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-rw-r--r--compiler-rt/test/hwasan/TestCases/Linux/release-shadow.c70
1 files changed, 70 insertions, 0 deletions
diff --git a/compiler-rt/test/hwasan/TestCases/Linux/release-shadow.c b/compiler-rt/test/hwasan/TestCases/Linux/release-shadow.c
new file mode 100644
index 00000000000..9aae3506336
--- /dev/null
+++ b/compiler-rt/test/hwasan/TestCases/Linux/release-shadow.c
@@ -0,0 +1,70 @@
+// Test that tagging a large region to 0 reduces RSS.
+// RUN: %clang_hwasan -mllvm -hwasan-instrument-stack=0 %s -o %t && %run %t 2>&1
+
+#include <assert.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <sanitizer/hwasan_interface.h>
+
+const unsigned char kTag = 42;
+const size_t kNumShadowPages = 256;
+const size_t kNumPages = 16 * kNumShadowPages;
+const size_t kPageSize = 4096;
+const size_t kMapSize = kNumPages * kPageSize;
+
+void sync_rss() {
+ char *page = (char *)mmap(0, kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+ // Linux kernel updates RSS counters after a set number of page faults.
+ for (int i = 0; i < 1000; ++i) {
+ page[0] = 42;
+ madvise(page, kPageSize, MADV_DONTNEED);
+ }
+ munmap(page, kPageSize);
+}
+
+size_t current_rss() {
+ sync_rss();
+ int statm_fd = open("/proc/self/statm", O_RDONLY);
+ assert(statm_fd >= 0);
+
+ char buf[100];
+ assert(read(statm_fd, &buf, sizeof(buf)) > 0);
+ size_t size, rss;
+ assert(sscanf(buf, "%zu %zu", &size, &rss) == 2);
+
+ close(statm_fd);
+ return rss;
+}
+
+void test_rss_difference(void *p) {
+ __hwasan_tag_memory(p, kTag, kMapSize);
+ size_t rss_before = current_rss();
+ __hwasan_tag_memory(p, 0, kMapSize);
+ size_t rss_after = current_rss();
+ fprintf(stderr, "%zu -> %zu\n", rss_before, rss_after);
+ assert(rss_before > rss_after);
+ size_t diff = rss_before - rss_after;
+ fprintf(stderr, "diff %zu\n", diff);
+ // Check that the difference is at least close to kNumShadowPages.
+ assert(diff > kNumShadowPages / 4 * 3);
+}
+
+int main() {
+ fprintf(stderr, "starting rss %zu\n", current_rss());
+ fprintf(stderr, "shadow pages: %zu\n", kNumShadowPages);
+
+ void *p = mmap(0, kMapSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+ fprintf(stderr, "p = %p\n", p);
+
+ test_rss_difference(p);
+ test_rss_difference(p);
+ test_rss_difference(p);
+
+ return 0;
+}
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