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>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 328774bd41ee..7949afc861dd 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -141,6 +141,7 @@ config PPC
         select GENERIC_ATOMIC64 if PPC32
         select HAVE_PERF_EVENTS
         select HAVE_REGS_AND_STACK_ACCESS_API
+        select HAVE_HW_BREAKPOINT if PERF_EVENTS && PPC_BOOK3S_64
 
 config EARLY_PRINTK
         bool