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 
---
  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;

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

[Paolo Bonzini]

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 
> ---
>  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;
>