1// DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -o %t && %run %t
2// DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -o %t && %run %t
3// DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
4// DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
5
6#include <assert.h>
7#include <sanitizer/dfsan_interface.h>
8#include <stdbool.h>
9#include <stdio.h>
10#include <string.h>
11#include <sys/mman.h>
12#include <unistd.h>
13
14size_t get_rss_kb() {
15 size_t ret = 0;
16 pid_t pid = getpid();
17
18 char fname[256];
19 sprintf(s: fname, format: "/proc/%ld/task/%ld/smaps", (long)pid, (long)pid);
20 FILE *f = fopen(filename: fname, modes: "r");
21 assert(f);
22
23 char buf[256];
24 while (fgets(s: buf, n: sizeof(buf), stream: f) != NULL) {
25 int64_t rss;
26 // DFSan's sscanf is broken and doesn't check for ordinary characters in
27 // the format string, hence we use strstr as a secondary check
28 // (https://github.com/llvm/llvm-project/issues/94769).
29 if ((sscanf(s: buf, format: "Rss: %ld kB", &rss) == 1) &&
30 (strstr(haystack: buf, needle: "Rss: ") != NULL))
31 ret += rss;
32 }
33 assert(feof(f));
34 fclose(stream: f);
35
36 return ret;
37}
38
39int main(int argc, char **argv) {
40 const size_t map_size = 100 << 20;
41 size_t before = get_rss_kb();
42
43 // mmap and touch all addresses. The overhead is 1x.
44 char *p = mmap(NULL, len: map_size, PROT_READ | PROT_WRITE,
45 MAP_PRIVATE | MAP_ANONYMOUS, fd: -1, offset: 0);
46 memset(s: p, c: 0xff, n: map_size);
47 size_t after_mmap = get_rss_kb();
48
49 // store labels to all addresses. The overhead is 2x.
50 const dfsan_label label = 8;
51 char val = 0xff;
52 dfsan_set_label(label, addr: &val, size: sizeof(val));
53 memset(s: p, c: val, n: map_size);
54 size_t after_mmap_and_set_label = get_rss_kb();
55
56 // fixed-mmap the same address. OS recyles pages and reinitializes data at the
57 // address. This should be the same to calling munmap.
58 p = mmap(addr: p, len: map_size, PROT_READ | PROT_WRITE,
59 MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, fd: -1, offset: 0);
60 size_t after_fixed_mmap = get_rss_kb();
61
62 // store labels to all addresses.
63 memset(s: p, c: val, n: map_size);
64 size_t after_mmap_and_set_label2 = get_rss_kb();
65
66 // munmap the addresses.
67 munmap(addr: p, len: map_size);
68 size_t after_munmap = get_rss_kb();
69
70 fprintf(
71 stderr,
72 format: "RSS at start: %zu, after mmap: %zu, after mmap+set label: %zu, after "
73 "fixed map: %zu, after another mmap+set label: %zu, after munmap: %zu\n",
74 before, after_mmap, after_mmap_and_set_label, after_fixed_mmap,
75 after_mmap_and_set_label2, after_munmap);
76
77 // This is orders of magnitude larger than we expect (typically < 10,000KB).
78 // It is a quick check to ensure that the RSS calculation function isn't
79 // egregriously wrong.
80 assert(before < 1000000);
81
82 const size_t mmap_cost_kb = map_size >> 10;
83 // Shadow space (1:1 with application memory)
84 const size_t mmap_shadow_cost_kb = sizeof(dfsan_label) * mmap_cost_kb;
85#ifdef ORIGIN_TRACKING
86 // Origin space (1:1 with application memory)
87 const size_t mmap_origin_cost_kb = mmap_cost_kb;
88#else
89 const size_t mmap_origin_cost_kb = 0;
90#endif
91 assert(after_mmap >= before + mmap_cost_kb);
92 assert(after_mmap_and_set_label >=
93 after_mmap + mmap_shadow_cost_kb + mmap_origin_cost_kb);
94 assert(after_mmap_and_set_label2 >=
95 before + mmap_cost_kb + mmap_shadow_cost_kb + mmap_origin_cost_kb);
96
97#ifdef ORIGIN_TRACKING
98 // This value is chosen based on observed difference.
99 const size_t mmap_origin_chain_kb = 4000;
100#else
101 const size_t mmap_origin_chain_kb = 0;
102#endif
103
104 // RSS may not change memory amount after munmap to the same level as the
105 // start of the program. The assert checks the memory up to a delta.
106 const size_t delta = 5000;
107 // Origin chains are not freed, even when the origin space which refers to
108 // them is freed, so mmap_origin_chain_kb is added to account for this.
109 assert(after_fixed_mmap <= before + delta + mmap_origin_chain_kb);
110 assert(after_munmap <= before + delta + mmap_origin_chain_kb);
111
112 return 0;
113}
114

source code of compiler-rt/test/dfsan/release_shadow_space.c