Re: [Qemu-devel] [PATCH] linux-user, sh4: fix signal retcode address

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Ping here as well: https://bugs.launchpad.net/qemu/+bug/1516408

Adrian

On 12/18/2015 04:08 PM, Laurent Vivier wrote:
> Ping ?
> 
> Le 23/11/2015 11:38, Laurent Vivier a écrit :
>> To return from a signal, setup_frame() puts an instruction to
>> be executed in the stack. This sequence calls the syscall sigreturn().
>>
>> The address of the instruction must be set in the PR register
>> to be executed.
>>
>> This patch fixes this: the current code sets the register to the address
>> of the instruction in the host address space (which can be 64bit whereas
>> PR is only 32bit), but the virtual CPU can't access this address space,
>> so we put in PR the address of the instruction in the guest address space.
>>
>> This patch also removes an useless variable (ret) in the modified functions.
>>
>> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
>> ---
>>  linux-user/signal.c | 16 ++++++----------
>>  1 file changed, 6 insertions(+), 10 deletions(-)
>>
>> diff --git a/linux-user/signal.c b/linux-user/signal.c
>> index 55e5405..5e8f6d8 100644
>> --- a/linux-user/signal.c
>> +++ b/linux-user/signal.c
>> @@ -3215,7 +3215,6 @@ static void setup_frame(int sig, struct target_sigaction *ka,
>>      struct target_sigframe *frame;
>>      abi_ulong frame_addr;
>>      int i;
>> -    int err = 0;
>>  
>>      frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
>>      if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
>> @@ -3233,15 +3232,14 @@ static void setup_frame(int sig, struct target_sigaction *ka,
>>          regs->pr = (unsigned long) ka->sa_restorer;
>>      } else {
>>          /* Generate return code (system call to sigreturn) */
>> +        abi_ulong retcode_addr = frame_addr +
>> +                                 offsetof(struct target_sigframe, retcode);
>>          __put_user(MOVW(2), &frame->retcode[0]);
>>          __put_user(TRAP_NOARG, &frame->retcode[1]);
>>          __put_user((TARGET_NR_sigreturn), &frame->retcode[2]);
>> -        regs->pr = (unsigned long) frame->retcode;
>> +        regs->pr = (unsigned long) retcode_addr;
>>      }
>>  
>> -    if (err)
>> -        goto give_sigsegv;
>> -
>>      /* Set up registers for signal handler */
>>      regs->gregs[15] = frame_addr;
>>      regs->gregs[4] = sig; /* Arg for signal handler */
>> @@ -3264,7 +3262,6 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
>>      struct target_rt_sigframe *frame;
>>      abi_ulong frame_addr;
>>      int i;
>> -    int err = 0;
>>  
>>      frame_addr = get_sigframe(ka, regs->gregs[15], sizeof(*frame));
>>      if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0))
>> @@ -3293,15 +3290,14 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka,
>>          regs->pr = (unsigned long) ka->sa_restorer;
>>      } else {
>>          /* Generate return code (system call to sigreturn) */
>> +        abi_ulong retcode_addr = frame_addr +
>> +                                 offsetof(struct target_rt_sigframe, retcode);
>>          __put_user(MOVW(2), &frame->retcode[0]);
>>          __put_user(TRAP_NOARG, &frame->retcode[1]);
>>          __put_user((TARGET_NR_rt_sigreturn), &frame->retcode[2]);
>> -        regs->pr = (unsigned long) frame->retcode;
>> +        regs->pr = (unsigned long) retcode_addr;
>>      }
>>  
>> -    if (err)
>> -        goto give_sigsegv;
>> -
>>      /* Set up registers for signal handler */
>>      regs->gregs[15] = frame_addr;
>>      regs->gregs[4] = sig; /* Arg for signal handler */
>>


-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913