Fernando Luis V?zquez Cao <fernando at oss.ntt.co.jp> writes: > Subject: [PATCH] boot: add early NMI counter > > From: Fernando Luis Vazquez Cao <fernando at oss.ntt.co.jp> > > We currently ignore early NMIs but it would be nice to be able to > know whether they actually occurred. > > This patch adds an early NMI counter and exports it trough > /proc/interrupts with the name of ENM (Early NMI). For a userspace interface I suspect we just want to dump the count into the NMI counter. It probably makes sense to have a separate variable in early boot like you do, but then about the time we setup the normal NMI handler move the NMI count over and possibly do something like reboot if that is our policy. I don't see it making sense to educate userspace for an edge case like this. Eric > Signed-off-by: Fernando Luis Vazquez Cao <fernando at oss.ntt.co.jp> > --- > > diff -urNp linux-3.3-rc6-orig/arch/x86/include/asm/processor.h linux-3.3-rc6/arch/x86/include/asm/processor.h > --- linux-3.3-rc6-orig/arch/x86/include/asm/processor.h 2012-03-07 15:49:01.826241682 +0900 > +++ linux-3.3-rc6/arch/x86/include/asm/processor.h 2012-03-07 18:52:27.668054122 +0900 > @@ -402,6 +402,7 @@ DECLARE_PER_CPU(char *, irq_stack_ptr); > DECLARE_PER_CPU(unsigned int, irq_count); > extern unsigned long kernel_eflags; > extern asmlinkage void ignore_sysret(void); > +extern unsigned int early_nmi_count; > #else /* X86_64 */ > #ifdef CONFIG_CC_STACKPROTECTOR > /* > diff -urNp linux-3.3-rc6-orig/arch/x86/kernel/head_64.S linux-3.3-rc6/arch/x86/kernel/head_64.S > --- linux-3.3-rc6-orig/arch/x86/kernel/head_64.S 2012-03-07 18:51:17.583160114 +0900 > +++ linux-3.3-rc6/arch/x86/kernel/head_64.S 2012-03-07 18:54:37.205699422 +0900 > @@ -327,6 +327,7 @@ early_exception_handler: > jmp 1b > > early_nmi_handler: > + incl early_nmi_count(%rip) # exported as ENM in /proc/interrupts > iretq > > #ifdef CONFIG_EARLY_PRINTK > @@ -340,6 +341,10 @@ early_idt_ripmsg: > #endif /* CONFIG_EARLY_PRINTK */ > .previous > > + .globl early_nmi_count > +early_nmi_count: > + .long 0 > + > #define NEXT_PAGE(name) \ > .balign PAGE_SIZE; \ > ENTRY(name) > diff -urNp linux-3.3-rc6-orig/arch/x86/kernel/irq.c linux-3.3-rc6/arch/x86/kernel/irq.c > --- linux-3.3-rc6-orig/arch/x86/kernel/irq.c 2012-03-07 15:49:01.838241839 +0900 > +++ linux-3.3-rc6/arch/x86/kernel/irq.c 2012-03-07 18:55:14.078179448 +0900 > @@ -125,6 +125,7 @@ int arch_show_interrupts(struct seq_file > #if defined(CONFIG_X86_IO_APIC) > seq_printf(p, "%*s: %10u\n", prec, "MIS", atomic_read(&irq_mis_count)); > #endif > + seq_printf(p, "%*s: %10u\n", prec, "ENM", early_nmi_count); > return 0; > } >
