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	unsigned long *target;
22	struct insn *insn;
23	ssize_t size;
24};
25
26static int __arch_jump_label_transform(void *data)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
27{
28	struct insn_args *args = data;
29	int rc;
30
31	rc = probe_kernel_write(args->target, args->insn, args->size);
32	WARN_ON_ONCE(rc < 0);
33	return 0;
34}
35
36void arch_jump_label_transform(struct jump_entry *entry,
37			       enum jump_label_type type)
38{
39	struct insn_args args;
40	struct insn insn;
41
42	if (type == JUMP_LABEL_ENABLE) {
43		/* brcl 15,offset */
44		insn.opcode = 0xc0f4;
45		insn.offset = (entry->target - entry->code) >> 1;
46	} else {
47		/* brcl 0,0 */
48		insn.opcode = 0xc004;
49		insn.offset = 0;
50	}
51
52	args.target = (void *) entry->code;
53	args.insn = &insn;
54	args.size = JUMP_LABEL_NOP_SIZE;
55
56	stop_machine(__arch_jump_label_transform, &args, NULL);
 
 
 
57}
58
59#endif

  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_make_nop(struct jump_entry *entry, struct insn *insn)
 26{
 27	/* brcl 0,0 */
 28	insn->opcode = 0xc004;
 29	insn->offset = 0;
 30}
 31
 32static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
 33{
 34	/* brcl 15,offset */
 35	insn->opcode = 0xc0f4;
 36	insn->offset = (entry->target - entry->code) >> 1;
 37}
 38
 39static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
 40			   struct insn *new)
 41{
 42	unsigned char *ipc = (unsigned char *)entry->code;
 43	unsigned char *ipe = (unsigned char *)expected;
 44	unsigned char *ipn = (unsigned char *)new;
 45
 46	pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc);
 47	pr_emerg("Found:    %6ph\n", ipc);
 48	pr_emerg("Expected: %6ph\n", ipe);
 49	pr_emerg("New:      %6ph\n", ipn);
 50	panic("Corrupted kernel text");
 51}
 52
 53static struct insn orignop = {
 54	.opcode = 0xc004,
 55	.offset = JUMP_LABEL_NOP_OFFSET >> 1,
 56};
 57
 58static void __jump_label_transform(struct jump_entry *entry,
 59				   enum jump_label_type type,
 60				   int init)
 61{
 62	struct insn old, new;
 63
 64	if (type == JUMP_LABEL_JMP) {
 65		jump_label_make_nop(entry, &old);
 66		jump_label_make_branch(entry, &new);
 67	} else {
 68		jump_label_make_branch(entry, &old);
 69		jump_label_make_nop(entry, &new);
 70	}
 71	if (init) {
 72		if (memcmp((void *)entry->code, &orignop, sizeof(orignop)))
 73			jump_label_bug(entry, &orignop, &new);
 74	} else {
 75		if (memcmp((void *)entry->code, &old, sizeof(old)))
 76			jump_label_bug(entry, &old, &new);
 77	}
 78	s390_kernel_write((void *)entry->code, &new, sizeof(new));
 79}
 80
 81static int __sm_arch_jump_label_transform(void *data)
 82{
 83	struct insn_args *args = data;
 
 84
 85	__jump_label_transform(args->entry, args->type, 0);
 
 86	return 0;
 87}
 88
 89void arch_jump_label_transform(struct jump_entry *entry,
 90			       enum jump_label_type type)
 91{
 92	struct insn_args args;
 
 93
 94	args.entry = entry;
 95	args.type = type;
 
 
 
 
 
 
 
 96
 97	stop_machine(__sm_arch_jump_label_transform, &args, NULL);
 98}
 
 99
100void arch_jump_label_transform_static(struct jump_entry *entry,
101				      enum jump_label_type type)
102{
103	__jump_label_transform(entry, type, 1);
104}
105
106#endif