compiler-rt/test/builtins/Unit/enable_execute_stack_test.c

   1 // REQUIRES: native-run
   2 // RUN: %clang_builtins %s %librt -o %t && %run_nomprotect %t
   3 // REQUIRES: librt_has_enable_execute_stack
   4 //===-- enable_execute_stack_test.c - Test __enable_execute_stack ----------===//
   5 //
   6 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   7 // See https://llvm.org/LICENSE.txt for license information.
   8 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   9 //
  10 //===----------------------------------------------------------------------===//
  11
  12
  13 #include <stdio.h>
  14 #include <string.h>
  15 #include <stdint.h>
  16 extern void __clear_cache(void* start, void* end);
  17 extern void __enable_execute_stack(void* addr);
  18
  19 typedef int (*pfunc)(void);
  20
  21 // Make these static to avoid ILT jumps for incremental linking on Windows.
  22 static int func1() { return 1; }
  23 static int func2() { return 2; }
  24
  25 void *__attribute__((noinline))
  26 memcpy_f(void *dst, const void *src, size_t n) {
  27 // ARM and MIPS nartually align functions, but use the LSB for ISA selection
  28 // (THUMB, MIPS16/uMIPS respectively).  Ensure that the ISA bit is ignored in
  29 // the memcpy
  30 #if defined(__arm__) || defined(__mips__)
  31   return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1), n) |
  32                   ((uintptr_t)src & 1));
  33 #else
  34   return memcpy(dst, (void *)((uintptr_t)src), n);
  35 #endif
  36 }
  37
  38 int main()
  39 {
  40     unsigned char execution_buffer[128];
  41     // mark stack page containing execution_buffer to be executable
  42     __enable_execute_stack(execution_buffer);
  43
  44     // verify you can copy and execute a function
  45     pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128);
  46     __clear_cache(execution_buffer, &execution_buffer[128]);
  47     printf("f1: %p\n", f1);
  48     if ((*f1)() != 1)
  49         return 1;
  50
  51     // verify you can overwrite a function with another
  52     pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128);
  53     __clear_cache(execution_buffer, &execution_buffer[128]);
  54     if ((*f2)() != 2)
  55         return 1;
  56
  57     return 0;
  58 }