1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Jump label s390 support
 4 *
 5 * Copyright IBM Corp. 2011
 6 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
 7 */
 8#include <linux/uaccess.h>
 
 9#include <linux/jump_label.h>
10#include <linux/module.h>
11#include <asm/text-patching.h>
12#include <asm/ipl.h>
13
 
 
14struct insn {
15	u16 opcode;
16	s32 offset;
17} __packed;
18
 
 
 
 
 
19static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
20{
21	/* brcl 0,offset */
22	insn->opcode = 0xc004;
23	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
24}
25
26static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
27{
28	/* brcl 15,offset */
29	insn->opcode = 0xc0f4;
30	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
31}
32
33static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
34			   struct insn *new)
35{
36	unsigned char *ipc = (unsigned char *)jump_entry_code(entry);
37	unsigned char *ipe = (unsigned char *)expected;
38	unsigned char *ipn = (unsigned char *)new;
39
40	pr_emerg("Jump label code mismatch at %pS [%px]\n", ipc, ipc);
41	pr_emerg("Found:    %6ph\n", ipc);
42	pr_emerg("Expected: %6ph\n", ipe);
43	pr_emerg("New:      %6ph\n", ipn);
44	panic("Corrupted kernel text");
45}
46
47static void jump_label_transform(struct jump_entry *entry,
48				 enum jump_label_type type)
 
 
 
 
 
 
49{
50	void *code = (void *)jump_entry_code(entry);
51	struct insn old, new;
52
53	if (type == JUMP_LABEL_JMP) {
54		jump_label_make_nop(entry, &old);
55		jump_label_make_branch(entry, &new);
56	} else {
57		jump_label_make_branch(entry, &old);
58		jump_label_make_nop(entry, &new);
59	}
60	if (memcmp(code, &old, sizeof(old)))
61		jump_label_bug(entry, &old, &new);
62	s390_kernel_write(code, &new, sizeof(new));
 
 
 
 
 
63}
64
65void arch_jump_label_transform(struct jump_entry *entry,
66			       enum jump_label_type type)
67{
68	jump_label_transform(entry, type);
69	text_poke_sync();
 
 
70}
71
72bool arch_jump_label_transform_queue(struct jump_entry *entry,
73				     enum jump_label_type type)
74{
75	jump_label_transform(entry, type);
76	return true;
 
 
 
 
77}
78
79void arch_jump_label_transform_apply(void)
 
80{
81	text_poke_sync();
82}

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Jump label s390 support
  4 *
  5 * Copyright IBM Corp. 2011
  6 * Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
  7 */
  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_cpuslocked(__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