1 files changed, 19 insertions, 14 deletions

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 2d1f4c7e4052..ce6650eb64e9 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -292,8 +292,10 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
         tsk->thread.error_code = error_code;
         tsk->thread.trap_no = 8;
 
-        /* This is always a kernel trap and never fixable (and thus must
-           never return). */
+        /*
+         * This is always a kernel trap and never fixable (and thus must
+         * never return).
+         */
         for (;;)
                 die(str, regs, error_code);
 }
@@ -520,9 +522,11 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
 }
 
 #ifdef CONFIG_X86_64
-/* 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 */
+/*
+ * 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 __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
 {
         struct pt_regs *regs = eregs;
@@ -532,8 +536,10 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
         /* Exception from user space */
         else if (user_mode(eregs))
                 regs = task_pt_regs(current);
-        /* Exception from kernel and interrupts are enabled. Move to
-           kernel process stack. */
+        /*
+         * Exception from kernel and interrupts are enabled. Move to
+         * kernel process stack.
+         */
         else if (eregs->flags & X86_EFLAGS_IF)
                 regs = (struct pt_regs *)(eregs->sp -= sizeof(struct pt_regs));
         if (eregs != regs)
@@ -685,12 +691,7 @@ void math_error(void __user *ip)
         cwd = get_fpu_cwd(task);
         swd = get_fpu_swd(task);
 
-        err = swd & ~cwd & 0x3f;
-
-#ifdef CONFIG_X86_32
-        if (!err)
-                return;
-#endif
+        err = swd & ~cwd;
 
         if (err & 0x001) {      /* Invalid op */
                 /*
@@ -708,7 +709,11 @@ void math_error(void __user *ip)
         } else if (err & 0x020) { /* Precision */
                 info.si_code = FPE_FLTRES;
         } else {
-                info.si_code = __SI_FAULT|SI_KERNEL; /* WTF? */
+                /*
+                 * If we're using IRQ 13, or supposedly even some trap 16
+                 * implementations, it's possible we get a spurious trap...
+                 */
+                return;         /* Spurious trap, no error */
         }
         force_sig_info(SIGFPE, &info, task);
 }