compiler-rt/test/msan/Linux/swapcontext_annotation.cpp

   1 // RUN: %clangxx_msan -O0 %s -o %t && %run %t
   2
   3 #include <assert.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <ucontext.h>
   7 #include <unistd.h>
   8
   9 #include <sanitizer/msan_interface.h>
  10
  11 namespace {
  12
  13 const int kStackSize = 1 << 20;
  14 char fiber_stack[kStackSize] = {};
  15
  16 ucontext_t main_ctx;
  17 ucontext_t fiber_ctx;
  18
  19 void fiber() {
  20   printf("%s: entering fiber\n", __FUNCTION__);
  21
  22   // This fiber was switched into from main. Verify the details of main's stack
  23   // have been populated by MSAN.
  24   const void *previous_stack_bottom = nullptr;
  25   size_t previous_stack_size = 0;
  26   __msan_finish_switch_fiber(&previous_stack_bottom, &previous_stack_size);
  27   assert(previous_stack_bottom != nullptr);
  28   assert(previous_stack_size != 0);
  29
  30   printf("%s: implicitly swapcontext to main\n", __FUNCTION__);
  31   __msan_start_switch_fiber(previous_stack_bottom, previous_stack_size);
  32 }
  33
  34 } // namespace
  35
  36 // Set up a fiber, switch to it, and switch back, invoking __msan_*_switch_fiber
  37 // functions along the way. At each step, validate the correct stack addresses and
  38 // sizes are returned from those functions.
  39 int main(int argc, char **argv) {
  40   if (getcontext(&fiber_ctx) == -1) {
  41     perror("getcontext");
  42     _exit(1);
  43   }
  44   fiber_ctx.uc_stack.ss_sp = fiber_stack;
  45   fiber_ctx.uc_stack.ss_size = sizeof(fiber_stack);
  46   fiber_ctx.uc_link = &main_ctx;
  47   makecontext(&fiber_ctx, fiber, 0);
  48
  49   // Tell MSAN a fiber switch is about to occur, then perform the switch
  50   printf("%s: swapcontext to fiber\n", __FUNCTION__);
  51   __msan_start_switch_fiber(fiber_stack, kStackSize);
  52   if (swapcontext(&main_ctx, &fiber_ctx) == -1) {
  53     perror("swapcontext");
  54     _exit(1);
  55   }
  56
  57   // The fiber switched to above now switched back here. Tell MSAN that switch
  58   // is complete and verify the fiber details return by MSAN are correct.
  59   const void *previous_stack_bottom = nullptr;
  60   size_t previous_stack_size = 0;
  61   __msan_finish_switch_fiber(&previous_stack_bottom, &previous_stack_size);
  62   assert(previous_stack_bottom == fiber_stack);
  63   assert(previous_stack_size == kStackSize);
  64
  65   printf("%s: exiting\n", __FUNCTION__);
  66
  67   return 0;
  68 }