e757cadb07
Once we start instrumenting globals, all addresses including those of string literals that we pass to the operating system will start being tagged. Since we can't rely on the operating system to be able to cope with these addresses, we need to untag them before passing them to the operating system. This change introduces a macro that does so and uses it everywhere it is needed. Differential Revision: https://reviews.llvm.org/D65768 llvm-svn: 367938
73 lines
2.0 KiB
C
73 lines
2.0 KiB
C
// 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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