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x86/entry, cpumask: Provide non-instrumented variant of cpu_is_offline()

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vmlinux.o: warning: objtool: exc_nmi()+0x12: call to cpumask_test_cpu.constprop.0() leaves .noinstr.text section
vmlinux.o: warning: objtool: mce_check_crashing_cpu()+0x12: call to cpumask_test_cpu.constprop.0()leaves .noinstr.text section

  cpumask_test_cpu()
    test_bit()
      instrument_atomic_read()
      arch_test_bit()

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Peter Zijlstra 2020-06-03 13:32:48 +02:00
parent 5144f8a8df
commit 14d3b376b6
3 changed files with 20 additions and 2 deletions
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18
arch/x86/include/asm/cpumask.h
View file

@ -11,5 +11,23 @@ extern cpumask_var_t cpu_sibling_setup_mask;
extern void setup_cpu_local_masks(void);
/*
* NMI and MCE exceptions need cpu_is_offline() _really_ early,
* provide an arch_ special for them to avoid instrumentation.
*/
#if NR_CPUS > 1
static __always_inline bool arch_cpu_online(int cpu)
{
return arch_test_bit(cpu, cpumask_bits(cpu_online_mask));
}
#else
static __always_inline bool arch_cpu_online(int cpu)
{
return cpu == 0;
}
#endif
#define arch_cpu_is_offline(cpu) unlikely(!arch_cpu_online(cpu))
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_CPUMASK_H */

2
arch/x86/kernel/cpu/mce/core.c
View file

@ -1083,7 +1083,7 @@ static noinstr bool mce_check_crashing_cpu(void)
{
unsigned int cpu = smp_processor_id();
if (cpu_is_offline(cpu) ||
if (arch_cpu_is_offline(cpu) ||
(crashing_cpu != -1 && crashing_cpu != cpu)) {
u64 mcgstatus;

2
arch/x86/kernel/nmi.c
View file

@ -478,7 +478,7 @@ static DEFINE_PER_CPU(unsigned long, nmi_dr7);
DEFINE_IDTENTRY_RAW(exc_nmi)
{
if (IS_ENABLED(CONFIG_SMP) && cpu_is_offline(smp_processor_id()))
if (IS_ENABLED(CONFIG_SMP) && arch_cpu_is_offline(smp_processor_id()))
return;
if (this_cpu_read(nmi_state) != NMI_NOT_RUNNING) {