From patchwork Tue May 25 09:15:05 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "K.Prasad" X-Patchwork-Id: 53521 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from bilbo.ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id 5A68C10082F for ; Tue, 25 May 2010 19:15:21 +1000 (EST) Received: by ozlabs.org (Postfix) id 4F39FB7D98; Tue, 25 May 2010 19:15:12 +1000 (EST) Delivered-To: linuxppc-dev@ozlabs.org Received: from e23smtp04.au.ibm.com (e23smtp04.au.ibm.com [202.81.31.146]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp04.au.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 3C809B7D93 for ; Tue, 25 May 2010 19:15:12 +1000 (EST) Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [202.81.31.247]) by e23smtp04.au.ibm.com (8.14.3/8.13.1) with ESMTP id o4P9B6As020396 for ; Tue, 25 May 2010 19:11:06 +1000 Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o4P9FBHk1568996 for ; Tue, 25 May 2010 19:15:11 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o4P9FAXC009098 for ; Tue, 25 May 2010 19:15:11 +1000 Received: from in.ibm.com ([9.124.35.26]) by d23av03.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVin) with ESMTP id o4P9F6Br008949 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Tue, 25 May 2010 19:15:08 +1000 Date: Tue, 25 May 2010 14:45:05 +0530 From: "K.Prasad" To: "linuxppc-dev@ozlabs.org" , Paul Mackerras Subject: [Patch 4/4] PPC64-HWBKPT: Enable hw-breakpoints while handling intervening signals Message-ID: <20100525091505.GE29003@in.ibm.com> References: <20100525083055.342788418@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Disposition: inline; filename=signal_handler_restore_05 User-Agent: Mutt/1.5.19 (2009-01-05) Cc: Michael Neuling , Benjamin Herrenschmidt , shaggy@linux.vnet.ibm.com, Frederic Weisbecker , David Gibson , Alan Stern , "K.Prasad" , Roland McGrath X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org A signal delivered between a hw_breakpoint_handler() and the single_step_dabr_instruction() will not have the breakpoint active during signal handling (since breakpoint will not be restored through single-stepping due to absence of MSR_SE bit on the signal frame). Enable breakpoints before signal delivery. Restore hw-breakpoints if the user-context is altered in the signal handler. Signed-off-by: K.Prasad --- arch/powerpc/include/asm/hw_breakpoint.h | 2 ++ arch/powerpc/kernel/hw_breakpoint.c | 16 ++++++++++++++++ arch/powerpc/kernel/signal.c | 3 +++ arch/powerpc/kernel/signal_32.c | 2 ++ arch/powerpc/kernel/signal_64.c | 2 ++ 5 files changed, 25 insertions(+) Index: linux-2.6.ppc64_test/arch/powerpc/include/asm/hw_breakpoint.h =================================================================== --- linux-2.6.ppc64_test.orig/arch/powerpc/include/asm/hw_breakpoint.h +++ linux-2.6.ppc64_test/arch/powerpc/include/asm/hw_breakpoint.h @@ -65,9 +65,11 @@ static inline void hw_breakpoint_disable { set_dabr(0); } +extern void thread_change_pc(struct task_struct *tsk); #else /* CONFIG_HAVE_HW_BREAKPOINT */ static inline void hw_breakpoint_disable(void) { } +static inline void thread_change_pc(struct task_struct *tsk) { } #endif /* CONFIG_HAVE_HW_BREAKPOINT */ #endif /* __KERNEL__ */ #endif /* _PPC_BOOK3S_64_HW_BREAKPOINT_H */ Index: linux-2.6.ppc64_test/arch/powerpc/kernel/hw_breakpoint.c =================================================================== --- linux-2.6.ppc64_test.orig/arch/powerpc/kernel/hw_breakpoint.c +++ linux-2.6.ppc64_test/arch/powerpc/kernel/hw_breakpoint.c @@ -176,6 +176,22 @@ int arch_validate_hwbkpt_settings(struct } /* + * Restores the breakpoint on the debug registers. + * Invoke this function if it is known that the execution context is about to + * change to cause loss of MSR_SE settings. + */ +void thread_change_pc(struct task_struct *tsk) +{ + struct arch_hw_breakpoint *info; + + if (likely(!tsk->thread.last_hit_ubp)) + return; + + info = counter_arch_bp(tsk->thread.last_hit_ubp); + set_dabr(info->address | info->type | DABR_TRANSLATION); +} + +/* * Handle debug exception notifications. */ int __kprobes hw_breakpoint_handler(struct die_args *args) Index: linux-2.6.ppc64_test/arch/powerpc/kernel/signal.c =================================================================== --- linux-2.6.ppc64_test.orig/arch/powerpc/kernel/signal.c +++ linux-2.6.ppc64_test/arch/powerpc/kernel/signal.c @@ -11,6 +11,7 @@ #include #include +#include #include #include @@ -149,6 +150,8 @@ static int do_signal_pending(sigset_t *o if (current->thread.dabr) set_dabr(current->thread.dabr); #endif + /* Re-enable the breakpoints for the signal stack */ + thread_change_pc(current); if (is32) { if (ka.sa.sa_flags & SA_SIGINFO) Index: linux-2.6.ppc64_test/arch/powerpc/kernel/signal_64.c =================================================================== --- linux-2.6.ppc64_test.orig/arch/powerpc/kernel/signal_64.c +++ linux-2.6.ppc64_test/arch/powerpc/kernel/signal_64.c @@ -33,6 +33,7 @@ #include #include #include +#include #include "signal.h" @@ -312,6 +313,7 @@ int sys_swapcontext(struct ucontext __us || __copy_to_user(&old_ctx->uc_sigmask, ¤t->blocked, sizeof(sigset_t))) return -EFAULT; + thread_change_pc(current); } if (new_ctx == NULL) return 0; Index: linux-2.6.ppc64_test/arch/powerpc/kernel/signal_32.c =================================================================== --- linux-2.6.ppc64_test.orig/arch/powerpc/kernel/signal_32.c +++ linux-2.6.ppc64_test/arch/powerpc/kernel/signal_32.c @@ -42,6 +42,7 @@ #include #include #include +#include #ifdef CONFIG_PPC64 #include "ppc32.h" #include @@ -996,6 +997,7 @@ long sys_swapcontext(struct ucontext __u || put_sigset_t(&old_ctx->uc_sigmask, ¤t->blocked) || __put_user(to_user_ptr(mctx), &old_ctx->uc_regs)) return -EFAULT; + thread_change_pc(current); } if (new_ctx == NULL) return 0;