arch/mips/include/asm/stackprotector.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * GCC stack protector support.
   4  *
   5  * (This is directly adopted from the ARM implementation)
   6  *
   7  * Stack protector works by putting predefined pattern at the start of
   8  * the stack frame and verifying that it hasn't been overwritten when
   9  * returning from the function.  The pattern is called stack canary
  10  * and gcc expects it to be defined by a global variable called
  11  * "__stack_chk_guard" on MIPS.  This unfortunately means that on SMP
  12  * we cannot have a different canary value per task.
  13  */
  14
  15 #ifndef _ASM_STACKPROTECTOR_H
  16 #define _ASM_STACKPROTECTOR_H 1
  17
  18 #include <linux/random.h>
  19 #include <linux/version.h>
  20
  21 extern unsigned long __stack_chk_guard;
  22
  23 /*
  24  * Initialize the stackprotector canary value.
  25  *
  26  * NOTE: this must only be called from functions that never return,
  27  * and it must always be inlined.
  28  */
  29 static __always_inline void boot_init_stack_canary(void)
  30 {
  31         unsigned long canary;
  32
  33         /* Try to get a semi random initial value. */
  34         get_random_bytes(&canary, sizeof(canary));
  35         canary ^= LINUX_VERSION_CODE;
  36
  37         current->stack_canary = canary;
  38         __stack_chk_guard = current->stack_canary;
  39 }
  40
  41 #endif  /* _ASM_STACKPROTECTOR_H */