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authorK.Prasad <prasad@linux.vnet.ibm.com>2010-06-15 11:35:41 +0530
committerPaul Mackerras <paulus@samba.org>2010-06-22 19:40:50 +1000
commit06532a6743d83fac4b79389fc8c86c88cb4e3302 (patch)
tree2ca694f5cb71a2296c6b4e0b36f3ddd6e2033084 /arch/powerpc/kernel/signal.c
parent2538c2d08f46141550a1e68819efa8fe31c6e3dc (diff)
powerpc, hw_breakpoint: Enable hw-breakpoints while handling intervening signals
A signal delivered between a hw_breakpoint_handler() and the single_step_dabr_instruction() will not have the breakpoint active while the signal handler is running -- the signal delivery will set up a new MSR value which will not have MSR_SE set, so we won't get the signal step interrupt until and unless the signal handler returns (which it may never do). To fix this, we restore the breakpoint when delivering a signal -- we clear the MSR_SE bit and set the DABR again. If the signal handler returns, the DABR interrupt will occur again when the instruction that we were originally trying to single-step gets re-executed. [Paul Mackerras <paulus@samba.org> pointed out the need to do this.] Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/kernel/signal.c')
-rw-r--r--arch/powerpc/kernel/signal.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index a0afb555a7c9..7109f5b1baa8 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/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 *oldset, struct pt_regs *regs)
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)