[patch v8 17/24] record-btrace: provide xfer_partial target method

Markus Metzger
2013-12-12T09:16:04Z

Provide the xfer_partial target method for the btrace record target.

Only allow memory accesses to readonly memory while we're replaying.

2013-12-12 Markus Metzger <markus.t.metzger@intel.com>

* record-btrace.c (record_btrace_xfer_partial): New.
(init_record_btrace_ops): Initialize xfer_partial.

---
gdb/record-btrace.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index cf30e17..ec99ba2 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -753,6 +753,56 @@ record_btrace_is_replaying (void)
return 0;
}

+/* The to_xfer_partial method of target record-btrace. */
+
+static LONGEST
+record_btrace_xfer_partial (struct target_ops *ops, enum target_object object,
+ const char *annex, gdb_byte *readbuf,
+ const gdb_byte *writebuf, ULONGEST offset,
+ LONGEST len)
+{
+ struct target_ops *t;
+
+ /* Filter out requests that don't make sense during replay. */
+ if (record_btrace_is_replaying ())
+ {
+ switch (object)
+ {
+ case TARGET_OBJECT_MEMORY:
+ case TARGET_OBJECT_RAW_MEMORY:
+ case TARGET_OBJECT_STACK_MEMORY:
+ {
+ /* We allow reading readonly memory. */
+ struct target_section *section;
+
+ section = target_section_by_addr (ops, offset);
+ if (section != NULL)
+ {
+ /* Check if the section we found is readonly. */
+ if ((bfd_get_section_flags (section->the_bfd_section->owner,
+ section->the_bfd_section)
+ & SEC_READONLY) != 0)
+ {
+ /* Truncate the request to fit into this section. */
+ len = min (len, section->endaddr - offset);
+ break;
+ }
+ }
+
+ return -1;
+ }
+ }
+ }
+
+ /* Forward the request. */
+ for (t = ops->beneath; t != NULL; t = t->beneath)
+ if (t->to_xfer_partial != NULL)
+ return t->to_xfer_partial (t, object, annex, readbuf, writebuf,
+ offset, len);
+
+ return -1;
+}
+
/* The to_fetch_registers method of target record-btrace. */

static void
@@ -930,6 +980,7 @@ init_record_btrace_ops (void)
ops->to_call_history_from = record_btrace_call_history_from;
ops->to_call_history_range = record_btrace_call_history_range;
ops->to_record_is_replaying = record_btrace_is_replaying;
+ ops->to_xfer_partial = record_btrace_xfer_partial;
ops->to_fetch_registers = record_btrace_fetch_registers;
ops->to_store_registers = record_btrace_store_registers;
ops->to_prepare_to_store = record_btrace_prepare_to_store;
--
1.8.3.1