Hi Will,
Sorry for responding to this after long-time, I missed this review during Linaro connect travels.
On 25 October 2013 20:52, Will Deacon will.deacon@arm.com wrote:
Hi Sandeepa,
This is getting there, thanks for persevering with it. I still have a few minor comments though.
On Thu, Oct 17, 2013 at 12:17:46PM +0100, Sandeepa Prabhu wrote:
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
arch/arm64/include/asm/debug-monitors.h | 21 ++++++++ arch/arm64/kernel/debug-monitors.c | 86 ++++++++++++++++++++++++++++++++- arch/arm64/kernel/entry.S | 2 + 3 files changed, 108 insertions(+), 1 deletion(-)
[...]
@@ -215,7 +257,10 @@ static int single_step_handler(unsigned long addr, unsigned int esr, */ user_rewind_single_step(current); } else {
/* TODO: route to KGDB */
/* call registered single step handlers */Don't bother with this comment (it's crystal clear from the code).
OK, I will remove this unnecessary print.
if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED)return 0;pr_warning("Unexpected kernel single-step exception at EL1\n"); /* * Re-enable stepping since we know that we will be@@ -227,11 +272,50 @@ static int single_step_handler(unsigned long addr, unsigned int esr, return 0; }
+static LIST_HEAD(break_hook); +DEFINE_RWLOCK(break_hook_lock);
This guy can be a plain old spinlock. That way, the readers have less overhead but things still work because we only call a single hook function.
well, kprobes need to support recursive breakpoints (i.e. breakpoint handler executing BRK once again) so I converted this lock to rw_lock. I should put this info in commit description to be more clearer. Let me know if you find any issue with re-cursing in breakpoint exception?
Thanks, Sandeepa
Will
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