The following commit has been merged into the objtool/urgent branch of tip: Commit-ID: a6a5eb269f6f3a2fe392f725a8d9052190c731e2 Gitweb: https://git.kernel.org/tip/a6a5eb269f6f3a2fe392f725a8d9052190c731e2 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Mon, 02 May 2022 12:15:23 +02:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Fri, 27 May 2022 12:34:43 +02:00 x86/cpu: Elide KCSAN for cpu_has() and friends As x86 uses the <asm-generic/bitops/instrumented-*.h> headers, the regular forms of all bitops are instrumented with explicit calls to KASAN and KCSAN checks. As these are explicit calls, these are not suppressed by the noinstr function attribute. This can result in calls to those check functions in noinstr code, which objtool warns about: vmlinux.o: warning: objtool: enter_from_user_mode+0x24: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: syscall_enter_from_user_mode+0x28: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: syscall_enter_from_user_mode_prepare+0x24: call to __kcsan_check_access() leaves .noinstr.text section vmlinux.o: warning: objtool: irqentry_enter_from_user_mode+0x24: call to __kcsan_check_access() leaves .noinstr.text section Prevent this by using the arch_*() bitops, which are the underlying bitops without explciit instrumentation. [null: Changelog] Reported-by: kernel test robot <lkp@xxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20220502111216.290518605@xxxxxxxxxxxxx --- arch/x86/include/asm/cpufeature.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 66d3e3b..ea34cc3 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -54,7 +54,7 @@ extern const char * const x86_power_flags[32]; extern const char * const x86_bug_flags[NBUGINTS*32]; #define test_cpu_cap(c, bit) \ - test_bit(bit, (unsigned long *)((c)->x86_capability)) + arch_test_bit(bit, (unsigned long *)((c)->x86_capability)) /* * There are 32 bits/features in each mask word. The high bits
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