arch/s390/include/asm/jump_label.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_S390_JUMP_LABEL_H
   3 #define _ASM_S390_JUMP_LABEL_H
   4
   5 #ifndef __ASSEMBLY__
   6
   7 #include <linux/types.h>
   8 #include <linux/stringify.h>
   9
  10 #define JUMP_LABEL_NOP_SIZE 6
  11 #define JUMP_LABEL_NOP_OFFSET 2
  12
  13 /*
  14  * We use a brcl 0,2 instruction for jump labels at compile time so it
  15  * can be easily distinguished from a hotpatch generated instruction.
  16  */
  17 static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
  18 {
  19         asm_volatile_goto("0:   brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
  20                 ".pushsection __jump_table, \"aw\"\n"
  21                 ".balign 8\n"
  22                 ".quad 0b, %l[label], %0\n"
  23                 ".popsection\n"
  24                 : : "X" (&((char *)key)[branch]) : : label);
  25
  26         return false;
  27 label:
  28         return true;
  29 }
  30
  31 static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
  32 {
  33         asm_volatile_goto("0:   brcl 15, %l[label]\n"
  34                 ".pushsection __jump_table, \"aw\"\n"
  35                 ".balign 8\n"
  36                 ".quad 0b, %l[label], %0\n"
  37                 ".popsection\n"
  38                 : : "X" (&((char *)key)[branch]) : : label);
  39
  40         return false;
  41 label:
  42         return true;
  43 }
  44
  45 typedef unsigned long jump_label_t;
  46
  47 struct jump_entry {
  48         jump_label_t code;
  49         jump_label_t target;
  50         jump_label_t key;
  51 };
  52
  53 #endif  /* __ASSEMBLY__ */
  54 #endif