1 | // SPDX-License-Identifier: GPL-2.0 |
2 | |
3 | #ifndef pr_fmt |
4 | #define pr_fmt(fmt) "alt: " fmt |
5 | #endif |
6 | |
7 | #include <linux/uaccess.h> |
8 | #include <linux/printk.h> |
9 | #include <asm/nospec-branch.h> |
10 | #include <asm/abs_lowcore.h> |
11 | #include <asm/alternative.h> |
12 | #include <asm/facility.h> |
13 | #include <asm/sections.h> |
14 | #include <asm/machine.h> |
15 | |
16 | #ifndef a_debug |
17 | #define a_debug pr_debug |
18 | #endif |
19 | |
20 | #ifndef __kernel_va |
21 | #define __kernel_va(x) (void *)(x) |
22 | #endif |
23 | |
24 | unsigned long __bootdata_preserved(machine_features[1]); |
25 | |
26 | struct alt_debug { |
27 | unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG]; |
28 | unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG]; |
29 | int spec; |
30 | }; |
31 | |
32 | static struct alt_debug __bootdata_preserved(alt_debug); |
33 | |
34 | static void alternative_dump(u8 *old, u8 *new, unsigned int len, unsigned int type, unsigned int data) |
35 | { |
36 | char oinsn[33], ninsn[33]; |
37 | unsigned long kptr; |
38 | unsigned int pos; |
39 | |
40 | for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++) |
41 | hex_byte_pack(buf: &oinsn[2 * pos], byte: old[pos]); |
42 | oinsn[2 * pos] = 0; |
43 | for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++) |
44 | hex_byte_pack(buf: &ninsn[2 * pos], byte: new[pos]); |
45 | ninsn[2 * pos] = 0; |
46 | kptr = (unsigned long)__kernel_va(old); |
47 | a_debug("[%d/%3d] %016lx: %s -> %s\n" , type, data, kptr, oinsn, ninsn); |
48 | } |
49 | |
50 | void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx) |
51 | { |
52 | struct alt_debug *d; |
53 | struct alt_instr *a; |
54 | bool debug, replace; |
55 | u8 *old, *new; |
56 | |
57 | /* |
58 | * The scan order should be from start to end. A later scanned |
59 | * alternative code can overwrite previously scanned alternative code. |
60 | */ |
61 | d = &alt_debug; |
62 | for (a = start; a < end; a++) { |
63 | if (!(a->ctx & ctx)) |
64 | continue; |
65 | switch (a->type) { |
66 | case ALT_TYPE_FACILITY: |
67 | replace = test_facility(a->data); |
68 | debug = __test_facility(a->data, d->facilities); |
69 | break; |
70 | case ALT_TYPE_FEATURE: |
71 | replace = test_machine_feature(a->data); |
72 | debug = __test_machine_feature(a->data, d->mfeatures); |
73 | break; |
74 | case ALT_TYPE_SPEC: |
75 | replace = nobp_enabled(); |
76 | debug = d->spec; |
77 | break; |
78 | default: |
79 | replace = false; |
80 | debug = false; |
81 | } |
82 | if (!replace) |
83 | continue; |
84 | old = (u8 *)&a->instr_offset + a->instr_offset; |
85 | new = (u8 *)&a->repl_offset + a->repl_offset; |
86 | if (debug) |
87 | alternative_dump(old, new, len: a->instrlen, type: a->type, data: a->data); |
88 | s390_kernel_write(old, new, a->instrlen); |
89 | } |
90 | } |
91 | |