From 6e274d144302068a00794ec22e73520c0615cb6f Mon Sep 17 00:00:00 2001 From: Alexander Nyberg Date: Sat, 25 Jun 2005 14:58:26 -0700 Subject: [PATCH] kdump: Use real pt_regs from exception Makes kexec_crashdump() take a pt_regs * as an argument. This allows to get exact register state at the point of the crash. If we come from direct panic assertion NULL will be passed and the current registers saved before crashdump. This hooks into two places: die(): check the conditions under which we will panic when calling do_exit and go there directly with the pt_regs that caused the fatal fault. die_nmi(): If we receive an NMI lockup while in the kernel use the pt_regs and go directly to crash_kexec(). We're probably nested up badly at this point so this might be the only chance to escape with proper information. Signed-off-by: Alexander Nyberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/crash.c | 36 ++++++++++++++++++++++++------------ 1 file changed, 24 insertions(+), 12 deletions(-) (limited to 'arch/i386/kernel/crash.c') diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c index a021681..8bdb4b6 100644 --- a/arch/i386/kernel/crash.c +++ b/arch/i386/kernel/crash.c @@ -100,12 +100,31 @@ static void crash_get_current_regs(struct pt_regs *regs) regs->eip = (unsigned long)current_text_addr(); } -static void crash_save_self(void) +/* CPU does not save ss and esp on stack if execution is already + * running in kernel mode at the time of NMI occurrence. This code + * fixes it. + */ +static void crash_setup_regs(struct pt_regs *newregs, struct pt_regs *oldregs) +{ + memcpy(newregs, oldregs, sizeof(*newregs)); + newregs->esp = (unsigned long)&(oldregs->esp); + __asm__ __volatile__("xorl %eax, %eax;"); + __asm__ __volatile__ ("movw %%ss, %%ax;" :"=a"(newregs->xss)); +} + +/* We may have saved_regs from where the error came from + * or it is NULL if via a direct panic(). + */ +static void crash_save_self(struct pt_regs *saved_regs) { struct pt_regs regs; int cpu; cpu = smp_processor_id(); - crash_get_current_regs(®s); + + if (saved_regs) + crash_setup_regs(®s, saved_regs); + else + crash_get_current_regs(®s); crash_save_this_cpu(®s, cpu); } @@ -124,15 +143,8 @@ static int crash_nmi_callback(struct pt_regs *regs, int cpu) return 1; local_irq_disable(); - /* CPU does not save ss and esp on stack if execution is already - * running in kernel mode at the time of NMI occurrence. This code - * fixes it. - */ if (!user_mode(regs)) { - memcpy(&fixed_regs, regs, sizeof(*regs)); - fixed_regs.esp = (unsigned long)&(regs->esp); - __asm__ __volatile__("xorl %eax, %eax;"); - __asm__ __volatile__ ("movw %%ss, %%ax;" :"=a"(fixed_regs.xss)); + crash_setup_regs(&fixed_regs, regs); regs = &fixed_regs; } crash_save_this_cpu(regs, cpu); @@ -184,7 +196,7 @@ static void nmi_shootdown_cpus(void) } #endif -void machine_crash_shutdown(void) +void machine_crash_shutdown(struct pt_regs *regs) { /* This function is only called after the system * has paniced or is otherwise in a critical state. @@ -204,5 +216,5 @@ void machine_crash_shutdown(void) #if defined(CONFIG_X86_IO_APIC) disable_IO_APIC(); #endif - crash_save_self(); + crash_save_self(regs); } -- cgit v1.1