From 2c818b45a202b8f632b4031edcba8599efda42b7 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sat, 25 Jun 2005 14:57:59 -0700 Subject: [PATCH] [PATCH] kexec: x86: snapshot registers during crash shutdown After the kernel panics if we wish to generate an entire machine core file it is very nice to know the register state at the time the machine crashed. After long discussion it was realized that if you are going to be saving the information anyway it is reasonable to store the information in a format that it will be used and recognized in so the register state is stored in the standard ELF note format. Signed-off-by: Eric Biederman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/crash.c | 80 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+) diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c index 882779c078..1bb5dd98d1 100644 --- a/arch/i386/kernel/crash.c +++ b/arch/i386/kernel/crash.c @@ -30,12 +30,91 @@ typedef u32 note_buf_t[MAX_NOTE_BYTES/4]; note_buf_t crash_notes[NR_CPUS]; +static u32 *append_elf_note(u32 *buf, + char *name, unsigned type, void *data, size_t data_len) +{ + struct elf_note note; + note.n_namesz = strlen(name) + 1; + note.n_descsz = data_len; + note.n_type = type; + memcpy(buf, ¬e, sizeof(note)); + buf += (sizeof(note) +3)/4; + memcpy(buf, name, note.n_namesz); + buf += (note.n_namesz + 3)/4; + memcpy(buf, data, note.n_descsz); + buf += (note.n_descsz + 3)/4; + return buf; +} + +static void final_note(u32 *buf) +{ + struct elf_note note; + note.n_namesz = 0; + note.n_descsz = 0; + note.n_type = 0; + memcpy(buf, ¬e, sizeof(note)); +} + + +static void crash_save_this_cpu(struct pt_regs *regs, int cpu) +{ + struct elf_prstatus prstatus; + u32 *buf; + if ((cpu < 0) || (cpu >= NR_CPUS)) { + return; + } + /* Using ELF notes here is opportunistic. + * I need a well defined structure format + * for the data I pass, and I need tags + * on the data to indicate what information I have + * squirrelled away. ELF notes happen to provide + * all of that that no need to invent something new. + */ + buf = &crash_notes[cpu][0]; + memset(&prstatus, 0, sizeof(prstatus)); + prstatus.pr_pid = current->pid; + elf_core_copy_regs(&prstatus.pr_reg, regs); + buf = append_elf_note(buf, "CORE", NT_PRSTATUS, + &prstatus, sizeof(prstatus)); + + final_note(buf); +} + +static void crash_get_current_regs(struct pt_regs *regs) +{ + __asm__ __volatile__("movl %%ebx,%0" : "=m"(regs->ebx)); + __asm__ __volatile__("movl %%ecx,%0" : "=m"(regs->ecx)); + __asm__ __volatile__("movl %%edx,%0" : "=m"(regs->edx)); + __asm__ __volatile__("movl %%esi,%0" : "=m"(regs->esi)); + __asm__ __volatile__("movl %%edi,%0" : "=m"(regs->edi)); + __asm__ __volatile__("movl %%ebp,%0" : "=m"(regs->ebp)); + __asm__ __volatile__("movl %%eax,%0" : "=m"(regs->eax)); + __asm__ __volatile__("movl %%esp,%0" : "=m"(regs->esp)); + __asm__ __volatile__("movw %%ss, %%ax;" :"=a"(regs->xss)); + __asm__ __volatile__("movw %%cs, %%ax;" :"=a"(regs->xcs)); + __asm__ __volatile__("movw %%ds, %%ax;" :"=a"(regs->xds)); + __asm__ __volatile__("movw %%es, %%ax;" :"=a"(regs->xes)); + __asm__ __volatile__("pushfl; popl %0" :"=m"(regs->eflags)); + + regs->eip = (unsigned long)current_text_addr(); +} + +static void crash_save_self(void) +{ + struct pt_regs regs; + int cpu; + cpu = smp_processor_id(); + crash_get_current_regs(®s); + crash_save_this_cpu(®s, cpu); +} + #ifdef CONFIG_SMP static atomic_t waiting_for_crash_ipi; static int crash_nmi_callback(struct pt_regs *regs, int cpu) { local_irq_disable(); + crash_save_this_cpu(regs, cpu); atomic_dec(&waiting_for_crash_ipi); /* Assume hlt works */ __asm__("hlt"); @@ -95,4 +174,5 @@ void machine_crash_shutdown(void) /* The kernel is broken so disable interrupts */ local_irq_disable(); nmi_shootdown_cpus(); + crash_save_self(); } -- 2.39.5