libipt, block: do not mix cache fill and cache use
When filling the cache, we recursively call pt_blk_proceed_cached() to make use
of the cache after proceeding a single instruction.
Stop doing that. Instead, check if there is a cache entry for the next IP and,
if not, recursively call pt_blk_proceed_fill_cache().
There shouldn't be any functional change but this new version will allow us to
bound the recursion more easily.
Change-Id: I6f479179c452d26e573d6922c8168e473b213759
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
diff --git a/libipt/src/pt_block_decoder.c b/libipt/src/pt_block_decoder.c
index 6a29fa0..9188752 100644
--- a/libipt/src/pt_block_decoder.c
+++ b/libipt/src/pt_block_decoder.c
@@ -40,10 +40,6 @@
static int pt_blk_proceed_no_event(struct pt_block_decoder *,
struct pt_block *);
-static int pt_blk_proceed_no_event_cached(struct pt_block_decoder *,
- struct pt_block *,
- struct pt_block_cache *,
- struct pt_section *, uint64_t);
/* Release a cached section.
@@ -1838,30 +1834,37 @@
return pt_bcache_add(bcache, insn.ip - laddr, bce);
}
- /* We proceeded one instruction. Let's proceed normally with caching.
- * This may fill the block cache for @nip.
- */
- status = pt_blk_proceed_no_event_cached(decoder, block, bcache,
- section, laddr);
- if (status < 0)
- return status;
-
- /* On our way back, we add a cache entry for this instruction based on
- * the cache entry of the succeeding instruction.
+ /* We proceeded one instruction. Let's see if we have a cache entry for
+ * the next instruction.
*/
status = pt_bcache_lookup(&bce, bcache, nip - laddr);
if (status < 0)
return status;
- /* If the cache entry for @nip isn't valid, @block overflowed before we
- * could reach a decision point in this iteration.
+ /* If we don't have a valid cache entry, yet, fill the cache some more.
*
- * We will proceed from @decoder->ip in the next iteration. Eventually,
- * we will find a decision point and, on our way back, populate the
- * block cache entries preceding it.
+ * On our way back, we add a cache entry for this instruction based on
+ * the cache entry of the succeeding instruction.
*/
- if (!pt_bce_is_valid(bce))
- return 0;
+ if (!pt_bce_is_valid(bce)) {
+ status = pt_blk_proceed_no_event_fill_cache(decoder, block,
+ bcache, section,
+ laddr);
+ if (status < 0)
+ return status;
+
+ /* Let's see if we have more luck this time. */
+ status = pt_bcache_lookup(&bce, bcache, nip - laddr);
+ if (status < 0)
+ return status;
+
+ /* If we still don't have a valid cache entry, we're done. Most
+ * likely, @block overflowed and we couldn't proceed past the
+ * next instruction.
+ */
+ if (!pt_bce_is_valid(bce))
+ return 0;
+ }
/* We must not have switched execution modes.
*
