LXR linux/arch/s390/kernel/jump

   1/*
   2 * Jump label s390 support
   3 *
   4 * Copyright IBM Corp. 2011
   5 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
   6 */
   7#include <linux/module.h>
   8#include <linux/uaccess.h>
   9#include <linux/stop_machine.h>
  10#include <linux/jump_label.h>
  11#include <asm/ipl.h>
  12
  13#ifdef HAVE_JUMP_LABEL
  14
  15struct insn {
  16        u16 opcode;
  17        s32 offset;
  18} __packed;
  19
  20struct insn_args {
  21        struct jump_entry *entry;
  22        enum jump_label_type type;
  23};
  24
  25static void __jump_label_transform(struct jump_entry *entry,
  26                                   enum jump_label_type type)
  27{
  28        struct insn insn;
  29        int rc;
  30
  31        if (type == JUMP_LABEL_ENABLE) {
  32                /* brcl 15,offset */
  33                insn.opcode = 0xc0f4;
  34                insn.offset = (entry->target - entry->code) >> 1;
  35        } else {
  36                /* brcl 0,0 */
  37                insn.opcode = 0xc004;
  38                insn.offset = 0;
  39        }
  40
  41        rc = probe_kernel_write((void *)entry->code, &insn, JUMP_LABEL_NOP_SIZE);
  42        WARN_ON_ONCE(rc < 0);
  43}
  44
  45static int __sm_arch_jump_label_transform(void *data)
  46{
  47        struct insn_args *args = data;
  48
  49        __jump_label_transform(args->entry, args->type);
  50        return 0;
  51}
  52
  53void arch_jump_label_transform(struct jump_entry *entry,
  54                               enum jump_label_type type)
  55{
  56        struct insn_args args;
  57
  58        args.entry = entry;
  59        args.type = type;
  60
  61        stop_machine(__sm_arch_jump_label_transform, &args, NULL);
  62}
  63
  64void arch_jump_label_transform_static(struct jump_entry *entry,
  65                                      enum jump_label_type type)
  66{
  67        __jump_label_transform(entry, type);
  68}
  69
  70#endif
  71