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.dea...@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.pra...@linaro.org> >> Signed-off-by: Deepak Saxena <dsax...@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 > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/