[TSan] Add 2 test cases related to incomplete shadow cleanup in unmap (llvm#145472)

Once part of PR llvm#144648, follow the reviewer's advice and split into
this separate PR.

`unmap` works at page granularity, but supports an arbitrary non-zero
size as an argument, which results in possible shadow undercleaning in
the existing TSan implementation when `size % kShadowCell != 0`.

This change introduces two test cases to verify the shadow cleaning
effect in `unmap`.

- java_heap_init2.cpp: Imitating java_heap_init cpp, verify the
incomplete cleaning of meta
- munmap_clear_shadow.c: verify the incomplete cleaning of shadow

Author: Camsyn

compiler-rt/test/tsan/java_heap_init2.cpp

@@ -0,0 +1,34 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+// XFAIL: *
+
+#include "java.h"
+#include <errno.h>
+#include <sys/mman.h>
+
+int main() {
+  // Test a non-regular kHeapSize
+  // Previously __tsan_java_init failed because it encountered non-zero meta
+  // shadow for the destination.
+  size_t const kPageSize = sysconf(_SC_PAGESIZE);
+  int const kSize = kPageSize - 1;
+  jptr jheap2 = (jptr)mmap(0, kSize, PROT_READ | PROT_WRITE,
+                           MAP_ANON | MAP_PRIVATE, -1, 0);
+  if (jheap2 == (jptr)MAP_FAILED)
+    return printf("mmap failed with %d\n", errno);
+  __atomic_store_n((int *)(jheap2 + kSize - 3), 1, __ATOMIC_RELEASE);
+  // Due to the previous incorrect meta-end calculation, the following munmap
+  // did not clear the tail meta shadow.
+  munmap((void *)jheap2, kSize);
+  int const kHeapSize2 = kSize + 1;
+  jheap2 = (jptr)mmap((void *)jheap2, kHeapSize2, PROT_READ | PROT_WRITE,
+                      MAP_ANON | MAP_PRIVATE, -1, 0);
+  if (jheap2 == (jptr)MAP_FAILED)
+    return printf("second mmap failed with %d\n", errno);
+  __tsan_java_init(jheap2, kHeapSize2);
+  __tsan_java_move(jheap2, jheap2 + kHeapSize2 - 8, 8);
+  fprintf(stderr, "DONE\n");
+  return __tsan_java_fini();
+}
+
+// CHECK-NOT: WARNING: ThreadSanitizer: data race
+// CHECK: DONE

compiler-rt/test/tsan/munmap_clear_shadow.c

@@ -0,0 +1,59 @@
+// RUN: %clang_tsan %s -o %t && %run %t | FileCheck %s
+// XFAIL: *
+
+#include "test.h"
+#include <assert.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+void __tsan_read1(void *addr);
+
+struct thread_params {
+  char *buf;
+  unsigned int size;
+};
+
+static void *thread_func(void *arg) {
+  struct thread_params *p = (struct thread_params *)arg;
+  // Access 1
+  p->buf[0] = 0x42;
+  p->buf[p->size - 1] = 0x42;
+  barrier_wait(&barrier);
+  return 0;
+}
+
+int main() {
+  const unsigned int kPageSize = sysconf(_SC_PAGESIZE);
+  // The relevant shadow memory size should be exactly multiple of kPageSize,
+  // even if Size = kPageSize - 1.
+  const unsigned int Size = kPageSize - 1;
+
+  barrier_init(&barrier, 2);
+  char *buf = (char *)mmap(NULL, Size, PROT_READ | PROT_WRITE,
+                           MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  assert(buf != MAP_FAILED);
+  assert(((uintptr_t)buf % kPageSize) == 0);
+
+  pthread_t t;
+  struct thread_params p = {buf, Size};
+  pthread_create(&t, 0, thread_func, &p);
+
+  barrier_wait(&barrier);
+  // Should clear all the shadow memory related to the mmaped memory.
+  munmap(buf, Size);
+
+  // If the shadow memory is cleared completely, the following reads should not
+  // cause races and behave the same. However, previously, __tsan_read1(&buf[0])
+  // would not report a race, while __tsan_read1(&buf[Size - 1]) did.
+  // CHECK-NOT: WARNING: ThreadSanitizer: data race
+  __tsan_read1(&buf[0]);        // Access 2
+  __tsan_read1(&buf[Size - 1]); // Access 2
+  pthread_join(t, 0);
+
+  puts("DONE");
+
+  return 0;
+}