Commit | Line | Data |
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5373db88 JG |
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 | ||
15 | struct insn { | |
16 | u16 opcode; | |
17 | s32 offset; | |
18 | } __packed; | |
19 | ||
20 | struct insn_args { | |
61f42183 JF |
21 | struct jump_entry *entry; |
22 | enum jump_label_type type; | |
5373db88 JG |
23 | }; |
24 | ||
5c6497c5 HC |
25 | static 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 | ||
32 | static 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 | ||
72dace96 HC |
39 | static void jump_label_bug(struct jump_entry *entry, struct insn *expected, |
40 | struct insn *new) | |
5c6497c5 HC |
41 | { |
42 | unsigned char *ipc = (unsigned char *)entry->code; | |
72dace96 HC |
43 | unsigned char *ipe = (unsigned char *)expected; |
44 | unsigned char *ipn = (unsigned char *)new; | |
5c6497c5 HC |
45 | |
46 | pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc); | |
47 | pr_emerg("Found: %02x %02x %02x %02x %02x %02x\n", | |
48 | ipc[0], ipc[1], ipc[2], ipc[3], ipc[4], ipc[5]); | |
49 | pr_emerg("Expected: %02x %02x %02x %02x %02x %02x\n", | |
50 | ipe[0], ipe[1], ipe[2], ipe[3], ipe[4], ipe[5]); | |
72dace96 HC |
51 | pr_emerg("New: %02x %02x %02x %02x %02x %02x\n", |
52 | ipn[0], ipn[1], ipn[2], ipn[3], ipn[4], ipn[5]); | |
5c6497c5 HC |
53 | panic("Corrupted kernel text"); |
54 | } | |
55 | ||
d5caa4db HC |
56 | static struct insn orignop = { |
57 | .opcode = 0xc004, | |
58 | .offset = JUMP_LABEL_NOP_OFFSET >> 1, | |
59 | }; | |
60 | ||
61f42183 | 61 | static void __jump_label_transform(struct jump_entry *entry, |
5c6497c5 HC |
62 | enum jump_label_type type, |
63 | int init) | |
5373db88 | 64 | { |
5c6497c5 | 65 | struct insn old, new; |
5373db88 JG |
66 | |
67 | if (type == JUMP_LABEL_ENABLE) { | |
5c6497c5 HC |
68 | jump_label_make_nop(entry, &old); |
69 | jump_label_make_branch(entry, &new); | |
5373db88 | 70 | } else { |
d5caa4db | 71 | jump_label_make_branch(entry, &old); |
5c6497c5 | 72 | jump_label_make_nop(entry, &new); |
5373db88 | 73 | } |
d5caa4db HC |
74 | if (init) { |
75 | if (memcmp((void *)entry->code, &orignop, sizeof(orignop))) | |
72dace96 | 76 | jump_label_bug(entry, &orignop, &new); |
d5caa4db HC |
77 | } else { |
78 | if (memcmp((void *)entry->code, &old, sizeof(old))) | |
72dace96 | 79 | jump_label_bug(entry, &old, &new); |
d5caa4db | 80 | } |
5c6497c5 | 81 | probe_kernel_write((void *)entry->code, &new, sizeof(new)); |
61f42183 | 82 | } |
5373db88 | 83 | |
61f42183 JF |
84 | static int __sm_arch_jump_label_transform(void *data) |
85 | { | |
86 | struct insn_args *args = data; | |
87 | ||
5c6497c5 | 88 | __jump_label_transform(args->entry, args->type, 0); |
61f42183 JF |
89 | return 0; |
90 | } | |
91 | ||
92 | void arch_jump_label_transform(struct jump_entry *entry, | |
93 | enum jump_label_type type) | |
94 | { | |
95 | struct insn_args args; | |
96 | ||
97 | args.entry = entry; | |
98 | args.type = type; | |
99 | ||
100 | stop_machine(__sm_arch_jump_label_transform, &args, NULL); | |
101 | } | |
102 | ||
103 | void arch_jump_label_transform_static(struct jump_entry *entry, | |
104 | enum jump_label_type type) | |
105 | { | |
5c6497c5 | 106 | __jump_label_transform(entry, type, 1); |
5373db88 JG |
107 | } |
108 | ||
109 | #endif |