diff options
| author | Andi Kleen <ak@suse.de> | 2007-07-22 11:12:32 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-22 20:03:37 +0200 |
| commit | 8f4e956b313dcccbc7be6f10808952345e3b638c (patch) | |
| tree | cc8c93fa1faf5e0b608e3a21330a32bd82fe6f47 /arch/x86_64 | |
| parent | x86: Fix alternatives and kprobes to remap write-protected kernel text (diff) | |
| download | linux-8f4e956b313dcccbc7be6f10808952345e3b638c.tar.xz linux-8f4e956b313dcccbc7be6f10808952345e3b638c.zip | |
x86: Stop MCEs and NMIs during code patching
When a machine check or NMI occurs while multiple byte code is patched
the CPU could theoretically see an inconsistent instruction and crash.
Prevent this by temporarily disabling MCEs and returning early in the
NMI handler.
Based on discussion with Mathieu Desnoyers.
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86_64')
| -rw-r--r-- | arch/x86_64/kernel/mce.c | 14 | ||||
| -rw-r--r-- | arch/x86_64/kernel/nmi.c | 17 |
2 files changed, 30 insertions, 1 deletions
diff --git a/arch/x86_64/kernel/mce.c b/arch/x86_64/kernel/mce.c index 4d8450ee3635..a66d607f5b92 100644 --- a/arch/x86_64/kernel/mce.c +++ b/arch/x86_64/kernel/mce.c @@ -667,6 +667,20 @@ static struct miscdevice mce_log_device = { &mce_chrdev_ops, }; +static unsigned long old_cr4 __initdata; + +void __init stop_mce(void) +{ + old_cr4 = read_cr4(); + clear_in_cr4(X86_CR4_MCE); +} + +void __init restart_mce(void) +{ + if (old_cr4 & X86_CR4_MCE) + set_in_cr4(X86_CR4_MCE); +} + /* * Old style boot options parsing. Only for compatibility. */ diff --git a/arch/x86_64/kernel/nmi.c b/arch/x86_64/kernel/nmi.c index edbbc59b7523..cb8ee9d02f86 100644 --- a/arch/x86_64/kernel/nmi.c +++ b/arch/x86_64/kernel/nmi.c @@ -384,11 +384,14 @@ int __kprobes nmi_watchdog_tick(struct pt_regs * regs, unsigned reason) return rc; } +static unsigned ignore_nmis; + asmlinkage __kprobes void do_nmi(struct pt_regs * regs, long error_code) { nmi_enter(); add_pda(__nmi_count,1); - default_do_nmi(regs); + if (!ignore_nmis) + default_do_nmi(regs); nmi_exit(); } @@ -401,6 +404,18 @@ int do_nmi_callback(struct pt_regs * regs, int cpu) return 0; } +void stop_nmi(void) +{ + acpi_nmi_disable(); + ignore_nmis++; +} + +void restart_nmi(void) +{ + ignore_nmis--; + acpi_nmi_enable(); +} + #ifdef CONFIG_SYSCTL static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu) |