arm64: support single-step and breakpoint handler hooks

AArch64 Single Steping and Breakpoint debug exceptions will be
used by multiple debug framworks like kprobes & kgdb.

This patch implements the hooks for those frameworks to register
their own handlers for handling breakpoint and single step events.

Reworked the debug exception handler in entry.S: do_dbg to route
software breakpoint (BRK64) exception to do_debug_exception()

Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@linaro.org>
Signed-off-by: Deepak Saxena <dsaxena@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 4d2c6f3f0c41..32d7fe6c3d6a 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -288,6 +288,8 @@ el1_dbg:
         /*
          * Debug exception handling
          */
+        cmp     x24, #ESR_EL1_EC_BRK64          // if BRK64
+        cinc    x24, x24, eq                    // set bit '0'
         tbz     x24, #0, el1_inv                // EL1 only
         mrs     x0, far_el1
         mov     x2, sp                          // struct pt_regs