1 files changed, 129 insertions, 0 deletions

diff --git a/gdb/target.c b/gdb/target.c
index edf03f1..214edb7 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -1271,6 +1271,82 @@ target_section_by_addr (struct target_ops *target, CORE_ADDR addr)
   return NULL;
 }
 
+/* Read memory from the live target, even if currently inspecting a
+   traceframe.  The return is the same as that of target_read.  */
+
+static LONGEST
+target_read_live_memory (enum target_object object,
+			 ULONGEST memaddr, gdb_byte *myaddr, LONGEST len)
+{
+  int ret;
+  struct cleanup *cleanup;
+
+  /* Switch momentarily out of tfind mode so to access live memory.
+     Note that this must not clear global state, such as the frame
+     cache, which must still remain valid for the previous traceframe.
+     We may be _building_ the frame cache at this point.  */
+  cleanup = make_cleanup_restore_traceframe_number ();
+  set_traceframe_number (-1);
+
+  ret = target_read (current_target.beneath, object, NULL,
+		     myaddr, memaddr, len);
+
+  do_cleanups (cleanup);
+  return ret;
+}
+
+/* Using the set of read-only target sections of OPS, read live
+   read-only memory.  Note that the actual reads start from the
+   top-most target again.  */
+
+static LONGEST
+memory_xfer_live_readonly_partial (struct target_ops *ops,
+				   enum target_object object,
+				   gdb_byte *readbuf, ULONGEST memaddr,
+				   LONGEST len)
+{
+  struct target_section *secp;
+  struct target_section_table *table;
+
+  secp = target_section_by_addr (ops, memaddr);
+  if (secp != NULL
+      && (bfd_get_section_flags (secp->bfd, secp->the_bfd_section)
+	  & SEC_READONLY))
+    {
+      struct target_section *p;
+      ULONGEST memend = memaddr + len;
+
+      table = target_get_section_table (ops);
+
+      for (p = table->sections; p < table->sections_end; p++)
+	{
+	  if (memaddr >= p->addr)
+	    {
+	      if (memend <= p->endaddr)
+		{
+		  /* Entire transfer is within this section.  */
+		  return target_read_live_memory (object, memaddr,
+						  readbuf, len);
+		}
+	      else if (memaddr >= p->endaddr)
+		{
+		  /* This section ends before the transfer starts.  */
+		  continue;
+		}
+	      else
+		{
+		  /* This section overlaps the transfer.  Just do half.  */
+		  len = p->endaddr - memaddr;
+		  return target_read_live_memory (object, memaddr,
+						  readbuf, len);
+		}
+	    }
+	}
+    }
+
+  return 0;
+}
+
 /* Perform a partial memory transfer.
    For docs see target.h, to_xfer_partial.  */
 
@@ -1329,6 +1405,59 @@ memory_xfer_partial (struct target_ops *ops, enum target_object object,
 	}
     }
 
+  /* If reading unavailable memory in the context of traceframes, and
+     this address falls within a read-only section, fallback to
+     reading from live memory.  */
+  if (readbuf != NULL && get_traceframe_number () != -1)
+    {
+      VEC(mem_range_s) *available;
+
+      /* If we fail to get the set of available memory, then the
+	 target does not support querying traceframe info, and so we
+	 attempt reading from the traceframe anyway (assuming the
+	 target implements the old QTro packet then).  */
+      if (traceframe_available_memory (&available, memaddr, len))
+	{
+	  struct cleanup *old_chain;
+
+	  old_chain = make_cleanup (VEC_cleanup(mem_range_s), &available);
+
+	  if (VEC_empty (mem_range_s, available)
+	      || VEC_index (mem_range_s, available, 0)->start != memaddr)
+	    {
+	      /* Don't read into the traceframe's available
+		 memory.  */
+	      if (!VEC_empty (mem_range_s, available))
+		{
+		  LONGEST oldlen = len;
+
+		  len = VEC_index (mem_range_s, available, 0)->start - memaddr;
+		  gdb_assert (len <= oldlen);
+		}
+
+	      do_cleanups (old_chain);
+
+	      /* This goes through the topmost target again.  */
+	      res = memory_xfer_live_readonly_partial (ops, object,
+						       readbuf, memaddr, len);
+	      if (res > 0)
+		return res;
+
+	      /* No use trying further, we know some memory starting
+		 at MEMADDR isn't available.  */
+	      return -1;
+	    }
+
+	  /* Don't try to read more than how much is available, in
+	     case the target implements the deprecated QTro packet to
+	     cater for older GDBs (the target's knowledge of read-only
+	     sections may be outdated by now).  */
+	  len = VEC_index (mem_range_s, available, 0)->length;
+
+	  do_cleanups (old_chain);
+	}
+    }
+
   /* Try GDB's internal data cache.  */
   region = lookup_mem_region (memaddr);
   /* region->hi == 0 means there's no upper bound.  */