arch/arm64/include/asm/jump_label.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2013 Huawei Ltd.
   4  * Author: Jiang Liu <liuj97@gmail.com>
   5  *
   6  * Based on arch/arm/include/asm/jump_label.h
   7  */
   8 #ifndef __ASM_JUMP_LABEL_H
   9 #define __ASM_JUMP_LABEL_H
  10
  11 #ifndef __ASSEMBLY__
  12
  13 #include <linux/types.h>
  14 #include <asm/insn.h>
  15
  16 #define JUMP_LABEL_NOP_SIZE             AARCH64_INSN_SIZE
  17
  18 /*
  19  * Prefer the constraint "S" to support PIC with GCC. Clang before 19 does not
  20  * support "S" on a symbol with a constant offset, so we use "i" as a fallback.
  21  */
  22 static __always_inline bool arch_static_branch(struct static_key * const key,
  23                                                const bool branch)
  24 {
  25         asm goto(
  26                 "1:     nop                                     \n\t"
  27                  "      .pushsection    __jump_table, \"aw\"    \n\t"
  28                  "      .align          3                       \n\t"
  29                  "      .long           1b - ., %l[l_yes] - .   \n\t"
  30                  "      .quad           (%[key] - .) + %[bit0]  \n\t"
  31                  "      .popsection                             \n\t"
  32                  :  :  [key]"Si"(key), [bit0]"i"(branch) :  : l_yes);
  33
  34         return false;
  35 l_yes:
  36         return true;
  37 }
  38
  39 static __always_inline bool arch_static_branch_jump(struct static_key * const key,
  40                                                     const bool branch)
  41 {
  42         asm goto(
  43                 "1:     b               %l[l_yes]               \n\t"
  44                  "      .pushsection    __jump_table, \"aw\"    \n\t"
  45                  "      .align          3                       \n\t"
  46                  "      .long           1b - ., %l[l_yes] - .   \n\t"
  47                  "      .quad           (%[key] - .) + %[bit0]  \n\t"
  48                  "      .popsection                             \n\t"
  49                  :  :  [key]"Si"(key), [bit0]"i"(branch) :  : l_yes);
  50
  51         return false;
  52 l_yes:
  53         return true;
  54 }
  55
  56 #endif  /* __ASSEMBLY__ */
  57 #endif  /* __ASM_JUMP_LABEL_H */