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/*
* 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();
}
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)
{
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();
/* 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));
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(void)
{
/* 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();
}
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