user/sven/linux.git/include/linux/compiler-clang.h, branch v6.2.7

Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-10-11T00:53:04Z

Pull MM updates from Andrew Morton: - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in linux-next for a couple of months without, to my knowledge, any negative reports (or any positive ones, come to that). - Also the Maple Tree from Liam Howlett. An overlapping range-based tree for vmas. It it apparently slightly more efficient in its own right, but is mainly targeted at enabling work to reduce mmap_lock contention. Liam has identified a number of other tree users in the kernel which could be beneficially onverted to mapletrees. Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat at [1]. This has yet to be addressed due to Liam's unfortunately timed vacation. He is now back and we'll get this fixed up. - Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses clang-generated instrumentation to detect used-unintialized bugs down to the single bit level. KMSAN keeps finding bugs. New ones, as well as the legacy ones. - Yang Shi adds a userspace mechanism (madvise) to induce a collapse of memory into THPs. - Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support file/shmem-backed pages. - userfaultfd updates from Axel Rasmussen - zsmalloc cleanups from Alexey Romanov - cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure - Huang Ying adds enhancements to NUMA balancing memory tiering mode's page promotion, with a new way of detecting hot pages. - memcg updates from Shakeel Butt: charging optimizations and reduced memory consumption. - memcg cleanups from Kairui Song. - memcg fixes and cleanups from Johannes Weiner. - Vishal Moola provides more folio conversions - Zhang Yi removed ll_rw_block() :( - migration enhancements from Peter Xu - migration error-path bugfixes from Huang Ying - Aneesh Kumar added ability for a device driver to alter the memory tiering promotion paths. For optimizations by PMEM drivers, DRM drivers, etc. - vma merging improvements from Jakub Matěn. - NUMA hinting cleanups from David Hildenbrand. - xu xin added aditional userspace visibility into KSM merging activity. - THP & KSM code consolidation from Qi Zheng. - more folio work from Matthew Wilcox. - KASAN updates from Andrey Konovalov. - DAMON cleanups from Kaixu Xia. - DAMON work from SeongJae Park: fixes, cleanups. - hugetlb sysfs cleanups from Muchun Song. - Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core. Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1] * tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits) hugetlb: allocate vma lock for all sharable vmas hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer hugetlb: fix vma lock handling during split vma and range unmapping mglru: mm/vmscan.c: fix imprecise comments mm/mglru: don't sync disk for each aging cycle mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol mm: memcontrol: use do_memsw_account() in a few more places mm: memcontrol: deprecate swapaccounting=0 mode mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled mm/secretmem: remove reduntant return value mm/hugetlb: add available_huge_pages() func mm: remove unused inline functions from include/linux/mm_inline.h selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd selftests/vm: add thp collapse shmem testing selftests/vm: add thp collapse file and tmpfs testing selftests/vm: modularize thp collapse memory operations selftests/vm: dedup THP helpers mm/khugepaged: add tracepoint to hpage_collapse_scan_file() mm/madvise: add file and shmem support to MADV_COLLAPSE ...

kmsan: introduce __no_sanitize_memory and __no_kmsan_checks

2022-10-03T21:03:19Z

__no_sanitize_memory is a function attribute that instructs KMSAN to skip a function during instrumentation. This is needed to e.g. implement the noinstr functions. __no_kmsan_checks is a function attribute that makes KMSAN ignore the uninitialized values coming from the function's inputs, and initialize the function's outputs. Functions marked with this attribute can't be inlined into functions not marked with it, and vice versa. This behavior is overridden by __always_inline. __SANITIZE_MEMORY__ is a macro that's defined iff the file is instrumented with KMSAN. This is not the same as CONFIG_KMSAN, which is defined for every file. Link: https://lkml.kernel.org/r/20220915150417.722975-8-glider@google.com Signed-off-by: Alexander Potapenko Reviewed-by: Marco Elver Cc: Alexander Viro Cc: Alexei Starovoitov Cc: Andrey Konovalov Cc: Andrey Konovalov Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Christoph Hellwig Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Eric Biggers Cc: Eric Biggers Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Herbert Xu Cc: Ilya Leoshkevich Cc: Ingo Molnar Cc: Jens Axboe Cc: Joonsoo Kim Cc: Kees Cook Cc: Mark Rutland Cc: Matthew Wilcox Cc: Michael S. Tsirkin Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Petr Mladek Cc: Stephen Rothwell Cc: Steven Rostedt Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vegard Nossum Cc: Vlastimil Babka Signed-off-by: Andrew Morton

cfi: Switch to -fsanitize=kcfi

2022-09-26T17:13:13Z

Switch from Clang's original forward-edge control-flow integrity implementation to -fsanitize=kcfi, which is better suited for the kernel, as it doesn't require LTO, doesn't use a jump table that requires altering function references, and won't break cross-module function address equality. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor Acked-by: Peter Zijlstra (Intel) Tested-by: Peter Zijlstra (Intel) Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220908215504.3686827-6-samitolvanen@google.com

cfi: Use __builtin_function_start

2022-04-13T19:16:00Z

Clang 14 added support for the __builtin_function_start function, which allows us to implement the function_nocfi macro without architecture-specific inline assembly and in a way that also works with static initializers. Change CONFIG_CFI_CLANG to depend on Clang >= 14, define function_nocfi using __builtin_function_start, and remove the arm64 inline assembly implementation. Link: https://github.com/llvm/llvm-project/commit/ec2e26eaf63558934f5b73a6e530edc453cf9508 Link: https://github.com/ClangBuiltLinux/linux/issues/1353 Signed-off-by: Sami Tolvanen Reviewed-by: Nick Desaulniers Reviewed-by: Mark Rutland Tested-by: Mark Rutland Acked-by: Will Deacon # arm64 Reviewed-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220405221618.633743-1-samitolvanen@google.com

compiler_types.h: Add unified __diag_ignore_all for GCC/LLVM

2022-03-05T23:29:36Z

Add a __diag_ignore_all macro, to ignore warnings for both GCC and LLVM, without having to specify the compiler type and version. By default, GCC 8 and clang 11 are used. This will be used by bpf subsystem to ignore -Wmissing-prototypes warning for functions that are meant to be global functions so that they are in vmlinux BTF, but don't have a prototype. Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220304224645.3677453-7-memxor@gmail.com

compiler-clang.h: Add __diag infrastructure for clang

2022-03-05T23:29:36Z

Add __diag macros similar to those in compiler-gcc.h, so that warnings that need to be adjusted for specific cases but not globally can be ignored when building with clang. Signed-off-by: Nathan Chancellor Signed-off-by: Kumar Kartikeya Dwivedi Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20220304224645.3677453-6-memxor@gmail.com [ Kartikeya: wrote commit message ]

compiler.h: drop fallback overflow checkers

2021-09-13T17:18:28Z

Once upgrading the minimum supported version of GCC to 5.1, we can drop the fallback code for !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW. This is effectively a revert of commit f0907827a8a9 ("compiler.h: enable builtin overflow checkers and add fallback code") Link: https://github.com/ClangBuiltLinux/linux/issues/1438#issuecomment-916745801 Suggested-by: Rasmus Villemoes Signed-off-by: Nick Desaulniers Acked-by: Kees Cook Reviewed-by: Nathan Chancellor Signed-off-by: Linus Torvalds

kcov: add __no_sanitize_coverage to fix noinstr for all architectures

2021-07-01T18:06:06Z

Until now no compiler supported an attribute to disable coverage instrumentation as used by KCOV. To work around this limitation on x86, noinstr functions have their coverage instrumentation turned into nops by objtool. However, this solution doesn't scale automatically to other architectures, such as arm64, which are migrating to use the generic entry code. Clang [1] and GCC [2] have added support for the attribute recently. [1] https://github.com/llvm/llvm-project/commit/280333021e9550d80f5c1152a34e33e81df1e178 [2] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=cec4d4a6782c9bd8d071839c50a239c49caca689 The changes will appear in Clang 13 and GCC 12. Add __no_sanitize_coverage for both compilers, and add it to noinstr. Note: In the Clang case, __has_feature(coverage_sanitizer) is only true if the feature is enabled, and therefore we do not require an additional defined(CONFIG_KCOV) (like in the GCC case where __has_attribute(..) is always true) to avoid adding redundant attributes to functions if KCOV is off. That being said, compilers that support the attribute will not generate errors/warnings if the attribute is redundantly used; however, where possible let's avoid it as it reduces preprocessed code size and associated compile-time overheads. [elver@google.com: Implement __has_feature(coverage_sanitizer) in Clang] Link: https://lkml.kernel.org/r/20210527162655.3246381-1-elver@google.com [elver@google.com: add comment explaining __has_feature() in Clang] Link: https://lkml.kernel.org/r/20210527194448.3470080-1-elver@google.com Link: https://lkml.kernel.org/r/20210525175819.699786-1-elver@google.com Signed-off-by: Marco Elver Acked-by: Peter Zijlstra (Intel) Reviewed-by: Miguel Ojeda Reviewed-by: Nathan Chancellor Cc: Nick Desaulniers Cc: Kees Cook Cc: Will Deacon Cc: Ard Biesheuvel Cc: Luc Van Oostenryck Cc: Arvind Sankar Cc: Masahiro Yamada Cc: Sami Tolvanen Cc: Arnd Bergmann Cc: Dmitry Vyukov Cc: Mark Rutland Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

cfi: add __cficanonical

2021-04-08T23:04:20Z

With CONFIG_CFI_CLANG, the compiler replaces a function address taken in C code with the address of a local jump table entry, which passes runtime indirect call checks. However, the compiler won't replace addresses taken in assembly code, which will result in a CFI failure if we later jump to such an address in instrumented C code. The code generated for the non-canonical jump table looks this: : /* In C, &noncanonical points here */ jmp noncanonical ... : /* function body */ ... This change adds the __cficanonical attribute, which tells the compiler to use a canonical jump table for the function instead. This means the compiler will rename the actual function to .cfi and points the original symbol to the jump table entry instead: : /* jump table entry */ jmp canonical.cfi ... : /* function body */ ... As a result, the address taken in assembly, or other non-instrumented code always points to the jump table and therefore, can be used for indirect calls in instrumented code without tripping CFI checks. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Bjorn Helgaas # pci.h Tested-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210408182843.1754385-3-samitolvanen@google.com

add support for Clang CFI

2021-04-08T23:04:20Z

This change adds support for Clang’s forward-edge Control Flow Integrity (CFI) checking. With CONFIG_CFI_CLANG, the compiler injects a runtime check before each indirect function call to ensure the target is a valid function with the correct static type. This restricts possible call targets and makes it more difficult for an attacker to exploit bugs that allow the modification of stored function pointers. For more details, see: https://clang.llvm.org/docs/ControlFlowIntegrity.html Clang requires CONFIG_LTO_CLANG to be enabled with CFI to gain visibility to possible call targets. Kernel modules are supported with Clang’s cross-DSO CFI mode, which allows checking between independently compiled components. With CFI enabled, the compiler injects a __cfi_check() function into the kernel and each module for validating local call targets. For cross-module calls that cannot be validated locally, the compiler calls the global __cfi_slowpath_diag() function, which determines the target module and calls the correct __cfi_check() function. This patch includes a slowpath implementation that uses __module_address() to resolve call targets, and with CONFIG_CFI_CLANG_SHADOW enabled, a shadow map that speeds up module look-ups by ~3x. Clang implements indirect call checking using jump tables and offers two methods of generating them. With canonical jump tables, the compiler renames each address-taken function to .cfi and points the original symbol to a jump table entry, which passes __cfi_check() validation. This isn’t compatible with stand-alone assembly code, which the compiler doesn’t instrument, and would result in indirect calls to assembly code to fail. Therefore, we default to using non-canonical jump tables instead, where the compiler generates a local jump table entry .cfi_jt for each address-taken function, and replaces all references to the function with the address of the jump table entry. Note that because non-canonical jump table addresses are local to each component, they break cross-module function address equality. Specifically, the address of a global function will be different in each module, as it's replaced with the address of a local jump table entry. If this address is passed to a different module, it won’t match the address of the same function taken there. This may break code that relies on comparing addresses passed from other components. CFI checking can be disabled in a function with the __nocfi attribute. Additionally, CFI can be disabled for an entire compilation unit by filtering out CC_FLAGS_CFI. By default, CFI failures result in a kernel panic to stop a potential exploit. CONFIG_CFI_PERMISSIVE enables a permissive mode, where the kernel prints out a rate-limited warning instead, and allows execution to continue. This option is helpful for locating type mismatches, but should only be enabled during development. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Nathan Chancellor Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210408182843.1754385-2-samitolvanen@google.com