btrace: Extend ptwrite event decoding.

Call the ptwrite filter function whenever a ptwrite event is decoded.
The returned string is written to the aux_data string table and a
corresponding auxiliary instruction is appended to the function segment.

Approved-By: Markus Metzger <markus.t.metzger@intel.com>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/gdb/btrace.c b/gdb/btrace.c
index d493fbe..95ff27c 100644
--- a/gdb/btrace.c
+++ b/gdb/btrace.c
@@ -41,6 +41,7 @@
 #include <inttypes.h>
 #include <ctype.h>
 #include <algorithm>
+#include <string>
 
 /* Command lists for btrace maintenance commands.  */
 static struct cmd_list_element *maint_btrace_cmdlist;
@@ -1204,6 +1205,24 @@ pt_btrace_insn (const struct pt_insn &insn)
 	  pt_btrace_insn_flags (insn)};
 }
 
+#if defined (HAVE_PT_INSN_EVENT)
+/* Helper for events that will result in an aux_insn.  */
+
+static void
+handle_pt_aux_insn (btrace_thread_info *btinfo, btrace_function *bfun,
+		    std::string &aux_str, CORE_ADDR ip)
+{
+  btinfo->aux_data.emplace_back (std::move (aux_str));
+  bfun = ftrace_update_function (btinfo, ip);
+
+  btrace_insn insn {btinfo->aux_data.size () - 1, 0,
+		    BTRACE_INSN_AUX, 0};
+
+  ftrace_update_insns (bfun, insn);
+}
+
+#endif /* defined (HAVE_PT_INSN_EVENT) */
+
 /* Handle instruction decode events (libipt-v2).  */
 
 static int
@@ -1252,6 +1271,60 @@ handle_pt_insn_events (struct btrace_thread_info *btinfo,
 		   bfun->insn_offset - 1, offset);
 
 	  break;
+#if defined (HAVE_STRUCT_PT_EVENT_VARIANT_PTWRITE)
+	case ptev_ptwrite:
+	  {
+	    uint64_t pc = 0;
+	    std::optional<std::string> ptw_string;
+
+	    /* Lookup the PC if available.  The event often doesn't provide
+	       one, so we look into the last function segment as well.
+	       Looking further back makes limited sense for ptwrite.  */
+	    if (event.ip_suppressed == 0)
+	      pc = event.variant.ptwrite.ip;
+	    else if (!btinfo->functions.empty ())
+	      {
+		std::vector<btrace_insn> &insns
+		  = btinfo->functions.back ().insn;
+		for (auto insn = insns.rbegin (); insn != insns.rend ();
+		     ++insn)
+		  {
+		    switch (insn->iclass)
+		    {
+		    case BTRACE_INSN_AUX:
+		      continue;
+
+		    case BTRACE_INSN_OTHER:
+		    case BTRACE_INSN_CALL:
+		    case BTRACE_INSN_RETURN:
+		    case BTRACE_INSN_JUMP:
+		      pc = insn->pc;
+		      break;
+		    /* No default to rely on compiler warnings.  */
+		    }
+		    break;
+		  }
+	      }
+
+	    if (pc == 0)
+	      warning (_("Failed to determine the PC for ptwrite."));
+
+	    if (btinfo->ptw_callback_fun != nullptr)
+	      ptw_string
+		= btinfo->ptw_callback_fun (event.variant.ptwrite.payload,
+					    pc, btinfo->ptw_context);
+
+	    if (ptw_string.has_value () && (*ptw_string).empty ())
+	      continue;
+
+	    if (!ptw_string.has_value ())
+	      *ptw_string = hex_string (event.variant.ptwrite.payload);
+
+	    handle_pt_aux_insn (btinfo, bfun, *ptw_string, pc);
+
+	    break;
+	  }
+#endif /* defined (HAVE_STRUCT_PT_EVENT_VARIANT_PTWRITE) */
 	}
     }
 #endif /* defined (HAVE_PT_INSN_EVENT) */