In entry_64.S version of ret_from_except_lite, you'll notice that
in the !preempt case, after we've checked MSR_PR we test for any
TIF flag in _TIF_USER_WORK_MASK to decide whether to go to do_work
or not. However, in the preempt case, we do a convoluted trick to
test SIGPENDING only if PR was set and always test NEED_RESCHED ...
but we forget to test any other bit of _TIF_USER_WORK_MASK !!! So
that means that with preempt, we completely fail to test for things
like single step, syscall tracing, etc...
This should be fixed as the following path:
- Test PR. If set, go to test_work_user, else continue.
- In test_work_user, always test for _TIF_USER_WORK_MASK to decide to
go to do_work, maybe call it do_user_work
- In test_work_kernel, test for _TIF_KERNEL_WORK_MASK which is set to
our new flag along with NEED_RESCHED if preempt is enabled and branch to
do_kernel_work.
Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Signed-off-by: Tiejun Chen <tiejun.c...@windriver.com>
---
arch/powerpc/kernel/entry_64.S | 33 +++++++++++++++------------------
1 files changed, 15 insertions(+), 18 deletions(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index d834425..9e70b9a 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -571,27 +571,26 @@ _GLOBAL(ret_from_except_lite)
mtmsrd r9,1 /* Update machine state */
#endif /* CONFIG_PPC_BOOK3E */
-#ifdef CONFIG_PREEMPT
- clrrdi r9,r1,THREAD_SHIFT /* current_thread_info() */
- li r0,_TIF_NEED_RESCHED /* bits to check */
- ld r3,_MSR(r1)
- ld r4,TI_FLAGS(r9)
- /* Move MSR_PR bit in r3 to _TIF_SIGPENDING position in r0 */
- rlwimi r0,r3,32+TIF_SIGPENDING-MSR_PR_LG,_TIF_SIGPENDING
- and. r0,r4,r0 /* check NEED_RESCHED and maybe SIGPENDING */
- bne do_work
-
-#else /* !CONFIG_PREEMPT */
ld r3,_MSR(r1) /* Returning to user mode? */
andi. r3,r3,MSR_PR
- beq restore /* if not, just restore regs and return */
+ bne test_work_user
+ clrrdi r9,r1,THREAD_SHIFT /* current_thread_info() */
+ li r0,_TIF_USER_WORK_MASK
+#ifdef CONFIG_PREEMPT
+ ori r0,r0,_TIF_NEED_RESCHED
+#endif
+ ld r4,TI_FLAGS(r9)
+ and. r0,r4,r0 /* check NEED_RESCHED and maybe
_TIF_USER_WORK_MASK */
+ bne do_kernel_work
+ b restore /* if so, just restore regs and return */
+
+test_work_user:
/* Check current_thread_info()->flags */
clrrdi r9,r1,THREAD_SHIFT
ld r4,TI_FLAGS(r9)
andi. r0,r4,_TIF_USER_WORK_MASK
- bne do_work
-#endif
+ bne do_user_work
restore:
BEGIN_FW_FTR_SECTION
@@ -693,10 +692,8 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS)
b .ret_from_except_lite /* loop back and handle more */
#endif
-do_work:
+do_kernel_work:
#ifdef CONFIG_PREEMPT
- andi. r0,r3,MSR_PR /* Returning to user mode? */
- bne user_work
/* Check that preempt_count() == 0 and interrupts are enabled */
lwz r8,TI_PREEMPT(r9)
cmpwi cr1,r8,0
@@ -738,9 +735,9 @@ do_work:
bne 1b
b restore
-user_work:
#endif /* CONFIG_PREEMPT */
+do_user_work:
/* Enable interrupts */
#ifdef CONFIG_PPC_BOOK3E
wrteei 1
--
1.5.6
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