projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 9fa1db4c | 1 | // SPDX-License-Identifier: GPL-2.0 |
| 686140a1 VG |
2 | #include <linux/module.h> |
| 3 | #include <asm/alternative.h> | |
| 4 | #include <asm/facility.h> | |
| 6e179d64 | 5 | #include <asm/nospec-branch.h> |
| 686140a1 VG |
6 | |
| 7 | #define MAX_PATCH_LEN (255 - 1) | |
| 8 | ||
| 9 | static int __initdata_or_module alt_instr_disabled; | |
| 10 | ||
| 11 | static int __init disable_alternative_instructions(char *str) | |
| 12 | { | |
| 13 | alt_instr_disabled = 1; | |
| 14 | return 0; | |
| 15 | } | |
| 16 | ||
| 17 | early_param("noaltinstr", disable_alternative_instructions); | |
| 18 | ||
| 19 | struct brcl_insn { | |
| 20 | u16 opc; | |
| 21 | s32 disp; | |
| 22 | } __packed; | |
| 23 | ||
| 24 | static u16 __initdata_or_module nop16 = 0x0700; | |
| 25 | static u32 __initdata_or_module nop32 = 0x47000000; | |
| 26 | static struct brcl_insn __initdata_or_module nop48 = { | |
| 27 | 0xc004, 0 | |
| 28 | }; | |
| 29 | ||
| 30 | static const void *nops[] __initdata_or_module = { | |
| 31 | &nop16, | |
| 32 | &nop32, | |
| 33 | &nop48 | |
| 34 | }; | |
| 35 | ||
| 36 | static void __init_or_module add_jump_padding(void *insns, unsigned int len) | |
| 37 | { | |
| 38 | struct brcl_insn brcl = { | |
| 39 | 0xc0f4, | |
| 40 | len / 2 | |
| 41 | }; | |
| 42 | ||
| 43 | memcpy(insns, &brcl, sizeof(brcl)); | |
| 44 | insns += sizeof(brcl); | |
| 45 | len -= sizeof(brcl); | |
| 46 | ||
| 47 | while (len > 0) { | |
| 48 | memcpy(insns, &nop16, 2); | |
| 49 | insns += 2; | |
| 50 | len -= 2; | |
| 51 | } | |
| 52 | } | |
| 53 | ||
| 54 | static void __init_or_module add_padding(void *insns, unsigned int len) | |
| 55 | { | |
| 56 | if (len > 6) | |
| 57 | add_jump_padding(insns, len); | |
| 58 | else if (len >= 2) | |
| 59 | memcpy(insns, nops[len / 2 - 1], len); | |
| 60 | } | |
| 61 | ||
| 62 | static void __init_or_module __apply_alternatives(struct alt_instr *start, | |
| 63 | struct alt_instr *end) | |
| 64 | { | |
| 65 | struct alt_instr *a; | |
| 66 | u8 *instr, *replacement; | |
| 67 | u8 insnbuf[MAX_PATCH_LEN]; | |
| 68 | ||
| 69 | /* | |
| 70 | * The scan order should be from start to end. A later scanned | |
| 71 | * alternative code can overwrite previously scanned alternative code. | |
| 72 | */ | |
| 73 | for (a = start; a < end; a++) { | |
| 74 | int insnbuf_sz = 0; | |
| 75 | ||
| 76 | instr = (u8 *)&a->instr_offset + a->instr_offset; | |
| 77 | replacement = (u8 *)&a->repl_offset + a->repl_offset; | |
| 78 | ||
| cf148998 MS |
79 | if (!__test_facility(a->facility, |
| 80 | S390_lowcore.alt_stfle_fac_list)) | |
| 686140a1 VG |
81 | continue; |
| 82 | ||
| 83 | if (unlikely(a->instrlen % 2 || a->replacementlen % 2)) { | |
| 84 | WARN_ONCE(1, "cpu alternatives instructions length is " | |
| 85 | "odd, skipping patching\n"); | |
| 86 | continue; | |
| 87 | } | |
| 88 | ||
| 89 | memcpy(insnbuf, replacement, a->replacementlen); | |
| 90 | insnbuf_sz = a->replacementlen; | |
| 91 | ||
| 92 | if (a->instrlen > a->replacementlen) { | |
| 93 | add_padding(insnbuf + a->replacementlen, | |
| 94 | a->instrlen - a->replacementlen); | |
| 95 | insnbuf_sz += a->instrlen - a->replacementlen; | |
| 96 | } | |
| 97 | ||
| 98 | s390_kernel_write(instr, insnbuf, insnbuf_sz); | |
| 99 | } | |
| 100 | } | |
| 101 | ||
| 102 | void __init_or_module apply_alternatives(struct alt_instr *start, | |
| 103 | struct alt_instr *end) | |
| 104 | { | |
| 105 | if (!alt_instr_disabled) | |
| 106 | __apply_alternatives(start, end); | |
| 107 | } | |
| 108 | ||
| 109 | extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; | |
| 110 | void __init apply_alternative_instructions(void) | |
| 111 | { | |
| 112 | apply_alternatives(__alt_instructions, __alt_instructions_end); | |
| 113 | } |