Messages in this thread | | | Subject | Re: Question: livepatch failed for new fork() task stack unreliable | From | "Wangshaobo (bobo)" <> | Date | Fri, 5 Jun 2020 09:26:42 +0800 |
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在 2020/6/4 10:40, Josh Poimboeuf 写道: > 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.
Hi, josh
Could i ask when are you free to send the patch, all the tests are passed by.
thanks for your help.
Wang ShaoBo
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