diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 36 |
1 files changed, 20 insertions, 16 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 4bb0f8447112..05da6b5b167b 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -37,11 +37,6 @@ #include <linux/mm.h> #include <linux/smp.h> #include <linux/io.h> - -#if defined(CONFIG_EDAC) -#include <linux/edac.h> -#endif - #include <asm/stacktrace.h> #include <asm/processor.h> #include <asm/debugreg.h> @@ -311,8 +306,23 @@ __visible void __noreturn handle_stack_overflow(const char *message, } #endif -#ifdef CONFIG_X86_64 -/* Runs on IST stack */ +#if defined(CONFIG_X86_64) || defined(CONFIG_DOUBLEFAULT) +/* + * Runs on an IST stack for x86_64 and on a special task stack for x86_32. + * + * On x86_64, this is more or less a normal kernel entry. Notwithstanding the + * SDM's warnings about double faults being unrecoverable, returning works as + * expected. Presumably what the SDM actually means is that the CPU may get + * the register state wrong on entry, so returning could be a bad idea. + * + * Various CPU engineers have promised that double faults due to an IRET fault + * while the stack is read-only are, in fact, recoverable. + * + * On x86_32, this is entered through a task gate, and regs are synthesized + * from the TSS. Returning is, in principle, okay, but changes to regs will + * be lost. If, for some reason, we need to return to a context with modified + * regs, the shim code could be adjusted to synchronize the registers. + */ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsigned long cr2) { static const char str[] = "double fault"; @@ -416,15 +426,9 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign handle_stack_overflow("kernel stack overflow (double-fault)", regs, cr2); #endif -#ifdef CONFIG_DOUBLEFAULT - df_debug(regs, error_code); -#endif - /* - * This is always a kernel trap and never fixable (and thus must - * never return). - */ - for (;;) - die(str, regs, error_code); + pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code); + die("double fault", regs, error_code); + panic("Machine halted."); } #endif |