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 #ifdef CONFIG_CC_IS_CLANG
  14 #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "i"
  15 #elif __GNUC__ < 9
  16 #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "X"
  17 #else
  18 #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd"
  19 #endif
  20
  21 /*
  22  * We use a brcl 0,2 instruction for jump labels at compile time so it
  23  * can be easily distinguished from a hotpatch generated instruction.
  24  */
  25 static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
  26 {
  27         asm_volatile_goto("0:   brcl    0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
  28                           ".pushsection __jump_table,\"aw\"\n"
  29                           ".balign      8\n"
  30                           ".long        0b-.,%l[label]-.\n"
  31                           ".quad        %0+%1-.\n"
  32                           ".popsection\n"
  33                           : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
  34         return false;
  35 label:
  36         return true;
  37 }
  38
  39 static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
  40 {
  41         asm_volatile_goto("0:   brcl 15,%l[label]\n"
  42                           ".pushsection __jump_table,\"aw\"\n"
  43                           ".balign      8\n"
  44                           ".long        0b-.,%l[label]-.\n"
  45                           ".quad        %0+%1-.\n"
  46                           ".popsection\n"
  47                           : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
  48         return false;
  49 label:
  50         return true;
  51 }
  52
  53 #endif  /* __ASSEMBLY__ */
  54 #endif