Re: [PATCH v2] gdb: CTF support

[Simon Marchi <simark@simark.ca>]

On 2019-09-23 5:11 p.m., Weimin Pan wrote:
> Hi Simon,
> 
> On 9/21/2019 3:21 PM, Simon Marchi wrote:
>> Hi Weimin,
>>
>> I'd like to give this a try and review this, but I hit a wall.  I compiled
>> gcc with this patch series (v5) applied:
>>
>>    https://gcc.gnu.org/ml/gcc-patches/2019-09/msg00457.html
>>
>> I am able to compile a simple .c file with -gt, and the resulting
>> binary contains a .ctf section.  But when loading the file in GDB,
>> I get this:
>>
>>    (gdb) file a.out
>>    Reading symbols from a.out...
>>    ctf_bfdopen failed on /home/simark/build/binutils-gdb/gdb/a.out - File data structure corruption detected
>>
>> The error occurs in ctf_bufopen, at line 1294:
>>
>>    1294	  if (hp.cth_lbloff > hp.cth_objtoff
>>    1295	      || hp.cth_objtoff > hp.cth_funcoff
>>    1296	      || hp.cth_funcoff > hp.cth_typeoff
>>    1297	      || hp.cth_funcoff > hp.cth_varoff
>>    1298	      || hp.cth_varoff > hp.cth_typeoff || hp.cth_typeoff > hp.cth_stroff)
>>    1299	    return (ctf_set_open_errno (errp, ECTF_CORRUPT));
>>
>> `hp` is:
>>
>>    $10 = {
>>      cth_preamble = {
>>        ctp_magic = 57330,
>>        ctp_version = 4 '\004',
>>        ctp_flags = 0 '\000'
>>      },
>>      cth_parlabel = 0,
>>      cth_parname = 0,
>>      cth_lbloff = 10,
>>      cth_objtoff = 0,
>>      cth_funcoff = 0,
>>      cth_varoff = 0,
>>      cth_typeoff = 12,
>>      cth_stroff = 12,
>>      cth_strlen = 16
>>    }
>>
>> The program I compiled is:
>>
>>    int main() {
>>        return 2;
>>   }
>>
>> compiled with:
>>
>>    /data/scratch/gcc-install/bin/gcc test.c -gt -O0
> 
> Looks like you're using the latest gcc patch with current upstream binutils.
> Unfortunately, these two are not compatible since the latter lacks two newer
> header fields and the ability to transparently upgrade the ctf header. The
> same problem can be reproduced with "readelf" from binutils master:
> 
> % readelf --ctf=".ctf" a.out
> readelf: Error: CTF open failure: File data structure corruption detected
> 
> Please try applying the linker patch series that NicK posted on Sep 6 to
> binutils, under the name of "CTF linking support", as mentioned in the
> gcc patch sited above:
> 
> NickA recently posted a changeset to the binutils mailing list that adds
> initial support for linking CTF sections. Please see
> 
> https://sourceware.org/ml/binutils/2019-09/msg00045.html
> 
> ( This current GCC  patch set has the ctf.h in sync with the above-mentioned
>     binutils patch set. )
> 
> which should fix this problem.

Oh ok thanks.  Do you happen to know if that binutils patchset is available on a
git branch somewhere?  I'd like to avoid applying these 33 patches by hand.  If
you have a combined branch with the binutils and gdb changes together, it would
be even better :).

Simon