".

   - More cleanups from Matthew Wilcox in the series "Various
     page->flags cleanups".

   - Vlastimil Babka has contributed maintainability improvements in the
     series "memcg_kmem hooks refactoring".

   - More folio conversions and cleanups in Matthew Wilcox's series:
	"Convert huge_zero_page to huge_zero_folio"
	"khugepaged folio conversions"
	"Remove page_idle and page_young wrappers"
	"Use folio APIs in procfs"
	"Clean up __folio_put()"
	"Some cleanups for memory-failure"
	"Remove page_mapping()"
	"More folio compat code removal"

   - David Hildenbrand chipped in with "fs/proc/task_mmu: convert
     hugetlb functions to work on folis".

   - Code consolidation and cleanup work related to GUP's handling of
     hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".

   - Rick Edgecombe has developed some fixes to stack guard gaps in the
     series "Cover a guard gap corner case".

   - Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the
     series "mm/ksm: fix ksm exec support for prctl".

   - Baolin Wang has implemented NUMA balancing for multi-size THPs.
     This is a simple first-cut implementation for now. The series is
     "support multi-size THP numa balancing".

   - Cleanups to vma handling helper functions from Matthew Wilcox in
     the series "Unify vma_address and vma_pgoff_address".

   - Some selftests maintenance work from Dev Jain in the series
     "selftests/mm: mremap_test: Optimizations and style fixes".

   - Improvements to the swapping of multi-size THPs from Ryan Roberts
     in the series "Swap-out mTHP without splitting".

   - Kefeng Wang has significantly optimized the handling of arm64's
     permission page faults in the series
	"arch/mm/fault: accelerate pagefault when badaccess"
	"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"

   - GUP cleanups from David Hildenbrand in "mm/gup: consistently call
     it GUP-fast".

   - hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault
     path to use struct vm_fault".

   - selftests build fixes from John Hubbard in the series "Fix
     selftests/mm build without requiring "make headers"".

   - Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
     series "Improved Memory Tier Creation for CPUless NUMA Nodes".
     Fixes the initialization code so that migration between different
     memory types works as intended.

   - David Hildenbrand has improved follow_pte() and fixed an errant
     driver in the series "mm: follow_pte() improvements and acrn
     follow_pte() fixes".

   - David also did some cleanup work on large folio mapcounts in his
     series "mm: mapcount for large folios + page_mapcount() cleanups".

   - Folio conversions in KSM in Alex Shi's series "transfer page to
     folio in KSM".

   - Barry Song has added some sysfs stats for monitoring multi-size
     THP's in the series "mm: add per-order mTHP alloc and swpout
     counters".

   - Some zswap cleanups from Yosry Ahmed in the series "zswap
     same-filled and limit checking cleanups".

   - Matthew Wilcox has been looking at buffer_head code and found the
     documentation to be lacking. The series is "Improve buffer head
     documentation".

   - Multi-size THPs get more work, this time from Lance Yang. His
     series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free"
     optimizes the freeing of these things.

   - Kemeng Shi has added more userspace-visible writeback
     instrumentation in the series "Improve visibility of writeback".

   - Kemeng Shi then sent some maintenance work on top in the series
     "Fix and cleanups to page-writeback".

   - Matthew Wilcox reduces mmap_lock traffic in the anon vma code in
     the series "Improve anon_vma scalability for anon VMAs". Intel's
     test bot reported an improbable 3x improvement in one test.

   - SeongJae Park adds some DAMON feature work in the series
	"mm/damon: add a DAMOS filter type for page granularity access recheck"
	"selftests/damon: add DAMOS quota goal test"

   - Also some maintenance work in the series
	"mm/damon/paddr: simplify page level access re-check for pageout"
	"mm/damon: misc fixes and improvements"

   - David Hildenbrand has disabled some known-to-fail selftests ni the
     series "selftests: mm: cow: flag vmsplice() hugetlb tests as
     XFAIL".

   - memcg metadata storage optimizations from Shakeel Butt in "memcg:
     reduce memory consumption by memcg stats".

   - DAX fixes and maintenance work from Vishal Verma in the series
     "dax/bus.c: Fixups for dax-bus locking""

* tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits)
  memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order
  selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime
  mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp
  mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault
  selftests: cgroup: add tests to verify the zswap writeback path
  mm: memcg: make alloc_mem_cgroup_per_node_info() return bool
  mm/damon/core: fix return value from damos_wmark_metric_value
  mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED
  selftests: cgroup: remove redundant enabling of memory controller
  Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree
  Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT
  Docs/mm/damon/design: use a list for supported filters
  Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command
  Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file
  selftests/damon: classify tests for functionalities and regressions
  selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None'
  selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts
  selftests/damon/_damon_sysfs: check errors from nr_schemes file reads
  mm/damon/core: initialize ->esz_bp from damos_quota_init_priv()
  selftests/damon: add a test for DAMOS quota goal
  ...
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux 2024-05-17T15:53:47+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-05-17T15:53:47+00:00 4853f1f6ace32c68a04287353e428c4cfc3fa8ed Pull ARM updates from Russell King: - Updates to AMBA bus subsystem to drop .owner struct device_driver initialisations, moving that to code instead. - Add LPAE privileged-access-never support - Add support for Clang CFI - clkdev: report over-sized device or connection strings * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux: (36 commits) ARM: 9398/1: Fix userspace enter on LPAE with CC_OPTIMIZE_FOR_SIZE=y clkdev: report over-sized strings when creating clkdev entries ARM: 9393/1: mm: Use conditionals for CFI branches ARM: 9392/2: Support CLANG CFI ARM: 9391/2: hw_breakpoint: Handle CFI breakpoints ARM: 9390/2: lib: Annotate loop delay instructions for CFI ARM: 9389/2: mm: Define prototypes for all per-processor calls ARM: 9388/2: mm: Type-annotate all per-processor assembly routines ARM: 9387/2: mm: Rewrite cacheflush vtables in CFI safe C ARM: 9386/2: mm: Use symbol alias for cache functions ARM: 9385/2: mm: Type-annotate all cache assembly routines ARM: 9384/2: mm: Make tlbflush routines CFI safe ARM: 9382/1: ftrace: Define ftrace_stub_graph ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement ARM: 9357/2: Reduce the number of #ifdef CONFIG_CPU_SW_DOMAIN_PAN ARM: 9356/2: Move asm statements accessing TTBCR into C functions ARM: 9355/2: Add TTBCR_* definitions to pgtable-3level-hwdef.h ARM: 9379/1: coresight: tpda: drop owner assignment ARM: 9378/1: coresight: etm4x: drop owner assignment ARM: 9377/1: hwrng: nomadik: drop owner assignment ... 
Pull ARM updates from Russell King:

 - Updates to AMBA bus subsystem to drop .owner struct device_driver
   initialisations, moving that to code instead.

 - Add LPAE privileged-access-never support

 - Add support for Clang CFI

 - clkdev: report over-sized device or connection strings

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux: (36 commits)
  ARM: 9398/1: Fix userspace enter on LPAE with CC_OPTIMIZE_FOR_SIZE=y
  clkdev: report over-sized strings when creating clkdev entries
  ARM: 9393/1: mm: Use conditionals for CFI branches
  ARM: 9392/2: Support CLANG CFI
  ARM: 9391/2: hw_breakpoint: Handle CFI breakpoints
  ARM: 9390/2: lib: Annotate loop delay instructions for CFI
  ARM: 9389/2: mm: Define prototypes for all per-processor calls
  ARM: 9388/2: mm: Type-annotate all per-processor assembly routines
  ARM: 9387/2: mm: Rewrite cacheflush vtables in CFI safe C
  ARM: 9386/2: mm: Use symbol alias for cache functions
  ARM: 9385/2: mm: Type-annotate all cache assembly routines
  ARM: 9384/2: mm: Make tlbflush routines CFI safe
  ARM: 9382/1: ftrace: Define ftrace_stub_graph
  ARM: 9358/2: Implement PAN for LPAE by TTBR0 page table walks disablement
  ARM: 9357/2: Reduce the number of #ifdef CONFIG_CPU_SW_DOMAIN_PAN
  ARM: 9356/2: Move asm statements accessing TTBCR into C functions
  ARM: 9355/2: Add TTBCR_* definitions to pgtable-3level-hwdef.h
  ARM: 9379/1: coresight: tpda: drop owner assignment
  ARM: 9378/1: coresight: etm4x: drop owner assignment
  ARM: 9377/1: hwrng: nomadik: drop owner assignment
  ...
Merge branches 'amba', 'cfi', 'clkdev' and 'misc' into for-linus 2024-05-16T11:35:01+00:00 Russell King (Oracle) rmk+kernel@armlinux.org.uk 2024-05-16T11:35:01+00:00 f698d314eec2e16b980128b503d96bd73df77e90 






arch: make execmem setup available regardless of CONFIG_MODULES
2024-05-14T07:31:44+00:00

Mike Rapoport (IBM)
rppt@kernel.org

2024-05-05T16:06:24+00:00

0cc2dc4902f425e346d46deeea2352d9fba75375

execmem does not depend on modules, on the contrary modules use
execmem.

To make execmem available when CONFIG_MODULES=n, for instance for
kprobes, split execmem_params initialization out from
arch/*/kernel/module.c and compile it when CONFIG_EXECMEM=y

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>





execmem does not depend on modules, on the contrary modules use
execmem.

To make execmem available when CONFIG_MODULES=n, for instance for
kprobes, split execmem_params initialization out from
arch/*/kernel/module.c and compile it when CONFIG_EXECMEM=y

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>







mm/execmem, arch: convert remaining overrides of module_alloc to execmem
2024-05-14T07:31:43+00:00

Mike Rapoport (IBM)
rppt@kernel.org

2024-05-05T16:06:20+00:00

223b5e57d0d50b0c07b933350dbcde92018d3080

Extend execmem parameters to accommodate more complex overrides of
module_alloc() by architectures.

This includes specification of a fallback range required by arm, arm64
and powerpc, EXECMEM_MODULE_DATA type required by powerpc, support for
allocation of KASAN shadow required by s390 and x86 and support for
late initialization of execmem required by arm64.

The core implementation of execmem_alloc() takes care of suppressing
warnings when the initial allocation fails but there is a fallback range
defined.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Tested-by: Liviu Dudau <liviu@dudau.co.uk>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>





Extend execmem parameters to accommodate more complex overrides of
module_alloc() by architectures.

This includes specification of a fallback range required by arm, arm64
and powerpc, EXECMEM_MODULE_DATA type required by powerpc, support for
allocation of KASAN shadow required by s390 and x86 and support for
late initialization of execmem required by arm64.

The core implementation of execmem_alloc() takes care of suppressing
warnings when the initial allocation fails but there is a fallback range
defined.

Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Tested-by: Liviu Dudau <liviu@dudau.co.uk>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>







Merge tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2024-05-14T00:18:51+00:00

Linus Torvalds
torvalds@linux-foundation.org

2024-05-14T00:18:51+00:00

6e5a0c30b616bfff6926ecca5d88e3d06e6bf79a

Pull scheduler updates from Ingo Molnar:

 - Add cpufreq pressure feedback for the scheduler

 - Rework misfit load-balancing wrt affinity restrictions

 - Clean up and simplify the code around ::overutilized and
   ::overload access.

 - Simplify sched_balance_newidle()

 - Bump SCHEDSTAT_VERSION to 16 due to a cleanup of CPU_MAX_IDLE_TYPES
   handling that changed the output.

 - Rework & clean up <asm/vtime.h> interactions wrt arch_vtime_task_switch()

 - Reorganize, clean up and unify most of the higher level
   scheduler balancing function names around the sched_balance_*()
   prefix

 - Simplify the balancing flag code (sched_balance_running)

 - Miscellaneous cleanups & fixes

* tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
  sched/pelt: Remove shift of thermal clock
  sched/cpufreq: Rename arch_update_thermal_pressure() => arch_update_hw_pressure()
  thermal/cpufreq: Remove arch_update_thermal_pressure()
  sched/cpufreq: Take cpufreq feedback into account
  cpufreq: Add a cpufreq pressure feedback for the scheduler
  sched/fair: Fix update of rd->sg_overutilized
  sched/vtime: Do not include <asm/vtime.h> header
  s390/irq,nmi: Include <asm/vtime.h> header directly
  s390/vtime: Remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover
  sched/vtime: Get rid of generic vtime_task_switch() implementation
  sched/vtime: Remove confusing arch_vtime_task_switch() declaration
  sched/balancing: Simplify the sg_status bitmask and use separate ->overloaded and ->overutilized flags
  sched/fair: Rename set_rd_overutilized_status() to set_rd_overutilized()
  sched/fair: Rename SG_OVERLOAD to SG_OVERLOADED
  sched/fair: Rename {set|get}_rd_overload() to {set|get}_rd_overloaded()
  sched/fair: Rename root_domain::overload to ::overloaded
  sched/fair: Use helper functions to access root_domain::overload
  sched/fair: Check root_domain::overload value before update
  sched/fair: Combine EAS check with root_domain::overutilized access
  sched/fair: Simplify the continue_balancing logic in sched_balance_newidle()
  ...





Pull scheduler updates from Ingo Molnar:

 - Add cpufreq pressure feedback for the scheduler

 - Rework misfit load-balancing wrt affinity restrictions

 - Clean up and simplify the code around ::overutilized and
   ::overload access.

 - Simplify sched_balance_newidle()

 - Bump SCHEDSTAT_VERSION to 16 due to a cleanup of CPU_MAX_IDLE_TYPES
   handling that changed the output.

 - Rework & clean up <asm/vtime.h> interactions wrt arch_vtime_task_switch()

 - Reorganize, clean up and unify most of the higher level
   scheduler balancing function names around the sched_balance_*()
   prefix

 - Simplify the balancing flag code (sched_balance_running)

 - Miscellaneous cleanups & fixes

* tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
  sched/pelt: Remove shift of thermal clock
  sched/cpufreq: Rename arch_update_thermal_pressure() => arch_update_hw_pressure()
  thermal/cpufreq: Remove arch_update_thermal_pressure()
  sched/cpufreq: Take cpufreq feedback into account
  cpufreq: Add a cpufreq pressure feedback for the scheduler
  sched/fair: Fix update of rd->sg_overutilized
  sched/vtime: Do not include <asm/vtime.h> header
  s390/irq,nmi: Include <asm/vtime.h> header directly
  s390/vtime: Remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover
  sched/vtime: Get rid of generic vtime_task_switch() implementation
  sched/vtime: Remove confusing arch_vtime_task_switch() declaration
  sched/balancing: Simplify the sg_status bitmask and use separate ->overloaded and ->overutilized flags
  sched/fair: Rename set_rd_overutilized_status() to set_rd_overutilized()
  sched/fair: Rename SG_OVERLOAD to SG_OVERLOADED
  sched/fair: Rename {set|get}_rd_overload() to {set|get}_rd_overloaded()
  sched/fair: Rename root_domain::overload to ::overloaded
  sched/fair: Use helper functions to access root_domain::overload
  sched/fair: Check root_domain::overload value before update
  sched/fair: Combine EAS check with root_domain::overutilized access
  sched/fair: Simplify the continue_balancing logic in sched_balance_newidle()
  ...







Merge tag 'perf-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2024-05-14T00:13:47+00:00

Linus Torvalds
torvalds@linux-foundation.org

2024-05-14T00:13:47+00:00

17ca7fc22f4bbc795e4d136449521b2fecb88e06

Pull perf events updates from Ingo Molnar:

 - Combine perf and BPF for fast evalution of HW breakpoint
   conditions

 - Add LBR capture support outside of hardware events

 - Trigger IO signals for watermark_wakeup

 - Add RAPL support for Intel Arrow Lake and Lunar Lake

 - Optimize frequency-throttling

 - Miscellaneous cleanups & fixes

* tag 'perf-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  perf/bpf: Mark perf_event_set_bpf_handler() and perf_event_free_bpf_handler() as inline too
  selftests/perf_events: Test FASYNC with watermark wakeups
  perf/ring_buffer: Trigger IO signals for watermark_wakeup
  perf: Move perf_event_fasync() to perf_event.h
  perf/bpf: Change the !CONFIG_BPF_SYSCALL stubs to static inlines
  selftest/bpf: Test a perf BPF program that suppresses side effects
  perf/bpf: Allow a BPF program to suppress all sample side effects
  perf/bpf: Remove unneeded uses_default_overflow_handler()
  perf/bpf: Call BPF handler directly, not through overflow machinery
  perf/bpf: Remove #ifdef CONFIG_BPF_SYSCALL from struct perf_event members
  perf/bpf: Create bpf_overflow_handler() stub for !CONFIG_BPF_SYSCALL
  perf/bpf: Reorder bpf_overflow_handler() ahead of __perf_event_overflow()
  perf/x86/rapl: Add support for Intel Lunar Lake
  perf/x86/rapl: Add support for Intel Arrow Lake
  perf/core: Reduce PMU access to adjust sample freq
  perf/core: Optimize perf_adjust_freq_unthr_context()
  perf/x86/amd: Don't reject non-sampling events with configured LBR
  perf/x86/amd: Support capturing LBR from software events
  perf/x86/amd: Avoid taking branches before disabling LBR
  perf/x86/amd: Ensure amd_pmu_core_disable_all() is always inlined
  ...





Pull perf events updates from Ingo Molnar:

 - Combine perf and BPF for fast evalution of HW breakpoint
   conditions

 - Add LBR capture support outside of hardware events

 - Trigger IO signals for watermark_wakeup

 - Add RAPL support for Intel Arrow Lake and Lunar Lake

 - Optimize frequency-throttling

 - Miscellaneous cleanups & fixes

* tag 'perf-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (21 commits)
  perf/bpf: Mark perf_event_set_bpf_handler() and perf_event_free_bpf_handler() as inline too
  selftests/perf_events: Test FASYNC with watermark wakeups
  perf/ring_buffer: Trigger IO signals for watermark_wakeup
  perf: Move perf_event_fasync() to perf_event.h
  perf/bpf: Change the !CONFIG_BPF_SYSCALL stubs to static inlines
  selftest/bpf: Test a perf BPF program that suppresses side effects
  perf/bpf: Allow a BPF program to suppress all sample side effects
  perf/bpf: Remove unneeded uses_default_overflow_handler()
  perf/bpf: Call BPF handler directly, not through overflow machinery
  perf/bpf: Remove #ifdef CONFIG_BPF_SYSCALL from struct perf_event members
  perf/bpf: Create bpf_overflow_handler() stub for !CONFIG_BPF_SYSCALL
  perf/bpf: Reorder bpf_overflow_handler() ahead of __perf_event_overflow()
  perf/x86/rapl: Add support for Intel Lunar Lake
  perf/x86/rapl: Add support for Intel Arrow Lake
  perf/core: Reduce PMU access to adjust sample freq
  perf/core: Optimize perf_adjust_freq_unthr_context()
  perf/x86/amd: Don't reject non-sampling events with configured LBR
  perf/x86/amd: Support capturing LBR from software events
  perf/x86/amd: Avoid taking branches before disabling LBR
  perf/x86/amd: Ensure amd_pmu_core_disable_all() is always inlined
  ...







ARM: 9391/2: hw_breakpoint: Handle CFI breakpoints
2024-04-29T13:14:22+00:00

Linus Walleij
linus.walleij@linaro.org

2024-04-23T07:53:09+00:00

c3f89986fde7bb9ccc86a901bf28e1f7d69fc3b3

This registers a breakpoint handler for the new breakpoint type
(0x03) inserted by LLVM CLANG for CFI breakpoints.

If we are in permissive mode, just print a backtrace and continue.

Example with CONFIG_CFI_PERMISSIVE enabled:

> echo CFI_FORWARD_PROTO > /sys/kernel/debug/provoke-crash/DIRECT
lkdtm: Performing direct entry CFI_FORWARD_PROTO
lkdtm: Calling matched prototype ...
lkdtm: Calling mismatched prototype ...
CFI failure at lkdtm_indirect_call+0x40/0x4c (target: 0x0; expected type: 0x00000000)
WARNING: CPU: 1 PID: 112 at lkdtm_indirect_call+0x40/0x4c
CPU: 1 PID: 112 Comm: sh Not tainted 6.8.0-rc1+ #150
Hardware name: ARM-Versatile Express
(...)
lkdtm: FAIL: survived mismatched prototype function call!
lkdtm: Unexpected! This kernel (6.8.0-rc1+ armv7l) was built with CONFIG_CFI_CLANG=y

As you can see the LKDTM test fails, but I expect that this would be
expected behaviour in the permissive mode.

We are currently not implementing target and type for the CFI
breakpoint as this requires additional operand bundling compiler
extensions.

CPUs without breakpoint support cannot handle breakpoints naturally,
in these cases the permissive mode will not work, CFI will fall over
on an undefined instruction:

Internal error: Oops - undefined instruction: 0 [#1] PREEMPT ARM
CPU: 0 PID: 186 Comm: ash Tainted: G        W          6.9.0-rc1+ #7
Hardware name: Gemini (Device Tree)
PC is at lkdtm_indirect_call+0x38/0x4c
LR is at lkdtm_CFI_FORWARD_PROTO+0x30/0x6c

This is reasonable I think: it's the best CFI can do to ascertain
the the control flow is not broken on these CPUs.

Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>





This registers a breakpoint handler for the new breakpoint type
(0x03) inserted by LLVM CLANG for CFI breakpoints.

If we are in permissive mode, just print a backtrace and continue.

Example with CONFIG_CFI_PERMISSIVE enabled:

> echo CFI_FORWARD_PROTO > /sys/kernel/debug/provoke-crash/DIRECT
lkdtm: Performing direct entry CFI_FORWARD_PROTO
lkdtm: Calling matched prototype ...
lkdtm: Calling mismatched prototype ...
CFI failure at lkdtm_indirect_call+0x40/0x4c (target: 0x0; expected type: 0x00000000)
WARNING: CPU: 1 PID: 112 at lkdtm_indirect_call+0x40/0x4c
CPU: 1 PID: 112 Comm: sh Not tainted 6.8.0-rc1+ #150
Hardware name: ARM-Versatile Express
(...)
lkdtm: FAIL: survived mismatched prototype function call!
lkdtm: Unexpected! This kernel (6.8.0-rc1+ armv7l) was built with CONFIG_CFI_CLANG=y

As you can see the LKDTM test fails, but I expect that this would be
expected behaviour in the permissive mode.

We are currently not implementing target and type for the CFI
breakpoint as this requires additional operand bundling compiler
extensions.

CPUs without breakpoint support cannot handle breakpoints naturally,
in these cases the permissive mode will not work, CFI will fall over
on an undefined instruction:

Internal error: Oops - undefined instruction: 0 [#1] PREEMPT ARM
CPU: 0 PID: 186 Comm: ash Tainted: G        W          6.9.0-rc1+ #7
Hardware name: Gemini (Device Tree)
PC is at lkdtm_indirect_call+0x38/0x4c
LR is at lkdtm_CFI_FORWARD_PROTO+0x30/0x6c

This is reasonable I think: it's the best CFI can do to ascertain
the the control flow is not broken on these CPUs.

Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>







ARM: 9381/1: kasan: clear stale stack poison
2024-04-29T13:11:25+00:00

Boy.Wu
boy.wu@mediatek.com

2024-04-15T04:21:55+00:00

c4238686f9093b98bd6245a348bcf059cdce23af

We found below OOB crash:

[   33.452494] ==================================================================
[   33.453513] BUG: KASAN: stack-out-of-bounds in refresh_cpu_vm_stats.constprop.0+0xcc/0x2ec
[   33.454660] Write of size 164 at addr c1d03d30 by task swapper/0/0
[   33.455515]
[   33.455767] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G           O       6.1.25-mainline #1
[   33.456880] Hardware name: Generic DT based system
[   33.457555]  unwind_backtrace from show_stack+0x18/0x1c
[   33.458326]  show_stack from dump_stack_lvl+0x40/0x4c
[   33.459072]  dump_stack_lvl from print_report+0x158/0x4a4
[   33.459863]  print_report from kasan_report+0x9c/0x148
[   33.460616]  kasan_report from kasan_check_range+0x94/0x1a0
[   33.461424]  kasan_check_range from memset+0x20/0x3c
[   33.462157]  memset from refresh_cpu_vm_stats.constprop.0+0xcc/0x2ec
[   33.463064]  refresh_cpu_vm_stats.constprop.0 from tick_nohz_idle_stop_tick+0x180/0x53c
[   33.464181]  tick_nohz_idle_stop_tick from do_idle+0x264/0x354
[   33.465029]  do_idle from cpu_startup_entry+0x20/0x24
[   33.465769]  cpu_startup_entry from rest_init+0xf0/0xf4
[   33.466528]  rest_init from arch_post_acpi_subsys_init+0x0/0x18
[   33.467397]
[   33.467644] The buggy address belongs to stack of task swapper/0/0
[   33.468493]  and is located at offset 112 in frame:
[   33.469172]  refresh_cpu_vm_stats.constprop.0+0x0/0x2ec
[   33.469917]
[   33.470165] This frame has 2 objects:
[   33.470696]  [32, 76) 'global_zone_diff'
[   33.470729]  [112, 276) 'global_node_diff'
[   33.471294]
[   33.472095] The buggy address belongs to the physical page:
[   33.472862] page:3cd72da8 refcount:1 mapcount:0 mapping:00000000 index:0x0 pfn:0x41d03
[   33.473944] flags: 0x1000(reserved|zone=0)
[   33.474565] raw: 00001000 ed741470 ed741470 00000000 00000000 00000000 ffffffff 00000001
[   33.475656] raw: 00000000
[   33.476050] page dumped because: kasan: bad access detected
[   33.476816]
[   33.477061] Memory state around the buggy address:
[   33.477732]  c1d03c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   33.478630]  c1d03c80: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
[   33.479526] >c1d03d00: 00 04 f2 f2 f2 f2 00 00 00 00 00 00 f1 f1 f1 f1
[   33.480415]                                                ^
[   33.481195]  c1d03d80: 00 00 00 00 00 00 00 00 00 00 04 f3 f3 f3 f3 f3
[   33.482088]  c1d03e00: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
[   33.482978] ==================================================================

We find the root cause of this OOB is that arm does not clear stale stack
poison in the case of cpuidle.

This patch refer to arch/arm64/kernel/sleep.S to resolve this issue.

From cited commit [1] that explain the problem

Functions which the compiler has instrumented for KASAN place poison on
the stack shadow upon entry and remove this poison prior to returning.

In the case of cpuidle, CPUs exit the kernel a number of levels deep in
C code.  Any instrumented functions on this critical path will leave
portions of the stack shadow poisoned.

If CPUs lose context and return to the kernel via a cold path, we
restore a prior context saved in __cpu_suspend_enter are forgotten, and
we never remove the poison they placed in the stack shadow area by
functions calls between this and the actual exit of the kernel.

Thus, (depending on stackframe layout) subsequent calls to instrumented
functions may hit this stale poison, resulting in (spurious) KASAN
splats to the console.

To avoid this, clear any stale poison from the idle thread for a CPU
prior to bringing a CPU online.

From cited commit [2]

Extend to check for CONFIG_KASAN_STACK

[1] commit 0d97e6d8024c ("arm64: kasan: clear stale stack poison")
[2] commit d56a9ef84bd0 ("kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK")

Signed-off-by: Boy Wu <boy.wu@mediatek.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Fixes: 5615f69bc209 ("ARM: 9016/2: Initialize the mapping of KASan shadow memory")
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>





We found below OOB crash:

[   33.452494] ==================================================================
[   33.453513] BUG: KASAN: stack-out-of-bounds in refresh_cpu_vm_stats.constprop.0+0xcc/0x2ec
[   33.454660] Write of size 164 at addr c1d03d30 by task swapper/0/0
[   33.455515]
[   33.455767] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G           O       6.1.25-mainline #1
[   33.456880] Hardware name: Generic DT based system
[   33.457555]  unwind_backtrace from show_stack+0x18/0x1c
[   33.458326]  show_stack from dump_stack_lvl+0x40/0x4c
[   33.459072]  dump_stack_lvl from print_report+0x158/0x4a4
[   33.459863]  print_report from kasan_report+0x9c/0x148
[   33.460616]  kasan_report from kasan_check_range+0x94/0x1a0
[   33.461424]  kasan_check_range from memset+0x20/0x3c
[   33.462157]  memset from refresh_cpu_vm_stats.constprop.0+0xcc/0x2ec
[   33.463064]  refresh_cpu_vm_stats.constprop.0 from tick_nohz_idle_stop_tick+0x180/0x53c
[   33.464181]  tick_nohz_idle_stop_tick from do_idle+0x264/0x354
[   33.465029]  do_idle from cpu_startup_entry+0x20/0x24
[   33.465769]  cpu_startup_entry from rest_init+0xf0/0xf4
[   33.466528]  rest_init from arch_post_acpi_subsys_init+0x0/0x18
[   33.467397]
[   33.467644] The buggy address belongs to stack of task swapper/0/0
[   33.468493]  and is located at offset 112 in frame:
[   33.469172]  refresh_cpu_vm_stats.constprop.0+0x0/0x2ec
[   33.469917]
[   33.470165] This frame has 2 objects:
[   33.470696]  [32, 76) 'global_zone_diff'
[   33.470729]  [112, 276) 'global_node_diff'
[   33.471294]
[   33.472095] The buggy address belongs to the physical page:
[   33.472862] page:3cd72da8 refcount:1 mapcount:0 mapping:00000000 index:0x0 pfn:0x41d03
[   33.473944] flags: 0x1000(reserved|zone=0)
[   33.474565] raw: 00001000 ed741470 ed741470 00000000 00000000 00000000 ffffffff 00000001
[   33.475656] raw: 00000000
[   33.476050] page dumped because: kasan: bad access detected
[   33.476816]
[   33.477061] Memory state around the buggy address:
[   33.477732]  c1d03c00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   33.478630]  c1d03c80: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 00
[   33.479526] >c1d03d00: 00 04 f2 f2 f2 f2 00 00 00 00 00 00 f1 f1 f1 f1
[   33.480415]                                                ^
[   33.481195]  c1d03d80: 00 00 00 00 00 00 00 00 00 00 04 f3 f3 f3 f3 f3
[   33.482088]  c1d03e00: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
[   33.482978] ==================================================================

We find the root cause of this OOB is that arm does not clear stale stack
poison in the case of cpuidle.

This patch refer to arch/arm64/kernel/sleep.S to resolve this issue.

From cited commit [1] that explain the problem

Functions which the compiler has instrumented for KASAN place poison on
the stack shadow upon entry and remove this poison prior to returning.

In the case of cpuidle, CPUs exit the kernel a number of levels deep in
C code.  Any instrumented functions on this critical path will leave
portions of the stack shadow poisoned.

If CPUs lose context and return to the kernel via a cold path, we
restore a prior context saved in __cpu_suspend_enter are forgotten, and
we never remove the poison they placed in the stack shadow area by
functions calls between this and the actual exit of the kernel.

Thus, (depending on stackframe layout) subsequent calls to instrumented
functions may hit this stale poison, resulting in (spurious) KASAN
splats to the console.

To avoid this, clear any stale poison from the idle thread for a CPU
prior to bringing a CPU online.

From cited commit [2]

Extend to check for CONFIG_KASAN_STACK

[1] commit 0d97e6d8024c ("arm64: kasan: clear stale stack poison")
[2] commit d56a9ef84bd0 ("kasan, arm64: unpoison stack only with CONFIG_KASAN_STACK")

Signed-off-by: Boy Wu <boy.wu@mediatek.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Fixes: 5615f69bc209 ("ARM: 9016/2: Initialize the mapping of KASan shadow memory")
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>