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>
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@ -558,27 +558,54 @@ _GLOBAL(ret_from_except_lite)
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mtmsrd r10,1 /* Update machine state */
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#endif /* CONFIG_PPC_BOOK3E */
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#ifdef CONFIG_PREEMPT
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clrrdi r9,r1,THREAD_SHIFT /* current_thread_info() */
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li r0,_TIF_NEED_RESCHED /* bits to check */
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ld r3,_MSR(r1)
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ld r4,TI_FLAGS(r9)
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/* Move MSR_PR bit in r3 to _TIF_SIGPENDING position in r0 */
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rlwimi r0,r3,32+TIF_SIGPENDING-MSR_PR_LG,_TIF_SIGPENDING
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and. r0,r4,r0 /* check NEED_RESCHED and maybe SIGPENDING */
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bne do_work
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#else /* !CONFIG_PREEMPT */
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ld r3,_MSR(r1) /* Returning to user mode? */
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andi. r3,r3,MSR_PR
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beq restore /* if not, just restore regs and return */
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beq resume_kernel
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/* Check current_thread_info()->flags */
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andi. r0,r4,_TIF_USER_WORK_MASK
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beq restore
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andi. r0,r4,_TIF_NEED_RESCHED
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beq 1f
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bl .restore_interrupts
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bl .schedule
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b .ret_from_except_lite
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1: bl .save_nvgprs
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bl .restore_interrupts
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addi r3,r1,STACK_FRAME_OVERHEAD
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bl .do_notify_resume
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b .ret_from_except
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resume_kernel:
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#ifdef CONFIG_PREEMPT
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/* Check if we need to preempt */
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andi. r0,r4,_TIF_NEED_RESCHED
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beq+ restore
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/* Check that preempt_count() == 0 and interrupts are enabled */
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lwz r8,TI_PREEMPT(r9)
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cmpwi cr1,r8,0
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ld r0,SOFTE(r1)
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cmpdi r0,0
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crandc eq,cr1*4+eq,eq
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bne restore
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/*
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* Here we are preempting the current task. We want to make
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* sure we are soft-disabled first
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*/
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SOFT_DISABLE_INTS(r3,r4)
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1: bl .preempt_schedule_irq
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/* Re-test flags and eventually loop */
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clrrdi r9,r1,THREAD_SHIFT
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ld r4,TI_FLAGS(r9)
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andi. r0,r4,_TIF_USER_WORK_MASK
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bne do_work
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#endif /* !CONFIG_PREEMPT */
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andi. r0,r4,_TIF_NEED_RESCHED
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bne 1b
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#endif /* CONFIG_PREEMPT */
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.globl fast_exc_return_irq
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fast_exc_return_irq:
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@ -759,50 +786,6 @@ restore_check_irq_replay:
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#endif /* CONFIG_PPC_BOOK3E */
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1: b .ret_from_except /* What else to do here ? */
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3:
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do_work:
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#ifdef CONFIG_PREEMPT
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andi. r0,r3,MSR_PR /* Returning to user mode? */
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bne user_work
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/* Check that preempt_count() == 0 and interrupts are enabled */
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lwz r8,TI_PREEMPT(r9)
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cmpwi cr1,r8,0
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ld r0,SOFTE(r1)
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cmpdi r0,0
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crandc eq,cr1*4+eq,eq
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bne restore
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/*
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* Here we are preempting the current task. We want to make
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* sure we are soft-disabled first
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*/
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SOFT_DISABLE_INTS(r3,r4)
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1: bl .preempt_schedule_irq
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/* Re-test flags and eventually loop */
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clrrdi r9,r1,THREAD_SHIFT
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ld r4,TI_FLAGS(r9)
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andi. r0,r4,_TIF_NEED_RESCHED
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bne 1b
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b restore
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user_work:
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#endif /* CONFIG_PREEMPT */
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andi. r0,r4,_TIF_NEED_RESCHED
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beq 1f
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bl .restore_interrupts
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bl .schedule
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b .ret_from_except_lite
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1: bl .save_nvgprs
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bl .restore_interrupts
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addi r3,r1,STACK_FRAME_OVERHEAD
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bl .do_notify_resume
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b .ret_from_except
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unrecov_restore:
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addi r3,r1,STACK_FRAME_OVERHEAD
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bl .unrecoverable_exception
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