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author | Borislav Petkov <bp@suse.de> | 2013-05-09 12:02:29 +0200 |
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committer | H. Peter Anvin <hpa@linux.intel.com> | 2013-05-13 13:42:44 -0700 |
commit | 4d067d8e056d76a3327f0517c7722db55e7888fc (patch) | |
tree | 995c147a839866f5d1c2c700c27214755054cd7d /arch/x86/kernel/doublefault.c | |
parent | f722406faae2d073cc1d01063d1123c35425939e (diff) | |
download | op-kernel-dev-4d067d8e056d76a3327f0517c7722db55e7888fc.zip op-kernel-dev-4d067d8e056d76a3327f0517c7722db55e7888fc.tar.gz |
x86: Extend #DF debugging aid to 64-bit
It is sometimes very helpful to be able to pinpoint the location which
causes a double fault before it turns into a triple fault and the
machine reboots. We have this for 32-bit already so extend it to 64-bit.
On 64-bit we get the register snapshot at #DF time and not from the
first exception which actually causes the #DF. It should be close
enough, though.
[ hpa: and definitely better than nothing, which is what we have now. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/1368093749-31296-1-git-send-email-bp@alien8.de
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/doublefault.c')
-rw-r--r-- | arch/x86/kernel/doublefault.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/arch/x86/kernel/doublefault.c b/arch/x86/kernel/doublefault.c new file mode 100644 index 0000000..5d3fe8d --- /dev/null +++ b/arch/x86/kernel/doublefault.c @@ -0,0 +1,84 @@ +#include <linux/mm.h> +#include <linux/sched.h> +#include <linux/init.h> +#include <linux/init_task.h> +#include <linux/fs.h> + +#include <asm/uaccess.h> +#include <asm/pgtable.h> +#include <asm/processor.h> +#include <asm/desc.h> + +#ifdef CONFIG_X86_32 + +#define DOUBLEFAULT_STACKSIZE (1024) +static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE]; +#define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE) + +#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM) + +static void doublefault_fn(void) +{ + struct desc_ptr gdt_desc = {0, 0}; + unsigned long gdt, tss; + + native_store_gdt(&gdt_desc); + gdt = gdt_desc.address; + + printk(KERN_EMERG "PANIC: double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size); + + if (ptr_ok(gdt)) { + gdt += GDT_ENTRY_TSS << 3; + tss = get_desc_base((struct desc_struct *)gdt); + printk(KERN_EMERG "double fault, tss at %08lx\n", tss); + + if (ptr_ok(tss)) { + struct x86_hw_tss *t = (struct x86_hw_tss *)tss; + + printk(KERN_EMERG "eip = %08lx, esp = %08lx\n", + t->ip, t->sp); + + printk(KERN_EMERG "eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n", + t->ax, t->bx, t->cx, t->dx); + printk(KERN_EMERG "esi = %08lx, edi = %08lx\n", + t->si, t->di); + } + } + + for (;;) + cpu_relax(); +} + +struct tss_struct doublefault_tss __cacheline_aligned = { + .x86_tss = { + .sp0 = STACK_START, + .ss0 = __KERNEL_DS, + .ldt = 0, + .io_bitmap_base = INVALID_IO_BITMAP_OFFSET, + + .ip = (unsigned long) doublefault_fn, + /* 0x2 bit is always set */ + .flags = X86_EFLAGS_SF | 0x2, + .sp = STACK_START, + .es = __USER_DS, + .cs = __KERNEL_CS, + .ss = __KERNEL_DS, + .ds = __USER_DS, + .fs = __KERNEL_PERCPU, + + .__cr3 = __pa_nodebug(swapper_pg_dir), + } +}; + +/* dummy for do_double_fault() call */ +void df_debug(struct pt_regs *regs, long error_code) {} + +#else /* !CONFIG_X86_32 */ + +void df_debug(struct pt_regs *regs, long error_code) +{ + pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code); + show_regs(regs); + panic("Machine halted."); +} +#endif |