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

   1/*
   2 * GCC stack protector support.
   3 *
   4 * (This is directly adopted from the ARM implementation)
   5 *
   6 * Stack protector works by putting predefined pattern at the start of
   7 * the stack frame and verifying that it hasn't been overwritten when
   8 * returning from the function.  The pattern is called stack canary
   9 * and gcc expects it to be defined by a global variable called
  10 * "__stack_chk_guard" on MIPS.  This unfortunately means that on SMP
  11 * we cannot have a different canary value per task.
  12 */
  13
  14#ifndef _ASM_STACKPROTECTOR_H
  15#define _ASM_STACKPROTECTOR_H 1
  16
  17#include <linux/random.h>
  18#include <linux/version.h>
  19
  20extern unsigned long __stack_chk_guard;
  21
  22/*
  23 * Initialize the stackprotector canary value.
  24 *
  25 * NOTE: this must only be called from functions that never return,
  26 * and it must always be inlined.
  27 */
  28static __always_inline void boot_init_stack_canary(void)
  29{
  30        unsigned long canary;
  31
  32        /* Try to get a semi random initial value. */
  33        get_random_bytes(&canary, sizeof(canary));
  34        canary ^= LINUX_VERSION_CODE;
  35
  36        current->stack_canary = canary;
  37        __stack_chk_guard = current->stack_canary;
  38}
  39
  40#endif  /* _ASM_STACKPROTECTOR_H */
  41