From c58ce2b1e3c75c55e7ebf751afce9f5a30f60b42 Mon Sep 17 00:00:00 2001 From: Tiejun Chen Date: Wed, 6 Jun 2012 20:56:43 +0000 Subject: [PATCH] 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 Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/entry_64.S | 97 ++++++++++++++-------------------- 1 file changed, 40 insertions(+), 57 deletions(-) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index ed1718feb9d9..5971c85df136 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -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 -- GitLab