Messages in this thread Patch in this message | | | Subject | Re: Question: livepatch failed for new fork() task stack unreliable | From | "Wangshaobo (bobo)" <> | Date | Thu, 4 Jun 2020 09:24:55 +0800 |
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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;
thanks,
Wang ShaoBo
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