1// RUN: %clang_tsan %s -o %t && %run %t | FileCheck %s
2
3// In these systems, the behavior of ReleaseMemoryPagesToOS is madvise(beg, end, MADV_FREE),
4// which tags the relevant pages as 'FREE' and does not release them immediately.
5// Therefore, we cannot assume that __tsan_read1 will not race with the shadow cleared.
6// UNSUPPORTED: darwin,target={{.*(freebsd|netbsd|solaris|haiku).*}}
7
8#include "test.h"
9#include <assert.h>
10#include <pthread.h>
11#include <stdint.h>
12#include <stdio.h>
13#include <sys/mman.h>
14#include <unistd.h>
15
16void __tsan_read1(void *addr);
17
18struct thread_params {
19 char *buf;
20 unsigned int size;
21};
22
23static void *thread_func(void *arg) {
24 struct thread_params *p = (struct thread_params *)arg;
25 // Access 1
26 p->buf[0] = 0x42;
27 p->buf[p->size - 1] = 0x42;
28 barrier_wait(barrier: &barrier);
29 return 0;
30}
31
32int main() {
33 const unsigned int kPageSize = sysconf(_SC_PAGESIZE);
34 // The relevant shadow memory size should be exactly multiple of kPageSize,
35 // even if Size = kPageSize - 1.
36 const unsigned int Size = kPageSize - 1;
37
38 barrier_init(barrier: &barrier, count: 2);
39 char *buf = (char *)mmap(NULL, len: Size, PROT_READ | PROT_WRITE,
40 MAP_PRIVATE | MAP_ANONYMOUS, fd: -1, offset: 0);
41 assert(buf != MAP_FAILED);
42 assert(((uintptr_t)buf % kPageSize) == 0);
43
44 pthread_t t;
45 struct thread_params p = {buf, Size};
46 pthread_create(newthread: &t, attr: 0, start_routine: thread_func, arg: &p);
47
48 barrier_wait(barrier: &barrier);
49 // Should clear all the shadow memory related to the mmaped memory.
50 munmap(addr: buf, len: Size);
51
52 // If the shadow memory is cleared completely, the following reads should not
53 // cause races and behave the same. However, previously, __tsan_read1(&buf[0])
54 // would not report a race, while __tsan_read1(&buf[Size - 1]) did.
55 // CHECK-NOT: WARNING: ThreadSanitizer: data race
56 __tsan_read1(addr: &buf[0]); // Access 2
57 __tsan_read1(addr: &buf[Size - 1]); // Access 2
58 pthread_join(th: t, thread_return: 0);
59
60 puts(s: "DONE");
61
62 return 0;
63}
64

source code of compiler-rt/test/tsan/munmap_clear_shadow.c