1 // Test that tagging a large region to 0 reduces RSS.
2 // RUN: %clang_hwasan -mllvm -hwasan-globals=0 -mllvm -hwasan-instrument-stack=0 %s -o %t && %run %t 2>&1
3
4 #include <assert.h>
5 #include <fcntl.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <sys/mman.h>
9 #include <sys/stat.h>
10 #include <sys/types.h>
11 #include <unistd.h>
12
13 #include <sanitizer/hwasan_interface.h>
14
15 const unsigned char kTag = 42;
16 const size_t kNumShadowPages = 256;
17 const size_t kNumPages = 16 * kNumShadowPages;
18 const size_t kPageSize = 4096;
19 const size_t kMapSize = kNumPages * kPageSize;
20
sync_rss()21 void sync_rss() {
22 char *page = (char *)mmap(0, kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
23 // Linux kernel updates RSS counters after a set number of page faults.
24 for (int i = 0; i < 1000; ++i) {
25 page[0] = 42;
26 madvise(page, kPageSize, MADV_DONTNEED);
27 }
28 munmap(page, kPageSize);
29 }
30
current_rss()31 size_t current_rss() {
32 sync_rss();
33 int statm_fd = open("/proc/self/statm", O_RDONLY);
34 assert(statm_fd >= 0);
35
36 char buf[100];
37 assert(read(statm_fd, &buf, sizeof(buf)) > 0);
38 size_t size, rss;
39 assert(sscanf(buf, "%zu %zu", &size, &rss) == 2);
40
41 close(statm_fd);
42 return rss;
43 }
44
test_rss_difference(void * p)45 void test_rss_difference(void *p) {
46 __hwasan_tag_memory(p, kTag, kMapSize);
47 size_t rss_before = current_rss();
48 __hwasan_tag_memory(p, 0, kMapSize);
49 size_t rss_after = current_rss();
50 fprintf(stderr, "%zu -> %zu\n", rss_before, rss_after);
51 assert(rss_before > rss_after);
52 size_t diff = rss_before - rss_after;
53 fprintf(stderr, "diff %zu\n", diff);
54 // Check that the difference is at least close to kNumShadowPages.
55 assert(diff > kNumShadowPages / 4 * 3);
56 }
57
main()58 int main() {
59 fprintf(stderr, "starting rss %zu\n", current_rss());
60 fprintf(stderr, "shadow pages: %zu\n", kNumShadowPages);
61
62 void *p = mmap(0, kMapSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
63 fprintf(stderr, "p = %p\n", p);
64
65 test_rss_difference(p);
66 test_rss_difference(p);
67 test_rss_difference(p);
68
69 return 0;
70 }
71