arch/arm64/include/asm/stackprotector.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * GCC stack protector support.
   4  *
   5  * Stack protector works by putting predefined pattern at the start of
   6  * the stack frame and verifying that it hasn't been overwritten when
   7  * returning from the function.  The pattern is called stack canary
   8  * and gcc expects it to be defined by a global variable called
   9  * "__stack_chk_guard" on ARM.  This unfortunately means that on SMP
  10  * we cannot have a different canary value per task.
  11  */
  12
  13 #ifndef __ASM_STACKPROTECTOR_H
  14 #define __ASM_STACKPROTECTOR_H
  15
  16 #include <asm/pointer_auth.h>
  17
  18 extern 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  */
  26 static __always_inline void boot_init_stack_canary(void)
  27 {
  28 #if defined(CONFIG_STACKPROTECTOR)
  29         unsigned long canary = get_random_canary();
  30
  31         current->stack_canary = canary;
  32         if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK))
  33                 __stack_chk_guard = current->stack_canary;
  34 #endif
  35         ptrauth_thread_init_kernel(current);
  36         ptrauth_thread_switch_kernel(current);
  37         ptrauth_enable();
  38 }
  39
  40 #endif  /* _ASM_STACKPROTECTOR_H */