If several threads read /proc/cpuinfo some can see in 'flags' values from c->x86_capability, before __do_cpuid_fault() called and masks applied. Fix this by forming 'flags' on stack first and copy them in per_cpu(cpu_flags, cpu) as a last step.
https://jira.sw.ru/browse/PSBM-121823 Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com> --- Changes since v1: - none arch/x86/kernel/cpu/proc.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c index 4fe1577d5e6f..4cc2951e34fb 100644 --- a/arch/x86/kernel/cpu/proc.c +++ b/arch/x86/kernel/cpu/proc.c @@ -69,11 +69,11 @@ static DEFINE_PER_CPU(struct cpu_flags, cpu_flags); static void init_cpu_flags(void *dummy) { int cpu = smp_processor_id(); - struct cpu_flags *flags = &per_cpu(cpu_flags, cpu); + struct cpu_flags flags; struct cpuinfo_x86 *c = &cpu_data(cpu); unsigned int eax, ebx, ecx, edx; - memcpy(flags->val, c->x86_capability, NCAPINTS * sizeof(u32)); + memcpy(&flags, c->x86_capability, sizeof(flags)); /* * Clear feature bits masked using cpuid masking/faulting. @@ -81,26 +81,27 @@ static void init_cpu_flags(void *dummy) if (c->cpuid_level >= 0x00000001) { __do_cpuid_fault(0x00000001, 0, &eax, &ebx, &ecx, &edx); - flags->val[4] &= ecx; - flags->val[0] &= edx; + flags.val[4] &= ecx; + flags.val[0] &= edx; } if (c->cpuid_level >= 0x00000007) { __do_cpuid_fault(0x00000007, 0, &eax, &ebx, &ecx, &edx); - flags->val[9] &= ebx; + flags.val[9] &= ebx; } if ((c->extended_cpuid_level & 0xffff0000) == 0x80000000 && c->extended_cpuid_level >= 0x80000001) { __do_cpuid_fault(0x80000001, 0, &eax, &ebx, &ecx, &edx); - flags->val[6] &= ecx; - flags->val[1] &= edx; + flags.val[6] &= ecx; + flags.val[1] &= edx; } if (c->cpuid_level >= 0x0000000d) { __do_cpuid_fault(0x0000000d, 1, &eax, &ebx, &ecx, &edx); - flags->val[10] &= eax; + flags.val[10] &= eax; } + memcpy(&per_cpu(cpu_flags, cpu), &flags, sizeof(flags)); } static int show_cpuinfo(struct seq_file *m, void *v) -- 2.26.2 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
