Commit Graph

129 Commits

Author SHA1 Message Date
Christophe Leroy 353e7300a1 kcsan: Don't expect 64 bits atomic builtins from 32 bits architectures
Activating KCSAN on a 32 bits architecture leads to the following
link-time failure:

    LD      .tmp_vmlinux.kallsyms1
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_load':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_load_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_store':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_store_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_exchange':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_exchange_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_fetch_add':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_fetch_add_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_fetch_sub':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_fetch_sub_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_fetch_and':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_fetch_and_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_fetch_or':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_fetch_or_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_fetch_xor':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_fetch_xor_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_fetch_nand':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_fetch_nand_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_compare_exchange_strong':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_compare_exchange_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_compare_exchange_weak':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_compare_exchange_8'
  powerpc64-linux-ld: kernel/kcsan/core.o: in function `__tsan_atomic64_compare_exchange_val':
  kernel/kcsan/core.c:1273: undefined reference to `__atomic_compare_exchange_8'

32 bits architectures don't have 64 bits atomic builtins. Only
include DEFINE_TSAN_ATOMIC_OPS(64) on 64 bits architectures.

Fixes: 0f8ad5f2e9 ("kcsan: Add support for atomic builtins")
Suggested-by: Marco Elver <elver@google.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/d9c6afc28d0855240171a4e0ad9ffcdb9d07fceb.1683892665.git.christophe.leroy@csgroup.eu
2023-06-09 23:29:50 +10:00
Linus Torvalds 7fa8a8ee94 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
switching from a user process to a kernel thread.
 
 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj Raghav.
 
 - zsmalloc performance improvements from Sergey Senozhatsky.
 
 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.
 
 - VFS rationalizations from Christoph Hellwig:
 
   - removal of most of the callers of write_one_page().
 
   - make __filemap_get_folio()'s return value more useful
 
 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing.  Use `mount -o noswap'.
 
 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.
 
 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).
 
 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.
 
 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive rather
   than exclusive, and has fixed a bunch of errors which were caused by its
   unintuitive meaning.
 
 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.
 
 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.
 
 - Cleanups to do_fault_around() by Lorenzo Stoakes.
 
 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.
 
 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.
 
 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.
 
 - Lorenzo has also contributed further cleanups of vma_merge().
 
 - Chaitanya Prakash provides some fixes to the mmap selftesting code.
 
 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.
 
 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.
 
 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.
 
 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.
 
 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.
 
 - Yosry Ahmed has improved the performance of memcg statistics flushing.
 
 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.
 
 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.
 
 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.
 
 - Pankaj Raghav has made page_endio() unneeded and has removed it.
 
 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.
 
 - Yosry Ahmed has fixed an issue around memcg's page recalim accounting.
 
 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.
 
 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.
 
 - Peter Xu fixes a few issues with uffd-wp at fork() time.
 
 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.
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Merge tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
   switching from a user process to a kernel thread.

 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
   Raghav.

 - zsmalloc performance improvements from Sergey Senozhatsky.

 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.

 - VFS rationalizations from Christoph Hellwig:
     - removal of most of the callers of write_one_page()
     - make __filemap_get_folio()'s return value more useful

 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing. Use `mount -o noswap'.

 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.

 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).

 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.

 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
   rather than exclusive, and has fixed a bunch of errors which were
   caused by its unintuitive meaning.

 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.

 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.

 - Cleanups to do_fault_around() by Lorenzo Stoakes.

 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.

 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.

 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.

 - Lorenzo has also contributed further cleanups of vma_merge().

 - Chaitanya Prakash provides some fixes to the mmap selftesting code.

 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.

 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.

 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.

 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.

 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.

 - Yosry Ahmed has improved the performance of memcg statistics
   flushing.

 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.

 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.

 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.

 - Pankaj Raghav has made page_endio() unneeded and has removed it.

 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.

 - Yosry Ahmed has fixed an issue around memcg's page recalim
   accounting.

 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.

 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.

 - Peter Xu fixes a few issues with uffd-wp at fork() time.

 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.

* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
  shmem: restrict noswap option to initial user namespace
  mm/khugepaged: fix conflicting mods to collapse_file()
  sparse: remove unnecessary 0 values from rc
  mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
  hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
  maple_tree: fix allocation in mas_sparse_area()
  mm: do not increment pgfault stats when page fault handler retries
  zsmalloc: allow only one active pool compaction context
  selftests/mm: add new selftests for KSM
  mm: add new KSM process and sysfs knobs
  mm: add new api to enable ksm per process
  mm: shrinkers: fix debugfs file permissions
  mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
  migrate_pages_batch: fix statistics for longterm pin retry
  userfaultfd: use helper function range_in_vma()
  lib/show_mem.c: use for_each_populated_zone() simplify code
  mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
  fs/buffer: convert create_page_buffers to folio_create_buffers
  fs/buffer: add folio_create_empty_buffers helper
  ...
2023-04-27 19:42:02 -07:00
Linus Torvalds 022e32094e Kernel concurrency sanitizer (KCSAN) updates for v6.4
This update fixes kernel-doc warnings and also updates instrumentation
 from READ_ONCE() to volatile in order to avoid unaligned load-acquire
 instructions on arm64 in kernels built with LTO.
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Merge tag 'kcsan.2023.04.04a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull KCSAN updates from Paul McKenney:
 "Kernel concurrency sanitizer (KCSAN) updates for v6.4

  This fixes kernel-doc warnings and also updates instrumentation from
  READ_ONCE() to volatile in order to avoid unaligned load-acquire
  instructions on arm64 in kernels built with LTO"

* tag 'kcsan.2023.04.04a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  kcsan: Avoid READ_ONCE() in read_instrumented_memory()
  instrumented.h: Fix all kernel-doc format warnings
2023-04-24 11:46:53 -07:00
Pavankumar Kondeti 1f6ab566cb printk: export console trace point for kcsan/kasan/kfence/kmsan
The console tracepoint is used by kcsan/kasan/kfence/kmsan test modules. 
Since this tracepoint is not exported, these modules iterate over all
available tracepoints to find the console trace point.  Export the trace
point so that it can be directly used.

Link: https://lkml.kernel.org/r/20230413100859.1492323-1-quic_pkondeti@quicinc.com
Signed-off-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Marco Elver <elver@google.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-04-18 16:30:11 -07:00
Marco Elver 5eb39cde1e kcsan: avoid passing -g for test
Nathan reported that when building with GNU as and a version of clang that
defaults to DWARF5, the assembler will complain with:

  Error: non-constant .uleb128 is not supported

This is because `-g` defaults to the compiler debug info default. If the
assembler does not support some of the directives used, the above errors
occur. To fix, remove the explicit passing of `-g`.

All the test wants is that stack traces print valid function names, and
debug info is not required for that. (I currently cannot recall why I
added the explicit `-g`.)

Link: https://lkml.kernel.org/r/20230316224705.709984-2-elver@google.com
Fixes: 1fe84fd4a4 ("kcsan: Add test suite")
Signed-off-by: Marco Elver <elver@google.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-03-23 17:18:35 -07:00
Marco Elver 8dec88070d kcsan: Avoid READ_ONCE() in read_instrumented_memory()
Haibo Li reported:

 | Unable to handle kernel paging request at virtual address
 |   ffffff802a0d8d7171
 | Mem abort info
 |   ESR = 0x9600002121
 |   EC = 0x25: DABT (current EL), IL = 32 bitsts
 |   SET = 0, FnV = 0 0
 |   EA = 0, S1PTW = 0 0
 |   FSC = 0x21: alignment fault
 | Data abort info
 |   ISV = 0, ISS = 0x0000002121
 |   CM = 0, WnR = 0 0
 | swapper pgtable: 4k pages, 39-bit VAs, pgdp=000000002835200000
 | [ffffff802a0d8d71] pgd=180000005fbf9003, p4d=180000005fbf9003,
 | pud=180000005fbf9003, pmd=180000005fbe8003, pte=006800002a0d8707
 | Internal error: Oops: 96000021 [#1] PREEMPT SMP
 | Modules linked in:
 | CPU: 2 PID: 45 Comm: kworker/u8:2 Not tainted
 |   5.15.78-android13-8-g63561175bbda-dirty #1
 | ...
 | pc : kcsan_setup_watchpoint+0x26c/0x6bc
 | lr : kcsan_setup_watchpoint+0x88/0x6bc
 | sp : ffffffc00ab4b7f0
 | x29: ffffffc00ab4b800 x28: ffffff80294fe588 x27: 0000000000000001
 | x26: 0000000000000019 x25: 0000000000000001 x24: ffffff80294fdb80
 | x23: 0000000000000000 x22: ffffffc00a70fb68 x21: ffffff802a0d8d71
 | x20: 0000000000000002 x19: 0000000000000000 x18: ffffffc00a9bd060
 | x17: 0000000000000001 x16: 0000000000000000 x15: ffffffc00a59f000
 | x14: 0000000000000001 x13: 0000000000000000 x12: ffffffc00a70faa0
 | x11: 00000000aaaaaaab x10: 0000000000000054 x9 : ffffffc00839adf8
 | x8 : ffffffc009b4cf00 x7 : 0000000000000000 x6 : 0000000000000007
 | x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffffffc00a70fb70
 | x2 : 0005ff802a0d8d71 x1 : 0000000000000000 x0 : 0000000000000000
 | Call trace:
 |  kcsan_setup_watchpoint+0x26c/0x6bc
 |  __tsan_read2+0x1f0/0x234
 |  inflate_fast+0x498/0x750
 |  zlib_inflate+0x1304/0x2384
 |  __gunzip+0x3a0/0x45c
 |  gunzip+0x20/0x30
 |  unpack_to_rootfs+0x2a8/0x3fc
 |  do_populate_rootfs+0xe8/0x11c
 |  async_run_entry_fn+0x58/0x1bc
 |  process_one_work+0x3ec/0x738
 |  worker_thread+0x4c4/0x838
 |  kthread+0x20c/0x258
 |  ret_from_fork+0x10/0x20
 | Code: b8bfc2a8 2a0803f7 14000007 d503249f (78bfc2a8) )
 | ---[ end trace 613a943cb0a572b6 ]-----

The reason for this is that on certain arm64 configuration since
e35123d83e ("arm64: lto: Strengthen READ_ONCE() to acquire when
CONFIG_LTO=y"), READ_ONCE() may be promoted to a full atomic acquire
instruction which cannot be used on unaligned addresses.

Fix it by avoiding READ_ONCE() in read_instrumented_memory(), and simply
forcing the compiler to do the required access by casting to the
appropriate volatile type. In terms of generated code this currently
only affects architectures that do not use the default READ_ONCE()
implementation.

The only downside is that we are not guaranteed atomicity of the access
itself, although on most architectures a plain load up to machine word
size should still be atomic (a fact the default READ_ONCE() still relies
on itself).

Reported-by: Haibo Li <haibo.li@mediatek.com>
Tested-by: Haibo Li <haibo.li@mediatek.com>
Cc: <stable@vger.kernel.org> # 5.17+
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-03-11 12:28:07 -08:00
Max Filippov 5b24ac2dfd kcsan: test: don't put the expect array on the stack
Size of the 'expect' array in the __report_matches is 1536 bytes, which
is exactly the default frame size warning limit of the xtensa
architecture.
As a result allmodconfig xtensa kernel builds with the gcc that does not
support the compiler plugins (which otherwise would push the said
warning limit to 2K) fail with the following message:

  kernel/kcsan/kcsan_test.c:257:1: error: the frame size of 1680 bytes
    is larger than 1536 bytes

Fix it by dynamically allocating the 'expect' array.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Tested-by: Marco Elver <elver@google.com>
2023-01-02 08:59:33 -08:00
Linus Torvalds 48ea09cdda hardening updates for v6.2-rc1
- Convert flexible array members, fix -Wstringop-overflow warnings,
   and fix KCFI function type mismatches that went ignored by
   maintainers (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook).
 
 - Remove the remaining side-effect users of ksize() by converting
   dma-buf, btrfs, and coredump to using kmalloc_size_roundup(),
   add more __alloc_size attributes, and introduce full testing
   of all allocator functions. Finally remove the ksize() side-effect
   so that each allocation-aware checker can finally behave without
   exceptions.
 
 - Introduce oops_limit (default 10,000) and warn_limit (default off)
   to provide greater granularity of control for panic_on_oops and
   panic_on_warn (Jann Horn, Kees Cook).
 
 - Introduce overflows_type() and castable_to_type() helpers for
   cleaner overflow checking.
 
 - Improve code generation for strscpy() and update str*() kern-doc.
 
 - Convert strscpy and sigphash tests to KUnit, and expand memcpy
   tests.
 
 - Always use a non-NULL argument for prepare_kernel_cred().
 
 - Disable structleak plugin in FORTIFY KUnit test (Anders Roxell).
 
 - Adjust orphan linker section checking to respect CONFIG_WERROR
   (Xin Li).
 
 - Make sure siginfo is cleared for forced SIGKILL (haifeng.xu).
 
 - Fix um vs FORTIFY warnings for always-NULL arguments.
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Merge tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull kernel hardening updates from Kees Cook:

 - Convert flexible array members, fix -Wstringop-overflow warnings, and
   fix KCFI function type mismatches that went ignored by maintainers
   (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook)

 - Remove the remaining side-effect users of ksize() by converting
   dma-buf, btrfs, and coredump to using kmalloc_size_roundup(), add
   more __alloc_size attributes, and introduce full testing of all
   allocator functions. Finally remove the ksize() side-effect so that
   each allocation-aware checker can finally behave without exceptions

 - Introduce oops_limit (default 10,000) and warn_limit (default off) to
   provide greater granularity of control for panic_on_oops and
   panic_on_warn (Jann Horn, Kees Cook)

 - Introduce overflows_type() and castable_to_type() helpers for cleaner
   overflow checking

 - Improve code generation for strscpy() and update str*() kern-doc

 - Convert strscpy and sigphash tests to KUnit, and expand memcpy tests

 - Always use a non-NULL argument for prepare_kernel_cred()

 - Disable structleak plugin in FORTIFY KUnit test (Anders Roxell)

 - Adjust orphan linker section checking to respect CONFIG_WERROR (Xin
   Li)

 - Make sure siginfo is cleared for forced SIGKILL (haifeng.xu)

 - Fix um vs FORTIFY warnings for always-NULL arguments

* tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (31 commits)
  ksmbd: replace one-element arrays with flexible-array members
  hpet: Replace one-element array with flexible-array member
  um: virt-pci: Avoid GCC non-NULL warning
  signal: Initialize the info in ksignal
  lib: fortify_kunit: build without structleak plugin
  panic: Expose "warn_count" to sysfs
  panic: Introduce warn_limit
  panic: Consolidate open-coded panic_on_warn checks
  exit: Allow oops_limit to be disabled
  exit: Expose "oops_count" to sysfs
  exit: Put an upper limit on how often we can oops
  panic: Separate sysctl logic from CONFIG_SMP
  mm/pgtable: Fix multiple -Wstringop-overflow warnings
  mm: Make ksize() a reporting-only function
  kunit/fortify: Validate __alloc_size attribute results
  drm/sti: Fix return type of sti_{dvo,hda,hdmi}_connector_mode_valid()
  drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
  driver core: Add __alloc_size hint to devm allocators
  overflow: Introduce overflows_type() and castable_to_type()
  coredump: Proactively round up to kmalloc bucket size
  ...
2022-12-14 12:20:00 -08:00
Linus Torvalds 8702f2c611 Non-MM patches for 6.2-rc1.
- A ptrace API cleanup series from Sergey Shtylyov
 
 - Fixes and cleanups for kexec from ye xingchen
 
 - nilfs2 updates from Ryusuke Konishi
 
 - squashfs feature work from Xiaoming Ni: permit configuration of the
   filesystem's compression concurrency from the mount command line.
 
 - A series from Akinobu Mita which addresses bound checking errors when
   writing to debugfs files.
 
 - A series from Yang Yingliang to address rapido memory leaks
 
 - A series from Zheng Yejian to address possible overflow errors in
   encode_comp_t().
 
 - And a whole shower of singleton patches all over the place.
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Merge tag 'mm-nonmm-stable-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - A ptrace API cleanup series from Sergey Shtylyov

 - Fixes and cleanups for kexec from ye xingchen

 - nilfs2 updates from Ryusuke Konishi

 - squashfs feature work from Xiaoming Ni: permit configuration of the
   filesystem's compression concurrency from the mount command line

 - A series from Akinobu Mita which addresses bound checking errors when
   writing to debugfs files

 - A series from Yang Yingliang to address rapidio memory leaks

 - A series from Zheng Yejian to address possible overflow errors in
   encode_comp_t()

 - And a whole shower of singleton patches all over the place

* tag 'mm-nonmm-stable-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (79 commits)
  ipc: fix memory leak in init_mqueue_fs()
  hfsplus: fix bug causing custom uid and gid being unable to be assigned with mount
  rapidio: devices: fix missing put_device in mport_cdev_open
  kcov: fix spelling typos in comments
  hfs: Fix OOB Write in hfs_asc2mac
  hfs: fix OOB Read in __hfs_brec_find
  relay: fix type mismatch when allocating memory in relay_create_buf()
  ocfs2: always read both high and low parts of dinode link count
  io-mapping: move some code within the include guarded section
  kernel: kcsan: kcsan_test: build without structleak plugin
  mailmap: update email for Iskren Chernev
  eventfd: change int to __u64 in eventfd_signal() ifndef CONFIG_EVENTFD
  rapidio: fix possible UAF when kfifo_alloc() fails
  relay: use strscpy() is more robust and safer
  cpumask: limit visibility of FORCE_NR_CPUS
  acct: fix potential integer overflow in encode_comp_t()
  acct: fix accuracy loss for input value of encode_comp_t()
  linux/init.h: include <linux/build_bug.h> and <linux/stringify.h>
  rapidio: rio: fix possible name leak in rio_register_mport()
  rapidio: fix possible name leaks when rio_add_device() fails
  ...
2022-12-12 17:28:58 -08:00
Linus Torvalds 268325bda5 Random number generator updates for Linux 6.2-rc1.
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Merge tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

Pull random number generator updates from Jason Donenfeld:

 - Replace prandom_u32_max() and various open-coded variants of it,
   there is now a new family of functions that uses fast rejection
   sampling to choose properly uniformly random numbers within an
   interval:

       get_random_u32_below(ceil) - [0, ceil)
       get_random_u32_above(floor) - (floor, U32_MAX]
       get_random_u32_inclusive(floor, ceil) - [floor, ceil]

   Coccinelle was used to convert all current users of
   prandom_u32_max(), as well as many open-coded patterns, resulting in
   improvements throughout the tree.

   I'll have a "late" 6.1-rc1 pull for you that removes the now unused
   prandom_u32_max() function, just in case any other trees add a new
   use case of it that needs to converted. According to linux-next,
   there may be two trivial cases of prandom_u32_max() reintroductions
   that are fixable with a 's/.../.../'. So I'll have for you a final
   conversion patch doing that alongside the removal patch during the
   second week.

   This is a treewide change that touches many files throughout.

 - More consistent use of get_random_canary().

 - Updates to comments, documentation, tests, headers, and
   simplification in configuration.

 - The arch_get_random*_early() abstraction was only used by arm64 and
   wasn't entirely useful, so this has been replaced by code that works
   in all relevant contexts.

 - The kernel will use and manage random seeds in non-volatile EFI
   variables, refreshing a variable with a fresh seed when the RNG is
   initialized. The RNG GUID namespace is then hidden from efivarfs to
   prevent accidental leakage.

   These changes are split into random.c infrastructure code used in the
   EFI subsystem, in this pull request, and related support inside of
   EFISTUB, in Ard's EFI tree. These are co-dependent for full
   functionality, but the order of merging doesn't matter.

 - Part of the infrastructure added for the EFI support is also used for
   an improvement to the way vsprintf initializes its siphash key,
   replacing an sleep loop wart.

 - The hardware RNG framework now always calls its correct random.c
   input function, add_hwgenerator_randomness(), rather than sometimes
   going through helpers better suited for other cases.

 - The add_latent_entropy() function has long been called from the fork
   handler, but is a no-op when the latent entropy gcc plugin isn't
   used, which is fine for the purposes of latent entropy.

   But it was missing out on the cycle counter that was also being mixed
   in beside the latent entropy variable. So now, if the latent entropy
   gcc plugin isn't enabled, add_latent_entropy() will expand to a call
   to add_device_randomness(NULL, 0), which adds a cycle counter,
   without the absent latent entropy variable.

 - The RNG is now reseeded from a delayed worker, rather than on demand
   when used. Always running from a worker allows it to make use of the
   CPU RNG on platforms like S390x, whose instructions are too slow to
   do so from interrupts. It also has the effect of adding in new inputs
   more frequently with more regularity, amounting to a long term
   transcript of random values. Plus, it helps a bit with the upcoming
   vDSO implementation (which isn't yet ready for 6.2).

 - The jitter entropy algorithm now tries to execute on many different
   CPUs, round-robining, in hopes of hitting even more memory latencies
   and other unpredictable effects. It also will mix in a cycle counter
   when the entropy timer fires, in addition to being mixed in from the
   main loop, to account more explicitly for fluctuations in that timer
   firing. And the state it touches is now kept within the same cache
   line, so that it's assured that the different execution contexts will
   cause latencies.

* tag 'random-6.2-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (23 commits)
  random: include <linux/once.h> in the right header
  random: align entropy_timer_state to cache line
  random: mix in cycle counter when jitter timer fires
  random: spread out jitter callback to different CPUs
  random: remove extraneous period and add a missing one in comments
  efi: random: refresh non-volatile random seed when RNG is initialized
  vsprintf: initialize siphash key using notifier
  random: add back async readiness notifier
  random: reseed in delayed work rather than on-demand
  random: always mix cycle counter in add_latent_entropy()
  hw_random: use add_hwgenerator_randomness() for early entropy
  random: modernize documentation comment on get_random_bytes()
  random: adjust comment to account for removed function
  random: remove early archrandom abstraction
  random: use random.trust_{bootloader,cpu} command line option only
  stackprotector: actually use get_random_canary()
  stackprotector: move get_random_canary() into stackprotector.h
  treewide: use get_random_u32_inclusive() when possible
  treewide: use get_random_u32_{above,below}() instead of manual loop
  treewide: use get_random_u32_below() instead of deprecated function
  ...
2022-12-12 16:22:22 -08:00
Anders Roxell 6fcd4267a8 kernel: kcsan: kcsan_test: build without structleak plugin
Building kcsan_test with structleak plugin enabled makes the stack frame
size to grow.

kernel/kcsan/kcsan_test.c:704:1: error: the frame size of 3296 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]

Turn off the structleak plugin checks for kcsan_test.

Link: https://lkml.kernel.org/r/20221128104358.2660634-1-anders.roxell@linaro.org
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Marco Elver <elver@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Gow <davidgow@google.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-12-11 19:30:18 -08:00
Kees Cook 79cc1ba7ba panic: Consolidate open-coded panic_on_warn checks
Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll
their own warnings, and each check "panic_on_warn". Consolidate this
into a single function so that future instrumentation can be added in
a single location.

Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Gow <davidgow@google.com>
Cc: tangmeng <tangmeng@uniontech.com>
Cc: Jann Horn <jannh@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: kasan-dev@googlegroups.com
Cc: linux-mm@kvack.org
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20221117234328.594699-4-keescook@chromium.org
2022-12-02 13:04:44 -08:00
Jason A. Donenfeld e8a533cbeb treewide: use get_random_u32_inclusive() when possible
These cases were done with this Coccinelle:

@@
expression H;
expression L;
@@
- (get_random_u32_below(H) + L)
+ get_random_u32_inclusive(L, H + L - 1)

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- + E
- - E
  )

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- - E
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- - E
  + F
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- + E
  + F
- - E
  )

And then subsequently cleaned up by hand, with several automatic cases
rejected if it didn't make sense contextually.

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-11-18 02:18:02 +01:00
Jason A. Donenfeld 8032bf1233 treewide: use get_random_u32_below() instead of deprecated function
This is a simple mechanical transformation done by:

@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
  (E)

Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Reviewed-by: SeongJae Park <sj@kernel.org> # for damon
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> # for infiniband
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> # for arm
Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-11-18 02:15:15 +01:00
Jason A. Donenfeld 6ce625939e kcsan: remove rng selftest
The first test of the kcsan selftest appears to test if get_random_u32()
returns two zeros in a row, and requires that it doesn't. This seems
like a bogus criteron. Remove it.

Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-11-17 17:36:47 +01:00
Marco Elver 7c201739be kcsan: Instrument memcpy/memset/memmove with newer Clang
With Clang version 16+, -fsanitize=thread will turn
memcpy/memset/memmove calls in instrumented functions into
__tsan_memcpy/__tsan_memset/__tsan_memmove calls respectively.

Add these functions to the core KCSAN runtime, so that we (a) catch data
races with mem* functions, and (b) won't run into linker errors with
such newer compilers.

Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-10-18 15:07:33 -07:00
Jason A. Donenfeld 197173db99 treewide: use get_random_bytes() when possible
The prandom_bytes() function has been a deprecated inline wrapper around
get_random_bytes() for several releases now, and compiles down to the
exact same code. Replace the deprecated wrapper with a direct call to
the real function. This was done as a basic find and replace.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> # powerpc
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-10-11 17:42:58 -06:00
Jason A. Donenfeld a251c17aa5 treewide: use get_random_u32() when possible
The prandom_u32() function has been a deprecated inline wrapper around
get_random_u32() for several releases now, and compiles down to the
exact same code. Replace the deprecated wrapper with a direct call to
the real function. The same also applies to get_random_int(), which is
just a wrapper around get_random_u32(). This was done as a basic find
and replace.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz> # for ext4
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk> # for sch_cake
Acked-by: Chuck Lever <chuck.lever@oracle.com> # for nfsd
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com> # for thunderbolt
Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs
Acked-by: Helge Deller <deller@gmx.de> # for parisc
Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-10-11 17:42:58 -06:00
David Gow 426752b253 kcsan: test: Add a .kunitconfig to run KCSAN tests
Add a .kunitconfig file, which provides a default, working config for
running the KCSAN tests. Note that it needs to run on an SMP machine, so
to run under kunit_tool, the --qemu_args option should be used (on a
supported architecture, like x86_64). For example:
./tools/testing/kunit/kunit.py run --arch=x86_64 --qemu_args='-smp 8'
					--kunitconfig=kernel/kcsan

Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2022-07-22 09:22:59 -06:00
Linus Torvalds 64e34b50d7 linux-kselftest-kunit-5.19-rc1
This KUnit update for Linux 5.19-rc1 consists of several fixes, cleanups,
 and enhancements to tests and framework:
 
 - introduces _NULL and _NOT_NULL macros to pointer error checks
 
 - reworks kunit_resource allocation policy to fix memory leaks when
   caller doesn't specify free() function to be used when allocating
   memory using kunit_add_resource() and kunit_alloc_resource() funcs.
 
 - adds ability to specify suite-level init and exit functions
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Merge tag 'linux-kselftest-kunit-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull KUnit updates from Shuah Khan:
 "Several fixes, cleanups, and enhancements to tests and framework:

   - introduce _NULL and _NOT_NULL macros to pointer error checks

   - rework kunit_resource allocation policy to fix memory leaks when
     caller doesn't specify free() function to be used when allocating
     memory using kunit_add_resource() and kunit_alloc_resource() funcs.

   - add ability to specify suite-level init and exit functions"

* tag 'linux-kselftest-kunit-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (41 commits)
  kunit: tool: Use qemu-system-i386 for i386 runs
  kunit: fix executor OOM error handling logic on non-UML
  kunit: tool: update riscv QEMU config with new serial dependency
  kcsan: test: use new suite_{init,exit} support
  kunit: tool: Add list of all valid test configs on UML
  kunit: take `kunit_assert` as `const`
  kunit: tool: misc cleanups
  kunit: tool: minor cosmetic cleanups in kunit_parser.py
  kunit: tool: make parser stop overwriting status of suites w/ no_tests
  kunit: tool: remove dead parse_crash_in_log() logic
  kunit: tool: print clearer error message when there's no TAP output
  kunit: tool: stop using a shell to run kernel under QEMU
  kunit: tool: update test counts summary line format
  kunit: bail out of test filtering logic quicker if OOM
  lib/Kconfig.debug: change KUnit tests to default to KUNIT_ALL_TESTS
  kunit: Rework kunit_resource allocation policy
  kunit: fix debugfs code to use enum kunit_status, not bool
  kfence: test: use new suite_{init/exit} support, add .kunitconfig
  kunit: add ability to specify suite-level init and exit functions
  kunit: rename print_subtest_{start,end} for clarity (s/subtest/suite)
  ...
2022-05-25 11:32:53 -07:00
Marco Elver 2434031c7c kcsan: test: use new suite_{init,exit} support
Use the newly added suite_{init,exit} support for suite-wide init and
cleanup. This avoids the unsupported method by which the test used to do
suite-wide init and cleanup (avoiding issues such as missing TAP
headers, and possible future conflicts).

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2022-05-16 13:23:49 -06:00
Valentin Schneider 5693fa74f9 kcsan: Use preemption model accessors
Per PREEMPT_DYNAMIC, checking CONFIG_PREEMPT doesn't tell you the actual
preemption model of the live kernel. Use the newly-introduced accessors
instead.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20211112185203.280040-4-valentin.schneider@arm.com
2022-04-05 10:24:42 +02:00
Linus Torvalds 1be5bdf8cd KCSAN updates for v5.17
This series provides KCSAN fixes and also the ability to take memory
 barriers into account for weakly-ordered systems.  This last can increase
 the probability of detecting certain types of data races.
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Merge tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull KCSAN updates from Paul McKenney:
 "This provides KCSAN fixes and also the ability to take memory barriers
  into account for weakly-ordered systems. This last can increase the
  probability of detecting certain types of data races"

* tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits)
  kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it
  kcsan: Avoid nested contexts reading inconsistent reorder_access
  kcsan: Turn barrier instrumentation into macros
  kcsan: Make barrier tests compatible with lockdep
  kcsan: Support WEAK_MEMORY with Clang where no objtool support exists
  compiler_attributes.h: Add __disable_sanitizer_instrumentation
  objtool, kcsan: Remove memory barrier instrumentation from noinstr
  objtool, kcsan: Add memory barrier instrumentation to whitelist
  sched, kcsan: Enable memory barrier instrumentation
  mm, kcsan: Enable barrier instrumentation
  x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock()
  x86/barriers, kcsan: Use generic instrumentation for non-smp barriers
  asm-generic/bitops, kcsan: Add instrumentation for barriers
  locking/atomics, kcsan: Add instrumentation for barriers
  locking/barriers, kcsan: Support generic instrumentation
  locking/barriers, kcsan: Add instrumentation for barriers
  kcsan: selftest: Add test case to check memory barrier instrumentation
  kcsan: Ignore GCC 11+ warnings about TSan runtime support
  kcsan: test: Add test cases for memory barrier instrumentation
  kcsan: test: Match reordered or normal accesses
  ...
2022-01-11 09:51:26 -08:00
Kefeng Wang dd03762ab6 arm64: Enable KCSAN
This patch enables KCSAN for arm64, with updates to build rules
to not use KCSAN for several incompatible compilation units.

Recent GCC version(at least GCC10) made outline-atomics as the
default option(unlike Clang), which will cause linker errors
for kernel/kcsan/core.o. Disables the out-of-line atomics by
no-outline-atomics to fix the linker errors.

Meanwhile, as Mark said[1], some latent issues are needed to be
fixed which isn't just a KCSAN problem, we make the KCSAN depends
on EXPERT for now.

Tested selftest and kcsan_test(built with GCC11 and Clang 13),
and all passed.

[1] https://lkml.kernel.org/r/YadiUPpJ0gADbiHQ@FVFF77S0Q05N

Acked-by: Marco Elver <elver@google.com> # kernel/kcsan
Tested-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Link: https://lore.kernel.org/r/20211211131734.126874-1-wangkefeng.wang@huawei.com
[catalin.marinas@arm.com: added comment to justify EXPERT]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-12-14 18:54:34 +00:00
Marco Elver b473a3891c kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it
Some architectures do not define clear_bit_unlock_is_negative_byte().
Only test it when it is actually defined (similar to other usage, such
as in lib/test_kasan.c).

Link: https://lkml.kernel.org/r/202112050757.x67rHnFU-lkp@intel.com
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:29 -08:00
Marco Elver e3d2b72bbf kcsan: Avoid nested contexts reading inconsistent reorder_access
Nested contexts, such as nested interrupts or scheduler code, share the
same kcsan_ctx. When such a nested context reads an inconsistent
reorder_access due to an interrupt during set_reorder_access(), we can
observe the following warning:

 | ------------[ cut here ]------------
 | Cannot find frame for torture_random kernel/torture.c:456 in stack trace
 | WARNING: CPU: 13 PID: 147 at kernel/kcsan/report.c:343 replace_stack_entry kernel/kcsan/report.c:343
 | ...
 | Call Trace:
 |  <TASK>
 |  sanitize_stack_entries kernel/kcsan/report.c:351 [inline]
 |  print_report kernel/kcsan/report.c:409
 |  kcsan_report_known_origin kernel/kcsan/report.c:693
 |  kcsan_setup_watchpoint kernel/kcsan/core.c:658
 |  rcutorture_one_extend kernel/rcu/rcutorture.c:1475
 |  rcutorture_loop_extend kernel/rcu/rcutorture.c:1558 [inline]
 |  ...
 |  </TASK>
 | ---[ end trace ee5299cb933115f5 ]---
 | ==================================================================
 | BUG: KCSAN: data-race in _raw_spin_lock_irqsave / rcutorture_one_extend
 |
 | write (reordered) to 0xffffffff8c93b300 of 8 bytes by task 154 on cpu 12:
 |  queued_spin_lock                include/asm-generic/qspinlock.h:80 [inline]
 |  do_raw_spin_lock                include/linux/spinlock.h:185 [inline]
 |  __raw_spin_lock_irqsave         include/linux/spinlock_api_smp.h:111 [inline]
 |  _raw_spin_lock_irqsave          kernel/locking/spinlock.c:162
 |  try_to_wake_up                  kernel/sched/core.c:4003
 |  sysvec_apic_timer_interrupt     arch/x86/kernel/apic/apic.c:1097
 |  asm_sysvec_apic_timer_interrupt arch/x86/include/asm/idtentry.h:638
 |  set_reorder_access              kernel/kcsan/core.c:416 [inline]    <-- inconsistent reorder_access
 |  kcsan_setup_watchpoint          kernel/kcsan/core.c:693
 |  rcutorture_one_extend           kernel/rcu/rcutorture.c:1475
 |  rcutorture_loop_extend          kernel/rcu/rcutorture.c:1558 [inline]
 |  rcu_torture_one_read            kernel/rcu/rcutorture.c:1600
 |  rcu_torture_reader              kernel/rcu/rcutorture.c:1692
 |  kthread                         kernel/kthread.c:327
 |  ret_from_fork                   arch/x86/entry/entry_64.S:295
 |
 | read to 0xffffffff8c93b300 of 8 bytes by task 147 on cpu 13:
 |  rcutorture_one_extend           kernel/rcu/rcutorture.c:1475
 |  rcutorture_loop_extend          kernel/rcu/rcutorture.c:1558 [inline]
 |  ...

The warning is telling us that there was a data race which KCSAN wants
to report, but the function where the original access (that is now
reordered) happened cannot be found in the stack trace, which prevents
KCSAN from generating the right stack trace. The stack trace of "write
(reordered)" now only shows where the access was reordered to, but
should instead show the stack trace of the original write, with a final
line saying "reordered to".

At the point where set_reorder_access() is interrupted, it just set
reorder_access->ptr and size, at which point size is non-zero. This is
sufficient (if ctx->disable_scoped is zero) for further accesses from
nested contexts to perform checking of this reorder_access.

That then happened in _raw_spin_lock_irqsave(), which is called by
scheduler code. However, since reorder_access->ip is still stale (ptr
and size belong to a different ip not yet set) this finally leads to
replace_stack_entry() not finding the frame in reorder_access->ip and
generating the above warning.

Fix it by ensuring that a nested context cannot access reorder_access
while we update it in set_reorder_access(): set ctx->disable_scoped for
the duration that reorder_access is updated, which effectively locks
reorder_access and prevents concurrent use by nested contexts. Note,
set_reorder_access() can do the update only if disabled_scoped is zero
on entry, and must therefore set disable_scoped back to non-zero after
the initial check in set_reorder_access().

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:29 -08:00
Marco Elver a70d36e6a0 kcsan: Make barrier tests compatible with lockdep
The barrier tests in selftest and the kcsan_test module only need the
spinlock and mutex to test correct barrier instrumentation. Therefore,
these were initially placed on the stack.

However, lockdep asserts that locks are in static storage, and will
generate this warning:

 | INFO: trying to register non-static key.
 | The code is fine but needs lockdep annotation, or maybe
 | you didn't initialize this object before use?
 | turning off the locking correctness validator.
 | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0-rc1+ #3208
 | Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
 | Call Trace:
 |  <TASK>
 |  dump_stack_lvl+0x88/0xd8
 |  dump_stack+0x15/0x1b
 |  register_lock_class+0x6b3/0x840
 |  ...
 |  test_barrier+0x490/0x14c7
 |  kcsan_selftest+0x47/0xa0
 |  ...

To fix, move the test locks into static storage.

Fixing the above also revealed that lock operations are strengthened on
first use with lockdep enabled, due to lockdep calling out into
non-instrumented files (recall that kernel/locking/lockdep.c is not
instrumented with KCSAN).

Only kcsan_test checks for over-instrumentation of *_lock() operations,
where we can simply "warm up" the test locks to avoid the test case
failing with lockdep.

Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:28 -08:00
Marco Elver 71b0e3aeb2 kcsan: selftest: Add test case to check memory barrier instrumentation
Memory barrier instrumentation is crucial to avoid false positives. To
avoid surprises, run a simple test case in the boot-time selftest to
ensure memory barriers are still instrumented correctly.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:27 -08:00
Marco Elver 8bc32b3481 kcsan: test: Add test cases for memory barrier instrumentation
Adds test cases to check that memory barriers are instrumented
correctly, and detection of missing memory barriers is working as
intended if CONFIG_KCSAN_STRICT=y.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:27 -08:00
Marco Elver 7310bd1f3e kcsan: test: Match reordered or normal accesses
Due to reordering accesses with weak memory modeling, any access can now
appear as "(reordered)".

Match any permutation of accesses if CONFIG_KCSAN_WEAK_MEMORY=y, so that
we effectively match an access if it is denoted "(reordered)" or not.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:27 -08:00
Marco Elver be3f6967ec kcsan: Show location access was reordered to
Also show the location the access was reordered to. An example report:

| ==================================================================
| BUG: KCSAN: data-race in test_kernel_wrong_memorder / test_kernel_wrong_memorder
|
| read-write to 0xffffffffc01e61a8 of 8 bytes by task 2311 on cpu 5:
|  test_kernel_wrong_memorder+0x57/0x90
|  access_thread+0x99/0xe0
|  kthread+0x2ba/0x2f0
|  ret_from_fork+0x22/0x30
|
| read-write (reordered) to 0xffffffffc01e61a8 of 8 bytes by task 2310 on cpu 7:
|  test_kernel_wrong_memorder+0x57/0x90
|  access_thread+0x99/0xe0
|  kthread+0x2ba/0x2f0
|  ret_from_fork+0x22/0x30
|   |
|   +-> reordered to: test_kernel_wrong_memorder+0x80/0x90
|
| Reported by Kernel Concurrency Sanitizer on:
| CPU: 7 PID: 2310 Comm: access_thread Not tainted 5.14.0-rc1+ #18
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
| ==================================================================

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:27 -08:00
Marco Elver 3cc21a5312 kcsan: Call scoped accesses reordered in reports
The scoping of an access simply denotes the scope in which it may be
reordered. However, in reports, it'll be less confusing to say the
access is "reordered". This is more accurate when the race occurred.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:26 -08:00
Marco Elver 0b8b0830ac kcsan: Add core memory barrier instrumentation functions
Add the core memory barrier instrumentation functions. These invalidate
the current in-flight reordered access based on the rules for the
respective barrier types and in-flight access type.

To obtain barrier instrumentation that can be disabled via __no_kcsan
with appropriate compiler-support (and not just with objtool help),
barrier instrumentation repurposes __atomic_signal_fence(), instead of
inserting explicit calls. Crucially, __atomic_signal_fence() normally
does not map to any real instructions, but is still intercepted by
fsanitize=thread. As a result, like any other instrumentation done by
the compiler, barrier instrumentation can be disabled with __no_kcsan.

Unfortunately Clang and GCC currently differ in their __no_kcsan aka
__no_sanitize_thread behaviour with respect to builtin atomics (and
__tsan_func_{entry,exit}) instrumentation. This is already reflected in
Kconfig.kcsan's dependencies for KCSAN_WEAK_MEMORY. A later change will
introduce support for newer versions of Clang that can implement
__no_kcsan to also remove the additional instrumentation introduced by
KCSAN_WEAK_MEMORY.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:26 -08:00
Marco Elver 69562e4983 kcsan: Add core support for a subset of weak memory modeling
Add support for modeling a subset of weak memory, which will enable
detection of a subset of data races due to missing memory barriers.

KCSAN's approach to detecting missing memory barriers is based on
modeling access reordering, and enabled if `CONFIG_KCSAN_WEAK_MEMORY=y`,
which depends on `CONFIG_KCSAN_STRICT=y`. The feature can be enabled or
disabled at boot and runtime via the `kcsan.weak_memory` boot parameter.

Each memory access for which a watchpoint is set up, is also selected
for simulated reordering within the scope of its function (at most 1
in-flight access).

We are limited to modeling the effects of "buffering" (delaying the
access), since the runtime cannot "prefetch" accesses (therefore no
acquire modeling). Once an access has been selected for reordering, it
is checked along every other access until the end of the function scope.
If an appropriate memory barrier is encountered, the access will no
longer be considered for reordering.

When the result of a memory operation should be ordered by a barrier,
KCSAN can then detect data races where the conflict only occurs as a
result of a missing barrier due to reordering accesses.

Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:26 -08:00
Marco Elver 9756f64c8f kcsan: Avoid checking scoped accesses from nested contexts
Avoid checking scoped accesses from nested contexts (such as nested
interrupts or in scheduler code) which share the same kcsan_ctx.

This is to avoid detecting false positive races of accesses in the same
thread with currently scoped accesses: consider setting up a watchpoint
for a non-scoped (normal) access that also "conflicts" with a current
scoped access. In a nested interrupt (or in the scheduler), which shares
the same kcsan_ctx, we cannot check scoped accesses set up in the parent
context -- simply ignore them in this case.

With the introduction of kcsan_ctx::disable_scoped, we can also clean up
kcsan_check_scoped_accesses()'s recursion guard, and do not need to
modify the list's prev pointer.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:26 -08:00
Marco Elver 71f8de7092 kcsan: Remove redundant zero-initialization of globals
They are implicitly zero-initialized, remove explicit initialization.
It keeps the upcoming additions to kcsan_ctx consistent with the rest.

No functional change intended.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:26 -08:00
Marco Elver 12305abe98 kcsan: Refactor reading of instrumented memory
Factor out the switch statement reading instrumented memory into a
helper read_instrumented_memory().

No functional change.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-09 16:42:26 -08:00
Marco Elver ac20e39e8d kcsan: selftest: Cleanup and add missing __init
Make test_encode_decode() more readable and add missing __init.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:20 -07:00
Marco Elver 78c3d954e2 kcsan: Move ctx to start of argument list
It is clearer if ctx is at the start of the function argument list;
it'll be more consistent when adding functions with varying arguments
but all requiring ctx.

No functional change intended.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Marco Elver d627c537c2 kcsan: Support reporting scoped read-write access type
Support generating the string representation of scoped read-write
accesses for completeness. They will become required in planned changes.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Marco Elver 6c65eb7568 kcsan: Start stack trace with explicit location if provided
If an explicit access address is set, as is done for scoped accesses,
always start the stack trace from that location. get_stack_skipnr() is
changed into sanitize_stack_entries(), which if given an address, scans
the stack trace for a matching function and then replaces that entry
with the explicitly provided address.

The previous reports for scoped accesses were all over the place, which
could be quite confusing. We now always point at the start of the scope.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Marco Elver f4c87dbbef kcsan: Save instruction pointer for scoped accesses
Save the instruction pointer for scoped accesses, so that it becomes
possible for the reporting code to construct more accurate stack traces
that will show the start of the scope.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Marco Elver 55a55fec50 kcsan: Add ability to pass instruction pointer of access to reporting
Add the ability to pass an explicitly set instruction pointer of access
from check_access() all the way through to reporting.

In preparation of using it in reporting.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Marco Elver ade3a58b2d kcsan: test: Fix flaky test case
If CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=n, then we may also see data
races between the writers only. If we get unlucky and never capture a
read-write data race, but only the write-write data races, then the
test_no_value_change* test cases may incorrectly fail.

The second problem is that the initial value needs to be reset, as
otherwise we might actually observe a value change at the start.

Fix it by also looking for the write-write data races, and resetting the
value to what will be written.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Marco Elver 8080428410 kcsan: test: Use kunit_skip() to skip tests
Use the new kunit_skip() to skip tests if requirements were not met.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Marco Elver e80704272f kcsan: test: Defer kcsan_test_init() after kunit initialization
When the test is built into the kernel (not a module), kcsan_test_init()
and kunit_init() both use late_initcall(), which means kcsan_test_init()
might see a NULL debugfs_rootdir as parent dentry, resulting in
kcsan_test_init() and kcsan_debugfs_init() both trying to create a
debugfs node named "kcsan" in debugfs root. One of them will show an
error and be unsuccessful.

Defer kcsan_test_init() until we're sure kunit was initialized.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13 16:41:19 -07:00
Linus Torvalds aa829778b1 LKMM updates:
- Update documentation and code example
 
 KCSAN updates:
 
  - Introduce CONFIG_KCSAN_STRICT (which RCU uses)
  - Optimize use of get_ctx() by kcsan_found_watchpoint()
  - Rework atomic.h into permissive.h
  - Add the ability to ignore writes that change only one bit of a given data-racy variable.
  - Improve comments
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-debug-2021-09-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull memory model updates from Ingo Molnar:
 "LKMM updates:

   - Update documentation and code example

  KCSAN updates:

   - Introduce CONFIG_KCSAN_STRICT (which RCU uses)

   - Optimize use of get_ctx() by kcsan_found_watchpoint()

   - Rework atomic.h into permissive.h

   - Add the ability to ignore writes that change only one bit of a
     given data-racy variable.

   - Improve comments"

* tag 'locking-debug-2021-09-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools/memory-model: Document data_race(READ_ONCE())
  tools/memory-model: Heuristics using data_race() must handle all values
  tools/memory-model: Add example for heuristic lockless reads
  tools/memory-model: Make read_foo_diagnostic() more clearly diagnostic
  kcsan: Make strict mode imply interruptible watchers
  kcsan: permissive: Ignore data-racy 1-bit value changes
  kcsan: Print if strict or non-strict during init
  kcsan: Rework atomic.h into permissive.h
  kcsan: Reduce get_ctx() uses in kcsan_found_watchpoint()
  kcsan: Introduce CONFIG_KCSAN_STRICT
  kcsan: Remove CONFIG_KCSAN_DEBUG
  kcsan: Improve some Kconfig comments
2021-09-02 13:00:15 -07:00
Heiko Carstens 09b1b13461 kcsan: use u64 instead of cycles_t
cycles_t has a different type across architectures: unsigned int,
unsinged long, or unsigned long long. Depending on architecture this
will generate this warning:

kernel/kcsan/debugfs.c: In function ‘microbenchmark’:
./include/linux/kern_levels.h:5:25: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘cycles_t’ {aka ‘long unsigned int’} [-Wformat=]

To avoid this simply change the type of cycle to u64 in microbenchmark(),
since u64 is of type unsigned long long for all architectures.

Acked-by: Marco Elver <elver@google.com>
Link: https://lore.kernel.org/r/20210729142811.1309391-1-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2021-07-30 17:09:02 +02:00
Marco Elver d8fd74d35a kcsan: permissive: Ignore data-racy 1-bit value changes
Add rules to ignore data-racy reads with only 1-bit value changes.
Details about the rules are captured in comments in
kernel/kcsan/permissive.h. More background follows.

While investigating a number of data races, we've encountered data-racy
accesses on flags variables to be very common. The typical pattern is a
reader masking all but one bit, and/or the writer setting/clearing only
1 bit (current->flags being a frequently encountered case; more examples
in mm/sl[au]b.c, which disable KCSAN for this reason).

Since these types of data-racy accesses are common (with the assumption
they are intentional and hard to miscompile) having the option (with
CONFIG_KCSAN_PERMISSIVE=y) to filter them will avoid forcing everyone to
mark them, and deliberately left to preference at this time.

One important motivation for having this option built-in is to move
closer to being able to enable KCSAN on CI systems or for testers
wishing to test the whole kernel, while more easily filtering
less interesting data races with higher probability.

For the implementation, we considered several alternatives, but had one
major requirement: that the rules be kept together with the Linux-kernel
tree. Adding them to the compiler would preclude us from making changes
quickly; if the rules require tweaks, having them part of the compiler
requires waiting another ~1 year for the next release -- that's not
realistic. We are left with the following options:

	1. Maintain compiler plugins as part of the kernel-tree that
	   removes instrumentation for some accesses (e.g. plain-& with
	   1-bit mask). The analysis would be reader-side focused, as
	   no assumption can be made about racing writers.

Because it seems unrealistic to maintain 2 plugins, one for LLVM and
GCC, we would likely pick LLVM. Furthermore, no kernel infrastructure
exists to maintain LLVM plugins, and the build-system implications and
maintenance overheads do not look great (historically, plugins written
against old LLVM APIs are not guaranteed to work with newer LLVM APIs).

	2. Find a set of rules that can be expressed in terms of
	   observed value changes, and make it part of the KCSAN runtime.
	   The analysis is writer-side focused, given we rely on observed
	   value changes.

The approach taken here is (2). While a complete approach requires both
(1) and (2), experiments show that the majority of data races involving
trivial bit operations on flags variables can be removed with (2) alone.

It goes without saying that the filtering of data races using (1) or (2)
does _not_ guarantee they are safe! Therefore, limiting ourselves to (2)
for now is the conservative choice for setups that wish to enable
CONFIG_KCSAN_PERMISSIVE=y.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-20 13:49:44 -07:00
Marco Elver 9c827cd1fc kcsan: Print if strict or non-strict during init
Show a brief message if KCSAN is strict or non-strict, and if non-strict
also say that CONFIG_KCSAN_STRICT=y can be used to see all data races.

This is to hint to users of KCSAN who blindly use the default config
that their configuration might miss data races of interest.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-20 13:49:44 -07:00