Messages in this thread | | | Date | Fri, 25 Oct 2013 16:22:36 +0100 | From | Will Deacon <> | Subject | Re: [PATCH RFC v4 1/6] arm64: support single-step and breakpoint handler hooks |
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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(-)
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> @@ -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).
> + 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.
Will
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