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

[Wei-cheng Wang]

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 <address@hidden>
> > ---
> >   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;