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e6ed91fd07
clang fails to handle ".if" statements in inline assembly which are heavily used in the alternatives code. To work around this remove this code, and enforce that users of alternatives must specify original and alternative instruction sequences which have identical sizes. Add a compile time check with two ".org" statements similar to arm64. In result not only clang can handle this, but also quite a lot of code can be removed. Acked-by: Vasily Gorbik <gor@linux.ibm.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1356 Link: https://lore.kernel.org/r/20220511120532.2228616-3-hca@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/module.h>
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#include <linux/cpu.h>
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#include <linux/smp.h>
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#include <asm/text-patching.h>
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#include <asm/alternative.h>
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#include <asm/facility.h>
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#include <asm/nospec-branch.h>
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static int __initdata_or_module alt_instr_disabled;
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static int __init disable_alternative_instructions(char *str)
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{
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alt_instr_disabled = 1;
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return 0;
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}
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early_param("noaltinstr", disable_alternative_instructions);
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static void __init_or_module __apply_alternatives(struct alt_instr *start,
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struct alt_instr *end)
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{
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struct alt_instr *a;
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u8 *instr, *replacement;
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/*
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* The scan order should be from start to end. A later scanned
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* alternative code can overwrite previously scanned alternative code.
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*/
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for (a = start; a < end; a++) {
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instr = (u8 *)&a->instr_offset + a->instr_offset;
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replacement = (u8 *)&a->repl_offset + a->repl_offset;
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if (!__test_facility(a->facility, alt_stfle_fac_list))
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continue;
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if (unlikely(a->instrlen % 2)) {
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WARN_ONCE(1, "cpu alternatives instructions length is "
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"odd, skipping patching\n");
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continue;
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}
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s390_kernel_write(instr, replacement, a->instrlen);
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}
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}
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void __init_or_module apply_alternatives(struct alt_instr *start,
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struct alt_instr *end)
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{
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if (!alt_instr_disabled)
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__apply_alternatives(start, end);
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}
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extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
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void __init apply_alternative_instructions(void)
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{
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apply_alternatives(__alt_instructions, __alt_instructions_end);
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}
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static void do_sync_core(void *info)
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{
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sync_core();
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}
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void text_poke_sync(void)
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{
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on_each_cpu(do_sync_core, NULL, 1);
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}
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void text_poke_sync_lock(void)
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{
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cpus_read_lock();
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text_poke_sync();
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cpus_read_unlock();
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}
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