[patch] only update dcache after write succeeds
Michael Snyder
msnyder@vmware.com
Mon Sep 14 19:26:00 GMT 2009
Doug Evans wrote:
> Hi.
>
> Marc, Greg: Can you see if this patch fixes things for you?
Hey Doug,
I tested this change, and it does indeed seem to fix the problem
with target record -- but. ;-)
Part of the reason that it works is that record_xfer_partial
calls error() instead of returning -1. If I change it so that
it returns -1, things get more complicated.
The do-while loop that used to follow and now preceeds this code
calls target-beneath, which in our case results in several different
target methods being called, one of which eventually returns > 0.
That just means that in the present case, calling error is correct.
But I worry about some of the other cases where the target method
returns -1, and whether badness might occur in some other cases.
Michael
> 2009-09-14 Doug Evans <dje@google.com>
>
> * target.c (memory_xfer_partial): Only update dcache after we know
> the write succeeded.
>
> Index: target.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/target.c,v
> retrieving revision 1.223
> diff -u -p -r1.223 target.c
> --- target.c 8 Sep 2009 23:52:45 -0000 1.223
> +++ target.c 14 Sep 2009 19:11:38 -0000
> @@ -1289,19 +1289,6 @@ memory_xfer_partial (struct target_ops *
> }
> }
>
> - /* Make sure the cache gets updated no matter what - if we are writing
> - to the stack, even if this write is not tagged as such, we still need
> - to update the cache. */
> -
> - if (inf != NULL
> - && readbuf == NULL
> - && !region->attrib.cache
> - && stack_cache_enabled_p
> - && object != TARGET_OBJECT_STACK_MEMORY)
> - {
> - dcache_update (target_dcache, memaddr, (void *) writebuf, reg_len);
> - }
> -
> /* If none of those methods found the memory we wanted, fall back
> to a target partial transfer. Normally a single call to
> to_xfer_partial is enough; if it doesn't recognize an object
> @@ -1331,6 +1318,20 @@ memory_xfer_partial (struct target_ops *
> if (readbuf && !show_memory_breakpoints)
> breakpoint_restore_shadows (readbuf, memaddr, reg_len);
>
> + /* Make sure the cache gets updated no matter what - if we are writing
> + to the stack. Even if this write is not tagged as such, we still need
> + to update the cache. */
> +
> + if (res > 0
> + && inf != NULL
> + && writebuf != NULL
> + && !region->attrib.cache
> + && stack_cache_enabled_p
> + && object != TARGET_OBJECT_STACK_MEMORY)
> + {
> + dcache_update (target_dcache, memaddr, (void *) writebuf, reg_len);
> + }
> +
> /* If we still haven't got anything, return the last error. We
> give up. */
> return res;
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