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2025-12-20clang: work around asm output constraint problemsEric Dumazet1-1/+2
Work around clang problems with "=rm" asm constraint. clang seems to always chose the memory output, while it is almost always the worst choice. Add ASM_OUTPUT_RM so that we can replace "=rm" constraint where it matters for clang, while not penalizing gcc. Signed-off-by: Eric Dumazet <edumazet@google.com> Suggested-by: Uros Bizjak <ubizjak@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2025-12-10Merge tag 'auto-type-conversion-for-v6.19-rc1' of ↵Linus Torvalds1-0/+13
git://git.kernel.org/pub/scm/linux/kernel/git/hpa/linux-auto Pull __auto_type to auto conversion from Peter Anvin: "Convert '__auto_type' to 'auto', defining a macro for 'auto' unless C23+ is in use" * tag 'auto-type-conversion-for-v6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/hpa/linux-auto: tools/virtio: replace "__auto_type" with "auto" selftests/bpf: replace "__auto_type" with "auto" arch/x86: replace "__auto_type" with "auto" arch/nios2: replace "__auto_type" and adjacent equivalent with "auto" fs/proc: replace "__auto_type" with "const auto" include/linux: change "__auto_type" to "auto" compiler_types.h: add "auto" as a macro for "__auto_type"
2025-12-08compiler_types.h: add "auto" as a macro for "__auto_type"H. Peter Anvin1-0/+13
"auto" was defined as a keyword back in the K&R days, but as a storage type specifier. No one ever used it, since it was and is the default storage type for local variables. C++11 recycled the keyword to allow a type to be declared based on the type of an initializer. This was finally adopted into standard C in C23. gcc and clang provide the "__auto_type" alias keyword as an extension for pre-C23, however, there is no reason to pollute the bulk of the source base with this temporary keyword; instead define "auto" as a macro unless the compiler is running in C23+ mode. This macro is added in <linux/compiler_types.h> because that header is included in some of the tools headers, wheres <linux/compiler.h> is not as it has a bunch of very kernel-specific things in it. [ Cc: stable to reduce potential backporting burden. ] Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Acked-by: Miguel Ojeda <ojeda@kernel.org> Cc: <stable@kernel.org>
2025-12-09Merge tag 'hyperv-next-signed-20251207' of ↵Linus Torvalds1-4/+4
git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux Pull hyperv updates from Wei Liu: - Enhancements to Linux as the root partition for Microsoft Hypervisor: - Support a new mode called L1VH, which allows Linux to drive the hypervisor running the Azure Host directly - Support for MSHV crash dump collection - Allow Linux's memory management subsystem to better manage guest memory regions - Fix issues that prevented a clean shutdown of the whole system on bare metal and nested configurations - ARM64 support for the MSHV driver - Various other bug fixes and cleanups - Add support for Confidential VMBus for Linux guest on Hyper-V - Secure AVIC support for Linux guests on Hyper-V - Add the mshv_vtl driver to allow Linux to run as the secure kernel in a higher virtual trust level for Hyper-V * tag 'hyperv-next-signed-20251207' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: (58 commits) mshv: Cleanly shutdown root partition with MSHV mshv: Use reboot notifier to configure sleep state mshv: Add definitions for MSHV sleep state configuration mshv: Add support for movable memory regions mshv: Add refcount and locking to mem regions mshv: Fix huge page handling in memory region traversal mshv: Move region management to mshv_regions.c mshv: Centralize guest memory region destruction mshv: Refactor and rename memory region handling functions mshv: adjust interrupt control structure for ARM64 Drivers: hv: use kmalloc_array() instead of kmalloc() mshv: Add ioctl for self targeted passthrough hvcalls Drivers: hv: Introduce mshv_vtl driver Drivers: hv: Export some symbols for mshv_vtl static_call: allow using STATIC_CALL_TRAMP_STR() from assembly mshv: Extend create partition ioctl to support cpu features mshv: Allow mappings that overlap in uaddr mshv: Fix create memory region overlap check mshv: add WQ_PERCPU to alloc_workqueue users Drivers: hv: Use kmalloc_array() instead of kmalloc() ...
2025-12-02Merge tag 'libcrypto-at-least-for-linus' of ↵Linus Torvalds1-0/+15
git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux Pull 'at_least' array size update from Eric Biggers: "C supports lower bounds on the sizes of array parameters, using the static keyword as follows: 'void f(int a[static 32]);'. This allows the compiler to warn about a too-small array being passed. As discussed, this reuse of the 'static' keyword, while standard, is a bit obscure. Therefore, add an alias 'at_least' to compiler_types.h. Then, add this 'at_least' annotation to the array parameters of various crypto library functions" * tag 'libcrypto-at-least-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux: lib/crypto: sha2: Add at_least decoration to fixed-size array params lib/crypto: sha1: Add at_least decoration to fixed-size array params lib/crypto: poly1305: Add at_least decoration to fixed-size array params lib/crypto: md5: Add at_least decoration to fixed-size array params lib/crypto: curve25519: Add at_least decoration to fixed-size array params lib/crypto: chacha: Add at_least decoration to fixed-size array params lib/crypto: chacha20poly1305: Statically check fixed array lengths compiler_types: introduce at_least parameter decoration pseudo keyword wifi: iwlwifi: trans: rename at_least variable to min_mode
2025-11-23compiler_types: introduce at_least parameter decoration pseudo keywordJason A. Donenfeld1-0/+15
Clang and recent gcc support warning if they are able to prove that the user is passing to a function an array that is too short in size. For example: void blah(unsigned char herp[at_least 7]); static void schma(void) { unsigned char good[] = { 1, 2, 3, 4, 5, 6, 7 }; unsigned char bad[] = { 1, 2, 3, 4, 5, 6 }; blah(good); blah(bad); } The notation here, `static 7`, which this commit makes explicit by allowing us to write it as `at_least 7`, means that it's incorrect to pass anything less than 7 elements. This is section 6.7.5.3 of C99: If the keyword static also appears within the [ and ] of the array type derivation, then for each call to the function, the value of the corresponding actual argument shall provide access to the first element of an array with at least as many elements as specified by the size expression. Here is the output from gcc 15: zx2c4@thinkpad /tmp $ gcc -c a.c a.c: In function ‘schma’: a.c:9:9: warning: ‘blah’ accessing 7 bytes in a region of size 6 [-Wstringop-overflow=] 9 | blah(bad); | ^~~~~~~~~ a.c:9:9: note: referencing argument 1 of type ‘unsigned char[7]’ a.c:2:6: note: in a call to function ‘blah’ 2 | void blah(unsigned char herp[at_least 7]); | ^~~~ And from clang 21: zx2c4@thinkpad /tmp $ clang -c a.c a.c:9:2: warning: array argument is too small; contains 6 elements, callee requires at least 7 [-Warray-bounds] 9 | blah(bad); | ^ ~~~ a.c:2:25: note: callee declares array parameter as static here 2 | void blah(unsigned char herp[at_least 7]); | ^ ~~~~~~~~~~ 1 warning generated. So these are covered by, variously, -Wstringop-overflow and -Warray-bounds. Acked-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: "Jason A. Donenfeld" <Jason@zx2c4.com> Link: https://lore.kernel.org/r/20251123054819.2371989-3-Jason@zx2c4.com Signed-off-by: Eric Biggers <ebiggers@kernel.org>
2025-11-15static_call: allow using STATIC_CALL_TRAMP_STR() from assemblyNaman Jain1-4/+4
STATIC_CALL_TRAMP_STR() could not be used from .S files because static_call_types.h was not safe to include in assembly as it pulled in C types/constructs that are unavailable under __ASSEMBLY__. Make the header assembly-friendly by adding __ASSEMBLY__ checks and providing only the minimal definitions needed for assembly, so that it can be safely included by .S code. This enables emitting the static call trampoline symbol name via STATIC_CALL_TRAMP_STR() directly in assembly sources, to be used with 'call' instruction. Also, move a certain definitions out of __ASSEMBLY__ checks in compiler_types.h to meet the dependencies. No functional change for C compilation. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Naman Jain <namjain@linux.microsoft.com> Signed-off-by: Wei Liu <wei.liu@kernel.org>
2025-11-09Merge tag 'kbuild-fixes-6.18-3' of ↵Linus Torvalds1-3/+2
git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux Pull Kbuild fixes from Nathan Chancellor: - Strip trailing padding bytes from modules.builtin.modinfo to fix error during modules_install with certain versions of kmod - Drop unused static inline function warning in .c files with clang from W=1 to W=2 - Ensure kernel-doc.py invocations use the PYTHON3 make variable to ensure user's choice of Python interpreter is always respected * tag 'kbuild-fixes-6.18-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: kbuild: Let kernel-doc.py use PYTHON3 override compiler_types: Move unused static inline functions warning to W=2 kbuild: Strip trailing padding bytes from modules.builtin.modinfo
2025-11-07compiler_types: Move unused static inline functions warning to W=2Peter Zijlstra1-3/+2
Per Nathan, clang catches unused "static inline" functions in C files since commit 6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions for W=1 build"). Linus said: > So I entirely ignore W=1 issues, because I think so many of the extra > warnings are bogus. > > But if this one in particular is causing more problems than most - > some teams do seem to use W=1 as part of their test builds - it's fine > to send me a patch that just moves bad warnings to W=2. > > And if anybody uses W=2 for their test builds, that's THEIR problem.. Here is the change to bump the warning from W=1 to W=2. Fixes: 6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions for W=1 build") Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20251106105000.2103276-1-andriy.shevchenko@linux.intel.com [nathan: Adjust comment as well] Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2025-10-29compiler_types: Introduce __nocfi_genericNathan Chancellor1-0/+6
There are two different ways that LLVM can expand kCFI operand bundles in LLVM IR: generically in the middle end or using an architecture specific sequence when lowering LLVM IR to machine code in the backend. The generic pass allows any architecture to take advantage of kCFI but the expansion of these bundles in the middle end can mess with optimizations that may turn indirect calls into direct calls when the call target is known at compile time, such as after inlining. Add __nocfi_generic, dependent on an architecture selecting CONFIG_ARCH_USES_CFI_GENERIC_LLVM_PASS, to disable kCFI bundle generation in functions where only the generic kCFI pass may cause problems. Link: https://github.com/ClangBuiltLinux/linux/issues/2124 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Link: https://patch.msgid.link/20251025-idpf-fix-arm-kcfi-build-error-v1-1-ec57221153ae@kernel.org Signed-off-by: Kees Cook <kees@kernel.org>
2025-10-11Merge tag 'x86_core_for_v6.18_rc1' of ↵Linus Torvalds1-1/+3
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull more x86 updates from Borislav Petkov: - Remove a bunch of asm implementing condition flags testing in KVM's emulator in favor of int3_emulate_jcc() which is written in C - Replace KVM fastops with C-based stubs which avoids problems with the fastop infra related to latter not adhering to the C ABI due to their special calling convention and, more importantly, bypassing compiler control-flow integrity checking because they're written in asm - Remove wrongly used static branches and other ugliness accumulated over time in hyperv's hypercall implementation with a proper static function call to the correct hypervisor call variant - Add some fixes and modifications to allow running FRED-enabled kernels in KVM even on non-FRED hardware - Add kCFI improvements like validating indirect calls and prepare for enabling kCFI with GCC. Add cmdline params documentation and other code cleanups - Use the single-byte 0xd6 insn as the official #UD single-byte undefined opcode instruction as agreed upon by both x86 vendors - Other smaller cleanups and touchups all over the place * tag 'x86_core_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) x86,retpoline: Optimize patch_retpoline() x86,ibt: Use UDB instead of 0xEA x86/cfi: Remove __noinitretpoline and __noretpoline x86/cfi: Add "debug" option to "cfi=" bootparam x86/cfi: Standardize on common "CFI:" prefix for CFI reports x86/cfi: Document the "cfi=" bootparam options x86/traps: Clarify KCFI instruction layout compiler_types.h: Move __nocfi out of compiler-specific header objtool: Validate kCFI calls x86/fred: KVM: VMX: Always use FRED for IRQs when CONFIG_X86_FRED=y x86/fred: Play nice with invoking asm_fred_entry_from_kvm() on non-FRED hardware x86/fred: Install system vector handlers even if FRED isn't fully enabled x86/hyperv: Use direct call to hypercall-page x86/hyperv: Clean up hv_do_hypercall() KVM: x86: Remove fastops KVM: x86: Convert em_salc() to C KVM: x86: Introduce EM_ASM_3WCL KVM: x86: Introduce EM_ASM_1SRC2 KVM: x86: Introduce EM_ASM_2CL KVM: x86: Introduce EM_ASM_2W ...
2025-09-18compiler_types: Add __assume macroHeiko Carstens1-0/+23
Make the statement attribute "assume" with a new __assume macro available. The assume attribute is used to indicate that a certain condition is assumed to be true. Compilers may or may not use this indication to generate optimized code. If this condition is violated at runtime, the behavior is undefined. Note that the clang documentation states that optimizers may react differently to this attribute, and this may even have a negative performance impact. Therefore this attribute should be used with care. Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2025-09-04compiler_types.h: Move __nocfi out of compiler-specific headerKees Cook1-1/+3
Prepare for GCC KCFI support and move the __nocfi attribute from compiler-clang.h to compiler_types.h. This was already gated by CONFIG_CFI_CLANG, so this remains safe for non-KCFI GCC builds. Signed-off-by: Kees Cook <kees@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/20250904034656.3670313-1-kees@kernel.org
2025-07-29compiler_types: Provide __no_kstack_erase to disable coverage only on ClangKees Cook1-0/+4
In order to support Clang's stack depth tracking (for Linux's kstack_erase feature), the coverage sanitizer needed to be disabled for __init (and __head) section code. Doing this universally (i.e. for GCC too) created a number of unexpected problems, ranging from changes to inlining logic to failures to DCE code on earlier GCC versions. Since this change is only needed for Clang, specialize it so that GCC doesn't see the change as it isn't needed there (the GCC implementation of kstack_erase uses a GCC plugin that removes stack depth tracking instrumentation from __init sections during a late pass in the IR). Successfully build and boot tested with GCC 12 and Clang 22. Fixes: 381a38ea53d2 ("init.h: Disable sanitizer coverage for __init and __head") Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202507270258.neWuiXLd-lkp@intel.com/ Reported-by: syzbot+5245cb609175fb6e8122@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6888d004.a00a0220.26d0e1.0004.GAE@google.com/ Reviewed-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Marco Elver <elver@google.com> Link: https://lore.kernel.org/r/20250729234055.it.233-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org>
2025-05-31Merge tag 'mm-nonmm-stable-2025-05-31-15-28' of ↵Linus Torvalds1-1/+7
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull non-MM updates from Andrew Morton: - "hung_task: extend blocking task stacktrace dump to semaphore" from Lance Yang enhances the hung task detector. The detector presently dumps the blocking tasks's stack when it is blocked on a mutex. Lance's series extends this to semaphores - "nilfs2: improve sanity checks in dirty state propagation" from Wentao Liang addresses a couple of minor flaws in nilfs2 - "scripts/gdb: Fixes related to lx_per_cpu()" from Illia Ostapyshyn fixes a couple of issues in the gdb scripts - "Support kdump with LUKS encryption by reusing LUKS volume keys" from Coiby Xu addresses a usability problem with kdump. When the dump device is LUKS-encrypted, the kdump kernel may not have the keys to the encrypted filesystem. A full writeup of this is in the series [0/N] cover letter - "sysfs: add counters for lockups and stalls" from Max Kellermann adds /sys/kernel/hardlockup_count and /sys/kernel/hardlockup_count and /sys/kernel/rcu_stall_count - "fork: Page operation cleanups in the fork code" from Pasha Tatashin implements a number of code cleanups in fork.c - "scripts/gdb/symbols: determine KASLR offset on s390 during early boot" from Ilya Leoshkevich fixes some s390 issues in the gdb scripts * tag 'mm-nonmm-stable-2025-05-31-15-28' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (67 commits) llist: make llist_add_batch() a static inline delayacct: remove redundant code and adjust indentation squashfs: add optional full compressed block caching crash_dump, nvme: select CONFIGFS_FS as built-in scripts/gdb/symbols: determine KASLR offset on s390 during early boot scripts/gdb/symbols: factor out pagination_off() scripts/gdb/symbols: factor out get_vmlinux() kernel/panic.c: format kernel-doc comments mailmap: update and consolidate Casey Connolly's name and email nilfs2: remove wbc->for_reclaim handling fork: define a local GFP_VMAP_STACK fork: check charging success before zeroing stack fork: clean-up naming of vm_stack/vm_struct variables in vmap stacks code fork: clean-up ifdef logic around stack allocation kernel/rcu/tree_stall: add /sys/kernel/rcu_stall_count kernel/watchdog: add /sys/kernel/{hard,soft}lockup_count x86/crash: make the page that stores the dm crypt keys inaccessible x86/crash: pass dm crypt keys to kdump kernel Revert "x86/mm: Remove unused __set_memory_prot()" crash_dump: retrieve dm crypt keys in kdump kernel ...
2025-05-11compiler_types.h: fix "unused variable" in __compiletime_assert()Marc Herbert1-1/+7
This refines commit c03567a8e8d5 ("include/linux/compiler.h: don't perform compiletime_assert with -O0") and restores #ifdef __OPTIMIZE__ symmetry by evaluating the 'condition' variable in both compile-time variants of __compiletimeassert(). As __OPTIMIZE__ is always true by default, this commit does not change anything by default. But it fixes warnings with _non-default_ CFLAGS like for instance this: make CFLAGS_tcp.o='-Og -U__OPTIMIZE__' from net/ipv4/tcp.c:273: include/net/sch_generic.h: In function `qdisc_cb_private_validate': include/net/sch_generic.h:511:30: error: unused variable `qcb' [-Werror=unused-variable] { struct qdisc_skb_cb *qcb; BUILD_BUG_ON(sizeof(skb->cb) < sizeof(*qcb)); ... } [akpm@linux-foundation.org: regularize comment layout, reflow comment] Link: https://lkml.kernel.org/r/20250424194048.652571-1-marc.herbert@linux.intel.com Signed-off-by: Marc Herbert <Marc.Herbert@linux.intel.com> Cc: Alexander Potapenko <glider@google.com> Cc: Changbin Du <changbin.du@intel.com> Cc: Jan Hendrik Farr <kernel@jfarr.cc> Cc: Macro Elver <elver@google.com> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Tony Ambardar <tony.ambardar@gmail.com> Cc: Uros Bizjak <ubizjak@gmail.com> Cc: Kees Cook <kees@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-04-28compiler_types: Identify compiler versions for __builtin_dynamic_object_sizeKees Cook1-0/+5
Clarify when __builtin_dynamic_object_size() is available. All our supported Clang versions support it. GCC 12 and later support it. Link to documentation for both. Acked-by: Miguel Ojeda <ojeda@kernel.org> Link: https://lore.kernel.org/r/20250416172016.work.154-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org>
2025-04-01Merge tag 'mm-stable-2025-03-30-16-52' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull MM updates from Andrew Morton: - The series "Enable strict percpu address space checks" from Uros Bizjak uses x86 named address space qualifiers to provide compile-time checking of percpu area accesses. This has caused a small amount of fallout - two or three issues were reported. In all cases the calling code was found to be incorrect. - The series "Some cleanup for memcg" from Chen Ridong implements some relatively monir cleanups for the memcontrol code. - The series "mm: fixes for device-exclusive entries (hmm)" from David Hildenbrand fixes a boatload of issues which David found then using device-exclusive PTE entries when THP is enabled. More work is needed, but this makes thins better - our own HMM selftests now succeed. - The series "mm: zswap: remove z3fold and zbud" from Yosry Ahmed remove the z3fold and zbud implementations. They have been deprecated for half a year and nobody has complained. - The series "mm: further simplify VMA merge operation" from Lorenzo Stoakes implements numerous simplifications in this area. No runtime effects are anticipated. - The series "mm/madvise: remove redundant mmap_lock operations from process_madvise()" from SeongJae Park rationalizes the locking in the madvise() implementation. Performance gains of 20-25% were observed in one MADV_DONTNEED microbenchmark. - The series "Tiny cleanup and improvements about SWAP code" from Baoquan He contains a number of touchups to issues which Baoquan noticed when working on the swap code. - The series "mm: kmemleak: Usability improvements" from Catalin Marinas implements a couple of improvements to the kmemleak user-visible output. - The series "mm/damon/paddr: fix large folios access and schemes handling" from Usama Arif provides a couple of fixes for DAMON's handling of large folios. - The series "mm/damon/core: fix wrong and/or useless damos_walk() behaviors" from SeongJae Park fixes a few issues with the accuracy of kdamond's walking of DAMON regions. - The series "expose mapping wrprotect, fix fb_defio use" from Lorenzo Stoakes changes the interaction between framebuffer deferred-io and core MM. No functional changes are anticipated - this is preparatory work for the future removal of page structure fields. - The series "mm/damon: add support for hugepage_size DAMOS filter" from Usama Arif adds a DAMOS filter which permits the filtering by huge page sizes. - The series "mm: permit guard regions for file-backed/shmem mappings" from Lorenzo Stoakes extends the guard region feature from its present "anon mappings only" state. The feature now covers shmem and file-backed mappings. - The series "mm: batched unmap lazyfree large folios during reclamation" from Barry Song cleans up and speeds up the unmapping for pte-mapped large folios. - The series "reimplement per-vma lock as a refcount" from Suren Baghdasaryan puts the vm_lock back into the vma. Our reasons for pulling it out were largely bogus and that change made the code more messy. This patchset provides small (0-10%) improvements on one microbenchmark. - The series "Docs/mm/damon: misc DAMOS filters documentation fixes and improves" from SeongJae Park does some maintenance work on the DAMON docs. - The series "hugetlb/CMA improvements for large systems" from Frank van der Linden addresses a pile of issues which have been observed when using CMA on large machines. - The series "mm/damon: introduce DAMOS filter type for unmapped pages" from SeongJae Park enables users of DMAON/DAMOS to filter my the page's mapped/unmapped status. - The series "zsmalloc/zram: there be preemption" from Sergey Senozhatsky teaches zram to run its compression and decompression operations preemptibly. - The series "selftests/mm: Some cleanups from trying to run them" from Brendan Jackman fixes a pile of unrelated issues which Brendan encountered while runnimg our selftests. - The series "fs/proc/task_mmu: add guard region bit to pagemap" from Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to determine whether a particular page is a guard page. - The series "mm, swap: remove swap slot cache" from Kairui Song removes the swap slot cache from the allocation path - it simply wasn't being effective. - The series "mm: cleanups for device-exclusive entries (hmm)" from David Hildenbrand implements a number of unrelated cleanups in this code. - The series "mm: Rework generic PTDUMP configs" from Anshuman Khandual implements a number of preparatoty cleanups to the GENERIC_PTDUMP Kconfig logic. - The series "mm/damon: auto-tune aggregation interval" from SeongJae Park implements a feedback-driven automatic tuning feature for DAMON's aggregation interval tuning. - The series "Fix lazy mmu mode" from Ryan Roberts fixes some issues in powerpc, sparc and x86 lazy MMU implementations. Ryan did this in preparation for implementing lazy mmu mode for arm64 to optimize vmalloc. - The series "mm/page_alloc: Some clarifications for migratetype fallback" from Brendan Jackman reworks some commentary to make the code easier to follow. - The series "page_counter cleanup and size reduction" from Shakeel Butt cleans up the page_counter code and fixes a size increase which we accidentally added late last year. - The series "Add a command line option that enables control of how many threads should be used to allocate huge pages" from Thomas Prescher does that. It allows the careful operator to significantly reduce boot time by tuning the parallalization of huge page initialization. - The series "Fix calculations in trace_balance_dirty_pages() for cgwb" from Tang Yizhou fixes the tracing output from the dirty page balancing code. - The series "mm/damon: make allow filters after reject filters useful and intuitive" from SeongJae Park improves the handling of allow and reject filters. Behaviour is made more consistent and the documention is updated accordingly. - The series "Switch zswap to object read/write APIs" from Yosry Ahmed updates zswap to the new object read/write APIs and thus permits the removal of some legacy code from zpool and zsmalloc. - The series "Some trivial cleanups for shmem" from Baolin Wang does as it claims. - The series "fs/dax: Fix ZONE_DEVICE page reference counts" from Alistair Popple regularizes the weird ZONE_DEVICE page refcount handling in DAX, permittig the removal of a number of special-case checks. - The series "refactor mremap and fix bug" from Lorenzo Stoakes is a preparatoty refactoring and cleanup of the mremap() code. - The series "mm: MM owner tracking for large folios (!hugetlb) + CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in which we determine whether a large folio is known to be mapped exclusively into a single MM. - The series "mm/damon: add sysfs dirs for managing DAMOS filters based on handling layers" from SeongJae Park adds a couple of new sysfs directories to ease the management of DAMON/DAMOS filters. - The series "arch, mm: reduce code duplication in mem_init()" from Mike Rapoport consolidates many per-arch implementations of mem_init() into code generic code, where that is practical. - The series "mm/damon/sysfs: commit parameters online via damon_call()" from SeongJae Park continues the cleaning up of sysfs access to DAMON internal data. - The series "mm: page_ext: Introduce new iteration API" from Luiz Capitulino reworks the page_ext initialization to fix a boot-time crash which was observed with an unusual combination of compile and cmdline options. - The series "Buddy allocator like (or non-uniform) folio split" from Zi Yan reworks the code to split a folio into smaller folios. The main benefit is lessened memory consumption: fewer post-split folios are generated. - The series "Minimize xa_node allocation during xarry split" from Zi Yan reduces the number of xarray xa_nodes which are generated during an xarray split. - The series "drivers/base/memory: Two cleanups" from Gavin Shan performs some maintenance work on the drivers/base/memory code. - The series "Add tracepoints for lowmem reserves, watermarks and totalreserve_pages" from Martin Liu adds some more tracepoints to the page allocator code. - The series "mm/madvise: cleanup requests validations and classifications" from SeongJae Park cleans up some warts which SeongJae observed during his earlier madvise work. - The series "mm/hwpoison: Fix regressions in memory failure handling" from Shuai Xue addresses two quite serious regressions which Shuai has observed in the memory-failure implementation. - The series "mm: reliable huge page allocator" from Johannes Weiner makes huge page allocations cheaper and more reliable by reducing fragmentation. - The series "Minor memcg cleanups & prep for memdescs" from Matthew Wilcox is preparatory work for the future implementation of memdescs. - The series "track memory used by balloon drivers" from Nico Pache introduces a way to track memory used by our various balloon drivers. - The series "mm/damon: introduce DAMOS filter type for active pages" from Nhat Pham permits users to filter for active/inactive pages, separately for file and anon pages. - The series "Adding Proactive Memory Reclaim Statistics" from Hao Jia separates the proactive reclaim statistics from the direct reclaim statistics. - The series "mm/vmscan: don't try to reclaim hwpoison folio" from Jinjiang Tu fixes our handling of hwpoisoned pages within the reclaim code. * tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (431 commits) mm/page_alloc: remove unnecessary __maybe_unused in order_to_pindex() x86/mm: restore early initialization of high_memory for 32-bits mm/vmscan: don't try to reclaim hwpoison folio mm/hwpoison: introduce folio_contain_hwpoisoned_page() helper cgroup: docs: add pswpin and pswpout items in cgroup v2 doc mm: vmscan: split proactive reclaim statistics from direct reclaim statistics selftests/mm: speed up split_huge_page_test selftests/mm: uffd-unit-tests support for hugepages > 2M docs/mm/damon/design: document active DAMOS filter type mm/damon: implement a new DAMOS filter type for active pages fs/dax: don't disassociate zero page entries MM documentation: add "Unaccepted" meminfo entry selftests/mm: add commentary about 9pfs bugs fork: use __vmalloc_node() for stack allocation docs/mm: Physical Memory: Populate the "Zones" section xen: balloon: update the NR_BALLOON_PAGES state hv_balloon: update the NR_BALLOON_PAGES state balloon_compaction: update the NR_BALLOON_PAGES state meminfo: add a per node counter for balloon drivers mm: remove references to folio in __memcg_kmem_uncharge_page() ...
2025-03-16percpu: repurpose __percpu tag as a named address space qualifierUros Bizjak1-1/+1
The patch introduces __percpu_qual define and repurposes __percpu tag as a named address space qualifier using the new define. Arches can now conditionally define __percpu_qual as their named address space qualifier for percpu variables. Link: https://lkml.kernel.org/r/20250127160709.80604-6-ubizjak@gmail.com Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Acked-by: Nadav Amit <nadav.amit@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Dennis Zhou <dennis@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-12compiler_types: Introduce __nonstring_arrayKees Cook1-0/+12
GCC has expanded support of the "nonstring" attribute so that it can be applied to arrays of character arrays[1], which is needed to identify correct static initialization of those kinds of objects. Since this was not supported prior to GCC 15, we need to distinguish the usage of Linux's existing __nonstring macro for the attribute for non-multi-dimensional char arrays. Until GCC 15 is the minimum version, use __nonstring_array to mark arrays of non-string character arrays. (Regular non-string character arrays can continue to use __nonstring.) Once GCC 15 is the minimum compiler version we can replace all uses of __nonstring_array with just __nonstring and remove this macro. This allows for changes like this: -static const char table_sigs[][ACPI_NAMESEG_SIZE] __initconst = { +static const char table_sigs[][ACPI_NAMESEG_SIZE] __nonstring_array __initconst = { ACPI_SIG_BERT, ACPI_SIG_BGRT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, Which will silence the coming -Wunterminated-string-initialization warnings in GCC 15: In file included from ../include/acpi/actbl.h:371, from ../include/acpi/acpi.h:26, from ../include/linux/acpi.h:26, from ../drivers/acpi/tables.c:19: ../include/acpi/actbl1.h:30:33: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (5 chars into 4 available) [-Wunterminated-string-initialization] 30 | #define ACPI_SIG_BERT "BERT" /* Boot Error Record Table */ | ^~~~~~ ../drivers/acpi/tables.c:400:9: note: in expansion of macro 'ACPI_SIG_BERT' 400 | ACPI_SIG_BERT, ACPI_SIG_BGRT, ACPI_SIG_CPEP, ACPI_SIG_ECDT, | ^~~~~~~~~~~~~ ../include/acpi/actbl1.h:31:33: warning: initializer-string for array of 'char' truncates NUL terminator but destination lacks 'nonstring' attribute (5 chars into 4 available) [-Wunterminated-string-initialization] 31 | #define ACPI_SIG_BGRT "BGRT" /* Boot Graphics Resource Table */ | ^~~~~~ Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117178 [1] Acked-by: Miguel Ojeda <ojeda@kernel.org> Link: https://lore.kernel.org/r/20250310214244.work.194-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org>
2025-03-07ubsan/overflow: Rework integer overflow sanitizer option to turn on everythingKees Cook1-1/+1
Since we're going to approach integer overflow mitigation a type at a time, we need to enable all of the associated sanitizers, and then opt into types one at a time. Rename the existing "signed wrap" sanitizer to just the entire topic area: "integer wrap". Enable the implicit integer truncation sanitizers, with required callbacks and tests. Notably, this requires features (currently) only available in Clang, so we can depend on the cc-option tests to determine availability instead of doing version tests. Link: https://lore.kernel.org/r/20250307041914.937329-1-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org>
2025-03-03compiler.h: Introduce __must_be_noncstr()Kees Cook1-3/+6
In preparation for adding more type checking to the memtostr/strtomem*() helpers, introduce the ability to check for the "nonstring" attribute. This is the reverse of what was added to strscpy*() in commit 559048d156ff ("string: Check for "nonstring" attribute on strscpy() arguments"). Note that __annotated() must be explicitly tested for, as GCC added __builtin_has_attribute() after it added the "nonstring" attribute. Do so here to avoid the !__annotated() test triggering build failures when __builtin_has_attribute() was missing but __nonstring was defined. (I've opted to squash this fix into this patch so we don't end up with a possible bisection target that would leave the kernel unbuildable.) Reported-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reported-by: Michael Kelley <mhklinux@outlook.com> Closes: https://lore.kernel.org/all/adbe8dd1-a725-4811-ae7e-76fe770cf096@linux.vnet.ibm.com/ Tested-by: Michael Kelley <mhklinux@outlook.com> Signed-off-by: Kees Cook <kees@kernel.org>
2024-11-25Merge tag 'hardening-v6.13-rc1' of ↵Linus Torvalds1-0/+19
git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux Pull hardening updates from Kees Cook: - Disable __counted_by in Clang < 19.1.3 (Jan Hendrik Farr) - string_helpers: Silence output truncation warning (Bartosz Golaszewski) - compiler.h: Avoid needing BUILD_BUG_ON_ZERO() (Philipp Reisner) - MAINTAINERS: Add kernel hardening keywords __counted_by{_le|_be} (Thorsten Blum) * tag 'hardening-v6.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: Compiler Attributes: disable __counted_by for clang < 19.1.3 compiler.h: Fix undefined BUILD_BUG_ON_ZERO() lib: string_helpers: silence snprintf() output truncation warning MAINTAINERS: Add kernel hardening keywords __counted_by{_le|_be}
2024-11-19Compiler Attributes: disable __counted_by for clang < 19.1.3Jan Hendrik Farr1-0/+19
This patch disables __counted_by for clang versions < 19.1.3 because of the two issues listed below. It does this by introducing CONFIG_CC_HAS_COUNTED_BY. 1. clang < 19.1.2 has a bug that can lead to __bdos returning 0: https://github.com/llvm/llvm-project/pull/110497 2. clang < 19.1.3 has a bug that can lead to __bdos being off by 4: https://github.com/llvm/llvm-project/pull/112636 Fixes: c8248faf3ca2 ("Compiler Attributes: counted_by: Adjust name and identifier expansion") Cc: stable@vger.kernel.org # 6.6.x: 16c31dd7fdf6: Compiler Attributes: counted_by: bump min gcc version Cc: stable@vger.kernel.org # 6.6.x: 2993eb7a8d34: Compiler Attributes: counted_by: fixup clang URL Cc: stable@vger.kernel.org # 6.6.x: 231dc3f0c936: lkdtm/bugs: Improve warning message for compilers without counted_by support Cc: stable@vger.kernel.org # 6.6.x Reported-by: Nathan Chancellor <nathan@kernel.org> Closes: https://lore.kernel.org/all/20240913164630.GA4091534@thelio-3990X/ Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202409260949.a1254989-oliver.sang@intel.com Link: https://lore.kernel.org/all/Zw8iawAF5W2uzGuh@archlinux/T/#m204c09f63c076586a02d194b87dffc7e81b8de7b Suggested-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Jan Hendrik Farr <kernel@jfarr.cc> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Thorsten Blum <thorsten.blum@linux.dev> Link: https://lore.kernel.org/r/20241029140036.577804-2-kernel@jfarr.cc Signed-off-by: Kees Cook <kees@kernel.org>
2024-11-03compiler_types: Add noinline_for_tracing annotationYafang Shao1-0/+6
Kernel functions that are not inlined can be easily hooked with BPF for tracing. However, functions intended for tracing may still be inlined unexpectedly. For example, in our case, after upgrading the compiler from GCC 9 to GCC 11, the tcp_drop_reason() function was inlined, which broke our monitoring tools. To prevent this, we need to ensure that the function remains non-inlined. The noinline_for_tracing annotation is introduced as a general solution for preventing inlining of kernel functions that need to be traced. This approach avoids the need for adding individual noinline comments to each function and provides a more consistent way to maintain traceability. Link: https://lore.kernel.org/netdev/CANn89iKvr44ipuRYFaPTpzwz=B_+pgA94jsggQ946mjwreV6Aw@mail.gmail.com/ Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> Link: https://patch.msgid.link/20241024093742.87681-2-laoar.shao@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-08-22string: Check for "nonstring" attribute on strscpy() argumentsKees Cook1-0/+7
GCC already checks for arguments that are marked with the "nonstring"[1] attribute when used on standard C String API functions (e.g. strcpy). Gain this compile-time checking also for the kernel's primary string copying function, strscpy(). Note that Clang has neither "nonstring" nor __builtin_has_attribute(). Link: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute [1] Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Tested-by: Miguel Ojeda <ojeda@kernel.org> Link: https://lore.kernel.org/r/20240805214340.work.339-kees@kernel.org Signed-off-by: Kees Cook <kees@kernel.org>
2024-06-14compiler_types.h: Define __retain for __attribute__((__retain__))Tony Ambardar1-0/+23
Some code includes the __used macro to prevent functions and data from being optimized out. This macro implements __attribute__((__used__)), which operates at the compiler and IR-level, and so still allows a linker to remove objects intended to be kept. Compilers supporting __attribute__((__retain__)) can address this gap by setting the flag SHF_GNU_RETAIN on the section of a function/variable, indicating to the linker the object should be retained. This attribute is available since gcc 11, clang 13, and binutils 2.36. Provide a __retain macro implementing __attribute__((__retain__)), whose first user will be the '__bpf_kfunc' tag. [ Additional remark from discussion: Why is CONFIG_LTO_CLANG added here? The __used macro permits garbage collection at section level, so CLANG_LTO_CLANG without CONFIG_LD_DEAD_CODE_DATA_ELIMINATION should not change final section dynamics? The conditional guard was included to ensure consistent behaviour between __retain and other features forcing split sections. In particular, the same guard is used in vmlinux.lds.h to merge split sections where needed. For example, using __retain in LLVM builds without CONFIG_LTO was failing CI tests on kernel-patches/bpf because the kernel didn't boot properly. And in further testing, the kernel had no issues loading BPF kfunc modules with such split sections, so the module (partial) linking scripts were left alone. ] Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/bpf/ZlmGoT9KiYLZd91S@krava/T/ Link: https://lore.kernel.org/bpf/b31bca5a5e6765a0f32cc8c19b1d9cdbfaa822b5.1717477560.git.Tony.Ambardar@gmail.com
2024-05-22Merge local branch 'x86-codegen'Linus Torvalds1-0/+9
Merge trivial x86 code generation annoyances - Introduce helper macros for clang asm input problems - use said macros to improve trivially stupid code generation issues in bitops and array_index_mask_nospec - also improve codegen with 32-bit array index comparisons None of these really matter, but I look at code generation and profiles fairly regularly, and these misfeatures caused the generated code to look really odd and distract from the real issues. * branch 'x86-codegen' of local tree: x86: improve bitop code generation with clang x86: improve array_index_mask_nospec() code generation clang: work around asm input constraint problems
2024-05-22clang: work around asm input constraint problemsLinus Torvalds1-0/+9
Work around clang problems with asm constraints that have multiple possibilities, particularly "g" and "rm". Clang seems to turn inputs like that into the most generic form, which is the memory input - but to make matters worse, clang won't even use a possible original memory location, but will spill the value to stack, and use the stack for the asm input. See https://github.com/llvm/llvm-project/issues/20571#issuecomment-980933442 for some explanation of why clang has this strange behavior, but the end result is that "g" and "rm" really end up generating horrid code. Link: https://github.com/llvm/llvm-project/issues/20571 Cc: Peter Zijlstra <peterz@infradead.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2024-05-14Merge tag 'net-next-6.10' of ↵Linus Torvalds1-0/+11
git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next Pull networking updates from Jakub Kicinski: "Core & protocols: - Complete rework of garbage collection of AF_UNIX sockets. AF_UNIX is prone to forming reference count cycles due to fd passing functionality. New method based on Tarjan's Strongly Connected Components algorithm should be both faster and remove a lot of workarounds we accumulated over the years. - Add TCP fraglist GRO support, allowing chaining multiple TCP packets and forwarding them together. Useful for small switches / routers which lack basic checksum offload in some scenarios (e.g. PPPoE). - Support using SMP threads for handling packet backlog i.e. packet processing from software interfaces and old drivers which don't use NAPI. This helps move the processing out of the softirq jumble. - Continue work of converting from rtnl lock to RCU protection. Don't require rtnl lock when reading: IPv6 routing FIB, IPv6 address labels, netdev threaded NAPI sysfs files, bonding driver's sysfs files, MPLS devconf, IPv4 FIB rules, netns IDs, tcp metrics, TC Qdiscs, neighbor entries, ARP entries via ioctl(SIOCGARP), a lot of the link information available via rtnetlink. - Small optimizations from Eric to UDP wake up handling, memory accounting, RPS/RFS implementation, TCP packet sizing etc. - Allow direct page recycling in the bulk API used by XDP, for +2% PPS. - Support peek with an offset on TCP sockets. - Add MPTCP APIs for querying last time packets were received/sent/acked and whether MPTCP "upgrade" succeeded on a TCP socket. - Add intra-node communication shortcut to improve SMC performance. - Add IPv6 (and IPv{4,6}-over-IPv{4,6}) support to the GTP protocol driver. - Add HSR-SAN (RedBOX) mode of operation to the HSR protocol driver. - Add reset reasons for tracing what caused a TCP reset to be sent. - Introduce direction attribute for xfrm (IPSec) states. State can be used either for input or output packet processing. Things we sprinkled into general kernel code: - Add bitmap_{read,write}(), bitmap_size(), expose BYTES_TO_BITS(). This required touch-ups and renaming of a few existing users. - Add Endian-dependent __counted_by_{le,be} annotations. - Make building selftests "quieter" by printing summaries like "CC object.o" rather than full commands with all the arguments. Netfilter: - Use GFP_KERNEL to clone elements, to deal better with OOM situations and avoid fa