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