[PATCH 3/4] ARM: context tracking: handle post exception/syscall/IRQ work

From: Kevin Hilman
Date: Wed Mar 20 2013 - 20:09:14 EST


do_work_pending() may be called on IRQ, exception or syscall exit (for
reschedule, signal handling, etc.) , but user_enter() may have already
been called (e.g. by syscall return path.)

Since do_work_pending() is still in kernel mode, keep context_tracker
up to date by using user_exit/user_enter.

Based on commit edf55fda35c7dc7f2d9241c3abaddaf759b457c6 (x86: Exit
RCU extended QS on notify resume)

Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxx>
---
arch/arm/kernel/signal.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 296786b..42514fd 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -12,6 +12,7 @@
#include <linux/personality.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>
+#include <linux/context_tracking.h>

#include <asm/elf.h>
#include <asm/cacheflush.h>
@@ -575,12 +576,15 @@ static int do_signal(struct pt_regs *regs, int syscall)
asmlinkage int
do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
+ int retval = 0;
+
+ user_exit();
do {
if (likely(thread_flags & _TIF_NEED_RESCHED)) {
schedule();
} else {
if (unlikely(!user_mode(regs)))
- return 0;
+ break;
local_irq_enable();
if (thread_flags & _TIF_SIGPENDING) {
int restart = do_signal(regs, syscall);
@@ -590,7 +594,8 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
* Deal with it without leaving
* the kernel space.
*/
- return restart;
+ retval = restart;
+ break;
}
syscall = 0;
} else {
@@ -601,5 +606,6 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
local_irq_disable();
thread_flags = current_thread_info()->flags;
} while (thread_flags & _TIF_WORK_MASK);
- return 0;
+ user_enter();
+ return retval;
}
--
1.8.2

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