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73 lines
2.0 KiB
73 lines
2.0 KiB
7 months ago
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// Test that tagging a large region to 0 reduces RSS.
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// RUN: %clang_hwasan -mllvm -hwasan-instrument-stack=0 %s -o %t && %run %t 2>&1
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#include <assert.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <sanitizer/hwasan_interface.h>
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#include "../utils.h"
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const unsigned char kTag = 42;
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const size_t kNumShadowPages = 256;
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const size_t kNumPages = 16 * kNumShadowPages;
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const size_t kPageSize = 4096;
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const size_t kMapSize = kNumPages * kPageSize;
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void sync_rss() {
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char *page = (char *)mmap(0, kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
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// Linux kernel updates RSS counters after a set number of page faults.
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for (int i = 0; i < 1000; ++i) {
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page[0] = 42;
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madvise(page, kPageSize, MADV_DONTNEED);
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}
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munmap(page, kPageSize);
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}
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size_t current_rss() {
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sync_rss();
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int statm_fd = open(UNTAG("/proc/self/statm"), O_RDONLY);
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assert(statm_fd >= 0);
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char buf[100];
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assert(read(statm_fd, &buf, sizeof(buf)) > 0);
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size_t size, rss;
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assert(sscanf(buf, UNTAG("%zu %zu"), &size, &rss) == 2);
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close(statm_fd);
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return rss;
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}
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void test_rss_difference(void *p) {
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__hwasan_tag_memory(p, kTag, kMapSize);
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size_t rss_before = current_rss();
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__hwasan_tag_memory(p, 0, kMapSize);
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size_t rss_after = current_rss();
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untag_fprintf(stderr, "%zu -> %zu\n", rss_before, rss_after);
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assert(rss_before > rss_after);
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size_t diff = rss_before - rss_after;
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untag_fprintf(stderr, "diff %zu\n", diff);
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// Check that the difference is at least close to kNumShadowPages.
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assert(diff > kNumShadowPages / 4 * 3);
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}
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int main() {
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untag_fprintf(stderr, "starting rss %zu\n", current_rss());
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untag_fprintf(stderr, "shadow pages: %zu\n", kNumShadowPages);
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void *p = mmap(0, kMapSize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
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untag_fprintf(stderr, "p = %p\n", p);
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test_rss_difference(p);
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test_rss_difference(p);
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test_rss_difference(p);
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return 0;
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}
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