diff options
Diffstat (limited to 'arch/i386/kernel/crash.c')
| -rw-r--r-- | arch/i386/kernel/crash.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c new file mode 100644 index 00000000000..e5fab12f792 --- /dev/null +++ b/arch/i386/kernel/crash.c @@ -0,0 +1,223 @@ +/* + * Architecture specific (i386) functions for kexec based crash dumps. + * + * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) + * + * Copyright (C) IBM Corporation, 2004. All rights reserved. + * + */ + +#include <linux/init.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/smp.h> +#include <linux/irq.h> +#include <linux/reboot.h> +#include <linux/kexec.h> +#include <linux/irq.h> +#include <linux/delay.h> +#include <linux/elf.h> +#include <linux/elfcore.h> + +#include <asm/processor.h> +#include <asm/hardirq.h> +#include <asm/nmi.h> +#include <asm/hw_irq.h> +#include <asm/apic.h> +#include <mach_ipi.h> + + +note_buf_t crash_notes[NR_CPUS]; +/* This keeps a track of which one is crashing cpu. */ +static int crashing_cpu; + +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(); +} + +/* 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(); + if (saved_regs) + crash_setup_regs(®s, saved_regs); + else + 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) +{ + struct pt_regs fixed_regs; + + /* Don't do anything if this handler is invoked on crashing cpu. + * Otherwise, system will completely hang. Crashing cpu can get + * an NMI if system was initially booted with nmi_watchdog parameter. + */ + if (cpu == crashing_cpu) + return 1; + local_irq_disable(); + + if (!user_mode(regs)) { + crash_setup_regs(&fixed_regs, regs); + regs = &fixed_regs; + } + crash_save_this_cpu(regs, cpu); + disable_local_APIC(); + atomic_dec(&waiting_for_crash_ipi); + /* Assume hlt works */ + __asm__("hlt"); + for(;;); + + return 1; +} + +/* + * By using the NMI code instead of a vector we just sneak thru the + * word generator coming out with just what we want. AND it does + * not matter if clustered_apic_mode is set or not. + */ +static void smp_send_nmi_allbutself(void) +{ + send_IPI_allbutself(APIC_DM_NMI); +} + +static void nmi_shootdown_cpus(void) +{ + unsigned long msecs; + + atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); + /* Would it be better to replace the trap vector here? */ + set_nmi_callback(crash_nmi_callback); + /* Ensure the new callback function is set before sending + * out the NMI + */ + wmb(); + + smp_send_nmi_allbutself(); + + msecs = 1000; /* Wait at most a second for the other cpus to stop */ + while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { + mdelay(1); + msecs--; + } + + /* Leave the nmi callback set */ + disable_local_APIC(); +} +#else +static void nmi_shootdown_cpus(void) +{ + /* There are no cpus to shootdown */ +} +#endif + +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. + * The minimum amount of code to allow a kexec'd kernel + * to run successfully needs to happen here. + * + * In practice this means shooting down the other cpus in + * an SMP system. + */ + /* The kernel is broken so disable interrupts */ + local_irq_disable(); + + /* Make a note of crashing cpu. Will be used in NMI callback.*/ + crashing_cpu = smp_processor_id(); + nmi_shootdown_cpus(); + lapic_shutdown(); +#if defined(CONFIG_X86_IO_APIC) + disable_IO_APIC(); +#endif + crash_save_self(regs); +} |