From 758370052fb602f9f23c3b8ae26a6133373c78e6 Mon Sep 17 00:00:00 2001 From: Matheus Tavares Bernardino Date: Thu, 4 May 2023 12:37:31 -0300 Subject: gdbstub: only send stop-reply packets when allowed to MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit GDB's remote serial protocol allows stop-reply messages to be sent by the stub either as a notification packet or as a reply to a GDB command (provided that the cmd accepts such a response). QEMU currently does not implement notification packets, so it should only send stop-replies synchronously and when requested. Nevertheless, it still issues unsolicited stop messages through gdb_vm_state_change(). Although this behavior doesn't seem to cause problems with GDB itself (the messages are just ignored), it can impact other debuggers that implement the GDB remote serial protocol, like hexagon-lldb. Let's change the gdbstub to send stop messages only as a response to a previous GDB command that accepts such a reply. Signed-off-by: Matheus Tavares Bernardino Acked-by: Alex Bennée Signed-off-by: Taylor Simpson Message-Id: --- gdbstub/user.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) (limited to 'gdbstub/user.c') diff --git a/gdbstub/user.c b/gdbstub/user.c index 80488b6bb9..5b375be1d9 100644 --- a/gdbstub/user.c +++ b/gdbstub/user.c @@ -108,8 +108,11 @@ void gdb_exit(int code) trace_gdbstub_op_exiting((uint8_t)code); - snprintf(buf, sizeof(buf), "W%02x", (uint8_t)code); - gdb_put_packet(buf); + if (gdbserver_state.allow_stop_reply) { + snprintf(buf, sizeof(buf), "W%02x", (uint8_t)code); + gdb_put_packet(buf); + gdbserver_state.allow_stop_reply = false; + } } int gdb_handlesig(CPUState *cpu, int sig) @@ -127,11 +130,14 @@ int gdb_handlesig(CPUState *cpu, int sig) if (sig != 0) { gdb_set_stop_cpu(cpu); - g_string_printf(gdbserver_state.str_buf, - "T%02xthread:", gdb_target_signal_to_gdb(sig)); - gdb_append_thread_id(cpu, gdbserver_state.str_buf); - g_string_append_c(gdbserver_state.str_buf, ';'); - gdb_put_strbuf(); + if (gdbserver_state.allow_stop_reply) { + g_string_printf(gdbserver_state.str_buf, + "T%02xthread:", gdb_target_signal_to_gdb(sig)); + gdb_append_thread_id(cpu, gdbserver_state.str_buf); + g_string_append_c(gdbserver_state.str_buf, ';'); + gdb_put_strbuf(); + gdbserver_state.allow_stop_reply = false; + } } /* * gdb_put_packet() might have detected that the peer terminated the @@ -174,12 +180,14 @@ void gdb_signalled(CPUArchState *env, int sig) { char buf[4]; - if (!gdbserver_state.init || gdbserver_user_state.fd < 0) { + if (!gdbserver_state.init || gdbserver_user_state.fd < 0 || + !gdbserver_state.allow_stop_reply) { return; } snprintf(buf, sizeof(buf), "X%02x", gdb_target_signal_to_gdb(sig)); gdb_put_packet(buf); + gdbserver_state.allow_stop_reply = false; } static void gdb_accept_init(int fd) -- cgit 1.4.1