compiler-rt/test/dfsan/release_shadow_space.c

   1 // https://github.com/llvm/llvm-project/issues/60678
   2 // XFAIL: glibc-2.37
   3
   4 // DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -o %t && %run %t
   5 // DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -o %t && %run %t
   6 // DFSAN_OPTIONS=no_huge_pages_for_shadow=false RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
   7 // DFSAN_OPTIONS=no_huge_pages_for_shadow=true RUN: %clang_dfsan %s -DORIGIN_TRACKING -mllvm -dfsan-track-origins=1 -o %t && %run %t
   8
   9 #include <assert.h>
  10 #include <sanitizer/dfsan_interface.h>
  11 #include <stdbool.h>
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <sys/mman.h>
  15 #include <unistd.h>
  16
  17 size_t get_rss_kb() {
  18   size_t ret = 0;
  19   pid_t pid = getpid();
  20
  21   char fname[256];
  22   sprintf(fname, "/proc/%ld/task/%ld/smaps", (long)pid, (long)pid);
  23   FILE *f = fopen(fname, "r");
  24   assert(f);
  25
  26   char buf[256];
  27   while (fgets(buf, sizeof(buf), f) != NULL) {
  28     int64_t rss;
  29     if (sscanf(buf, "Rss: %ld kB", &rss) == 1)
  30       ret += rss;
  31   }
  32   assert(feof(f));
  33   fclose(f);
  34
  35   return ret;
  36 }
  37
  38 int main(int argc, char **argv) {
  39   const size_t map_size = 100 << 20;
  40   size_t before = get_rss_kb();
  41
  42   // mmap and touch all addresses. The overhead is 1x.
  43   char *p = mmap(NULL, map_size, PROT_READ | PROT_WRITE,
  44                  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  45   memset(p, 0xff, map_size);
  46   size_t after_mmap = get_rss_kb();
  47
  48   // store labels to all addresses. The overhead is 2x.
  49   const dfsan_label label = 8;
  50   char val = 0xff;
  51   dfsan_set_label(label, &val, sizeof(val));
  52   memset(p, val, map_size);
  53   size_t after_mmap_and_set_label = get_rss_kb();
  54
  55   // fixed-mmap the same address. OS recyles pages and reinitializes data at the
  56   // address. This should be the same to calling munmap.
  57   p = mmap(p, map_size, PROT_READ | PROT_WRITE,
  58            MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
  59   size_t after_fixed_mmap = get_rss_kb();
  60
  61   // store labels to all addresses.
  62   memset(p, val, map_size);
  63   size_t after_mmap_and_set_label2 = get_rss_kb();
  64
  65   // munmap the addresses.
  66   munmap(p, map_size);
  67   size_t after_munmap = get_rss_kb();
  68
  69   fprintf(
  70       stderr,
  71       "RSS at start: %zu, after mmap: %zu, after mmap+set label: %zu, after "
  72       "fixed map: %zu, after another mmap+set label: %zu, after munmap: %zu\n",
  73       before, after_mmap, after_mmap_and_set_label, after_fixed_mmap,
  74       after_mmap_and_set_label2, after_munmap);
  75
  76   const size_t mmap_cost_kb = map_size >> 10;
  77   // Shadow space (1:1 with application memory)
  78   const size_t mmap_shadow_cost_kb = sizeof(dfsan_label) * mmap_cost_kb;
  79 #ifdef ORIGIN_TRACKING
  80   // Origin space (1:1 with application memory)
  81   const size_t mmap_origin_cost_kb = mmap_cost_kb;
  82 #else
  83   const size_t mmap_origin_cost_kb = 0;
  84 #endif
  85   assert(after_mmap >= before + mmap_cost_kb);
  86   assert(after_mmap_and_set_label >=
  87          after_mmap + mmap_shadow_cost_kb + mmap_origin_cost_kb);
  88   assert(after_mmap_and_set_label2 >=
  89          before + mmap_cost_kb + mmap_shadow_cost_kb + mmap_origin_cost_kb);
  90
  91 #ifdef ORIGIN_TRACKING
  92   // This value is chosen based on observed difference.
  93   const size_t mmap_origin_chain_kb = 4000;
  94 #else
  95   const size_t mmap_origin_chain_kb = 0;
  96 #endif
  97
  98   // RSS may not change memory amount after munmap to the same level as the
  99   // start of the program. The assert checks the memory up to a delta.
 100   const size_t delta = 5000;
 101   // Origin chains are not freed, even when the origin space which refers to
 102   // them is freed, so mmap_origin_chain_kb is added to account for this.
 103   assert(after_fixed_mmap <= before + delta + mmap_origin_chain_kb);
 104   assert(after_munmap <= before + delta + mmap_origin_chain_kb);
 105
 106   return 0;
 107 }