From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.windriver.com (mail.windriver.com [147.11.1.11]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mail.windriver.com", Issuer "Intel External Basic Issuing CA 3A" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 2A80E1007D3 for ; Tue, 13 Dec 2011 16:02:22 +1100 (EST) Message-ID: <4EE6DC33.6090409@windriver.com> Date: Tue, 13 Dec 2011 13:01:39 +0800 From: "tiejun.chen" MIME-Version: 1.0 To: Subject: Re: [PATCH 1/1] ppc64: fix missing to check all bits of _TIF_USER_WORK_MASK in preempt References: <1323681035-19350-1-git-send-email-tiejun.chen@windriver.com> In-Reply-To: <1323681035-19350-1-git-send-email-tiejun.chen@windriver.com> Content-Type: text/plain; charset="UTF-8" Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Tiejun Chen wrote: > 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. Ben, Any comment for this? Tiejun > > Signed-off-by: Benjamin Herrenschmidt > Signed-off-by: Tiejun Chen > --- > 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