Re: [Qemu-devel] [PATCH] linux-user/signal.c: Generate opcode data for restorer in setup_rt_frame

[Laurent Vivier <laurent@vivier.eu>]

Le 27/03/2016 11:44, Chen Gang a écrit :
> Hello All:
> 
> Please help check this patch when you have time.
> 
> After this patch, we can let gcc testsuite cleanup-10 run successfully.
> 
> Next, I shall continue to implement floating point instructions: remove
> (u)int64_to_float64 from fdouble implementation.
> 
> 
> Thanks.
> 
> On 3/15/16 05:51, chengang@emindsoft.com.cn wrote:
>> From: Chen Gang <chengang@emindsoft.com.cn>
>>
>> Original implementation uses do_rt_sigreturn directly in host space,
>> when a guest program is in unwind procedure in guest space, it will get
>> an incorrect restore address, then causes unwind failure.
>>
>> Also cleanup the original incorrect indentation.
>>
>> Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
>> ---
>>  linux-user/signal.c | 12 ++++++++++--
>>  1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/linux-user/signal.c b/linux-user/signal.c
>> index 919aa83..0e3b1c6 100644
>> --- a/linux-user/signal.c
>> +++ b/linux-user/signal.c
>> @@ -5566,8 +5566,13 @@ struct target_rt_sigframe {
>>      unsigned char save_area[16]; /* caller save area */
>>      struct target_siginfo info;
>>      struct target_ucontext uc;
>> +    abi_ulong retcode[2];
>>  };
>>  
>> +#define INSN_MOVELI_R10_139  0x00045fe551483000ULL /* { moveli r10, 139 } */
>> +#define INSN_SWINT1          0x286b180051485000ULL /* { swint1 } */
>> +
>> +
>>  static void setup_sigcontext(struct target_sigcontext *sc,
>>                               CPUArchState *env, int signo)
>>  {
>> @@ -5643,9 +5648,12 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
>>      __put_user(target_sigaltstack_used.ss_size, &frame->uc.tuc_stack.ss_size);
>>      setup_sigcontext(&frame->uc.tuc_mcontext, env, info->si_signo);
>>  
>> -    restorer = (unsigned long) do_rt_sigreturn;
>>      if (ka->sa_flags & TARGET_SA_RESTORER) {
>> -            restorer = (unsigned long) ka->sa_restorer;
>> +        restorer = (unsigned long) ka->sa_restorer;
>> +    } else {
>> +        __put_user(INSN_MOVELI_R10_139, &frame->retcode[0]);
>> +        __put_user(INSN_SWINT1, &frame->retcode[1]);
>> +        restorer = (unsigned long)frame->retcode;

The address of retcode in host and guest can differ.
You need something like:

	restorer = (unsigned long)(frame_addr + offsetof(struct
target_rt_sigframe, retcode));

I've experienced this on sh4 (see commit 2a0fa68)

>>      }
>>      env->pc = (unsigned long) ka->_sa_handler;
>>      env->regs[TILEGX_R_SP] = (unsigned long) frame;
>>
> 

Laurent