diff options
Diffstat (limited to 'arch/x86_64/kernel/crash.c')
| -rw-r--r-- | arch/x86_64/kernel/crash.c | 156 |
1 files changed, 154 insertions, 2 deletions
diff --git a/arch/x86_64/kernel/crash.c b/arch/x86_64/kernel/crash.c index 535e0446607..4e6c3b729e3 100644 --- a/arch/x86_64/kernel/crash.c +++ b/arch/x86_64/kernel/crash.c @@ -11,19 +11,156 @@ #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/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/mach_apic.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 = (u32*)per_cpu_ptr(crash_notes, cpu); + + if (!buf) + return; + + 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_save_self(struct pt_regs *regs) +{ + int cpu; + + cpu = smp_processor_id(); + crash_save_this_cpu(regs, cpu); +} + +#ifdef CONFIG_SMP +static atomic_t waiting_for_crash_ipi; + +static int crash_nmi_callback(struct pt_regs *regs, int cpu) +{ + /* + * 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(); + + crash_save_this_cpu(regs, cpu); + disable_local_APIC(); + atomic_dec(&waiting_for_crash_ipi); + /* Assume hlt works */ + for(;;) + asm("hlt"); + + return 1; +} + +static void smp_send_nmi_allbutself(void) +{ + send_IPI_allbutself(APIC_DM_NMI); +} + +/* + * This code is a best effort heuristic to get the + * other cpus to stop executing. So races with + * cpu hotplug shouldn't matter. + */ + +static void nmi_shootdown_cpus(void) +{ + unsigned long msecs; + + atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); + 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 + /* + * 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. @@ -31,4 +168,19 @@ void machine_crash_shutdown(struct pt_regs *regs) * 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(); + + if(cpu_has_apic) + disable_local_APIC(); + +#if defined(CONFIG_X86_IO_APIC) + disable_IO_APIC(); +#endif + + crash_save_self(regs); } |