kernel/linux.git/include/linux/compiler_attributes.h, branch v6.12.80

Compiler Attributes: disable __counted_by for clang < 19.1.3

2024-12-05T13:02:45+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: Greg Kroah-Hartman

Compiler Attributes: Add __always_used macro

2024-05-09T16:25:08+00:00

In some cases like performance benchmarking, we need to call a function, but don't need to read the returned value. If compiler recognizes the function as pure or const, it can remove the function invocation, which is not what we want. To prevent that, the common practice is assigning the return value to a temporary static volatile variable. From compiler's point of view, the variable is unused because never read back after been assigned. To make sure the variable is always emitted, we provide a __used attribute. This works with GCC, but clang still emits Wunused-but-set-variable. To suppress that warning, we need to teach clang to do that with the 'unused' attribute. Nathan Chancellor explained that in details: While having used and unused attributes together might look unusual, reading the GCC attribute manual makes it seem like these attributes fulfill similar yet different roles, __unused__ prevents any unused warnings while __used__ forces the variable to be emitted. A strict reading of that does not make it seem like __used__ implies disabling unused warnings The compiler documentation makes it clear what happens behind the 'used' and 'unused' attributes, but the chosen names may confuse readers if such combination catches an eye in a random code. This patch adds __always_used macro, which combines both attributes and comments on what happens for those interested in details. Suggested-by: Nathan Chancellor Reported-by: kernel test robot Reviewed-by: Nathan Chancellor Closes: https://lore.kernel.org/oe-kbuild-all/202405030808.UsoMKFNP-lkp@intel.com/ Acked-by: Miguel Ojeda Signed-off-by: Yury Norov

Merge tag 's390-6.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2024-03-12T17:14:22+00:00

Pull s390 updates from Heiko Carstens: - Various virtual vs physical address usage fixes - Fix error handling in Processor Activity Instrumentation device driver, and export number of counters with a sysfs file - Allow for multiple events when Processor Activity Instrumentation counters are monitored in system wide sampling - Change multiplier and shift values of the Time-of-Day clock source to improve steering precision - Remove a couple of unneeded GFP_DMA flags from allocations - Disable mmap alignment if randomize_va_space is also disabled, to avoid a too small heap - Various changes to allow s390 to be compiled with LLVM=1, since ld.lld and llvm-objcopy will have proper s390 support witch clang 19 - Add __uninitialized macro to Compiler Attributes. This is helpful with s390's FPU code where some users have up to 520 byte stack frames. Clearing such stack frames (if INIT_STACK_ALL_PATTERN or INIT_STACK_ALL_ZERO is enabled) before they are used contradicts the intention (performance improvement) of such code sections. - Convert switch_to() to an out-of-line function, and use the generic switch_to header file - Replace the usage of s390's debug feature with pr_debug() calls within the zcrypt device driver - Improve hotplug support of the Adjunct Processor device driver - Improve retry handling in the zcrypt device driver - Various changes to the in-kernel FPU code: - Make in-kernel FPU sections preemptible - Convert various larger inline assemblies and assembler files to C, mainly by using singe instruction inline assemblies. This increases readability, but also allows makes it easier to add proper instrumentation hooks - Cleanup of the header files - Provide fast variants of csum_partial() and csum_partial_copy_nocheck() based on vector instructions - Introduce and use a lock to synchronize accesses to zpci device data structures to avoid inconsistent states caused by concurrent accesses - Compile the kernel without -fPIE. This addresses the following problems if the kernel is compiled with -fPIE: - It uses dynamic symbols (.dynsym), for which the linker refuses to allow more than 64k sections. This can break features which use '-ffunction-sections' and '-fdata-sections', including kpatch-build and function granular KASLR - It unnecessarily uses GOT relocations, adding an extra layer of indirection for many memory accesses - Fix shared_cpu_list for CPU private L2 caches, which incorrectly were reported as globally shared * tag 's390-6.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (117 commits) s390/tools: handle rela R_390_GOTPCDBL/R_390_GOTOFF64 s390/cache: prevent rebuild of shared_cpu_list s390/crypto: remove retry loop with sleep from PAES pkey invocation s390/pkey: improve pkey retry behavior s390/zcrypt: improve zcrypt retry behavior s390/zcrypt: introduce retries on in-kernel send CPRB functions s390/ap: introduce mutex to lock the AP bus scan s390/ap: rework ap_scan_bus() to return true on config change s390/ap: clarify AP scan bus related functions and variables s390/ap: rearm APQNs bindings complete completion s390/configs: increase number of LOCKDEP_BITS s390/vfio-ap: handle hardware checkstop state on queue reset operation s390/pai: change sampling event assignment for PMU device driver s390/boot: fix minor comment style damages s390/boot: do not check for zero-termination relocation entry s390/boot: make type of __vmlinux_relocs_64_start|end consistent s390/boot: sanitize kaslr_adjust_relocs() function prototype s390/boot: simplify GOT handling s390: vmlinux.lds.S: fix .got.plt assertion s390/boot: workaround current 'llvm-objdump -t -j ...' behavior ...

Compiler Attributes: Add __uninitialized macro

2024-02-09T12:58:16+00:00

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

Compiler Attributes: counted_by: fixup clang URL

2024-01-23T19:38:18+00:00

The URL in question 404 now, fix it up (and switch to github). Signed-off-by: Sergey Senozhatsky Reviewed-by: Kees Cook Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/b7babeb9c5b14af9189f0d6225673e6e9a8f4ad3.1704855496.git.senozhatsky@chromium.org Signed-off-by: Miguel Ojeda

Compiler Attributes: counted_by: bump min gcc version

2024-01-23T19:38:18+00:00

GCC is expected to implement this feature in version 15, so bump the version. Signed-off-by: Sergey Senozhatsky Reviewed-by: Nathan Chancellor Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/e1c27b64ae7abe2ebe647be11b71cf1bca84f677.1704855495.git.senozhatsky@chromium.org Signed-off-by: Miguel Ojeda

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