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
13struct insn {
14	u16 opcode;
15	s32 offset;
16} __packed;
17
18static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
19{
20	/* brcl 0,offset */
21	insn->opcode = 0xc004;
22	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
23}
24
25static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
26{
27	/* brcl 15,offset */
28	insn->opcode = 0xc0f4;
29	insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
30}
31
32static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
33			   struct insn *new)
34{
35	unsigned char *ipc = (unsigned char *)jump_entry_code(entry);
36	unsigned char *ipe = (unsigned char *)expected;
37	unsigned char *ipn = (unsigned char *)new;
38
39	pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc);
40	pr_emerg("Found:    %6ph\n", ipc);
41	pr_emerg("Expected: %6ph\n", ipe);
42	pr_emerg("New:      %6ph\n", ipn);
43	panic("Corrupted kernel text");
44}
45
46static struct insn orignop = {
47	.opcode = 0xc004,
48	.offset = JUMP_LABEL_NOP_OFFSET >> 1,
49};
50
51static void __jump_label_transform(struct jump_entry *entry,
52				   enum jump_label_type type,
53				   int init)
54{
55	void *code = (void *)jump_entry_code(entry);
56	struct insn old, new;
57
58	if (type == JUMP_LABEL_JMP) {
59		jump_label_make_nop(entry, &old);
60		jump_label_make_branch(entry, &new);
61	} else {
62		jump_label_make_branch(entry, &old);
63		jump_label_make_nop(entry, &new);
64	}
65	if (init) {
66		if (memcmp(code, &orignop, sizeof(orignop)))
67			jump_label_bug(entry, &orignop, &new);
68	} else {
69		if (memcmp(code, &old, sizeof(old)))
70			jump_label_bug(entry, &old, &new);
71	}
72	s390_kernel_write(code, &new, sizeof(new));
73}
74
75static void __jump_label_sync(void *dummy)
 
76{
 
 
77}
78
79void arch_jump_label_transform(struct jump_entry *entry,
80			       enum jump_label_type type)
81{
82	__jump_label_transform(entry, type, 0);
83	smp_call_function(__jump_label_sync, NULL, 1);
84}
85
86void arch_jump_label_transform_static(struct jump_entry *entry,
87				      enum jump_label_type type)
88{
89	__jump_label_transform(entry, type, 1);
90}