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x86/nmi: Protect NMI entry against instrumentation

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Mark all functions in the fragile code parts noinstr or force inlining so
they can't be instrumented.

Also make the hardware latency tracer invocation explicit outside of
non-instrumentable section.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505135314.716186134@linutronix.de
This commit is contained in:
Thomas Gleixner
2020-04-06 15:55:06 +02:00
parent 6271fef00b
commit f051f69795
3 changed files with 15 additions and 14 deletions
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15
arch/x86/kernel/nmi.c
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@@ -303,7 +303,7 @@ NOKPROBE_SYMBOL(unknown_nmi_error);
static DEFINE_PER_CPU(bool, swallow_nmi);
static DEFINE_PER_CPU(unsigned long, last_nmi_rip);
static void default_do_nmi(struct pt_regs *regs)
static noinstr void default_do_nmi(struct pt_regs *regs)
{
unsigned char reason = 0;
int handled;
@@ -329,6 +329,8 @@ static void default_do_nmi(struct pt_regs *regs)
__this_cpu_write(last_nmi_rip, regs->ip);
instrumentation_begin();
handled = nmi_handle(NMI_LOCAL, regs);
__this_cpu_add(nmi_stats.normal, handled);
if (handled) {
@@ -342,7 +344,7 @@ static void default_do_nmi(struct pt_regs *regs)
*/
if (handled > 1)
__this_cpu_write(swallow_nmi, true);
return;
goto out;
}
/*
@@ -374,7 +376,7 @@ static void default_do_nmi(struct pt_regs *regs)
#endif
__this_cpu_add(nmi_stats.external, 1);
raw_spin_unlock(&nmi_reason_lock);
return;
goto out;
}
raw_spin_unlock(&nmi_reason_lock);
@@ -412,8 +414,10 @@ static void default_do_nmi(struct pt_regs *regs)
__this_cpu_add(nmi_stats.swallow, 1);
else
unknown_nmi_error(reason, regs);
out:
instrumentation_end();
}
NOKPROBE_SYMBOL(default_do_nmi);
/*
* NMIs can page fault or hit breakpoints which will cause it to lose
@@ -485,7 +489,7 @@ static DEFINE_PER_CPU(unsigned long, nmi_cr2);
*/
static DEFINE_PER_CPU(int, update_debug_stack);
static bool notrace is_debug_stack(unsigned long addr)
static noinstr bool is_debug_stack(unsigned long addr)
{
struct cea_exception_stacks *cs = __this_cpu_read(cea_exception_stacks);
unsigned long top = CEA_ESTACK_TOP(cs, DB);
@@ -500,7 +504,6 @@ static bool notrace is_debug_stack(unsigned long addr)
*/
return addr >= bot && addr < top;
}
NOKPROBE_SYMBOL(is_debug_stack);
#endif
DEFINE_IDTENTRY_NMI(exc_nmi)