| Message ID | 1370361038-6101-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index e514de5..4498467 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -851,7 +851,7 @@ resume_kernel: /* check current_thread_info, _TIF_EMULATE_STACK_STORE */ CURRENT_THREAD_INFO(r9, r1) lwz r8,TI_FLAGS(r9) - andis. r8,r8,_TIF_EMULATE_STACK_STORE@h + andis. r0,r8,_TIF_EMULATE_STACK_STORE@h beq+ 1f addi r8,r1,INT_FRAME_SIZE /* Get the kprobed function entry */
This is a note to let you know that I have just added a patch titled powerpc/32bit:Store temporary result in r0 instead of r8 to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.2. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 582045a249b5c140bb33fbb41b3aa02a53b9a60a Mon Sep 17 00:00:00 2001 From: Priyanka Jain <Priyanka.Jain@freescale.com> Date: Fri, 31 May 2013 01:20:02 +0000 Subject: powerpc/32bit:Store temporary result in r0 instead of r8 commit f7b3367774f92a688d39ed767f0ae9b93af7873a upstream. Commit a9c4e541ea9b22944da356f2a9258b4eddcc953b "powerpc/kprobe: Complete kprobe and migrate exception frame" introduced a regression: While returning from exception handling in case of PREEMPT enabled, _TIF_NEED_RESCHED bit is checked in TI_FLAGS (thread_info flag) of current task. Only if this bit is set, it should continue with the process of calling preempt_schedule_irq() to schedule highest priority task if available. Current code assumes that r8 contains TI_FLAGS and check this for _TIF_NEED_RESCHED, but as r8 is modified in the code which executes before this check, r8 no longer contains the expected TI_FLAGS information. As a result check for comparison with _TIF_NEED_RESCHED was failing even if NEED_RESCHED bit is set in the current thread_info flag. Due to this, preempt_schedule_irq() and in turn scheduler was not getting called even if highest priority task is ready for execution. So, store temporary results in r0 instead of r8 to prevent r8 from getting modified as subsequent code is dependent on its value. Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/powerpc/kernel/entry_32.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 1.8.1.2