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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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8
arch/x86/include/asm/desc.h
View File

@ -214,7 +214,7 @@ static inline void native_load_gdt(const struct desc_ptr *dtr)
asm volatile("lgdt %0"::"m" (*dtr));
}
static inline void native_load_idt(const struct desc_ptr *dtr)
static __always_inline void native_load_idt(const struct desc_ptr *dtr)
{
asm volatile("lidt %0"::"m" (*dtr));
}
@ -392,7 +392,7 @@ extern unsigned long system_vectors[];
#ifdef CONFIG_X86_64
DECLARE_PER_CPU(u32, debug_idt_ctr);
static inline bool is_debug_idt_enabled(void)
static __always_inline bool is_debug_idt_enabled(void)
{
if (this_cpu_read(debug_idt_ctr))
return true;
@ -400,7 +400,7 @@ static inline bool is_debug_idt_enabled(void)
return false;
}
static inline void load_debug_idt(void)
static __always_inline void load_debug_idt(void)
{
load_idt((const struct desc_ptr *)&debug_idt_descr);
}
@ -422,7 +422,7 @@ static inline void load_debug_idt(void)
* that doesn't need to disable interrupts, as nothing should be
* bothering the CPU then.
*/
static inline void load_current_idt(void)
static __always_inline void load_current_idt(void)
{
if (is_debug_idt_enabled())
load_debug_idt();

6
arch/x86/kernel/cpu/common.c
View File

@ -1709,21 +1709,19 @@ void syscall_init(void)
DEFINE_PER_CPU(int, debug_stack_usage);
DEFINE_PER_CPU(u32, debug_idt_ctr);
void debug_stack_set_zero(void)
noinstr void debug_stack_set_zero(void)
{
this_cpu_inc(debug_idt_ctr);
load_current_idt();
}
NOKPROBE_SYMBOL(debug_stack_set_zero);
void debug_stack_reset(void)
noinstr void debug_stack_reset(void)
{
if (WARN_ON(!this_cpu_read(debug_idt_ctr)))
return;
if (this_cpu_dec_return(debug_idt_ctr) == 0)
load_current_idt();
}
NOKPROBE_SYMBOL(debug_stack_reset);
#else /* CONFIG_X86_64 */

15
arch/x86/kernel/nmi.c
View File

@ -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)