arch/x86/include/asm/jump_label.h

   1 #ifndef _ASM_X86_JUMP_LABEL_H
   2 #define _ASM_X86_JUMP_LABEL_H
   3
   4 #ifdef __KERNEL__
   5
   6 #include <linux/stringify.h>
   7 #include <linux/types.h>
   8 #include <asm/nops.h>
   9 #include <asm/asm.h>
  10
  11 #define JUMP_LABEL_NOP_SIZE 5
  12
  13 #ifdef CONFIG_X86_64
  14 # define STATIC_KEY_INIT_NOP P6_NOP5_ATOMIC
  15 #else
  16 # define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC
  17 #endif
  18
  19 static __always_inline bool arch_static_branch(struct static_key *key)
  20 {
  21         asm_volatile_goto("1:"
  22                 ".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
  23                 ".pushsection __jump_table,  \"aw\" \n\t"
  24                 _ASM_ALIGN "\n\t"
  25                 _ASM_PTR "1b, %l[l_yes], %c0 \n\t"
  26                 ".popsection \n\t"
  27                 : :  "i" (key) : : l_yes);
  28         return false;
  29 l_yes:
  30         return true;
  31 }
  32
  33 #endif /* __KERNEL__ */
  34
  35 #ifdef CONFIG_X86_64
  36 typedef u64 jump_label_t;
  37 #else
  38 typedef u32 jump_label_t;
  39 #endif
  40
  41 struct jump_entry {
  42         jump_label_t code;
  43         jump_label_t target;
  44         jump_label_t key;
  45 };
  46
  47 #endif