compiler-rt/test/shadowcallstack/minimal_runtime.h

   1 // A shadow call stack runtime is not yet included with compiler-rt, provide a
   2 // minimal runtime to allocate a shadow call stack and assign an
   3 // architecture-specific register to point at it.
   4
   5 #pragma once
   6
   7 #include <stdlib.h>
   8 #include <sys/mman.h>
   9 #include <sys/prctl.h>
  10
  11 #include "libc_support.h"
  12
  13 __attribute__((no_sanitize("shadow-call-stack")))
  14 static void __shadowcallstack_init() {
  15   void *stack = mmap(NULL, 8192, PROT_READ | PROT_WRITE,
  16                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  17   if (stack == MAP_FAILED)
  18     abort();
  19
  20 #if defined(__aarch64__)
  21   __asm__ __volatile__("mov x18, %0" ::"r"(stack));
  22 #else
  23 #error Unsupported platform
  24 #endif
  25 }
  26
  27 int scs_main(void);
  28
  29 __attribute__((no_sanitize("shadow-call-stack"))) int main(void) {
  30   __shadowcallstack_init();
  31
  32   // We can't simply return scs_main() because scs_main might have corrupted our
  33   // return address for testing purposes (see overflow.c), so we need to exit
  34   // ourselves.
  35   exit(scs_main());
  36 }