1 #include <linux/module.h>
2 #include <asm/alternative.h>
3 #include <asm/facility.h>
5 #define MAX_PATCH_LEN (255 - 1)
7 static int __initdata_or_module alt_instr_disabled;
9 static int __init disable_alternative_instructions(char *str)
11 alt_instr_disabled = 1;
15 early_param("noaltinstr", disable_alternative_instructions);
22 static u16 __initdata_or_module nop16 = 0x0700;
23 static u32 __initdata_or_module nop32 = 0x47000000;
24 static struct brcl_insn __initdata_or_module nop48 = {
28 static const void *nops[] __initdata_or_module = {
34 static void __init_or_module add_jump_padding(void *insns, unsigned int len)
36 struct brcl_insn brcl = {
41 memcpy(insns, &brcl, sizeof(brcl));
42 insns += sizeof(brcl);
46 memcpy(insns, &nop16, 2);
52 static void __init_or_module add_padding(void *insns, unsigned int len)
55 add_jump_padding(insns, len);
57 memcpy(insns, nops[len / 2 - 1], len);
60 static void __init_or_module __apply_alternatives(struct alt_instr *start,
61 struct alt_instr *end)
64 u8 *instr, *replacement;
65 u8 insnbuf[MAX_PATCH_LEN];
68 * The scan order should be from start to end. A later scanned
69 * alternative code can overwrite previously scanned alternative code.
71 for (a = start; a < end; a++) {
74 instr = (u8 *)&a->instr_offset + a->instr_offset;
75 replacement = (u8 *)&a->repl_offset + a->repl_offset;
77 if (!test_facility(a->facility))
80 if (unlikely(a->instrlen % 2 || a->replacementlen % 2)) {
81 WARN_ONCE(1, "cpu alternatives instructions length is "
82 "odd, skipping patching\n");
86 memcpy(insnbuf, replacement, a->replacementlen);
87 insnbuf_sz = a->replacementlen;
89 if (a->instrlen > a->replacementlen) {
90 add_padding(insnbuf + a->replacementlen,
91 a->instrlen - a->replacementlen);
92 insnbuf_sz += a->instrlen - a->replacementlen;
95 s390_kernel_write(instr, insnbuf, insnbuf_sz);
99 void __init_or_module apply_alternatives(struct alt_instr *start,
100 struct alt_instr *end)
102 if (!alt_instr_disabled)
103 __apply_alternatives(start, end);
106 extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
107 void __init apply_alternative_instructions(void)
109 apply_alternatives(__alt_instructions, __alt_instructions_end);