Re: [PATCH] gdb.reverse/time-reverse.exp: test both time syscall and C time function (was: Re: [pushed] [gdb/testsuite] Require syscall time in gdb.reverse/time-reverse.exp)

[Pedro Alves <pedro@palves.net>]

On 2023-02-22 5:06 p.m., Tom de Vries wrote:
> On 2/22/23 17:12, Pedro Alves wrote:
>> On 2023-02-21 1:10 p.m., Tom de Vries via Gdb-patches wrote:
>>> On aarch64-linux, I run into:
>>> ...
>>> Running gdb.reverse/time-reverse.exp ...
>>> gdb compile failed, gdb.reverse/time-reverse.c: In function 'main':
>>> gdb.reverse/time-reverse.c:39:12: error: 'SYS_time' undeclared \
>>>    (first use in this function); did you mean 'SYS_times'?
>>>     syscall (SYS_time, &time_global);
>>>              ^~~~~~~~
>>>              SYS_times
>>> gdb.reverse/time-reverse.c:39:12: note: each undeclared identifier is \
>>>    reported only once for each function it appears in
>>> UNTESTED: gdb.reverse/time-reverse.exp: failed to prepare
>>> ...
>>>
>>> Fix this by adding a new proc have_syscall, and requiring syscall time, such
>>> that we have instead:
>>> ...
>>> UNSUPPORTED: gdb.reverse/time-reverse.exp: require failed: \
>>>    expr [have_syscall time]
>>> ...
>>>
>>> Tested on x86_64-linux and aarch64-linux.
>>
>> I think the patch below would be even better.  Does it work on aarch64?
>>
> 
> It does for me.

Thanks.

> 
> FWIW, doing an strace on the exec, I don't see any syscall related to time.

Googling around, it seems like Aarch64 uses the vDSO for time.

> 
> LGTM.
> 

Thanks, I've merged it, with one small tweak:

>> --- a/gdb/testsuite/gdb.reverse/time-reverse.c
>> +++ b/gdb/testsuite/gdb.reverse/time-reverse.c
>> @@ -20,6 +20,12 @@
>>   #include <sys/syscall.h>
>>   #include <unistd.h>
>>   +#ifdef USE_SYSCALL
>> +# define my_time(TLOC) syscall (SYS_time, &time_global)

I did not mean to hardcode the global here.  I meant to write instead:

 # define my_time(TLOC) syscall (SYS_time, TLOC)

Fixed in the pushed version.

>> +#else
>> +# define my_time(TLOC) time (TLOC)
>> +#endif
>> +