From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4565 invoked by alias); 2 Sep 2014 03:26:55 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 4534 invoked by uid 89); 2 Sep 2014 03:26:47 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-ob0-f169.google.com Received: from mail-ob0-f169.google.com (HELO mail-ob0-f169.google.com) (209.85.214.169) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Tue, 02 Sep 2014 03:26:44 +0000 Received: by mail-ob0-f169.google.com with SMTP id wp4so4397378obc.14 for ; Mon, 01 Sep 2014 20:26:42 -0700 (PDT) X-Received: by 10.60.82.170 with SMTP id j10mr29775474oey.37.1409628402106; Mon, 01 Sep 2014 20:26:42 -0700 (PDT) MIME-Version: 1.0 Received: by 10.60.47.38 with HTTP; Mon, 1 Sep 2014 20:26:02 -0700 (PDT) In-Reply-To: <1409238683-17886-1-git-send-email-teawater@gmail.com> References: <1409238683-17886-1-git-send-email-teawater@gmail.com> From: Hui Zhu Date: Tue, 02 Sep 2014 03:26:00 -0000 Message-ID: Subject: Re: [PATCH] Add gdbarch_sizeof_g_packet to "struct remote_arch_state" to handle the issue that get error "Remote 'g' packet reply is too long" with qemu-system-x86_64 To: gdb-patches ml Cc: Hui Zhu Content-Type: text/plain; charset=ISO-8859-1 X-IsSubscribed: yes X-SW-Source: 2014-09/txt/msg00042.txt.bz2 Ping. Thanks, Hui On Thu, Aug 28, 2014 at 11:11 PM, Hui Zhu wrote: > If qemu-system-x86_64 start with -S, gdb will get error "Remote 'g' packet reply > is too long", for example: > sudo qemu-system-x86_64 -nographic -k en-us -kernel /boot/vmlinuz-3.13.0-34-generic -gdb tcp::12345 -append "console=ttyS0,115200 root=/dev/sda rw kmemleak=off" -S -m 512 -smp 1 > gdb /usr/lib/debug/boot/vmlinux-$(uname -r) > (gdb) set debug remote 1 > (gdb) target remote :12345 > ... > ... > Sending packet: $g#67...Ack > Packet received: 0000000000000000630600000000000000000000000000000000000 > 000000000f0ff00000200000000f00000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000007f03000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 0000000000000000000000000000000000000000000000000801f0000 > (gdb) b start_kernel > (gdb) c > Continuing. > ... > ... > Sending packet: $g#67...Ack > Packet received: 0000000000000000d381ffffffff000040000000000000000010060 > 00000000000f009000000000010f4ce81ffffffff981fc081ffffffff901fc081fffffff > f0030c1010000000000000000000000000000000000000000a869270200000000fffffff > f0000000020000000000000002051d381ffffffffb01fc081ffffffff385bd381fffffff > f96000000100000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 07f030000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 0801f0000 > Remote 'g' packet reply is too long: 0000000000000000d381ffffffff0000400 > 0000000000000001006000000000000f009000000000010f4ce81ffffffff981fc081fff > fffff901fc081ffffffff0030c1010000000000000000000000000000000000000000a86 > 9270200000000ffffffff0000000020000000000000002051d381ffffffffb01fc081fff > fffff385bd381ffffffff960000001000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 0000000000000000000007f0300000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000000000000000000000000000000000000000000000000000000 > 000000000000000000000801f0000 > (gdb) c > Continuing. > Cannot execute this command while the selected thread is running. > > The root cause of this issue is: > When GDB load a debug binary, function init_remote_state will be called and > rsa->sizeof_g_packet will be initialized. > /* Record the maximum possible size of the g packet - it may turn out > to be smaller. */ > rsa->sizeof_g_packet = map_regcache_remote_table (gdbarch, rsa->regs); > When remote.c get first reply of g that its size is smaller than > rsa->sizeof_g_packet in function process_g_packet, sizeof_g_packet will be > updated to this smaller size. > rsa->sizeof_g_packet = buf_len / 2; > When inferior is breaked by breakpoint, because some reason architecture reason, > QEMU send a packet for "g" that is more bigger than previous one. Then GDB will > get error in function process_g_packet. > /* Further sanity checks, with knowledge of the architecture. */ > if (buf_len > 2 * rsa->sizeof_g_packet) > error (_("Remote 'g' packet reply is too long: %s"), rs->buf); > > To handle this issue: > This patch add "gdbarch_sizeof_g_packet" to "struct remote_arch_state", it will > keep the size of g packet that get from gdbarch. And function process_g_packet > use it do the check for the reply of "g". And update sizeof_g_packet if it is > not same with reply of "g". > > 2014-08-21 Hui Zhu > > * remote.c (struct remote_arch_state): Add gdbarch_sizeof_g_packet. > (init_remote_state): Initialize rsa->gdbarch_sizeof_g_packet. > (process_g_packet): Check buf_len with rsa->gdbarch_sizeof_g_packet. > Update code to update rsa->sizeof_g_packet if buf_len is not for it. > --- > gdb/remote.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/gdb/remote.c b/gdb/remote.c > index 357e9f2..9727915 100644 > --- a/gdb/remote.c > +++ b/gdb/remote.c > @@ -439,6 +439,11 @@ struct remote_arch_state > /* Description of the remote protocol registers. */ > long sizeof_g_packet; > > + /* The sizeof_g_packet will be changed in some GDBstub (QEMU) when it executes. > + Description of the remote protocol registers that get form current > + gdbarch. */ > + long gdbarch_sizeof_g_packet; > + > /* Description of the remote protocol registers indexed by REGNUM > (making an array gdbarch_num_regs in size). */ > struct packet_reg *regs; > @@ -673,7 +678,8 @@ init_remote_state (struct gdbarch *gdbarch) > > /* Record the maximum possible size of the g packet - it may turn out > to be smaller. */ > - rsa->sizeof_g_packet = map_regcache_remote_table (gdbarch, rsa->regs); > + rsa->gdbarch_sizeof_g_packet = map_regcache_remote_table (gdbarch, rsa->regs); > + rsa->sizeof_g_packet = rsa->gdbarch_sizeof_g_packet; > > /* Default maximum number of characters in a packet body. Many > remote stubs have a hardwired buffer size of 400 bytes > @@ -693,8 +699,8 @@ init_remote_state (struct gdbarch *gdbarch) > header / footer. NOTE: cagney/1999-10-26: I suspect that 8 > (``$NN:G...#NN'') is a better guess, the below has been padded a > little. */ > - if (rsa->sizeof_g_packet > ((rsa->remote_packet_size - 32) / 2)) > - rsa->remote_packet_size = (rsa->sizeof_g_packet * 2 + 32); > + if (rsa->gdbarch_sizeof_g_packet > ((rsa->remote_packet_size - 32) / 2)) > + rsa->remote_packet_size = (rsa->gdbarch_sizeof_g_packet * 2 + 32); > > /* Make sure that the packet buffer is plenty big enough for > this architecture. */ > @@ -6070,7 +6076,7 @@ process_g_packet (struct regcache *regcache) > buf_len = strlen (rs->buf); > > /* Further sanity checks, with knowledge of the architecture. */ > - if (buf_len > 2 * rsa->sizeof_g_packet) > + if (buf_len > 2 * rsa->gdbarch_sizeof_g_packet) > error (_("Remote 'g' packet reply is too long: %s"), rs->buf); > > /* Save the size of the packet sent to us by the target. It is used > @@ -6079,11 +6085,11 @@ process_g_packet (struct regcache *regcache) > if (rsa->actual_register_packet_size == 0) > rsa->actual_register_packet_size = buf_len; > > - /* If this is smaller than we guessed the 'g' packet would be, > + /* If this is not same with we guessed the 'g' packet would be, > update our records. A 'g' reply that doesn't include a register's > value implies either that the register is not available, or that > the 'p' packet must be used. */ > - if (buf_len < 2 * rsa->sizeof_g_packet) > + if (buf_len != 2 * rsa->sizeof_g_packet) > { > rsa->sizeof_g_packet = buf_len / 2; > > -- > 1.9.3 >