Re: [Qemu-devel] [PATCH] gdbstub: Support AUXV packet for debugging PIE executables.

[Wei-cheng Wang <cole945@gmail.com>]

Ping :)

Thanks,
Wei-cheng

On 11/28/2014 12:57 AM, Paolo Bonzini wrote:
> CCing Riku Voipio for a review.
>
> Paolo
>
> On 23/11/2014 14:28, Wei-cheng, Wang wrote:
>> Hi,
>>
>> This patch adds support for sending AUXV packet.
>> This is required for debugging Linux position independent executables.
>> Otherwise, gdb client cannot find out where the executable is loaded.
>>
>> Signed-off-by: Wei-cheng, Wang <cole945@gmail.com>
>> ---
>>   gdbstub.c | 41 +++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 41 insertions(+)
>>
>> diff --git a/gdbstub.c b/gdbstub.c
>> index d1b5afd..30f3bbc 100644
>> --- a/gdbstub.c
>> +++ b/gdbstub.c
>> @@ -1127,6 +1127,7 @@ static int gdb_handle_packet(GDBState *s, const
>> char *line_buf)
>>               if (cc->gdb_core_xml_file != NULL) {
>>                   pstrcat(buf, sizeof(buf), ";qXfer:features:read+");
>>               }
>> +            pstrcat(buf, sizeof(buf), ";qXfer:auxv:read+");
>>               put_packet(s, buf);
>>               break;
>>           }
>> @@ -1173,6 +1174,46 @@ static int gdb_handle_packet(GDBState *s, const
>> char *line_buf)
>>               put_packet_binary(s, buf, len + 1);
>>               break;
>>           }
>> +#ifdef CONFIG_USER_ONLY
>> +        if (strncmp(p, "Xfer:auxv:read:", 15) == 0) {
>> +            TaskState *ts = s->c_cpu->opaque;
>> +            target_ulong auxv = ts->info->saved_auxv;
>> +            target_ulong auxv_len = ts->info->auxv_len;
>> +            char *ptr;
>> +
>> +            p += 15;
>> +            while (*p && *p != ':')
>> +                p++;
>> +            p++;
>> +
>> +            addr = strtoul(p, (char **)&p, 16);
>> +            if (*p == ',')
>> +                p++;
>> +            len = strtoul(p, (char **)&p, 16);
>> +
>> +            ptr = lock_user(VERIFY_READ, auxv, auxv_len, 0);
>> +            if (ptr == NULL) {
>> +                break;
>> +            }
>> +
>> +            if (addr > len) {
>> +                snprintf(buf, sizeof(buf), "E00");
>> +                put_packet(s, buf);
>> +                break;
>> +            }
>> +            if (len > (MAX_PACKET_LENGTH - 5) / 2)
>> +                len = (MAX_PACKET_LENGTH - 5) / 2;
>> +            if (len < auxv_len - addr) {
>> +                buf[0] = 'm';
>> +                len = memtox(buf + 1, ptr + addr, len);
>> +            } else {
>> +                buf[0] = 'l';
>> +                len = memtox(buf + 1, ptr + addr, auxv_len - addr);
>> +            }
>> +            put_packet_binary(s, buf, len + 1);
>> +            unlock_user(ptr, auxv, len);
>> +        }
>> +#endif /* !CONFIG_USER_ONLY */
>>           /* Unrecognised 'q' command.  */
>>           goto unknown_command;
>>