x86/entry/64: Allocate and enable the SYSENTER stack

[mirror_ubuntu-artful-kernel.git] / arch / x86 / kernel / traps.c

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index bf54309b85da279147d6dbae5bff34381fa789a8..7b1d0df624cf4aef7c5f1929c84a68d712310082 100644 (file)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -153,8 +153,7 @@ void ist_begin_non_atomic(struct pt_regs *regs)
         * will catch asm bugs and any attempt to use ist_preempt_enable
         * from double_fault.
         */
-       BUG_ON((unsigned long)(current_top_of_stack() -
-                              current_stack_pointer()) >= THREAD_SIZE);
+       BUG_ON(!on_thread_stack());
 
        preempt_enable_no_resched();
 }
@@ -221,9 +220,6 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
                if (fixup_exception(regs, trapnr))
                        return 0;
 
-               if (fixup_bug(regs, trapnr))
-                       return 0;
-
                tsk->thread.error_code = error_code;
                tsk->thread.trap_nr = trapnr;
                die(str, regs, error_code);
@@ -304,6 +300,13 @@ static void do_error_trap(struct pt_regs *regs, long error_code, char *str,
 
        RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
 
+       /*
+        * WARN*()s end up here; fix them up before we call the
+        * notifier chain.
+        */
+       if (!user_mode(regs) && fixup_bug(regs, trapnr))
+               return;
+
        if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
                        NOTIFY_STOP) {
                cond_local_irq_enable(regs);
@@ -803,14 +806,13 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
        debug_stack_usage_dec();
 
 exit:
-#if defined(CONFIG_X86_32)
        /*
         * This is the most likely code path that involves non-trivial use
         * of the SYSENTER stack.  Check that we haven't overrun it.
         */
        WARN(this_cpu_read(cpu_tss.SYSENTER_stack_canary) != STACK_END_MAGIC,
             "Overran or corrupted SYSENTER stack\n");
-#endif
+
        ist_exit(regs);
 }
 NOKPROBE_SYMBOL(do_debug);