Re: Seems like a bug in target_read_stack / dcache_xfer_memory?

Doug Evans
2009-10-23T17:18:41Z

On Thu, Oct 22, 2009 at 12:54 PM, Michael Snyder <msnyder@vmware.com> wrote:
> Michael Snyder wrote:
>>
>> Doug Evans wrote:
>>>
>>> On Mon, Oct 19, 2009 at 2:35 PM, Michael Snyder <msnyder@vmware.com>
>>> wrote:
>>>>
>>>> Anyway, yes, that's what it does.  dcache returns zero,
>>>> and memory_xfer_partial bails out instead of trying the
>>>> next target down the target stack.
>>>
>>> Hi.  If it will help I'll play with your testcase tomorrow.
>>> I'll also volunteer to make a pass through the code and add some
>>> comments.
>>> [I mention that just in case you or someone is already in the process
>>> of doing that.]
>>
>> Sure it will help.  Thanks, Doug.
>
> And the test case is in the repo now -- solib-precsave.exp.
> How to run tests:
> http://www.sourceware.org/gdb/wiki/ProcessRecord#head-2f56f7474cf60c6a5879ba6d8a4e4d034e6d0c8e

Thanks for the testcase.
You may be right about needing to test for "res == 0" but I'm less
sure now, so I'm going to leave it as is, at least for now.
dcache calls target_read (TARGET_OBJECT_RAW_MEMORY) which should DTRT.
And in fact it does with this patch. :-)
Checked in.

2009-10-23 Doug Evans <dje@google.com>

* record.c (record_core_xfer_partial): Pass correct offset to
record_beneath_to_xfer_partial.

Index: record.c
===================================================================
RCS file: /cvs/src/src/gdb/record.c,v
retrieving revision 1.33
diff -u -p -r1.33 record.c
--- record.c 23 Oct 2009 16:11:37 -0000 1.33
+++ record.c 23 Oct 2009 17:07:08 -0000
@@ -1629,6 +1629,7 @@ record_core_xfer_partial (struct target_
if (offset >= p->addr)
{
struct record_core_buf_entry *entry;
+ ULONGEST sec_offset;

if (offset >= p->endaddr)
continue;
@@ -1636,7 +1637,7 @@ record_core_xfer_partial (struct target_
if (offset + len > p->endaddr)
len = p->endaddr - offset;

- offset -= p->addr;
+ sec_offset = offset - p->addr;

/* Read readbuf or write writebuf p, offset, len. */
/* Check flags. */
@@ -1673,7 +1674,8 @@ record_core_xfer_partial (struct target_
record_core_buf_list = entry;
}

- memcpy (entry->buf + offset, writebuf, (size_t) len);
+ memcpy (entry->buf + sec_offset, writebuf,
+ (size_t) len);
}
else
{
@@ -1683,7 +1685,8 @@ record_core_xfer_partial (struct target_
object, annex, readbuf, writebuf,
offset, len);

- memcpy (readbuf, entry->buf + offset, (size_t) len);
+ memcpy (readbuf, entry->buf + sec_offset,
+ (size_t) len);
}

return len;