ppc64: fix missing to check all bits of _TIF_USER_WORK_MASK in preempt
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 not set, go to resume_kernel, else continue.
- If go resume_kernel, to do that original do_work.
- If else, then always test for _TIF_USER_WORK_MASK to decide to do
that original user_work, else restore directly.
Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index ed1718f..5971c85 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -558,27 +558,54 @@
mtmsrd r10,1 /* 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 */
+ beq resume_kernel
/* Check current_thread_info()->flags */
+ andi. r0,r4,_TIF_USER_WORK_MASK
+ beq restore
+
+ andi. r0,r4,_TIF_NEED_RESCHED
+ beq 1f
+ bl .restore_interrupts
+ bl .schedule
+ b .ret_from_except_lite
+
+1: bl .save_nvgprs
+ bl .restore_interrupts
+ addi r3,r1,STACK_FRAME_OVERHEAD
+ bl .do_notify_resume
+ b .ret_from_except
+
+resume_kernel:
+#ifdef CONFIG_PREEMPT
+ /* Check if we need to preempt */
+ andi. r0,r4,_TIF_NEED_RESCHED
+ beq+ restore
+ /* Check that preempt_count() == 0 and interrupts are enabled */
+ lwz r8,TI_PREEMPT(r9)
+ cmpwi cr1,r8,0
+ ld r0,SOFTE(r1)
+ cmpdi r0,0
+ crandc eq,cr1*4+eq,eq
+ bne restore
+
+ /*
+ * Here we are preempting the current task. We want to make
+ * sure we are soft-disabled first
+ */
+ SOFT_DISABLE_INTS(r3,r4)
+1: bl .preempt_schedule_irq
+
+ /* Re-test flags and eventually loop */
clrrdi r9,r1,THREAD_SHIFT
ld r4,TI_FLAGS(r9)
- andi. r0,r4,_TIF_USER_WORK_MASK
- bne do_work
-#endif /* !CONFIG_PREEMPT */
+ andi. r0,r4,_TIF_NEED_RESCHED
+ bne 1b
+#endif /* CONFIG_PREEMPT */
.globl fast_exc_return_irq
fast_exc_return_irq:
@@ -759,50 +786,6 @@
#endif /* CONFIG_PPC_BOOK3E */
1: b .ret_from_except /* What else to do here ? */
-
-
-3:
-do_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
- ld r0,SOFTE(r1)
- cmpdi r0,0
- crandc eq,cr1*4+eq,eq
- bne restore
-
- /*
- * Here we are preempting the current task. We want to make
- * sure we are soft-disabled first
- */
- SOFT_DISABLE_INTS(r3,r4)
-1: bl .preempt_schedule_irq
-
- /* Re-test flags and eventually loop */
- clrrdi r9,r1,THREAD_SHIFT
- ld r4,TI_FLAGS(r9)
- andi. r0,r4,_TIF_NEED_RESCHED
- bne 1b
- b restore
-
-user_work:
-#endif /* CONFIG_PREEMPT */
-
- andi. r0,r4,_TIF_NEED_RESCHED
- beq 1f
- bl .restore_interrupts
- bl .schedule
- b .ret_from_except_lite
-
-1: bl .save_nvgprs
- bl .restore_interrupts
- addi r3,r1,STACK_FRAME_OVERHEAD
- bl .do_notify_resume
- b .ret_from_except
-
unrecov_restore:
addi r3,r1,STACK_FRAME_OVERHEAD
bl .unrecoverable_exception
