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[COMMIT PATCH] [gdbserver] Fix trace-buffer-size.exp FAILs.
- From: Pedro Alves <palves at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Mon, 02 Sep 2013 16:16:22 +0100
- Subject: [COMMIT PATCH] [gdbserver] Fix trace-buffer-size.exp FAILs.
- Authentication-results: sourceware.org; auth=none
I'm seeing trace-buffer-size.exp failing (with gdbserver):
(gdb) PASS: gdb.trace/trace-buffer-size.exp: tstatus check 2
show trace-buffer-size 4
Requested size of trace buffer is 4.
(gdb) PASS: gdb.trace/trace-buffer-size.exp: show trace buffer size
set trace-buffer-size -1
memory clobbered past end of allocated block
Remote connection closed
(gdb) FAIL: gdb.trace/trace-buffer-size.exp: set trace buffer size 2
set trace-buffer-size unlimited
(gdb) PASS: gdb.trace/trace-buffer-size.exp: set trace-buffer-size unlimited
That "memory clobbered past end of allocated block" is mcheck triggering.
Valgrind shows:
==23624== Invalid write of size 1
==23624== at 0x418DD8: clear_trace_buffer (tracepoint.c:1443)
==23624== by 0x418F3A: init_trace_buffer (tracepoint.c:1497)
==23624== by 0x41D95B: cmd_bigqtbuffer_size (tracepoint.c:4061)
==23624== by 0x41DEEC: handle_tracepoint_general_set (tracepoint.c:4193)
clear_trace_buffer does:
static void
clear_trace_buffer (void)
{
trace_buffer_start = trace_buffer_lo;
trace_buffer_free = trace_buffer_lo;
trace_buffer_end_free = trace_buffer_hi;
trace_buffer_wrap = trace_buffer_hi;
/* A traceframe with zeroed fields marks the end of trace data. */
((struct traceframe *) trace_buffer_free)->tpnum = 0;
((struct traceframe *) trace_buffer_free)->data_size = 0;
traceframe_read_count = traceframe_write_count = 0;
traceframes_created = 0;
}
And the tpnum+data_size fields are over 4 bytes... This fixes it by
ensuring we allocate space at least for an EOB. We have code
elsewhere that relies on the EOB being present (like e.g.,
find_traceframe), so this seems simplest.
gdb/gdbserver/
2013-09-02 Pedro Alves <palves@redhat.com>
* tracepoint.c (TRACEFRAME_EOB_MARKER_SIZE): New macro.
(init_trace_buffer): Ensure at least TRACEFRAME_EOB_MARKER_SIZE is
allocated.
(trace_buffer_alloc): Use TRACEFRAME_EOB_MARKER_SIZE.
---
gdb/gdbserver/tracepoint.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/gdb/gdbserver/tracepoint.c b/gdb/gdbserver/tracepoint.c
index 5c0dec7..1327845 100644
--- a/gdb/gdbserver/tracepoint.c
+++ b/gdb/gdbserver/tracepoint.c
@@ -982,6 +982,10 @@ struct traceframe
} ATTR_PACKED;
+/* The size of the EOB marker, in bytes. A traceframe with zeroed
+ fields (and no data) marks the end of trace data. */
+#define TRACEFRAME_EOB_MARKER_SIZE offsetof (struct traceframe, data)
+
/* The traceframe to be used as the source of data to send back to
GDB. A value of -1 means to get data from the live program. */
@@ -1487,12 +1491,17 @@ clear_inferior_trace_buffer (void)
static void
init_trace_buffer (LONGEST bufsize)
{
+ size_t alloc_size;
+
trace_buffer_size = bufsize;
- /* If we already have a trace buffer, try realloc'ing. */
- trace_buffer_lo = xrealloc (trace_buffer_lo, bufsize);
+ /* Make sure to internally allocate at least space for the EOB
+ marker. */
+ alloc_size = (bufsize < TRACEFRAME_EOB_MARKER_SIZE
+ ? TRACEFRAME_EOB_MARKER_SIZE : bufsize);
+ trace_buffer_lo = xrealloc (trace_buffer_lo, alloc_size);
- trace_buffer_hi = trace_buffer_lo + bufsize;
+ trace_buffer_hi = trace_buffer_lo + trace_buffer_size;
clear_trace_buffer ();
}
@@ -1532,7 +1541,7 @@ trace_buffer_alloc (size_t amt)
(long) amt, (long) sizeof (struct traceframe));
/* Account for the EOB marker. */
- amt += sizeof (struct traceframe);
+ amt += TRACEFRAME_EOB_MARKER_SIZE;
#ifdef IN_PROCESS_AGENT
again: