[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <c3a81224-bea1-116b-7528-f03f90be5264@huawei.com>
Date: Fri, 5 Jun 2020 09:26:42 +0800
From: "Wangshaobo (bobo)" <bobo.shaobowang@...wei.com>
To: Josh Poimboeuf <jpoimboe@...hat.com>
CC: <huawei.libin@...wei.com>, <xiexiuqi@...wei.com>,
<cj.chengjian@...wei.com>, <mingo@...hat.com>, <x86@...nel.org>,
<linux-kernel@...r.kernel.org>, <live-patching@...r.kernel.org>,
<mbenes@...e.cz>, <devel@...ukata.com>, <viro@...iv.linux.org.uk>,
<esyr@...hat.com>
Subject: Re: Question: livepatch failed for new fork() task stack unreliable
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
>
Powered by blists - more mailing lists