86 lines
2.1 KiB
C
86 lines
2.1 KiB
C
/*
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* alternative runtime patching
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* inspired by the x86 version
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*
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* Copyright (C) 2014 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#define pr_fmt(fmt) "alternatives: " fmt
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#include <linux/init.h>
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#include <linux/cpu.h>
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#include <asm/cacheflush.h>
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#include <asm/alternative.h>
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#include <asm/cpufeature.h>
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#include <linux/stop_machine.h>
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extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
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struct alt_region {
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struct alt_instr *begin;
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struct alt_instr *end;
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};
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static int __apply_alternatives(void *alt_region)
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{
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struct alt_instr *alt;
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struct alt_region *region = alt_region;
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u8 *origptr, *replptr;
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for (alt = region->begin; alt < region->end; alt++) {
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if (!cpus_have_cap(alt->cpufeature))
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continue;
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BUG_ON(alt->alt_len > alt->orig_len);
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pr_info_once("patching kernel code\n");
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origptr = (u8 *)&alt->orig_offset + alt->orig_offset;
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replptr = (u8 *)&alt->alt_offset + alt->alt_offset;
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memcpy(origptr, replptr, alt->alt_len);
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flush_icache_range((uintptr_t)origptr,
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(uintptr_t)(origptr + alt->alt_len));
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}
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return 0;
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}
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void apply_alternatives_all(void)
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{
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struct alt_region region = {
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.begin = __alt_instructions,
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.end = __alt_instructions_end,
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};
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/* better not try code patching on a live SMP system */
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stop_machine(__apply_alternatives, ®ion, NULL);
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}
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void apply_alternatives(void *start, size_t length)
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{
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struct alt_region region = {
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.begin = start,
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.end = start + length,
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};
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__apply_alternatives(®ion);
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}
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void free_alternatives_memory(void)
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{
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free_reserved_area(__alt_instructions, __alt_instructions_end,
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0, "alternatives");
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}
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