On Thu, Jun 04, 2020 at 09:24:55AM +0800, Wangshaobo (bobo) wrote: > > 在 2020/6/3 23:33, Josh Poimboeuf 写道: > > On Wed, Jun 03, 2020 at 10:06:07PM +0800, Wangshaobo (bobo) wrote: > > To be honest, I don't remember what I meant by sibling calls. They > > don't even leave anything on the stack. > > > > For noreturns, the code might be laid out like this: > > > > func1: > > ... > > call noreturn_foo > > func2: > > > > func2 is immediately after the call to noreturn_foo. So the return > > address on the stack will actually be 'func2'. We want to retrieve the > > ORC data for the call instruction (inside func1), instead of the > > instruction at the beginning of func2. > > > > I should probably update that comment. > > So, I want to ask is there any side effects if i modify like this ? this > modification is based on > > your fix. It looks like ok with proper test. > > diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c > index e9cc182aa97e..ecce5051e8fd 100644 > --- a/arch/x86/kernel/unwind_orc.c > +++ b/arch/x86/kernel/unwind_orc.c > @@ -620,6 +620,7 @@ void __unwind_start(struct unwind_state *state, struct > task_struct *task, > state->sp = task->thread.sp; > state->bp = READ_ONCE_NOCHECK(frame->bp); > state->ip = READ_ONCE_NOCHECK(frame->ret_addr); > + state->signal = ((void *)state->ip == ret_from_fork); > } > > diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c > index 7f969b2d240f..d7396431261a 100644 > --- a/arch/x86/kernel/unwind_orc.c > +++ b/arch/x86/kernel/unwind_orc.c > @@ -540,7 +540,7 @@ bool unwind_next_frame(struct unwind_state *state) > state->sp = sp; > state->regs = NULL; > state->prev_regs = NULL; > - state->signal = ((void *)state->ip == ret_from_fork); > + state->signal = false; > break; Yes that's correct. -- Josh
