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ppc64: fix missing to check all bits of _TIF_USER_WORK_MASK in preempt

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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>
This commit is contained in:
Tiejun Chen 2012-06-06 20:56:43 +00:00 committed by Benjamin Herrenschmidt
parent 82b2521d25
commit c58ce2b1e3
1 changed files with 40 additions and 57 deletions
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97
arch/powerpc/kernel/entry_64.S
View file

@ -558,27 +558,54 @@ _GLOBAL(ret_from_except_lite)
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 @@ restore_check_irq_replay:
#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