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/*
 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