Messages in this thread | | | Date | Mon, 30 May 2022 15:14:44 +0200 | From | Marco Elver <> | Subject | Re: [PATCH 4/7] x86/cpu: Elide KCSAN for cpu_has() and friends |
| |
On Thu, May 26, 2022 at 12:52PM +0200, Peter Zijlstra wrote: > 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. > > Reported-by: kernel test robot <lkp@intel.com> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Link: https://lkml.kernel.org/r/20220502111216.290518605@infradead.org
Acked-by: Marco Elver <elver@google.com>
> --- > arch/x86/include/asm/cpufeature.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/arch/x86/include/asm/cpufeature.h > +++ b/arch/x86/include/asm/cpufeature.h > @@ -51,7 +51,7 @@ extern const char * const x86_power_flag > 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 > >
| |