Re: [RFA] Resubmit process record and replay, 5/10

[teawater <teawater@gmail.com>]

According to your mail. I think maybe you didn't get my answer. And I
am sorry that send "[RFA] Resubmit" without get you answer.

http://sourceware.org/ml/gdb-patches/2008-11/msg00310.html
Following is the content of the answer:
Thanks Thiago.
On Fri, Nov 14, 2008 at 03:56, Thiago Jung Bauermann
<bauerman@br.ibm.com> wrote:
> El jue, 06-11-2008 a las 15:48 +0800, teawater escribió:
>> +/* Record the values of the registers and memory that will be changed in
>> +   current system call.
>> +   Return -1 if something wrong.  */
>> +
>> +int
>> +record_linux_system_call (int num, linux_record_tdep_t * tdep)
>> +{
>> +  uint32_t tmpu32;
>> +
>> +  switch (num)
>> +    {
> <snip>
>> +      /* sys_read */
>> +    case 3:
>> +      {
>> +     uint32_t addr, count;
>> +     regcache_raw_read (record_regcache, tdep->arg2, (gdb_byte *) & addr);
>> +     regcache_raw_read (record_regcache, tdep->arg3, (gdb_byte *) & count);
>> +     if (record_arch_list_add_mem (addr, count))
>> +       {
>> +         return (-1);
>> +       }
>> +      }
>> +      break;
> <snip>
>> +    case 84:
>> +      regcache_raw_read (record_regcache, tdep->arg2, (gdb_byte *) & tmpu32);
>> +      if (record_arch_list_add_mem (tmpu32, tdep->size__old_kernel_stat))
>> +     {
>> +       return (-1);
>> +     }
>> +      break;
>
> Syscalls have different numbers across different architectures in Linux,
> so this file should be named i386-linux-record.c.



This number is same with i386 number. It's friendly to other arch.

Let me do a introduce of it.
When a record get a system call. It will get the the system number
with itself and convert it to the number that you found in
linux-record.c. I think it can use a table or something like it to
make covert speed up.
There is not some limit of this number. So I make it same with I386.




>
> Do you know if what you need to record for a syscall in one architecture
> is the same as what you need to record in the others? If so, it wouldn't
> be hard to make this file general for Linux in all architectures, and
> just get the syscall number mapping from the XML in the catch syscall
> feature (here are we talking about it again... :-) ). Otherwise, you'll
> have to rename the file, and also you can't directly call
> record_linux_system_call directly from i386-linux-tdep.c like you do
> now. You'd have to add a gdbarch method and reach this code through
> that.

I think most of system call in each arch are same. Except the size of
variables is not same. So I let arch set the size to argv "tdep" of
record_linux_system_call.

And if some system call of a arch is not same with others. It can deal
with it in code of itself. For example, If i386 have a special system
call that not same with other arch. It can deal with it in function
"i386_linux_intx80_sysenter_record".

Put it to xml file it's been talk in
"http://sourceware.org/ml/gdb-patches/2008-11/msg00171.html";.
What about do it later?


Hui


On Thu, Nov 20, 2008 at 12:00, Thiago Jung Bauermann
<bauerman@br.ibm.com> wrote:
> El mié, 19-11-2008 a las 17:49 -0800, Michael Snyder escribió:
>> Thiago, you had a question about whether the syscall id numbers
>> were invariant across architectures, and I think Hui answered that
>> he was using the i386 numbering as representative, and would use
>> a target-specific header file or something to translate them.
>>
>> Or something to that effect.
>>
>> Did that answer your concern?
>
> I had two different but related concerns, regarding this 5th patch:
>
> 1. linux-record.c is really i386 specific, so it should be called
> i386-linux-record.c.
>
> 2. If the information that needs to be recorded for each syscall (not
> the syscall number) is the same accross architectures, the code in
> linux-record.c could be made arch-independent and then we wouldn't need
> to have this big chunk of code duplicated for each arch supporting
> record functionality.
>
> I'm fine with leaving 2 to be investigated/addressed when record adds
> support for its 2nd arch. It also may prove impractical, since there may
> be slight differences in syscalls for each arch.
> --
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
>
>