Add support for serialized property contexts
This adds support for reading a serialized
/dev/__properties__/property_info file, which contains a
serialized trie that maps property names to the SELinux context to
which they belong.
Performance wise on walleye, this change reduces the start up cost in
libc from ~3000us to ~430us. On a benchmark that calls
__system_property_find() for each property set on the system, it
reduces the time per iteration from ~650us to ~292us.
Bug: 36001741
Test: Boot bullhead, walleye, run unit tests
Test: Benchmark initialization and lookup performance
Change-Id: I0887a3a7da88eb51b6d1bd494fa5bce593423599
diff --git a/libc/system_properties/system_properties.cpp b/libc/system_properties/system_properties.cpp
index 89a6fe7..f67fc4d 100644
--- a/libc/system_properties/system_properties.cpp
+++ b/libc/system_properties/system_properties.cpp
@@ -59,6 +59,7 @@
#include "context_node.h"
#include "contexts.h"
#include "contexts_pre_split.h"
+#include "contexts_serialized.h"
#include "contexts_split.h"
#include "prop_area.h"
#include "prop_info.h"
@@ -71,6 +72,7 @@
static union ContextsUnion {
ContextsUnion() {}
~ContextsUnion() {}
+ ContextsSerialized contexts_serialized;
ContextsSplit contexts_split;
ContextsPreSplit contexts_pre_split;
} contexts_union;
@@ -283,11 +285,19 @@
}
contexts = nullptr;
if (is_dir(property_filename)) {
- new (&contexts_union.contexts_split) ContextsSplit();
- if (!contexts_union.contexts_split.Initialize(false)) {
- return -1;
+ if (access("/dev/__properties__/property_info", R_OK) == 0) {
+ new (&contexts_union.contexts_serialized) ContextsSerialized();
+ if (!contexts_union.contexts_serialized.Initialize(false)) {
+ return -1;
+ }
+ contexts = &contexts_union.contexts_serialized;
+ } else {
+ new (&contexts_union.contexts_split) ContextsSplit();
+ if (!contexts_union.contexts_split.Initialize(false)) {
+ return -1;
+ }
+ contexts = &contexts_union.contexts_split;
}
- contexts = &contexts_union.contexts_split;
} else {
new (&contexts_union.contexts_pre_split) ContextsPreSplit();
if (!contexts_union.contexts_pre_split.Initialize(false)) {
@@ -314,9 +324,9 @@
}
// We set this unconditionally as we want tests to continue on regardless of if this failed
// and property_service will abort on an error condition, so no harm done.
- new (&contexts_union.contexts_split) ContextsSplit;
- contexts = &contexts_union.contexts_split;
- if (!contexts_union.contexts_split.Initialize(true)) {
+ new (&contexts_union.contexts_serialized) ContextsSerialized;
+ contexts = &contexts_union.contexts_serialized;
+ if (!contexts_union.contexts_serialized.Initialize(true)) {
return -1;
}
return 0;