| Message ID | 9d2c9444762f1623e75b7de9e5783a94a257a00d.1478068479.git.panand@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wednesday 02 November 2016 03:30 PM, Sandeepa Prabhu wrote: > > > On Wed, Nov 2, 2016 at 2:40 PM, Pratyush Anand <panand@redhat.com > <mailto:panand@redhat.com>> wrote: > > ARM64 step exception does not have any syndrome information. So, it is > responsibility of exception handler to take care that they handle it > only if exception was raised for them. > > Since kgdb_step_brk_fn() always returns 0, therefore we might have > problem > when we will have other step handler registered as well. > > This patch fixes kgdb_step_brk_fn() to return error in case of step > handler > was not meant for kgdb. > > Signed-off-by: Pratyush Anand <panand@redhat.com > <mailto:panand@redhat.com>> > --- > arch/arm64/kernel/kgdb.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c > index e017a9493b92..d217c9e95b06 100644 > --- a/arch/arm64/kernel/kgdb.c > +++ b/arch/arm64/kernel/kgdb.c > @@ -247,6 +247,9 @@ NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); > > static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) > { > + if (!kgdb_single_step) > + return DBG_HOOK_ERROR; > + > > This is needed. So, single stepping in kprobes working all these days > because kprobes handler was registered earlier to kgdb handler! Actually kprobe_single_step_handler() is not called through call_step_hook(), so it is always safe. We had discussed here (https://lkml.org/lkml/2016/9/7/6) that why we can not register kprobe_single_step_handler() via register_set_hook() and only invoke call_step_hook(). ~Pratyush
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index e017a9493b92..d217c9e95b06 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -247,6 +247,9 @@ NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) { + if (!kgdb_single_step) + return DBG_HOOK_ERROR; + kgdb_handle_exception(1, SIGTRAP, 0, regs); return 0; }
ARM64 step exception does not have any syndrome information. So, it is responsibility of exception handler to take care that they handle it only if exception was raised for them. Since kgdb_step_brk_fn() always returns 0, therefore we might have problem when we will have other step handler registered as well. This patch fixes kgdb_step_brk_fn() to return error in case of step handler was not meant for kgdb. Signed-off-by: Pratyush Anand <panand@redhat.com> --- arch/arm64/kernel/kgdb.c | 3 +++ 1 file changed, 3 insertions(+)