kernel/linux.git/include/linux/compiler_attributes.h, branch v6.6.143

iommu, debugobjects: avoid gcc-16.1 section mismatch warnings

2026-06-19T11:39:19+00:00

commit 4c9ad387aa2d6785299722e54224d34764edaeb3 upstream. gcc-16 has gained some more advanced inter-procedual optimization techniques that enable it to inline the dummy_tlb_add_page() and dummy_tlb_flush() function pointers into a specialized version of __arm_v7s_unmap: WARNING: modpost: vmlinux: section mismatch in reference: __arm_v7s_unmap+0x2cc (section: .text) -> dummy_tlb_add_page (section: .init.text) ERROR: modpost: Section mismatches detected. >From what I can tell, the transformation is correct, as this is only called when __arm_v7s_unmap() is called from arm_v7s_do_selftests(), which is also __init. Since __arm_v7s_unmap() however is not __init, gcc cannot inline the inner function calls directly. In debug_objects_selftest(), the same thing happens. Both the caller and the leaf function are __init, but the IPA pulls it into a non-init one: WARNING: modpost: vmlinux: section mismatch in reference: lookup_object_or_alloc+0x7c (section: .text.lookup_object_or_alloc) -> is_static_object (section: .init.text) Marking the affected functions as not "__init" would reliably avoid this issue but is not a good solution because it removes an otherwise correct annotation. I tried marking the functions as 'noinline', but that ended up not covering all the affected configurations. With some more experimenting, I found that marking these functions as __attribute__((noipa)) is both logical and reliable. In order to keep the syntax readable, add a custom macro for this in include/linux/compiler_attributes.h next to other related macros and use it to annotate both files. Link: https://lore.kernel.org/all/abRB6g-48ZX6Yl2r@willie-the-truck/ Cc: Will Deacon Cc: Thomas Gleixner Cc: Andrew Morton Cc: Miguel Ojeda Cc: linux-kbuild@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Arnd Bergmann Acked-by: Will Deacon Acked-by: Thomas Gleixner Acked-by: Miguel Ojeda Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman

Compiler Attributes: disable __counted_by for clang < 19.1.3

2024-12-09T09:32:46+00:00

commit f06e108a3dc53c0f5234d18de0bd224753db5019 upstream. 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 Closes: https://lore.kernel.org/all/20240913164630.GA4091534@thelio-3990X/ Reported-by: kernel test robot 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 Signed-off-by: Jan Hendrik Farr Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Reviewed-by: Miguel Ojeda Reviewed-by: Thorsten Blum Link: https://lore.kernel.org/r/20241029140036.577804-2-kernel@jfarr.cc Signed-off-by: Kees Cook Signed-off-by: Jan Hendrik Farr Signed-off-by: Greg Kroah-Hartman

Compiler Attributes: Add __uninitialized macro

2024-07-18T11:21:09+00:00

commit fd7eea27a3aed79b63b1726c00bde0d50cf207e2 upstream. With INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO enabled the kernel will be compiled with -ftrivial-auto-var-init=<...> which causes initialization of stack variables at function entry time. In order to avoid the performance impact that comes with this users can use the "uninitialized" attribute to prevent such initialization. Therefore provide the __uninitialized macro which can be used for cases where INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO is enabled, but only selected variables should not be initialized. Acked-by: Kees Cook Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20240205154844.3757121-2-hca@linux.ibm.com Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman

Compiler Attributes: counted_by: Adjust name and identifier expansion

2023-08-17T23:46:35+00:00

GCC and Clang's current RFCs name this attribute "counted_by", and have moved away from using a string for the member name. Update the kernel's macros to match. Additionally provide a UAPI no-op macro for UAPI structs that will gain annotations. Cc: Miguel Ojeda Cc: Nick Desaulniers Fixes: dd06e72e68bc ("Compiler Attributes: Add __counted_by macro") Acked-by: Miguel Ojeda Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20230817200558.never.077-kees@kernel.org Signed-off-by: Kees Cook

Merge tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue

2023-07-04T20:50:38+00:00

Pull scope-based resource management infrastructure from Peter Zijlstra: "These are the first few patches in the Scope-based Resource Management series that introduce the infrastructure but not any conversions as of yet. Adding the infrastructure now allows multiple people to start using them. Of note is that Sparse will need some work since it doesn't yet understand this attribute and might have decl-after-stmt issues" * tag 'core_guards_for_6.5_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue: kbuild: Drop -Wdeclaration-after-statement locking: Introduce __cleanup() based infrastructure apparmor: Free up __cleanup() name dmaengine: ioat: Free up __cleanup() name

Merge tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2023-06-28T04:24:18+00:00

Pull hardening updates from Kees Cook: "There are three areas of note: A bunch of strlcpy()->strscpy() conversions ended up living in my tree since they were either Acked by maintainers for me to carry, or got ignored for multiple weeks (and were trivial changes). The compiler option '-fstrict-flex-arrays=3' has been enabled globally, and has been in -next for the entire devel cycle. This changes compiler diagnostics (though mainly just -Warray-bounds which is disabled) and potential UBSAN_BOUNDS and FORTIFY _warning_ coverage. In other words, there are no new restrictions, just potentially new warnings. Any new FORTIFY warnings we've seen have been fixed (usually in their respective subsystem trees). For more details, see commit df8fc4e934c12b. The under-development compiler attribute __counted_by has been added so that we can start annotating flexible array members with their associated structure member that tracks the count of flexible array elements at run-time. It is possible (likely?) that the exact syntax of the attribute will change before it is finalized, but GCC and Clang are working together to sort it out. Any changes can be made to the macro while we continue to add annotations. As an example of that last case, I have a treewide commit waiting with such annotations found via Coccinelle: https://git.kernel.org/linus/adc5b3cb48a049563dc673f348eab7b6beba8a9b Also see commit dd06e72e68bcb4 for more details. Summary: - Fix KMSAN vs FORTIFY in strlcpy/strlcat (Alexander Potapenko) - Convert strreplace() to return string start (Andy Shevchenko) - Flexible array conversions (Arnd Bergmann, Wyes Karny, Kees Cook) - Add missing function prototypes seen with W=1 (Arnd Bergmann) - Fix strscpy() kerndoc typo (Arne Welzel) - Replace strlcpy() with strscpy() across many subsystems which were either Acked by respective maintainers or were trivial changes that went ignored for multiple weeks (Azeem Shaikh) - Remove unneeded cc-option test for UBSAN_TRAP (Nick Desaulniers) - Add KUnit tests for strcat()-family - Enable KUnit tests of FORTIFY wrappers under UML - Add more complete FORTIFY protections for strlcat() - Add missed disabling of FORTIFY for all arch purgatories. - Enable -fstrict-flex-arrays=3 globally - Tightening UBSAN_BOUNDS when using GCC - Improve checkpatch to check for strcpy, strncpy, and fake flex arrays - Improve use of const variables in FORTIFY - Add requested struct_size_t() helper for types not pointers - Add __counted_by macro for annotating flexible array size members" * tag 'hardening-v6.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (54 commits) netfilter: ipset: Replace strlcpy with strscpy uml: Replace strlcpy with strscpy um: Use HOST_DIR for mrproper kallsyms: Replace all non-returning strlcpy with strscpy sh: Replace all non-returning strlcpy with strscpy of/flattree: Replace all non-returning strlcpy with strscpy sparc64: Replace all non-returning strlcpy with strscpy Hexagon: Replace all non-returning strlcpy with strscpy kobject: Use return value of strreplace() lib/string_helpers: Change returned value of the strreplace() jbd2: Avoid printing outside the boundary of the buffer checkpatch: Check for 0-length and 1-element arrays riscv/purgatory: Do not use fortified string functions s390/purgatory: Do not use fortified string functions x86/purgatory: Do not use fortified string functions acpi: Replace struct acpi_table_slit 1-element array with flex-array clocksource: Replace all non-returning strlcpy with strscpy string: use __builtin_memcpy() in strlcpy/strlcat staging: most: Replace all non-returning strlcpy with strscpy drm/i2c: tda998x: Replace all non-returning strlcpy with strscpy ...

locking: Introduce __cleanup() based infrastructure

2023-06-26T09:14:18+00:00

Use __attribute__((__cleanup__(func))) to build: - simple auto-release pointers using __free() - 'classes' with constructor and destructor semantics for scope-based resource management. - lock guards based on the above classes. Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230612093537.614161713%40infradead.org

Compiler Attributes: Add __counted_by macro

2023-05-30T23:42:00+00:00

In an effort to annotate all flexible array members with their run-time size information, the "element_count" attribute is being introduced by Clang[1] and GCC[2] in future releases. This annotation will provide the CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE features the ability to perform run-time bounds checking on otherwise unknown-size flexible arrays. Even though the attribute is under development, we can start the annotation process in the kernel. This requires defining a macro for it, even if we have to change the name of the actual attribute later. Since it is likely that this attribute may change its name to "counted_by" in the future (to better align with a future total bytes "sized_by" attribute), name the wrapper macro "__counted_by", which also reads more clearly (and concisely) in structure definitions. [1] https://reviews.llvm.org/D148381 [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 Cc: Bill Wendling Cc: Qing Zhao Cc: Gustavo A. R. Silva Cc: Nick Desaulniers Cc: Nathan Chancellor Cc: Tom Rix Cc: llvm@lists.linux.dev Signed-off-by: Kees Cook Reviewed-by: Gustavo A. R. Silva Reviewed-by: Nathan Chancellor Acked-by: Miguel Ojeda Link: https://lore.kernel.org/r/20230517190841.gonna.796-kees@kernel.org

start_kernel: Add __no_stack_protector function attribute

2023-05-16T13:28:15+00:00

Back during the discussion of commit a9a3ed1eff36 ("x86: Fix early boot crash on gcc-10, third try") we discussed the need for a function attribute to control the omission of stack protectors on a per-function basis; at the time Clang had support for no_stack_protector but GCC did not. This was fixed in gcc-11. Now that the function attribute is available, let's start using it. Callers of boot_init_stack_canary need to use this function attribute unless they're compiled with -fno-stack-protector, otherwise the canary stored in the stack slot of the caller will differ upon the call to boot_init_stack_canary. This will lead to a call to __stack_chk_fail() then panic. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94722 Link: https://lore.kernel.org/all/20200316130414.GC12561@hirez.programming.kicks-ass.net/ Tested-by: Nathan Chancellor Acked-by: Michael Ellerman (powerpc) Acked-by: Miguel Ojeda Acked-by: Peter Zijlstra (Intel) Signed-off-by: Nick Desaulniers Link: https://lore.kernel.org/r/20230412-no_stackp-v2-1-116f9fe4bbe7@google.com Signed-off-by: Josh Poimboeuf Signed-off-by: ndesaulniers@google.com

Remove Intel compiler support

2023-03-05T18:49:37+00:00

include/linux/compiler-intel.h had no update in the past 3 years. We often forget about the third C compiler to build the kernel. For example, commit a0a12c3ed057 ("asm goto: eradicate CC_HAS_ASM_GOTO") only mentioned GCC and Clang. init/Kconfig defines CC_IS_GCC and CC_IS_CLANG but not CC_IS_ICC, and nobody has reported any issue. I guess the Intel Compiler support is broken, and nobody is caring about it. Harald Arnesen pointed out ICC (classic Intel C/C++ compiler) is deprecated: $ icc -v icc: remark #10441: The Intel(R) C++ Compiler Classic (ICC) is deprecated and will be removed from product release in the second half of 2023. The Intel(R) oneAPI DPC++/C++ Compiler (ICX) is the recommended compiler moving forward. Please transition to use this compiler. Use '-diag-disable=10441' to disable this message. icc version 2021.7.0 (gcc version 12.1.0 compatibility) Arnd Bergmann provided a link to the article, "Intel C/C++ compilers complete adoption of LLVM". lib/zstd/common/compiler.h and lib/zstd/compress/zstd_fast.c were kept untouched for better sync with https://github.com/facebook/zstd Link: https://www.intel.com/content/www/us/en/developer/articles/technical/adoption-of-llvm-complete-icx.html Signed-off-by: Masahiro Yamada Acked-by: Arnd Bergmann Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Reviewed-by: Miguel Ojeda Signed-off-by: Linus Torvalds