arch/riscv/include/asm/jump_label.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * Copyright (C) 2020 Emil Renner Berthing
   4  *
   5  * Based on arch/arm64/include/asm/jump_label.h
   6  */
   7 #ifndef __ASM_JUMP_LABEL_H
   8 #define __ASM_JUMP_LABEL_H
   9
  10 #ifndef __ASSEMBLY__
  11
  12 #include <linux/types.h>
  13 #include <asm/asm.h>
  14
  15 #define HAVE_JUMP_LABEL_BATCH
  16
  17 #define JUMP_LABEL_NOP_SIZE 4
  18
  19 #define JUMP_TABLE_ENTRY(key, label)                    \
  20         ".pushsection   __jump_table, \"aw\"    \n\t"   \
  21         ".align         " RISCV_LGPTR "         \n\t"   \
  22         ".long          1b - ., " label " - .   \n\t"   \
  23         "" RISCV_PTR "  " key " - .             \n\t"   \
  24         ".popsection                            \n\t"
  25
  26 /* This macro is also expanded on the Rust side. */
  27 #define ARCH_STATIC_BRANCH_ASM(key, label)              \
  28         "       .align          2               \n\t"   \
  29         "       .option push                    \n\t"   \
  30         "       .option norelax                 \n\t"   \
  31         "       .option norvc                   \n\t"   \
  32         "1:     nop                             \n\t"   \
  33         "       .option pop                     \n\t"   \
  34         JUMP_TABLE_ENTRY(key, label)
  35
  36 static __always_inline bool arch_static_branch(struct static_key * const key,
  37                                                const bool branch)
  38 {
  39         asm goto(
  40                 ARCH_STATIC_BRANCH_ASM("%0", "%l[label]")
  41                 :  :  "i"(&((char *)key)[branch]) :  : label);
  42
  43         return false;
  44 label:
  45         return true;
  46 }
  47
  48 #define ARCH_STATIC_BRANCH_JUMP_ASM(key, label)         \
  49         "       .align          2               \n\t"   \
  50         "       .option push                    \n\t"   \
  51         "       .option norelax                 \n\t"   \
  52         "       .option norvc                   \n\t"   \
  53         "1:     j       " label "               \n\t" \
  54         "       .option pop                     \n\t"   \
  55         JUMP_TABLE_ENTRY(key, label)
  56
  57 static __always_inline bool arch_static_branch_jump(struct static_key * const key,
  58                                                     const bool branch)
  59 {
  60         asm goto(
  61                 ARCH_STATIC_BRANCH_JUMP_ASM("%0", "%l[label]")
  62                 :  :  "i"(&((char *)key)[branch]) :  : label);
  63
  64         return false;
  65 label:
  66         return true;
  67 }
  68
  69 #endif  /* __ASSEMBLY__ */
  70 #endif  /* __ASM_JUMP_LABEL_H */