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authorSteven Rostedt <rostedt@goodmis.org>2007-06-07 05:34:04 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-06-08 02:05:03 +0200
commite5e3c84b70e58fc605635fd340fb8dba3cc59058 (patch)
tree7ebba42dc0a402ef54bcbd4552e1fe47c519de2b
parentMerge master.kernel.org:/home/rmk/linux-2.6-arm (diff)
downloadlinux-e5e3c84b70e58fc605635fd340fb8dba3cc59058.tar.xz
linux-e5e3c84b70e58fc605635fd340fb8dba3cc59058.zip
enable interrupts in user path of page fault.
This is a minor fix, but what is currently there is essentially wrong. In do_page_fault, if the faulting address from user code happens to be in kernel address space (int *p = (int*)-1; p = 0xbed;) then the do_page_fault handler will jump over the local_irq_enable with the goto bad_area_nosemaphore; But the first line there sees this is user code and goes through the process of sending a signal to send SIGSEGV to the user task. This whole time interrupts are disabled and the task can not be preempted by a higher priority task. This patch always enables interrupts in the user path of the bad_area_nosemaphore. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/i386/mm/fault.c5
-rw-r--r--arch/x86_64/mm/fault.c6
2 files changed, 11 insertions, 0 deletions
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index 29d7d61543a1..1ecb3e43b523 100644
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -458,6 +458,11 @@ bad_area:
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (error_code & 4) {
+ /*
+ * It's possible to have interrupts off here.
+ */
+ local_irq_enable();
+
/*
* Valid to do another page fault here because this one came
* from user space.
diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c
index bfb62a13d7ee..635e58d443d7 100644
--- a/arch/x86_64/mm/fault.c
+++ b/arch/x86_64/mm/fault.c
@@ -476,6 +476,12 @@ bad_area:
bad_area_nosemaphore:
/* User mode accesses just cause a SIGSEGV */
if (error_code & PF_USER) {
+
+ /*
+ * It's possible to have interrupts off here.
+ */
+ local_irq_enable();
+
if (is_prefetch(regs, address, error_code))
return;