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authorAristeu Rozanski <aris@redhat.com>2008-09-22 13:13:59 -0400
committerIngo Molnar <mingo@elte.hu>2008-09-22 19:48:19 +0200
commitb3e15bdef689641e7f1bb03efbe56112c3ee82e2 (patch)
treed972fcf64e45285b47b6204ce7558f15524432bb /arch/x86/kernel/vmi_32.c
parent28b166a700899a0f88b1cc283c449fb5bf72a635 (diff)
downloadlinux-linaro-android-b3e15bdef689641e7f1bb03efbe56112c3ee82e2.tar.gz
x86, NMI watchdog: setup before enabling NMI watchdog
There's a small window when NMI watchdog is being set up that if any NMIs are triggered, the NMI code will make make use of not initalized wd_ops elements: void setup_apic_nmi_watchdog(void *unused) { if (__get_cpu_var(wd_enabled)) return; /* cheap hack to support suspend/resume */ /* if cpu0 is not active neither should the other cpus */ if (smp_processor_id() != 0 && atomic_read(&nmi_active) <= 0) return; switch (nmi_watchdog) { case NMI_LOCAL_APIC: /* enable it before to avoid race with handler */ --> __get_cpu_var(wd_enabled) = 1; --> if (lapic_watchdog_init(nmi_hz) < 0) { (...) asmlinkage notrace __kprobes void default_do_nmi(struct pt_regs *regs) { (...) if (nmi_watchdog_tick(regs, reason)) return; (...) notrace __kprobes int nmi_watchdog_tick(struct pt_regs *regs, unsigned reason) { (...) if (!__get_cpu_var(wd_enabled)) return rc; switch (nmi_watchdog) { case NMI_LOCAL_APIC: rc |= lapic_wd_event(nmi_hz); (...) int lapic_wd_event(unsigned nmi_hz) { struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk); u64 ctr; --> rdmsrl(wd->perfctr_msr, ctr); and wd->*_msr will be initialized on each processor type specific setup, after enabling NMIs for PMIs. Since the counter was just set, the chances of an performance counter generated NMI is minimal, but any other unknown NMI would trigger the problem. This patch fixes the problem by setting everything up before enabling performance counter generated NMIs and will set wd_enabled using a callback function. Signed-off-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Don Zickus <dzickus@redhat.com> Acked-by: Prarit Bhargava <prarit@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/vmi_32.c')
0 files changed, 0 insertions, 0 deletions