arch/s390/include/asm/jump_label.h

   1 #ifndef _ASM_S390_JUMP_LABEL_H
   2 #define _ASM_S390_JUMP_LABEL_H
   3
   4 #ifndef __ASSEMBLY__
   5
   6 #include <linux/types.h>
   7 #include <linux/stringify.h>
   8
   9 #define JUMP_LABEL_NOP_SIZE 6
  10 #define JUMP_LABEL_NOP_OFFSET 2
  11
  12 /*
  13  * We use a brcl 0,2 instruction for jump labels at compile time so it
  14  * can be easily distinguished from a hotpatch generated instruction.
  15  */
  16 static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
  17 {
  18         asm_volatile_goto("0:   brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
  19                 ".pushsection __jump_table, \"aw\"\n"
  20                 ".balign 8\n"
  21                 ".quad 0b, %l[label], %0\n"
  22                 ".popsection\n"
  23                 : : "X" (&((char *)key)[branch]) : : label);
  24
  25         return false;
  26 label:
  27         return true;
  28 }
  29
  30 static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
  31 {
  32         asm_volatile_goto("0:   brcl 15, %l[label]\n"
  33                 ".pushsection __jump_table, \"aw\"\n"
  34                 ".balign 8\n"
  35                 ".quad 0b, %l[label], %0\n"
  36                 ".popsection\n"
  37                 : : "X" (&((char *)key)[branch]) : : label);
  38
  39         return false;
  40 label:
  41         return true;
  42 }
  43
  44 typedef unsigned long jump_label_t;
  45
  46 struct jump_entry {
  47         jump_label_t code;
  48         jump_label_t target;
  49         jump_label_t key;
  50 };
  51
  52 #endif  /* __ASSEMBLY__ */
  53 #endif