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kernel/linux-rt-4.4.41/arch/mips/include/asm/stackprotector.h 1.11 KB
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  /*
   * GCC stack protector support.
   *
   * (This is directly adopted from the ARM implementation)
   *
   * Stack protector works by putting predefined pattern at the start of
   * the stack frame and verifying that it hasn't been overwritten when
   * returning from the function.  The pattern is called stack canary
   * and gcc expects it to be defined by a global variable called
   * "__stack_chk_guard" on MIPS.  This unfortunately means that on SMP
   * we cannot have a different canary value per task.
   */
  
  #ifndef _ASM_STACKPROTECTOR_H
  #define _ASM_STACKPROTECTOR_H 1
  
  #include <linux/random.h>
  #include <linux/version.h>
  
  extern unsigned long __stack_chk_guard;
  
  /*
   * Initialize the stackprotector canary value.
   *
   * NOTE: this must only be called from functions that never return,
   * and it must always be inlined.
   */
  static __always_inline void boot_init_stack_canary(void)
  {
  	unsigned long canary;
  
  	/* Try to get a semi random initial value. */
  	get_random_bytes(&canary, sizeof(canary));
  	canary ^= LINUX_VERSION_CODE;
  
  	current->stack_canary = canary;
  	__stack_chk_guard = current->stack_canary;
  }
  
  #endif	/* _ASM_STACKPROTECTOR_H */