[binutils-gdb] btrace, gdbserver: check btrace target pointers

[Markus Metzger <mmetzger at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b1223e789040e9e8cdc6869a8a1fd1fd7acc109d

commit b1223e789040e9e8cdc6869a8a1fd1fd7acc109d
Author: Markus Metzger <markus.t.metzger@intel.com>
Date:   Mon Feb 26 11:59:43 2018 +0100

    btrace, gdbserver: check btrace target pointers
    
    By removing the supports_btrace gdbserver target method we relied on GDB
    trying to enable branch tracing and failing on the attempt.
    
    For targets that do not provide the btrace methods, however, an initial
    request from GDB for the branch trace configuration to detect whether
    gdbserver is already recording resulted in a protocol error.
    
    Have the btrace target methods throw a "Target does not suppor branch
    tracing" error and be prepared to handle exceptions in all functions that
    call btrace target methods.  We therefore turn the target_* macros into
    static inline functions.
    
    Also remove the additional btrace target method checks that resulted in
    the above protocol error.
    
    Thanks to Maciej W. Rozycki <macro@mips.com> for reporting this.
    
    gdbserver/
    	* target.h (target_enable_btrace, target_disable_btrace)
    	(target_read_btrace, target_read_btrace_conf): Turn macro into
    	inline function.  Throw error if target method is not defined.
    	* server.c (handle_qxfer_btrace, handle_qxfer_btrace_conf): Remove
    	check for btrace target method.  Be prepared to handle exceptions
    	from btrace target methods.

Diff:
---
 gdb/gdbserver/ChangeLog |  9 +++++++++
 gdb/gdbserver/server.c  | 38 ++++++++++++++++++++++++++++----------
 gdb/gdbserver/target.h  | 43 +++++++++++++++++++++++++++++++++++--------
 3 files changed, 72 insertions(+), 18 deletions(-)

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index ac88a9d..703bdfb 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,12 @@
+2018-03-01  Markus Metzger  <markus.t.metzger@intel.com>
+
+	* target.h (target_enable_btrace, target_disable_btrace)
+	(target_read_btrace, target_read_btrace_conf): Turn macro into
+	inline function.  Throw error if target method is not defined.
+	* server.c (handle_qxfer_btrace handle_qxfer_btrace_conf): Remove
+	check for btrace target method.  Be prepared to handle exceptions
+	from btrace target methods.
+
 2018-02-28  Sergio Durigan Junior  <sergiodj@redhat.com>
 
 	* server.c (captured_main): Change order of error message printed
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index f373d8a..ad327be 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -1852,7 +1852,7 @@ handle_qxfer_btrace (const char *annex,
   enum btrace_read_type type;
   int result;
 
-  if (the_target->read_btrace == NULL || writebuf != NULL)
+  if (writebuf != NULL)
     return -2;
 
   if (ptid_equal (general_thread, null_ptid)
@@ -1891,12 +1891,21 @@ handle_qxfer_btrace (const char *annex,
     {
       buffer_free (&cache);
 
-      result = target_read_btrace (thread->btrace, &cache, type);
-      if (result != 0)
+      TRY
 	{
-	  memcpy (own_buf, cache.buffer, cache.used_size);
-	  return -3;
+	  result = target_read_btrace (thread->btrace, &cache, type);
+	  if (result != 0)
+	    memcpy (own_buf, cache.buffer, cache.used_size);
 	}
+      CATCH (exception, RETURN_MASK_ERROR)
+	{
+	  sprintf (own_buf, "E.%s", exception.message);
+	  result = -1;
+	}
+      END_CATCH
+
+      if (result != 0)
+	return -3;
     }
   else if (offset > cache.used_size)
     {
@@ -1923,7 +1932,7 @@ handle_qxfer_btrace_conf (const char *annex,
   struct thread_info *thread;
   int result;
 
-  if (the_target->read_btrace_conf == NULL || writebuf != NULL)
+  if (writebuf != NULL)
     return -2;
 
   if (annex[0] != '\0')
@@ -1953,12 +1962,21 @@ handle_qxfer_btrace_conf (const char *annex,
     {
       buffer_free (&cache);
 
-      result = target_read_btrace_conf (thread->btrace, &cache);
-      if (result != 0)
+      TRY
 	{
-	  memcpy (own_buf, cache.buffer, cache.used_size);
-	  return -3;
+	  result = target_read_btrace_conf (thread->btrace, &cache);
+	  if (result != 0)
+	    memcpy (own_buf, cache.buffer, cache.used_size);
 	}
+      CATCH (exception, RETURN_MASK_ERROR)
+	{
+	  sprintf (own_buf, "E.%s", exception.message);
+	  result = -1;
+	}
+      END_CATCH
+
+      if (result != 0)
+	return -3;
     }
   else if (offset > cache.used_size)
     {
diff --git a/gdb/gdbserver/target.h b/gdb/gdbserver/target.h
index dcefe1a..25accd2 100644
--- a/gdb/gdbserver/target.h
+++ b/gdb/gdbserver/target.h
@@ -620,17 +620,44 @@ int kill_inferior (int);
   (the_target->supports_agent ? \
    (*the_target->supports_agent) () : 0)
 
-#define target_enable_btrace(ptid, conf) \
-  (*the_target->enable_btrace) (ptid, conf)
+static inline struct btrace_target_info *
+target_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
+{
+  if (the_target->enable_btrace == nullptr)
+    error (_("Target does not support branch tracing."));
+
+  return (*the_target->enable_btrace) (ptid, conf);
+}
+
+static inline int
+target_disable_btrace (struct btrace_target_info *tinfo)
+{
+  if (the_target->disable_btrace == nullptr)
+    error (_("Target does not support branch tracing."));
 
-#define target_disable_btrace(tinfo) \
-  (*the_target->disable_btrace) (tinfo)
+  return (*the_target->disable_btrace) (tinfo);
+}
 
-#define target_read_btrace(tinfo, buffer, type)	\
-  (*the_target->read_btrace) (tinfo, buffer, type)
+static inline int
+target_read_btrace (struct btrace_target_info *tinfo,
+		    struct buffer *buffer,
+		    enum btrace_read_type type)
+{
+  if (the_target->read_btrace == nullptr)
+    error (_("Target does not support branch tracing."));
+
+  return (*the_target->read_btrace) (tinfo, buffer, type);
+}
+
+static inline int
+target_read_btrace_conf (struct btrace_target_info *tinfo,
+			 struct buffer *buffer)
+{
+  if (the_target->read_btrace_conf == nullptr)
+    error (_("Target does not support branch tracing."));
 
-#define target_read_btrace_conf(tinfo, buffer)	\
-  (*the_target->read_btrace_conf) (tinfo, buffer)
+  return (*the_target->read_btrace_conf) (tinfo, buffer);
+}
 
 #define target_supports_range_stepping() \
   (the_target->supports_range_stepping ? \