[PATCH] x86_64: Regularize exception stack handling

[deliverable/linux.git] / arch / x86_64 / kernel / traps.c

diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 09e4a6460e74d09b9bc7e5562a0aba1eae57b55b..1b06ab24538bd61517ff7a85e75d77fbc952018d 100644 (file)
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -488,24 +488,8 @@ DO_ERROR(10, SIGSEGV, "invalid TSS", invalid_TSS)
 DO_ERROR(11, SIGBUS,  "segment not present", segment_not_present)
 DO_ERROR_INFO(17, SIGBUS, "alignment check", alignment_check, BUS_ADRALN, 0)
 DO_ERROR(18, SIGSEGV, "reserved", reserved)
-
-#define DO_ERROR_STACK(trapnr, signr, str, name) \
-asmlinkage void *do_##name(struct pt_regs * regs, long error_code) \
-{ \
-       struct pt_regs *pr = ((struct pt_regs *)(current->thread.rsp0))-1; \
-       if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
-                                                       == NOTIFY_STOP) \
-               return regs; \
-       if (regs->cs & 3) { \
-               memcpy(pr, regs, sizeof(struct pt_regs)); \
-               regs = pr; \
-       } \
-       do_trap(trapnr, signr, str, regs, error_code, NULL); \
-       return regs;            \
-}
-
-DO_ERROR_STACK(12, SIGBUS,  "stack segment", stack_segment)
-DO_ERROR_STACK( 8, SIGSEGV, "double fault", double_fault)
+DO_ERROR(12, SIGBUS,  "stack segment", stack_segment)
+DO_ERROR( 8, SIGSEGV, "double fault", double_fault)
 
 asmlinkage void do_general_protection(struct pt_regs * regs, long error_code)
 {
@@ -584,6 +568,8 @@ static void unknown_nmi_error(unsigned char reason, struct pt_regs * regs)
        printk("Do you have a strange power saving mode enabled?\n");
 }
 
+/* Runs on IST stack. This code must keep interrupts off all the time.
+   Nested NMIs are prevented by the CPU. */
 asmlinkage void default_do_nmi(struct pt_regs *regs)
 {
        unsigned char reason = 0;
@@ -629,20 +615,34 @@ asmlinkage void do_int3(struct pt_regs * regs, long error_code)
        return;
 }
 
+/* Help handler running on IST stack to switch back to user stack
+   for scheduling or signal handling. The actual stack switch is done in
+   entry.S */
+asmlinkage struct pt_regs *sync_regs(struct pt_regs *eregs)
+{
+       struct pt_regs *regs = eregs;
+       /* Did already sync */
+       if (eregs == (struct pt_regs *)eregs->rsp)
+               ;
+       /* Exception from user space */
+       else if (eregs->cs & 3)
+               regs = ((struct pt_regs *)current->thread.rsp0) - 1;
+       /* Exception from kernel and interrupts are enabled. Move to
+          kernel process stack. */
+       else if (eregs->eflags & X86_EFLAGS_IF)
+               regs = (struct pt_regs *)(eregs->rsp -= sizeof(struct pt_regs));
+       if (eregs != regs)
+               *regs = *eregs;
+       return regs;
+}
+
 /* runs on IST stack. */
-asmlinkage void *do_debug(struct pt_regs * regs, unsigned long error_code)
+asmlinkage void do_debug(struct pt_regs * regs, unsigned long error_code)
 {
-       struct pt_regs *pr;
        unsigned long condition;
        struct task_struct *tsk = current;
        siginfo_t info;
 
-       pr = (struct pt_regs *)(current->thread.rsp0)-1;
-       if (regs->cs & 3) {
-               memcpy(pr, regs, sizeof(struct pt_regs));
-               regs = pr;
-       }       
-
 #ifdef CONFIG_CHECKING
        { 
               /* RED-PEN interaction with debugger - could destroy gs */
@@ -660,7 +660,7 @@ asmlinkage void *do_debug(struct pt_regs * regs, unsigned long error_code)
 
        if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code,
                                                SIGTRAP) == NOTIFY_STOP) {
-               return regs;
+               return;
        }
        conditional_sti(regs);
 
@@ -712,7 +712,7 @@ asmlinkage void *do_debug(struct pt_regs * regs, unsigned long error_code)
 clear_dr7:
        asm volatile("movq %0,%%db7"::"r"(0UL));
        notify_die(DIE_DEBUG, "debug", regs, condition, 1, SIGTRAP);
-       return regs;
+       return;
 
 clear_TF_reenable:
        set_tsk_thread_flag(tsk, TIF_SINGLESTEP);
@@ -722,7 +722,6 @@ clear_TF:
        if (notify_die(DIE_DEBUG, "debug2", regs, condition, 1, SIGTRAP) 
                                                                != NOTIFY_STOP)
        regs->eflags &= ~TF_MASK;
-       return regs;    
 }
 
 static int kernel_math_error(struct pt_regs *regs, char *str)