arch/xtensa/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 Xtensa.  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 extern unsigned long __stack_chk_guard;
  18
  19 /*
  20  * Initialize the stackprotector canary value.
  21  *
  22  * NOTE: this must only be called from functions that never return,
  23  * and it must always be inlined.
  24  */
  25 static __always_inline void boot_init_stack_canary(void)
  26 {
  27         unsigned long canary = get_random_canary();
  28
  29         current->stack_canary = canary;
  30         __stack_chk_guard = current->stack_canary;
  31 }
  32
  33 #endif  /* _ASM_STACKPROTECTOR_H */