Re: [PATCH 1/1] linux-user/s390x: Apply h2g to address of sigreturn stub

[Laurent Vivier <laurent@vivier.eu>]

Le 24/03/2021 à 10:17, David Hildenbrand a écrit :
> On 24.03.21 09:51, Andreas Krebbel wrote:
>> The sigreturn SVC is put onto the stack by the emulation code.  Hence
>> the address of it should not be subject to guest_base transformation
>> when fetching it.
>>
>> The fix applies h2g to the address when writing it into the return
>> address register to nullify the transformation applied to it later.
>>
>> Note: This only caused problems if Qemu has been built with
>> --disable-pie (as it is in distros nowadays). Otherwise guest_base
>> defaults to 0 hiding the actual problem.
>>
>> Signed-off-by: Andreas Krebbel <krebbel@linux.ibm.com>
>> ---
>>   linux-user/s390x/signal.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/linux-user/s390x/signal.c b/linux-user/s390x/signal.c
>> index ecfa2a14a9..1412376958 100644
>> --- a/linux-user/s390x/signal.c
>> +++ b/linux-user/s390x/signal.c
>> @@ -152,7 +152,7 @@ void setup_frame(int sig, struct target_sigaction *ka,
>>           env->regs[14] = (unsigned long)
>>                   ka->sa_restorer | PSW_ADDR_AMODE;
>>       } else {
>> -        env->regs[14] = (frame_addr + offsetof(sigframe, retcode))
>> +        env->regs[14] = h2g(frame_addr + offsetof(sigframe, retcode))
>>                           | PSW_ADDR_AMODE;

Well, it really doesn't sound good as frame_addr is a guest address (and sa_restorer is too)

Where is the code that does the g2h() you want to nullify?

Thanks,
Laurent