arch/mips/kernel/jump_label.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (c) 2010 Cavium Networks, Inc.
   7  */
   8
   9 #include <linux/jump_label.h>
  10 #include <linux/kernel.h>
  11 #include <linux/memory.h>
  12 #include <linux/mutex.h>
  13 #include <linux/types.h>
  14 #include <linux/cpu.h>
  15
  16 #include <asm/cacheflush.h>
  17 #include <asm/inst.h>
  18
  19 #ifdef HAVE_JUMP_LABEL
  20
  21 #define J_RANGE_MASK ((1ul << 28) - 1)
  22
  23 void arch_jump_label_transform(struct jump_entry *e,
  24                                enum jump_label_type type)
  25 {
  26         union mips_instruction insn;
  27         union mips_instruction *insn_p =
  28                 (union mips_instruction *)(unsigned long)e->code;
  29
  30         /* Jump only works within a 256MB aligned region. */
  31         BUG_ON((e->target & ~J_RANGE_MASK) != (e->code & ~J_RANGE_MASK));
  32
  33         /* Target must have 4 byte alignment. */
  34         BUG_ON((e->target & 3) != 0);
  35
  36         if (type == JUMP_LABEL_ENABLE) {
  37                 insn.j_format.opcode = j_op;
  38                 insn.j_format.target = (e->target & J_RANGE_MASK) >> 2;
  39         } else {
  40                 insn.word = 0; /* nop */
  41         }
  42
  43         get_online_cpus();
  44         mutex_lock(&text_mutex);
  45         *insn_p = insn;
  46
  47         flush_icache_range((unsigned long)insn_p,
  48                            (unsigned long)insn_p + sizeof(*insn_p));
  49
  50         mutex_unlock(&text_mutex);
  51         put_online_cpus();
  52 }
  53
  54 #endif /* HAVE_JUMP_LABEL */