[v8,07/10] btrace, gdbserver: Add ptwrite to btrace_config_pt.

Message ID 20230321154626.448816-8-felix.willgerodt@intel.com
State New
Headers
Series Extensions for PTWRITE |

Commit Message

Willgerodt, Felix March 21, 2023, 3:46 p.m. UTC
  This enables gdb and gdbserver to communicate about ptwrite support.  If
ptwrite support would be enabled unconditionally, GDBs with older libipt
versions would break.
---
 gdb/btrace.c                 |  8 +++++++-
 gdb/doc/gdb.texinfo          | 21 +++++++++++++++++++++
 gdb/features/btrace-conf.dtd |  1 +
 gdb/remote.c                 | 33 +++++++++++++++++++++++++++++++++
 gdbserver/linux-low.cc       |  3 +++
 gdbserver/server.cc          | 18 ++++++++++++++++++
 gdbsupport/btrace-common.h   |  6 ++++++
 7 files changed, 89 insertions(+), 1 deletion(-)
  

Patch

diff --git a/gdb/btrace.c b/gdb/btrace.c
index b0afc1735f8..f2fc4786e21 100644
--- a/gdb/btrace.c
+++ b/gdb/btrace.c
@@ -2273,7 +2273,7 @@  parse_xml_btrace_conf_pt (struct gdb_xml_parser *parser,
 			  std::vector<gdb_xml_value> &attributes)
 {
   struct btrace_config *conf;
-  struct gdb_xml_value *size;
+  struct gdb_xml_value *size, *ptwrite;
 
   conf = (struct btrace_config *) user_data;
   conf->format = BTRACE_FORMAT_PT;
@@ -2282,10 +2282,16 @@  parse_xml_btrace_conf_pt (struct gdb_xml_parser *parser,
   size = xml_find_attribute (attributes, "size");
   if (size != NULL)
     conf->pt.size = (unsigned int) *(ULONGEST *) size->value.get ();
+
+  ptwrite = xml_find_attribute (attributes, "ptwrite");
+  if (ptwrite != nullptr)
+    conf->pt.ptwrite = (bool) *(ULONGEST *) ptwrite->value.get ();
 }
 
 static const struct gdb_xml_attribute btrace_conf_pt_attributes[] = {
   { "size", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_ulongest, NULL },
+  { "ptwrite", GDB_XML_AF_OPTIONAL, gdb_xml_parse_attr_enum,
+    gdb_xml_enums_boolean },
   { NULL, GDB_XML_AF_NONE, NULL, NULL }
 };
 
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 2d8cf143262..cd2313cdb6a 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -43779,6 +43779,11 @@  These are the currently defined stub features and their properties:
 @tab @samp{-}
 @tab Yes
 
+@item @samp{Qbtrace-conf:pt:ptwrite}
+@tab Yes
+@tab @samp{-}
+@tab Yes
+
 @item @samp{QNonStop}
 @tab No
 @tab @samp{-}
@@ -44090,6 +44095,9 @@  The remote stub understands the @samp{Qbtrace-conf:bts:size} packet.
 @item Qbtrace-conf:pt:size
 The remote stub understands the @samp{Qbtrace-conf:pt:size} packet.
 
+@item Qbtrace-conf:pt:ptwrite
+The remote stub understands the @samp{Qbtrace-conf:pt:ptwrite} packet.
+
 @item swbreak
 The remote stub reports the @samp{swbreak} stop reason for memory
 breakpoints.
@@ -44597,6 +44605,18 @@  The ring buffer size has been set.
 A badly formed request or an error was encountered.
 @end table
 
+@item Qbtrace-conf:pt:ptwrite=@var{(yes|no)}
+Indicate support for @code{PTWRITE} packets.  This allows for backwards
+compatibility.
+
+Reply:
+@table @samp
+@item OK
+The ptwrite config parameter has been set.
+@item E.errtext
+A badly formed request or an error was encountered.
+@end table
+
 @end table
 
 @node Architecture-Specific Protocol Details
@@ -47245,6 +47265,7 @@  The formal DTD for the branch trace configuration format is given below:
 
 <!ELEMENT pt	EMPTY>
 <!ATTLIST pt	size	CDATA	#IMPLIED>
+<!ATTLIST pt	ptwrite	(yes | no)	#IMPLIED>
 @end smallexample
 
 @include agentexpr.texi
diff --git a/gdb/features/btrace-conf.dtd b/gdb/features/btrace-conf.dtd
index 3fbe3a4dc32..7aeaa4695e1 100644
--- a/gdb/features/btrace-conf.dtd
+++ b/gdb/features/btrace-conf.dtd
@@ -12,3 +12,4 @@ 
 
 <!ELEMENT pt	EMPTY>
 <!ATTLIST pt	size	CDATA	#IMPLIED>
+<!ATTLIST pt	ptwrite	(yes | no) #IMPLIED>
diff --git a/gdb/remote.c b/gdb/remote.c
index 526df313ea7..d0b96f2f2f6 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -286,6 +286,9 @@  enum {
   /* Support for the Qbtrace-conf:pt:size packet.  */
   PACKET_Qbtrace_conf_pt_size,
 
+  /* Support for the Qbtrace-conf:pt:ptwrite packet.  */
+  PACKET_Qbtrace_conf_pt_ptwrite,
+
   /* Support for exec events.  */
   PACKET_exec_event_feature,
 
@@ -5599,6 +5602,8 @@  static const struct protocol_feature remote_protocol_features[] = {
     PACKET_exec_event_feature },
   { "Qbtrace-conf:pt:size", PACKET_DISABLE, remote_supported_packet,
     PACKET_Qbtrace_conf_pt_size },
+  { "Qbtrace-conf:pt:ptwrite", PACKET_DISABLE, remote_supported_packet,
+    PACKET_Qbtrace_conf_pt_ptwrite },
   { "vContSupported", PACKET_DISABLE, remote_supported_packet, PACKET_vContSupported },
   { "QThreadEvents", PACKET_DISABLE, remote_supported_packet, PACKET_QThreadEvents },
   { "no-resumed", PACKET_DISABLE, remote_supported_packet, PACKET_no_resumed },
@@ -14213,6 +14218,31 @@  remote_target::btrace_sync_conf (const btrace_config *conf)
 
       rs->btrace_config.pt.size = conf->pt.size;
     }
+
+  if ((m_features.packet_support (PACKET_Qbtrace_conf_pt_ptwrite)
+       == PACKET_ENABLE)
+	&& conf->pt.ptwrite != rs->btrace_config.pt.ptwrite)
+    {
+      pos = buf;
+      const char *ptw = conf->pt.ptwrite ? "yes" : "no";
+      const char *name
+	= packets_descriptions[PACKET_Qbtrace_conf_pt_ptwrite].name;
+      pos += xsnprintf (pos, endbuf - pos, "%s=\"%s\"", name, ptw);
+
+      putpkt (buf);
+      getpkt (&rs->buf, 0);
+
+      if (m_features.packet_ok (buf, PACKET_Qbtrace_conf_pt_ptwrite)
+	  == PACKET_ERROR)
+	{
+	  if (buf[0] == 'E' && buf[1] == '.')
+	    error (_("Failed to sync ptwrite config: %s"), buf + 2);
+	  else
+	    error (_("Failed to sync ptwrite config."));
+	}
+
+      rs->btrace_config.pt.ptwrite = conf->pt.ptwrite;
+    }
 }
 
 /* Read TP's btrace configuration from the target and store it into CONF.  */
@@ -15392,6 +15422,9 @@  Show the maximum size of the address (in bits) in a memory packet."), NULL,
   add_packet_config_cmd (PACKET_Qbtrace_conf_pt_size, "Qbtrace-conf:pt:size",
 			 "btrace-conf-pt-size", 0);
 
+  add_packet_config_cmd (PACKET_Qbtrace_conf_pt_ptwrite, "Qbtrace-conf:pt:ptwrite",
+			 "btrace-conf-pt-ptwrite", 0);
+
   add_packet_config_cmd (PACKET_vContSupported, "vContSupported",
 			 "verbose-resume-supported", 0);
 
diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index e6a39202a98..12ba2314308 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -6876,6 +6876,9 @@  linux_process_target::read_btrace_conf (const btrace_target_info *tinfo,
 	  string_xml_appendf (*buffer, "<pt");
 	  string_xml_appendf (*buffer, " size=\"0x%x\"", conf->pt.size);
 	  string_xml_appendf (*buffer, "/>\n");
+	  string_xml_appendf (*buffer, " ptwrite=\"%s\"",
+			     conf->pt.ptwrite ? "yes" : "no");
+	  string_xml_appendf (*buffer, "/>\n");
 	  break;
 	}
     }
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 949849b63a2..4e62c1a4ced 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -547,6 +547,23 @@  handle_btrace_conf_general_set (char *own_buf)
 
       current_btrace_conf.pt.size = (unsigned int) size;
     }
+  else if (strncmp (op, "pt:ptwrite=", strlen ("pt:ptwrite=")) == 0)
+    {
+      bool ptwrite;
+
+      op += strlen ("pt:ptwrite=");
+      if (strncmp (op, "\"yes\"", strlen ("\"yes\"")) == 0)
+	ptwrite = true;
+      else if (strncmp (op, "\"no\"", strlen ("\"no\"")) == 0)
+	ptwrite = false;
+      else
+	{
+	  strcpy (own_buf, "E.Bad ptwrite value.");
+	  return -1;
+	}
+
+      current_btrace_conf.pt.ptwrite = ptwrite;
+    }
   else
     {
       strcpy (own_buf, "E.Bad Qbtrace configuration option.");
@@ -2146,6 +2163,7 @@  supported_btrace_packets (char *buf)
   strcat (buf, ";Qbtrace-conf:bts:size+");
   strcat (buf, ";Qbtrace:pt+");
   strcat (buf, ";Qbtrace-conf:pt:size+");
+  strcat (buf, ";Qbtrace-conf:pt:ptwrite+");
   strcat (buf, ";Qbtrace:off+");
   strcat (buf, ";qXfer:btrace:read+");
   strcat (buf, ";qXfer:btrace-conf:read+");
diff --git a/gdbsupport/btrace-common.h b/gdbsupport/btrace-common.h
index e287c93a6c1..03cc60648e9 100644
--- a/gdbsupport/btrace-common.h
+++ b/gdbsupport/btrace-common.h
@@ -117,6 +117,12 @@  struct btrace_config_pt
      This is unsigned int and not size_t since it is registered as
      control variable for "set record btrace pt buffer-size".  */
   unsigned int size;
+
+  /* Configuration bit for ptwrite packets.
+
+     If both gdb and gdbserver support this, gdb will try to enable ptwrite
+     packets when tracing is started.  */
+  bool ptwrite;
 };
 
 /* A branch tracing configuration.