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Re: [Qemu-devel] [PATCH] gdbstub: Support AUXV packet for debugging PIE
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] gdbstub: Support AUXV packet for debugging PIE executables. |
Date: |
Thu, 27 Nov 2014 17:57:17 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
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;
>