arch/riscv/kernel/jump_label.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2020 Emil Renner Berthing
   4  *
   5  * Based on arch/arm64/kernel/jump_label.c
   6  */
   7 #include <linux/jump_label.h>
   8 #include <linux/kernel.h>
   9 #include <linux/memory.h>
  10 #include <linux/mutex.h>
  11 #include <asm/bug.h>
  12 #include <asm/cacheflush.h>
  13 #include <asm/patch.h>
  14
  15 #define RISCV_INSN_NOP 0x00000013U
  16 #define RISCV_INSN_JAL 0x0000006fU
  17
  18 bool arch_jump_label_transform_queue(struct jump_entry *entry,
  19                                      enum jump_label_type type)
  20 {
  21         void *addr = (void *)jump_entry_code(entry);
  22         u32 insn;
  23
  24         if (type == JUMP_LABEL_JMP) {
  25                 long offset = jump_entry_target(entry) - jump_entry_code(entry);
  26
  27                 if (WARN_ON(offset & 1 || offset < -524288 || offset >= 524288))
  28                         return true;
  29
  30                 insn = RISCV_INSN_JAL |
  31                         (((u32)offset & GENMASK(19, 12)) << (12 - 12)) |
  32                         (((u32)offset & GENMASK(11, 11)) << (20 - 11)) |
  33                         (((u32)offset & GENMASK(10,  1)) << (21 -  1)) |
  34                         (((u32)offset & GENMASK(20, 20)) << (31 - 20));
  35         } else {
  36                 insn = RISCV_INSN_NOP;
  37         }
  38
  39         mutex_lock(&text_mutex);
  40         patch_insn_write(addr, &insn, sizeof(insn));
  41         mutex_unlock(&text_mutex);
  42
  43         return true;
  44 }
  45
  46 void arch_jump_label_transform_apply(void)
  47 {
  48         flush_icache_all();
  49 }