gdb, gdbserver: update thread identifier in enable_btrace target method

The enable_btrace target method takes a ptid_t to identify the thread on
which tracing shall be enabled.

Change this to thread_info * to avoid translating back and forth between
the two.  This will be used in a subsequent patch.
diff --git a/gdb/btrace.c b/gdb/btrace.c
index dc4d686..ea733fe 100644
--- a/gdb/btrace.c
+++ b/gdb/btrace.c
@@ -1618,7 +1618,7 @@ btrace_enable (struct thread_info *tp, const struct btrace_config *conf)
   DEBUG ("enable thread %s (%s)", print_thread_id (tp),
 	 tp->ptid.to_string ().c_str ());
 
-  tp->btrace.target = target_enable_btrace (tp->ptid, conf);
+  tp->btrace.target = target_enable_btrace (tp, conf);
 
   if (tp->btrace.target == NULL)
     error (_("Failed to enable recording on thread %s (%s)."),
diff --git a/gdb/ravenscar-thread.c b/gdb/ravenscar-thread.c
index 5f040ce..60fc353 100644
--- a/gdb/ravenscar-thread.c
+++ b/gdb/ravenscar-thread.c
@@ -120,12 +120,16 @@ struct ravenscar_thread_target final : public target_ops
 
   ptid_t get_ada_task_ptid (long lwp, ULONGEST thread) override;
 
-  struct btrace_target_info *enable_btrace (ptid_t ptid,
+  struct btrace_target_info *enable_btrace (thread_info *tp,
 					    const struct btrace_config *conf)
     override
   {
-    ptid = get_base_thread_from_ravenscar_task (ptid);
-    return beneath ()->enable_btrace (ptid, conf);
+    process_stratum_target *proc_target
+      = as_process_stratum_target (this->beneath ());
+    ptid_t underlying = get_base_thread_from_ravenscar_task (tp->ptid);
+    tp = find_thread_ptid (proc_target, underlying);
+
+    return beneath ()->enable_btrace (tp, conf);
   }
 
   void mourn_inferior () override;
diff --git a/gdb/remote.c b/gdb/remote.c
index f19a2f7..9f2c63b 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -658,8 +658,8 @@ class remote_target : public process_stratum_target
   bool use_agent (bool use) override;
   bool can_use_agent () override;
 
-  struct btrace_target_info *enable_btrace (ptid_t ptid,
-					    const struct btrace_config *conf) override;
+  struct btrace_target_info *
+    enable_btrace (thread_info *tp, const struct btrace_config *conf) override;
 
   void disable_btrace (struct btrace_target_info *tinfo) override;
 
@@ -14178,7 +14178,8 @@ remote_target::remote_btrace_maybe_reopen ()
 /* Enable branch tracing.  */
 
 struct btrace_target_info *
-remote_target::enable_btrace (ptid_t ptid, const struct btrace_config *conf)
+remote_target::enable_btrace (thread_info *tp,
+			      const struct btrace_config *conf)
 {
   struct btrace_target_info *tinfo = NULL;
   struct packet_config *packet = NULL;
@@ -14202,6 +14203,7 @@ remote_target::enable_btrace (ptid_t ptid, const struct btrace_config *conf)
 
   btrace_sync_conf (conf);
 
+  ptid_t ptid = tp->ptid;
   set_general_thread (ptid);
 
   buf += xsnprintf (buf, endbuf - buf, "%s", packet->name);
diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c
index 9636e32..ca1734f 100644
--- a/gdb/target-delegates.c
+++ b/gdb/target-delegates.c
@@ -145,7 +145,7 @@ struct dummy_target : public target_ops
   traceframe_info_up traceframe_info () override;
   bool use_agent (bool arg0) override;
   bool can_use_agent () override;
-  struct btrace_target_info *enable_btrace (ptid_t arg0, const struct btrace_config *arg1) override;
+  struct btrace_target_info *enable_btrace (thread_info *arg0, const struct btrace_config *arg1) override;
   void disable_btrace (struct btrace_target_info *arg0) override;
   void teardown_btrace (struct btrace_target_info *arg0) override;
   enum btrace_error read_btrace (struct btrace_data *arg0, struct btrace_target_info *arg1, enum btrace_read_type arg2) override;
@@ -319,7 +319,7 @@ struct debug_target : public target_ops
   traceframe_info_up traceframe_info () override;
   bool use_agent (bool arg0) override;
   bool can_use_agent () override;
-  struct btrace_target_info *enable_btrace (ptid_t arg0, const struct btrace_config *arg1) override;
+  struct btrace_target_info *enable_btrace (thread_info *arg0, const struct btrace_config *arg1) override;
   void disable_btrace (struct btrace_target_info *arg0) override;
   void teardown_btrace (struct btrace_target_info *arg0) override;
   enum btrace_error read_btrace (struct btrace_data *arg0, struct btrace_target_info *arg1, enum btrace_read_type arg2) override;
@@ -3761,25 +3761,25 @@ debug_target::can_use_agent ()
 }
 
 struct btrace_target_info *
-target_ops::enable_btrace (ptid_t arg0, const struct btrace_config *arg1)
+target_ops::enable_btrace (thread_info *arg0, const struct btrace_config *arg1)
 {
   return this->beneath ()->enable_btrace (arg0, arg1);
 }
 
 struct btrace_target_info *
-dummy_target::enable_btrace (ptid_t arg0, const struct btrace_config *arg1)
+dummy_target::enable_btrace (thread_info *arg0, const struct btrace_config *arg1)
 {
   tcomplain ();
 }
 
 struct btrace_target_info *
-debug_target::enable_btrace (ptid_t arg0, const struct btrace_config *arg1)
+debug_target::enable_btrace (thread_info *arg0, const struct btrace_config *arg1)
 {
   struct btrace_target_info * result;
   fprintf_unfiltered (gdb_stdlog, "-> %s->enable_btrace (...)\n", this->beneath ()->shortname ());
   result = this->beneath ()->enable_btrace (arg0, arg1);
   fprintf_unfiltered (gdb_stdlog, "<- %s->enable_btrace (", this->beneath ()->shortname ());
-  target_debug_print_ptid_t (arg0);
+  target_debug_print_thread_info_p (arg0);
   fputs_unfiltered (", ", gdb_stdlog);
   target_debug_print_const_struct_btrace_config_p (arg1);
   fputs_unfiltered (") = ", gdb_stdlog);
diff --git a/gdb/target.c b/gdb/target.c
index f3f1c80..548cfad 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -4060,9 +4060,9 @@ target_ranged_break_num_registers (void)
 /* See target.h.  */
 
 struct btrace_target_info *
-target_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
+target_enable_btrace (thread_info *tp, const struct btrace_config *conf)
 {
-  return current_inferior ()->top_target ()->enable_btrace (ptid, conf);
+  return current_inferior ()->top_target ()->enable_btrace (tp, conf);
 }
 
 /* See target.h.  */
diff --git a/gdb/target.h b/gdb/target.h
index 1ac7a45..4cc79df 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -1151,10 +1151,10 @@ struct target_ops
     virtual bool can_use_agent ()
       TARGET_DEFAULT_RETURN (false);
 
-    /* Enable branch tracing for PTID using CONF configuration.
+    /* Enable branch tracing for TP using CONF configuration.
        Return a branch trace target information struct for reading and for
        disabling branch trace.  */
-    virtual struct btrace_target_info *enable_btrace (ptid_t ptid,
+    virtual struct btrace_target_info *enable_btrace (thread_info *tp,
 						      const struct btrace_config *conf)
       TARGET_DEFAULT_NORETURN (tcomplain ());
 
@@ -2502,7 +2502,7 @@ extern void update_target_permissions (void);
 
 /* See to_enable_btrace in struct target_ops.  */
 extern struct btrace_target_info *
-  target_enable_btrace (ptid_t ptid, const struct btrace_config *);
+  target_enable_btrace (thread_info *tp, const struct btrace_config *);
 
 /* See to_disable_btrace in struct target_ops.  */
 extern void target_disable_btrace (struct btrace_target_info *btinfo);
diff --git a/gdb/x86-linux-nat.c b/gdb/x86-linux-nat.c
index 55d2a1d..80be973 100644
--- a/gdb/x86-linux-nat.c
+++ b/gdb/x86-linux-nat.c
@@ -212,10 +212,11 @@ x86_linux_nat_target::read_description ()
 /* Enable branch tracing.  */
 
 struct btrace_target_info *
-x86_linux_nat_target::enable_btrace (ptid_t ptid,
+x86_linux_nat_target::enable_btrace (thread_info *tp,
 				     const struct btrace_config *conf)
 {
   struct btrace_target_info *tinfo = nullptr;
+  ptid_t ptid = tp->ptid;
   try
     {
       tinfo = linux_enable_btrace (ptid, conf);
diff --git a/gdb/x86-linux-nat.h b/gdb/x86-linux-nat.h
index e0a78bf..1a56234 100644
--- a/gdb/x86-linux-nat.h
+++ b/gdb/x86-linux-nat.h
@@ -32,7 +32,7 @@ struct x86_linux_nat_target : public x86_nat_target<linux_nat_target>
   /* Add the description reader.  */
   const struct target_desc *read_description () override;
 
-  struct btrace_target_info *enable_btrace (ptid_t ptid,
+  struct btrace_target_info *enable_btrace (thread_info *tp,
 					    const struct btrace_config *conf) override;
   void disable_btrace (struct btrace_target_info *tinfo) override;
   void teardown_btrace (struct btrace_target_info *tinfo) override;
diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index 9e571a4..cf73bbc 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -6669,10 +6669,10 @@
 #ifdef HAVE_LINUX_BTRACE
 
 btrace_target_info *
-linux_process_target::enable_btrace (ptid_t ptid,
+linux_process_target::enable_btrace (thread_info *tp,
 				     const btrace_config *conf)
 {
-  return linux_enable_btrace (ptid, conf);
+  return linux_enable_btrace (tp->id, conf);
 }
 
 /* See to_disable_btrace target method.  */
diff --git a/gdbserver/linux-low.h b/gdbserver/linux-low.h
index 6ee72d7..27cc964 100644
--- a/gdbserver/linux-low.h
+++ b/gdbserver/linux-low.h
@@ -276,7 +276,7 @@ class linux_process_target : public process_stratum_target
   bool supports_agent () override;
 
 #ifdef HAVE_LINUX_BTRACE
-  btrace_target_info *enable_btrace (ptid_t ptid,
+  btrace_target_info *enable_btrace (thread_info *tp,
 				     const btrace_config *conf) override;
 
   int disable_btrace (btrace_target_info *tinfo) override;
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 4177239..8e53f22 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -409,7 +409,7 @@
     error (_("Btrace already enabled."));
 
   current_btrace_conf.format = BTRACE_FORMAT_BTS;
-  thread->btrace = target_enable_btrace (thread->id, &current_btrace_conf);
+  thread->btrace = target_enable_btrace (thread, &current_btrace_conf);
 }
 
 /* Handle btrace enabling in Intel Processor Trace format.  */
@@ -421,7 +421,7 @@
     error (_("Btrace already enabled."));
 
   current_btrace_conf.format = BTRACE_FORMAT_PT;
-  thread->btrace = target_enable_btrace (thread->id, &current_btrace_conf);
+  thread->btrace = target_enable_btrace (thread, &current_btrace_conf);
 }
 
 /* Handle btrace disabling.  */
diff --git a/gdbserver/target.cc b/gdbserver/target.cc
index 5165957..5009146 100644
--- a/gdbserver/target.cc
+++ b/gdbserver/target.cc
@@ -736,7 +736,8 @@
 }
 
 btrace_target_info *
-process_stratum_target::enable_btrace (ptid_t ptid, const btrace_config *conf)
+process_stratum_target::enable_btrace (thread_info *tp,
+				       const btrace_config *conf)
 {
   error (_("Target does not support branch tracing."));
 }
diff --git a/gdbserver/target.h b/gdbserver/target.h
index f58ed9d..aaa9dab 100644
--- a/gdbserver/target.h
+++ b/gdbserver/target.h
@@ -403,9 +403,9 @@ class process_stratum_target
   /* Return true if target supports debugging agent.  */
   virtual bool supports_agent ();
 
-  /* Enable branch tracing for PTID based on CONF and allocate a branch trace
+  /* 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 (ptid_t ptid,
+  virtual btrace_target_info *enable_btrace (thread_info *tp,
 					     const btrace_config *conf);
 
   /* Disable branch tracing.
@@ -635,9 +635,9 @@ int kill_inferior (process_info *proc);
   the_target->supports_agent ()
 
 static inline struct btrace_target_info *
-target_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
+target_enable_btrace (thread_info *tp, const struct btrace_config *conf)
 {
-  return the_target->enable_btrace (ptid, conf);
+  return the_target->enable_btrace (tp, conf);
 }
 
 static inline int