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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>&13 4// REQUIRES: pointer-tagging5 6#include <assert.h>7#include <fcntl.h>8#include <stdio.h>9#include <stdlib.h>10#include <sys/auxv.h>11#include <sys/mman.h>12#include <sys/stat.h>13#include <sys/types.h>14#include <unistd.h>15 16#include <sanitizer/hwasan_interface.h>17 18const unsigned char kTag = 42;19const size_t kNumShadowPages = 1024;20const size_t kNumPages = 16 * kNumShadowPages;21 22size_t page_size, map_size;23 24void sync_rss() {25 char *page = (char *)mmap(0, page_size, PROT_READ | PROT_WRITE,26 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);27 // Linux kernel updates RSS counters after a set number of page faults.28 for (int i = 0; i < 100; ++i) {29 page[0] = 42;30 madvise(page, page_size, MADV_DONTNEED);31 }32 munmap(page, page_size);33}34 35size_t current_rss() {36 sync_rss();37 int statm_fd = open("/proc/self/statm", O_RDONLY);38 assert(statm_fd >= 0);39 40 char buf[100];41 assert(read(statm_fd, &buf, sizeof(buf)) > 0);42 size_t size, rss;43 assert(sscanf(buf, "%zu %zu", &size, &rss) == 2);44 45 close(statm_fd);46 return rss;47}48 49int test_rss_difference(void *p) {50 __hwasan_tag_memory(p, kTag, map_size);51 size_t rss_before = current_rss();52 __hwasan_tag_memory(p, 0, map_size);53 size_t rss_after = current_rss();54 fprintf(stderr, "%zu -> %zu\n", rss_before, rss_after);55 if (rss_before <= rss_after)56 return 0;57 size_t diff = rss_before - rss_after;58 fprintf(stderr, "diff %zu\n", diff);59 // Check that the difference is at least close to kNumShadowPages.60 return diff >= kNumShadowPages / 2;61}62 63int main() {64 page_size = getauxval(AT_PAGESZ);65 map_size = kNumPages * page_size;66 67 fprintf(stderr, "starting rss %zu\n", current_rss());68 fprintf(stderr, "shadow pages: %zu\n", kNumShadowPages);69 70 void *p = mmap(0, map_size, PROT_READ | PROT_WRITE,71 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);72 fprintf(stderr, "p = %p\n", p);73 74 size_t total_count = 10;75 size_t success_count = 0;76 for (size_t i = 0; i < total_count; ++i)77 success_count += test_rss_difference(p);78 79 fprintf(stderr, "p = %p\n", p);80 fprintf(stderr, "passed %zu out of %zu\n", success_count, total_count);81 assert(success_count > total_count * 0.8);82 83 return 0;84}85