btrace: fix gap indication

Trace gaps due to overflows or non-contiguous trace are ignored in the 'info
record' command.  Fix that.

Also add a warning when decoding the trace and print the instruction number
preceding the trace gap in that warning message.  It looks like this:

    (gdb) info record
    Active record target: record-btrace
    Recording format: Intel Processor Trace.
    Buffer size: 16kB.
    warning: Decode error (-13) at instruction 101044 (offset = 0x29f0, pc = 0x7ffff728a642): no memory mapped at this address.
    Recorded 101044 instructions in 2093 functions (1 gaps) for thread 1 (process 5360).
    (gdb) record instruction-history 101044
    101044     0x00007ffff728a640:  pop    %r13
    [decode error (-13): no memory mapped at this address]

Remove the dead code that was supposed to print a gaps warning at the end of
trace decode.  This isn't really needed since we now print a warning for each
gap.

gdb/
	* btrace.c (ftrace_add_pt): Fix gap indication.  Add warning for non-
	contiguous trace and overflow.  Rephrase trace decode warning and print
	instruction number.  Remove dead gaps warning.
	(btrace_compute_ftrace_bts): Rephrase warnings and print instruction
	number.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 768d166..988a50a 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2016-10-28  Markus Metzger  <markus.t.metzger@intel.com>
+
+       * btrace.c (ftrace_add_pt): Fix gap indication.  Add warning for non-
+       contiguous trace and overflow.  Rephrase trace decode warning and print
+       instruction number.  Remove dead gaps warning.
+       (btrace_compute_ftrace_bts): Rephrase warnings and print instruction
+       number.
+
 2016-10-25  Sandra Loosemore  <sandra@codesourcery.com>
            Luis Machado  <lgustavo@codesourcery.com>
            Pedro Alves  <palves@redhat.com>

diff --git a/gdb/btrace.c b/gdb/btrace.c
index d1af128..3b4e60d 100644 (file)
--- a/gdb/btrace.c
+++ b/gdb/btrace.c
@@ -630,11 +630,12 @@ btrace_compute_ftrace_bts (struct thread_info *tp,
                 beginning.  */
              if (begin != NULL)
                {
-                 warning (_("Recorded trace may be corrupted around %s."),
-                          core_addr_to_string_nz (pc));
-
                  end = ftrace_new_gap (end, BDE_BTS_OVERFLOW);
                  ngaps += 1;
+
+                 warning (_("Recorded trace may be corrupted at instruction "
+                            "%u (pc = %s)."), end->insn_offset - 1,
+                          core_addr_to_string_nz (pc));
                }
              break;
            }
@@ -672,14 +673,15 @@ btrace_compute_ftrace_bts (struct thread_info *tp,
          /* We can't continue if we fail to compute the size.  */
          if (size <= 0)
            {
-             warning (_("Recorded trace may be incomplete around %s."),
-                      core_addr_to_string_nz (pc));
-
              /* Indicate the gap in the trace.  We just added INSN so we're
                 not at the beginning.  */
              end = ftrace_new_gap (end, BDE_BTS_INSN_SIZE);
              ngaps += 1;
 
+             warning (_("Recorded trace may be incomplete at instruction %u "
+                        "(pc = %s)."), end->insn_offset - 1,
+                      core_addr_to_string_nz (pc));
+
              break;
            }
 
@@ -750,11 +752,10 @@ ftrace_add_pt (struct pt_insn_decoder *decoder,
 {
   struct btrace_function *begin, *end, *upd;
   uint64_t offset;
-  int errcode, nerrors;
+  int errcode;
 
   begin = *pbegin;
   end = *pend;
-  nerrors = 0;
   for (;;)
     {
       struct btrace_insn btinsn;
@@ -785,11 +786,29 @@ ftrace_add_pt (struct pt_insn_decoder *decoder,
                 flag.  The ENABLED instruction flag means that we continued
                 from some other instruction.  Indicate this as a trace gap.  */
              if (insn.enabled)
-               *pend = end = ftrace_new_gap (end, BDE_PT_DISABLED);
+               {
+                 *pend = end = ftrace_new_gap (end, BDE_PT_DISABLED);
+                 *ngaps += 1;
+
+                 pt_insn_get_offset (decoder, &offset);
+
+                 warning (_("Non-contiguous trace at instruction %u (offset "
+                            "= 0x%" PRIx64 ", pc = 0x%" PRIx64 ")."),
+                          end->insn_offset - 1, offset, insn.ip);
+               }
 
              /* Indicate trace overflows.  */
              if (insn.resynced)
-               *pend = end = ftrace_new_gap (end, BDE_PT_OVERFLOW);
+               {
+                 *pend = end = ftrace_new_gap (end, BDE_PT_OVERFLOW);
+                 *ngaps += 1;
+
+                 pt_insn_get_offset (decoder, &offset);
+
+                 warning (_("Overflow at instruction %u (offset = 0x%" PRIx64
+                            ", pc = 0x%" PRIx64 ")."), end->insn_offset - 1,
+                          offset, insn.ip);
+               }
            }
 
          upd = ftrace_update_function (end, insn.ip);
@@ -820,19 +839,16 @@ ftrace_add_pt (struct pt_insn_decoder *decoder,
       if (begin == NULL)
        continue;
 
-      pt_insn_get_offset (decoder, &offset);
-
-      warning (_("Failed to decode Intel Processor Trace near trace "
-                "offset 0x%" PRIx64 " near recorded PC 0x%" PRIx64 ": %s."),
-              offset, insn.ip, pt_errstr (pt_errcode (errcode)));
-
       /* Indicate the gap in the trace.  */
       *pend = end = ftrace_new_gap (end, errcode);
       *ngaps += 1;
-    }
 
-  if (nerrors > 0)
-    warning (_("The recorded execution trace may have gaps."));
+      pt_insn_get_offset (decoder, &offset);
+
+      warning (_("Decode error (%d) at instruction %u (offset = 0x%" PRIx64
+                ", pc = 0x%" PRIx64 "): %s."), errcode, end->insn_offset - 1,
+              offset, insn.ip, pt_errstr (pt_errcode (errcode)));
+    }
 }
 
 /* A callback function to allow the trace decoder to read the inferior's