From 8263b346fa07e3f679b05a8b369d491af51e6de8 Mon Sep 17 00:00:00 2001
From: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Date: Wed, 9 Nov 2022 17:46:21 +0100
Subject: [PATCH] gdbserver: do not report btrace support if target does not
 announce it

Gdbserver unconditionally reports support for btrace packets.  Do not
report the support, if the underlying target does not say it supports
it.  Otherwise GDB would query the server with btrace-related packets
unnecessarily.
---
 gdbserver/linux-low.cc | 6 ++++++
 gdbserver/linux-low.h  | 2 ++
 gdbserver/server.cc    | 3 ++-
 gdbserver/target.cc    | 6 ++++++
 gdbserver/target.h     | 3 +++
 5 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index 1676328fc88..0cbfeb99086 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -6712,6 +6712,12 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
 
 #ifdef HAVE_LINUX_BTRACE
 
+bool
+linux_process_target::supports_btrace ()
+{
+  return true;
+}
+
 btrace_target_info *
 linux_process_target::enable_btrace (thread_info *tp,
 				     const btrace_config *conf)
diff --git a/gdbserver/linux-low.h b/gdbserver/linux-low.h
index 79be31b8f72..1594f063f47 100644
--- a/gdbserver/linux-low.h
+++ b/gdbserver/linux-low.h
@@ -275,6 +275,8 @@ public:
   bool supports_agent () override;
 
 #ifdef HAVE_LINUX_BTRACE
+  bool supports_btrace () override;
+
   btrace_target_info *enable_btrace (thread_info *tp,
 				     const btrace_config *conf) override;
 
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 366a843ea89..aaef38e0062 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -2475,7 +2475,8 @@ handle_query (char *own_buf, int packet_len, int *new_packet_len_p)
       if (target_supports_agent ())
 	strcat (own_buf, ";QAgent+");
 
-      supported_btrace_packets (own_buf);
+      if (the_target->supports_btrace ())
+	supported_btrace_packets (own_buf);
 
       if (target_supports_stopped_by_sw_breakpoint ())
 	strcat (own_buf, ";swbreak+");
diff --git a/gdbserver/target.cc b/gdbserver/target.cc
index adcfe6e7bcc..c06a67600b1 100644
--- a/gdbserver/target.cc
+++ b/gdbserver/target.cc
@@ -694,6 +694,12 @@ process_stratum_target::supports_agent ()
   return false;
 }
 
+bool
+process_stratum_target::supports_btrace ()
+{
+  return false;
+}
+
 btrace_target_info *
 process_stratum_target::enable_btrace (thread_info *tp,
 				       const btrace_config *conf)
diff --git a/gdbserver/target.h b/gdbserver/target.h
index 6c536a30778..18ab969dda7 100644
--- a/gdbserver/target.h
+++ b/gdbserver/target.h
@@ -388,6 +388,9 @@ public:
   /* Return true if target supports debugging agent.  */
   virtual bool supports_agent ();
 
+  /* Return true if target supports btrace.  */
+  virtual bool supports_btrace ();
+
   /* Enable branch tracing for TP based on CONF and allocate a branch trace
      target information struct for reading and for disabling branch trace.  */
   virtual btrace_target_info *enable_btrace (thread_info *tp,