Re: [PATCH] Disable get_ptrace_pid for NetBSD

[Kamil Rytarowski <n54@gmx.com>]

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On 18.03.2020 22:15, Simon Marchi wrote:
> On 2020-03-18 12:29 p.m., Kamil Rytarowski wrote:
>> Unlike most other Operating Systems, NetBSD tracks both pid and lwp.
>> The process id on NetBSD is stored always in the pid field of ptid.
>>
>> gdb/ChangeLog:
>>
>> 	* inf-ptrace.h: Disable get_ptrace_pid on NetBSD.
>> 	* inf-ptrace.c: Likewise.
>> 	* (inf_ptrace_target::resume): Update.
>> 	* (inf_ptrace_target::xfer_partial): Likewise.
>> ---
>>  gdb/ChangeLog    |  7 +++++++
>>  gdb/inf-ptrace.c | 19 +++++++++++++++++--
>>  gdb/inf-ptrace.h |  2 ++
>>  3 files changed, 26 insertions(+), 2 deletions(-)
>>
>> diff --git a/gdb/ChangeLog b/gdb/ChangeLog
>> index 84964dc00ac..36e333ec8ba 100644
>> --- a/gdb/ChangeLog
>> +++ b/gdb/ChangeLog
>> @@ -1,3 +1,10 @@
>> +2020-03-18  Kamil Rytarowski  <n54@gmx.com>
>> +
>> +	* inf-ptrace.h: Disable get_ptrace_pid on NetBSD.
>> +	* inf-ptrace.c: Likewise.
>> +	* (inf_ptrace_target::resume): Update.
>> +	* (inf_ptrace_target::xfer_partial): Likewise.
>> +
>>  2020-03-17  Kamil Rytarowski  <n54@gmx.com>
>>
>>  	* regformats/regdef.h: Put reg in gdb namespace.
>> diff --git a/gdb/inf-ptrace.c b/gdb/inf-ptrace.c
>> index db17a76d946..e8bf66ed45f 100644
>> --- a/gdb/inf-ptrace.c
>> +++ b/gdb/inf-ptrace.c
>> @@ -313,8 +313,12 @@ inf_ptrace_target::kill ()
>>    target_mourn_inferior (inferior_ptid);
>>  }
>>
>> +#ifndef __NetBSD__
>>  /* Return which PID to pass to ptrace in order to observe/control the
>> -   tracee identified by PTID.  */
>> +   tracee identified by PTID.
>> +
>> +   Unlike most other Operating Systems, NetBSD tracks both pid and lwp
>> +   and avoids this function.  */
>>
>>  pid_t
>>  get_ptrace_pid (ptid_t ptid)
>> @@ -328,6 +332,7 @@ get_ptrace_pid (ptid_t ptid)
>>      pid = ptid.pid ();
>>    return pid;
>>  }
>> +#endif
>>
>>  /* Resume execution of thread PTID, or all threads if PTID is -1.  If
>>     STEP is nonzero, single-step it.  If SIGNAL is nonzero, give it
>> @@ -344,7 +349,13 @@ inf_ptrace_target::resume (ptid_t ptid, int step, enum gdb_signal signal)
>>         single-threaded processes, so simply resume the inferior.  */
>>      pid = inferior_ptid.pid ();
>>    else
>> -    pid = get_ptrace_pid (ptid);
>> +    {
>> +#ifdef __NetBSD__
>> +      pid = ptid. pid();
>> +#else
>> +      pid = get_ptrace_pid (ptid);
>> +#endif
>> +    }
> 
> To avoid the ifdefs in this more complex code, can't you use a gdb_ptrace function like in
> the other patches?  This time, it would look like:
> 
> static int
> gdb_ptrace (PTRACE_TYPE_ARG1 request, ptid_t ptid, PTRACE_TYPE_ARG3 addr,
> 	    PTRACE_TYPE_ARG4 data)
> {
> #ifdef __NetBSD__
>   return ptrace (request, ptid.pid (), addr, data);
> #else
>   pid_t pid = get_ptrace_pid (ptid);
>   return ptrace (request, pid, addr, data);
> #endif
> }
> 
> Simon
> 

I will go for it, but only for a selection of ptrace () calls in this file.

In certain places there would need to be need to compose ptid_t out of
plain pid. Another case is PT_TRACE_ME.


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