[PATCH] x86_64: Don't schedule on exception stack on preemptive kernels
Extends an earlier patch from John Blackwood to more exception handlers
that also run on the exception stacks.
Expand the use of preempt_conditional_{sti,cli} to all cases where
interrupts are to be re-enabled during exception handling while running
on an IST stack.
Based on original patch from Jan Beulich.
Cc: John Blackwood <john.blackwood@ccur.com>
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/kernel/traps.c b/arch/x86_64/kernel/traps.c
index 6b87268..cea335e 100644
--- a/arch/x86_64/kernel/traps.c
+++ b/arch/x86_64/kernel/traps.c
@@ -102,6 +102,8 @@
{
if (regs->eflags & X86_EFLAGS_IF)
local_irq_disable();
+ /* Make sure to not schedule here because we could be running
+ on an exception stack. */
preempt_enable_no_resched();
}
@@ -483,8 +485,6 @@
{
struct task_struct *tsk = current;
- conditional_sti(regs);
-
tsk->thread.error_code = error_code;
tsk->thread.trap_no = trapnr;
@@ -521,6 +521,7 @@
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
+ conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, NULL); \
}
@@ -535,6 +536,7 @@
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) \
== NOTIFY_STOP) \
return; \
+ conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, &info); \
}
@@ -548,7 +550,17 @@
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)
-DO_ERROR(12, SIGBUS, "stack segment", stack_segment)
+
+/* Runs on IST stack */
+asmlinkage void do_stack_segment(struct pt_regs *regs, long error_code)
+{
+ if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
+ 12, SIGBUS) == NOTIFY_STOP)
+ return;
+ preempt_conditional_sti(regs);
+ do_trap(12, SIGBUS, "stack segment", regs, error_code, NULL);
+ preempt_conditional_cli(regs);
+}
asmlinkage void do_double_fault(struct pt_regs * regs, long error_code)
{
@@ -682,8 +694,9 @@
if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP) == NOTIFY_STOP) {
return;
}
+ preempt_conditional_sti(regs);
do_trap(3, SIGTRAP, "int3", regs, error_code, NULL);
- return;
+ preempt_conditional_cli(regs);
}
/* Help handler running on IST stack to switch back to user stack
