/* * 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/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/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 */ halt(); 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); }