compiler-rt/test/hwasan/TestCases/Linux/release-shadow.c

   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 // REQUIRES: pointer-tagging
   5
   6 #include <assert.h>
   7 #include <fcntl.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <sys/mman.h>
  11 #include <sys/stat.h>
  12 #include <sys/types.h>
  13 #include <unistd.h>
  14
  15 #include <sanitizer/hwasan_interface.h>
  16
  17 const unsigned char kTag = 42;
  18 const size_t kNumShadowPages = 1024;
  19 const size_t kNumPages = 16 * kNumShadowPages;
  20 const size_t kPageSize = 4096;
  21 const size_t kMapSize = kNumPages * kPageSize;
  22
  23 void sync_rss() {
  24   char *page = (char *)mmap(0, kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
  25   // Linux kernel updates RSS counters after a set number of page faults.
  26   for (int i = 0; i < 100; ++i) {
  27     page[0] = 42;
  28     madvise(page, kPageSize, MADV_DONTNEED);
  29   }
  30   munmap(page, kPageSize);
  31 }
  32
  33 size_t current_rss() {
  34   sync_rss();
  35   int statm_fd = open("/proc/self/statm", O_RDONLY);
  36   assert(statm_fd >= 0);
  37
  38   char buf[100];
  39   assert(read(statm_fd, &buf, sizeof(buf)) > 0);
  40   size_t size, rss;
  41   assert(sscanf(buf, "%zu %zu", &size, &rss) == 2);
  42
  43   close(statm_fd);
  44   return rss;
  45 }
  46
  47 int test_rss_difference(void *p) {
  48   __hwasan_tag_memory(p, kTag, kMapSize);
  49   size_t rss_before = current_rss();
  50   __hwasan_tag_memory(p, 0, kMapSize);
  51   size_t rss_after = current_rss();
  52   fprintf(stderr, "%zu -> %zu\n", rss_before, rss_after);
  53   if (rss_before <= rss_after)
  54     return 0;
  55   size_t diff = rss_before - rss_after;
  56   fprintf(stderr, "diff %zu\n", diff);
  57   // Check that the difference is at least close to kNumShadowPages.
  58   return diff > kNumShadowPages / 2;
  59 }
  60
  61 int main() {
  62   fprintf(stderr, "starting rss %zu\n", current_rss());
  63   fprintf(stderr, "shadow pages: %zu\n", kNumShadowPages);
  64
  65   void *p = mmap(0, kMapSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
  66   fprintf(stderr, "p = %p\n", p);
  67
  68   size_t total_count = 10;
  69   size_t success_count = 0;
  70   for (size_t i = 0; i < total_count; ++i)
  71     success_count += test_rss_difference(p);
  72
  73   fprintf(stderr, "p = %p\n", p);
  74   fprintf(stderr, "passed %zu out of %zu\n", success_count, total_count);
  75   assert(success_count > total_count * 0.8);
  76
  77   return 0;
  78 }