Re: [Qemu-devel] [Qemu-ppc] [PATCH] linux-user: fill target sigcontext struct accordingly

[Laurent Vivier]

Le 28/02/2017 à 02:09, David Gibson a écrit :
> On Wed, Feb 01, 2017 at 09:43:57PM +0100, Laurent Vivier wrote:
>> Le 31/01/2017 à 23:05, Jose Ricardo Ziviani a écrit :
>>> A segfault is noticed when an emulated program uses any of ucontext
>>> regs fields. Risu detected this issue in the following operation when
>>> handling a signal:
>>>   ucontext_t *uc = (ucontext_t*)uc;
>>>   uc->uc_mcontext.regs->nip += 4;
>>>
>>> but this works fine:
>>>   uc->uc_mcontext.gp_regs[PT_NIP] += 4;
>>>
>>> This patch set regs to a valid location as well as other sigcontext
>>> fields.
>>>
>>> Signed-off-by: Jose Ricardo Ziviani <address@hidden>
>>> ---
>>>  linux-user/signal.c | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/linux-user/signal.c b/linux-user/signal.c
>>> index 5064de0..8209539 100644
>>> --- a/linux-user/signal.c
>>> +++ b/linux-user/signal.c
>>> @@ -5155,6 +5155,7 @@ static void setup_rt_frame(int sig, struct 
>>> target_sigaction *ka,
>>>      target_ulong rt_sf_addr, newsp = 0;
>>>      int i, err = 0;
>>>  #if defined(TARGET_PPC64)
>>> +    struct target_sigcontext *sc = 0;
>>>      struct image_info *image = ((TaskState *)thread_cpu->opaque)->info;
>>>  #endif
>>>  
>>> @@ -5183,6 +5184,10 @@ static void setup_rt_frame(int sig, struct 
>>> target_sigaction *ka,
>>>  #if defined(TARGET_PPC64)
>>>      mctx = &rt_sf->uc.tuc_sigcontext.mcontext;
>>>      trampptr = &rt_sf->trampoline[0];
>>> +
>>> +    sc = &rt_sf->uc.tuc_sigcontext;
>>> +    __put_user(h2g(mctx), &sc->regs);
>>> +    __put_user(sig, &sc->signal);
>>>  #else
>>>      mctx = &rt_sf->uc.tuc_mcontext;
>>>      trampptr = (uint32_t *)&rt_sf->uc.tuc_mcontext.tramp;
>>>
>>
>> Reviewed-by: Laurent Vivier <address@hidden>
>>
>> This is correct, but QEMU and kernel implementation are really
>> different.
> 

Hi David,

> Laurent, I'm a bit clear on what the upshot is here.
> 
> Should I merge the patch above?

I've already included this patch in a linux-user pull request a couple
of weeks ago, and it is now in the master.

So you have nothing to do :)

Thanks,
Laurent

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