alternative.c (1740B)
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 10static int __initdata_or_module alt_instr_disabled; 11 12static int __init disable_alternative_instructions(char *str) 13{ 14 alt_instr_disabled = 1; 15 return 0; 16} 17 18early_param("noaltinstr", disable_alternative_instructions); 19 20static 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 47void __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 54extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; 55void __init apply_alternative_instructions(void) 56{ 57 apply_alternatives(__alt_instructions, __alt_instructions_end); 58} 59 60static void do_sync_core(void *info) 61{ 62 sync_core(); 63} 64 65void text_poke_sync(void) 66{ 67 on_each_cpu(do_sync_core, NULL, 1); 68} 69 70void text_poke_sync_lock(void) 71{ 72 cpus_read_lock(); 73 text_poke_sync(); 74 cpus_read_unlock(); 75}