LXR linux/arch/arm/include/asm/stackprotector.h

   1/*
   2 * GCC stack protector support.
   3 *
   4 * Stack protector works by putting predefined pattern at the start of
   5 * the stack frame and verifying that it hasn't been overwritten when
   6 * returning from the function.  The pattern is called stack canary
   7 * and gcc expects it to be defined by a global variable called
   8 * "__stack_chk_guard" on ARM.  This unfortunately means that on SMP
   9 * we cannot have a different canary value per task.
  10 */
  11
  12#ifndef _ASM_STACKPROTECTOR_H
  13#define _ASM_STACKPROTECTOR_H 1
  14
  15#include <linux/random.h>
  16#include <linux/version.h>
  17
  18extern unsigned long __stack_chk_guard;
  19
  20/*
  21 * Initialize the stackprotector canary value.
  22 *
  23 * NOTE: this must only be called from functions that never return,
  24 * and it must always be inlined.
  25 */
  26static __always_inline void boot_init_stack_canary(void)
  27{
  28        unsigned long canary;
  29
  30        /* Try to get a semi random initial value. */
  31        get_random_bytes(&canary, sizeof(canary));
  32        canary ^= LINUX_VERSION_CODE;
  33
  34        current->stack_canary = canary;
  35        __stack_chk_guard = current->stack_canary;
  36}
  37
  38#endif  /* _ASM_STACKPROTECTOR_H */
  39