diff options
Diffstat (limited to 'arch/s390/kernel/alternative.c')
| -rw-r--r-- | arch/s390/kernel/alternative.c | 153 |
1 files changed, 65 insertions, 88 deletions
diff --git a/arch/s390/kernel/alternative.c b/arch/s390/kernel/alternative.c index 8e1f2aee85ef..90c0e6408992 100644 --- a/arch/s390/kernel/alternative.c +++ b/arch/s390/kernel/alternative.c @@ -1,113 +1,90 @@ // SPDX-License-Identifier: GPL-2.0 -#include <linux/module.h> -#include <asm/alternative.h> -#include <asm/facility.h> -#include <asm/nospec-branch.h> - -#define MAX_PATCH_LEN (255 - 1) -static int __initdata_or_module alt_instr_disabled; +#ifndef pr_fmt +#define pr_fmt(fmt) "alt: " fmt +#endif -static int __init disable_alternative_instructions(char *str) -{ - alt_instr_disabled = 1; - return 0; -} +#include <linux/uaccess.h> +#include <linux/printk.h> +#include <asm/nospec-branch.h> +#include <asm/abs_lowcore.h> +#include <asm/alternative.h> +#include <asm/facility.h> +#include <asm/sections.h> +#include <asm/machine.h> -early_param("noaltinstr", disable_alternative_instructions); +#ifndef a_debug +#define a_debug pr_debug +#endif -struct brcl_insn { - u16 opc; - s32 disp; -} __packed; +#ifndef __kernel_va +#define __kernel_va(x) (void *)(x) +#endif -static u16 __initdata_or_module nop16 = 0x0700; -static u32 __initdata_or_module nop32 = 0x47000000; -static struct brcl_insn __initdata_or_module nop48 = { - 0xc004, 0 -}; +unsigned long __bootdata_preserved(machine_features[1]); -static const void *nops[] __initdata_or_module = { - &nop16, - &nop32, - &nop48 +struct alt_debug { + unsigned long facilities[MAX_FACILITY_BIT / BITS_PER_LONG]; + unsigned long mfeatures[MAX_MFEATURE_BIT / BITS_PER_LONG]; + int spec; }; -static void __init_or_module add_jump_padding(void *insns, unsigned int len) -{ - struct brcl_insn brcl = { - 0xc0f4, - len / 2 - }; - - memcpy(insns, &brcl, sizeof(brcl)); - insns += sizeof(brcl); - len -= sizeof(brcl); - - while (len > 0) { - memcpy(insns, &nop16, 2); - insns += 2; - len -= 2; - } -} +static struct alt_debug __bootdata_preserved(alt_debug); -static void __init_or_module add_padding(void *insns, unsigned int len) +static void alternative_dump(u8 *old, u8 *new, unsigned int len, unsigned int type, unsigned int data) { - if (len > 6) - add_jump_padding(insns, len); - else if (len >= 2) - memcpy(insns, nops[len / 2 - 1], len); + char oinsn[33], ninsn[33]; + unsigned long kptr; + unsigned int pos; + + for (pos = 0; pos < len && 2 * pos < sizeof(oinsn) - 3; pos++) + hex_byte_pack(&oinsn[2 * pos], old[pos]); + oinsn[2 * pos] = 0; + for (pos = 0; pos < len && 2 * pos < sizeof(ninsn) - 3; pos++) + hex_byte_pack(&ninsn[2 * pos], new[pos]); + ninsn[2 * pos] = 0; + kptr = (unsigned long)__kernel_va(old); + a_debug("[%d/%3d] %016lx: %s -> %s\n", type, data, kptr, oinsn, ninsn); } -static void __init_or_module __apply_alternatives(struct alt_instr *start, - struct alt_instr *end) +void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsigned int ctx) { + struct alt_debug *d; struct alt_instr *a; - u8 *instr, *replacement; - u8 insnbuf[MAX_PATCH_LEN]; + bool debug, replace; + u8 *old, *new; /* * The scan order should be from start to end. A later scanned * alternative code can overwrite previously scanned alternative code. */ + d = &alt_debug; for (a = start; a < end; a++) { - int insnbuf_sz = 0; - - instr = (u8 *)&a->instr_offset + a->instr_offset; - replacement = (u8 *)&a->repl_offset + a->repl_offset; - - if (!__test_facility(a->facility, - S390_lowcore.alt_stfle_fac_list)) - continue; - - if (unlikely(a->instrlen % 2 || a->replacementlen % 2)) { - WARN_ONCE(1, "cpu alternatives instructions length is " - "odd, skipping patching\n"); + if (!(a->ctx & ctx)) continue; + switch (a->type) { + case ALT_TYPE_FACILITY: + replace = test_facility(a->data); + debug = __test_facility(a->data, d->facilities); + break; + case ALT_TYPE_FEATURE: + replace = test_machine_feature(a->data); + debug = __test_machine_feature(a->data, d->mfeatures); + break; + case ALT_TYPE_SPEC: + replace = nobp_enabled(); + debug = d->spec; + break; + default: + replace = false; + debug = false; } - - memcpy(insnbuf, replacement, a->replacementlen); - insnbuf_sz = a->replacementlen; - - if (a->instrlen > a->replacementlen) { - add_padding(insnbuf + a->replacementlen, - a->instrlen - a->replacementlen); - insnbuf_sz += a->instrlen - a->replacementlen; - } - - s390_kernel_write(instr, insnbuf, insnbuf_sz); + if (!replace) + continue; + old = (u8 *)&a->instr_offset + a->instr_offset; + new = (u8 *)&a->repl_offset + a->repl_offset; + if (debug) + alternative_dump(old, new, a->instrlen, a->type, a->data); + s390_kernel_write(old, new, a->instrlen); } } - -void __init_or_module apply_alternatives(struct alt_instr *start, - struct alt_instr *end) -{ - if (!alt_instr_disabled) - __apply_alternatives(start, end); -} - -extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; -void __init apply_alternative_instructions(void) -{ - apply_alternatives(__alt_instructions, __alt_instructions_end); -} |