1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/module.h>
3 #include <linux/cpu.h>
4 #include <linux/smp.h>
5 #include <asm/text-patching.h>
6 #include <asm/alternative.h>
7 #include <asm/facility.h>
8 #include <asm/nospec-branch.h>
9
10 static int __initdata_or_module alt_instr_disabled;
11
disable_alternative_instructions(char * str)12 static int __init disable_alternative_instructions(char *str)
13 {
14 alt_instr_disabled = 1;
15 return 0;
16 }
17
18 early_param("noaltinstr", disable_alternative_instructions);
19
__apply_alternatives(struct alt_instr * start,struct alt_instr * end)20 static void __init_or_module __apply_alternatives(struct alt_instr *start,
21 struct alt_instr *end)
22 {
23 struct alt_instr *a;
24 u8 *instr, *replacement;
25
26 /*
27 * The scan order should be from start to end. A later scanned
28 * alternative code can overwrite previously scanned alternative code.
29 */
30 for (a = start; a < end; a++) {
31 instr = (u8 *)&a->instr_offset + a->instr_offset;
32 replacement = (u8 *)&a->repl_offset + a->repl_offset;
33
34 if (!__test_facility(a->facility, alt_stfle_fac_list))
35 continue;
36
37 if (unlikely(a->instrlen % 2)) {
38 WARN_ONCE(1, "cpu alternatives instructions length is "
39 "odd, skipping patching\n");
40 continue;
41 }
42
43 s390_kernel_write(instr, replacement, a->instrlen);
44 }
45 }
46
apply_alternatives(struct alt_instr * start,struct alt_instr * end)47 void __init_or_module apply_alternatives(struct alt_instr *start,
48 struct alt_instr *end)
49 {
50 if (!alt_instr_disabled)
51 __apply_alternatives(start, end);
52 }
53
54 extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
apply_alternative_instructions(void)55 void __init apply_alternative_instructions(void)
56 {
57 apply_alternatives(__alt_instructions, __alt_instructions_end);
58 }
59
do_sync_core(void * info)60 static void do_sync_core(void *info)
61 {
62 sync_core();
63 }
64
text_poke_sync(void)65 void text_poke_sync(void)
66 {
67 on_each_cpu(do_sync_core, NULL, 1);
68 }
69
text_poke_sync_lock(void)70 void text_poke_sync_lock(void)
71 {
72 cpus_read_lock();
73 text_poke_sync();
74 cpus_read_unlock();
75 }
76