arch/tile/kernel/jump_label.c

   1 /*
   2  * Copyright 2015 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * jump label TILE-Gx support
  15  */
  16
  17 #include <linux/jump_label.h>
  18 #include <linux/memory.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/cpu.h>
  22
  23 #include <asm/cacheflush.h>
  24 #include <asm/insn.h>
  25
  26 #ifdef HAVE_JUMP_LABEL
  27
  28 static void __jump_label_transform(struct jump_entry *e,
  29                                    enum jump_label_type type)
  30 {
  31         tilegx_bundle_bits opcode;
  32         /* Operate on writable kernel text mapping. */
  33         unsigned long pc_wr = ktext_writable_addr(e->code);
  34
  35         if (type == JUMP_LABEL_JMP)
  36                 opcode = tilegx_gen_branch(e->code, e->target, false);
  37         else
  38                 opcode = NOP();
  39
  40         *(tilegx_bundle_bits *)pc_wr = opcode;
  41         /* Make sure that above mem writes were issued towards the memory. */
  42         smp_wmb();
  43 }
  44
  45 void arch_jump_label_transform(struct jump_entry *e,
  46                                 enum jump_label_type type)
  47 {
  48         get_online_cpus();
  49         mutex_lock(&text_mutex);
  50
  51         __jump_label_transform(e, type);
  52         flush_icache_range(e->code, e->code + sizeof(tilegx_bundle_bits));
  53
  54         mutex_unlock(&text_mutex);
  55         put_online_cpus();
  56 }
  57
  58 __init_or_module void arch_jump_label_transform_static(struct jump_entry *e,
  59                                                 enum jump_label_type type)
  60 {
  61         __jump_label_transform(e, type);
  62 }
  63
  64 #endif /* HAVE_JUMP_LABEL */