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}

 
 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