powerpc, hw_breakpoints: Implement hw_breakpoints for 64-bit server processors
Implement perf-events based hw-breakpoint interfaces for PowerPC
64-bit server (Book III S) processors. This allows access to a
given location to be used as an event that can be counted or
profiled by the perf_events subsystem.
This is done using the DABR (data breakpoint register), which can
also be used for process debugging via ptrace. When perf_event
hw_breakpoint support is configured in, the perf_event subsystem
manages the DABR and arbitrates access to it, and ptrace then
creates a perf_event when it is requested to set a data breakpoint.
[Adopted suggestions from Paul Mackerras <paulus@samba.org> to
- emulate_step() all system-wide breakpoints and single-step only the
per-task breakpoints
- perform arch-specific cleanup before unregistration through
arch_unregister_hw_breakpoint()
]
Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 3e423fb..f53029a 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -828,6 +828,7 @@
/* We have a data breakpoint exception - handle it */
handle_dabr_fault:
+ bl .save_nvgprs
ld r4,_DAR(r1)
ld r5,_DSISR(r1)
addi r3,r1,STACK_FRAME_OVERHEAD