From: "K.Prasad" <prasad@linux.vnet.ibm.com>
To: "linuxppc-dev@ozlabs.org" <linuxppc-dev@ozlabs.org>,
Paul Mackerras <paulus@samba.org>
Cc: Michael Neuling <mikey@neuling.org>,
Benjamin Herrenschmidt <benh@au1.ibm.com>,
shaggy@linux.vnet.ibm.com,
Frederic Weisbecker <fweisbec@gmail.com>,
David Gibson <dwg@au1.ibm.com>,
Alan Stern <stern@rowland.harvard.edu>,
"K.Prasad" <prasad@linux.vnet.ibm.com>,
Roland McGrath <roland@redhat.com>
Subject: [Patch 4/4] PPC64-HWBKPT: Enable hw-breakpoints while handling intervening signals
Date: Tue, 25 May 2010 14:45:05 +0530 [thread overview]
Message-ID: <20100525091505.GE29003@in.ibm.com> (raw)
In-Reply-To: 20100525083055.342788418@linux.vnet.ibm.com
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 <prasad@linux.vnet.ibm.com>
---
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 <linux/tracehook.h>
#include <linux/signal.h>
+#include <asm/hw_breakpoint.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -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 <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/vdso.h>
+#include <asm/hw_breakpoint.h>
#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 <asm/syscalls.h>
#include <asm/sigcontext.h>
#include <asm/vdso.h>
+#include <asm/hw_breakpoint.h>
#ifdef CONFIG_PPC64
#include "ppc32.h"
#include <asm/unistd.h>
@@ -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;
next prev parent reply other threads:[~2010-05-25 9:15 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20100525083055.342788418@linux.vnet.ibm.com>
2010-05-25 9:13 ` [Patch 1/4] Allow arch-specific cleanup before breakpoint unregistration K.Prasad
2010-05-25 11:39 ` Millton Miller
2010-05-26 6:51 ` K.Prasad
2010-05-26 9:54 ` David Howells
2010-05-26 15:13 ` Michael Ellerman
2010-05-26 17:17 ` K.Prasad
2010-05-26 17:23 ` Frederic Weisbecker
2010-05-26 17:31 ` K.Prasad
2010-05-26 17:35 ` Frederic Weisbecker
2010-05-26 17:28 ` K.Prasad
2010-05-25 9:14 ` [Patch 2/4] PPC64-HWBKPT: Implement hw-breakpoints for PowerPC BookIII S K.Prasad
2010-05-27 6:19 ` Paul Mackerras
2010-05-28 7:39 ` K.Prasad
2010-05-25 9:14 ` [Patch 3/4] PPC64-HWBKPT: Handle concurrent alignment interrupts K.Prasad
2010-05-27 6:20 ` Paul Mackerras
2010-05-28 7:41 ` K.Prasad
2010-05-25 9:15 ` K.Prasad [this message]
2010-05-27 6:32 ` [Patch 4/4] PPC64-HWBKPT: Enable hw-breakpoints while handling intervening signals Paul Mackerras
[not found] <20100524102614.040177456@linux.vnet.ibm.com>
2010-05-24 10:34 ` K.Prasad
2010-05-24 12:24 ` Paul Mackerras
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