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https://github.com/edk2-porting/linux-next.git
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932ded4b0b
Currently the kernel patches all necessary instructions once at boot time, so modules are not covered by this. Change the apply_alternatives() function to take a beginning and an end pointer and introduce a new variant (apply_alternatives_all()) to cover the existing use case for the static kernel image section. Add a module_finalize() function to arm64 to check for an alternatives section in a module and patch only the instructions from that specific area. Since that module code is not touched before the module initialization has ended, we don't need to halt the machine before doing the patching in the module's code. Signed-off-by: Andre Przywara <andre.przywara@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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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