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authorMatheus Tavares Bernardino <quic_mathbern@quicinc.com>2023-05-04 12:37:31 -0300
committerTaylor Simpson <tsimpson@quicinc.com>2023-05-18 12:40:52 -0700
commit758370052fb602f9f23c3b8ae26a6133373c78e6 (patch)
tree6953d7d93c67618e73669f4b6102ebb99d10b6a4 /gdbstub/user.c
parent9e6d4938d106ca775108ec2a1fecc6d789543088 (diff)
downloadfocaccia-qemu-758370052fb602f9f23c3b8ae26a6133373c78e6.tar.gz
focaccia-qemu-758370052fb602f9f23c3b8ae26a6133373c78e6.zip
gdbstub: only send stop-reply packets when allowed to
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 <quic_mathbern@quicinc.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <a49c0897fc22a6a7827c8dfc32aef2e1d933ec6b.1683214375.git.quic_mathbern@quicinc.com>
Diffstat (limited to 'gdbstub/user.c')
-rw-r--r--gdbstub/user.c24
1 files changed, 16 insertions, 8 deletions
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)