From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp03.au.ibm.com (e23smtp03.au.ibm.com [202.81.31.145]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp03.au.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTPS id 79521B7EC2 for ; Fri, 28 May 2010 16:40:52 +1000 (EST) Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [202.81.31.246]) by e23smtp03.au.ibm.com (8.14.3/8.13.1) with ESMTP id o4S6bLux001609 for ; Fri, 28 May 2010 16:37:21 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o4S6ekSv1138694 for ; Fri, 28 May 2010 16:40:46 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id o4S6ejrD028484 for ; Fri, 28 May 2010 16:40:46 +1000 Date: Fri, 28 May 2010 12:10:39 +0530 From: "K.Prasad" To: "linuxppc-dev@ozlabs.org" , Paul Mackerras Subject: [Patch 4/5] PPC64-HWBKPT: Enable hw-breakpoints while handling intervening signals Message-ID: <20100528064039.GE8679@in.ibm.com> References: <20100528061928.677651410@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Michael Neuling , Benjamin Herrenschmidt , shaggy@linux.vnet.ibm.com, Frederic Weisbecker , David Gibson , Alan Stern , "K.Prasad" , Roland McGrath List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 | 3 +++ arch/powerpc/kernel/hw_breakpoint.c | 18 ++++++++++++++++++ arch/powerpc/kernel/signal.c | 3 +++ 3 files changed, 24 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 +65,12 @@ static inline void hw_breakpoint_disable { set_dabr(0); } +extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs); #else /* CONFIG_HAVE_HW_BREAKPOINT */ static inline void hw_breakpoint_disable(void) { } +static inline void thread_change_pc(struct task_struct *tsk, + struct pt_regs *regs) { } #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 +176,24 @@ 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 pt_regs *regs) +{ + struct arch_hw_breakpoint *info; + + if (likely(!tsk->thread.last_hit_ubp)) + return; + + info = counter_arch_bp(tsk->thread.last_hit_ubp); + regs->msr &= ~MSR_SE; + set_dabr(info->address | info->type | DABR_TRANSLATION); + tsk->thread.last_hit_ubp = NULL; +} + +/* * 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, regs); if (is32) { if (ka.sa.sa_flags & SA_SIGINFO)