1 // RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
2 // REQUIRES: x86_64-target-arch
3 // UNSUPPORTED: tvos, watchos
4 #include "test.h"
5 
6 struct ucontext {
7   void *sp;
8   void *fiber;
9 };
10 
11 extern "C" {
12   void ucontext_do_switch(void **save, void **load);
13   void ucontext_trampoline();
14 }
15 
16 __asm__(".global " ASM_SYMBOL(ucontext_do_switch) "\n"
17         ASM_SYMBOL(ucontext_do_switch) ":\n\t"
18         "pushq %rbp\n\t"
19         "pushq %r15\n\t"
20         "pushq %r14\n\t"
21         "pushq %r13\n\t"
22         "pushq %r12\n\t"
23         "pushq %rbx\n\t"
24         "movq %rsp, (%rdi)\n\t"
25         "movq (%rsi), %rsp\n\t"
26         "popq %rbx\n\t"
27         "popq %r12\n\t"
28         "popq %r13\n\t"
29         "popq %r14\n\t"
30         "popq %r15\n\t"
31         "popq %rbp\n\t"
32         "retq");
33 
34 __asm__(".global " ASM_SYMBOL(ucontext_trampoline) "\n"
35         ASM_SYMBOL(ucontext_trampoline) ":\n\t"
36         ".cfi_startproc\n\t"
37         ".cfi_undefined rip\n\t"
38         "movq %r12, %rdi\n\t"
39         "jmpq *%rbx\n\t"
40         ".cfi_endproc");
41 
42 void ucontext_init(ucontext *context, void *stack, unsigned stack_sz,
43                    void (*func)(void*), void *arg) {
44   void **sp = reinterpret_cast<void **>(static_cast<char *>(stack) + stack_sz);
45   *(--sp) = 0;
46   *(--sp) = reinterpret_cast<void *>(ucontext_trampoline);
47   *(--sp) = 0;   // rbp
48   *(--sp) = 0;   // r15
49   *(--sp) = 0;   // r14
50   *(--sp) = 0;   // r13
51   *(--sp) = arg; // r12
52   *(--sp) = reinterpret_cast<void *>(func); // rbx
53   context->sp = sp;
54   context->fiber = __tsan_create_fiber(0);
55 }
56 
57 void ucontext_free(ucontext *context) {
58   __tsan_destroy_fiber(context->fiber);
59 }
60 
61 __attribute__((no_sanitize_thread))
62 void ucontext_switch(ucontext *save, ucontext *load) {
63   save->fiber = __tsan_get_current_fiber();
64   __tsan_switch_to_fiber(load->fiber, 0);
65   ucontext_do_switch(&save->sp, &load->sp);
66 }
67 
68 char stack[64 * 1024] __attribute__((aligned(16)));
69 
70 ucontext uc, orig_uc;
71 
72 void func(void *arg) {
73   __asm__ __volatile__(".cfi_undefined rip");
74   ucontext_switch(&uc, &orig_uc);
75 }
76 
77 int main() {
78   ucontext_init(&uc, stack, sizeof(stack), func, 0);
79   ucontext_switch(&orig_uc, &uc);
80   ucontext_free(&uc);
81   fprintf(stderr, "PASS\n");
82   return 0;
83 }
84 
85 // CHECK-NOT: WARNING: ThreadSanitizer:
86 // CHECK: PASS
87