mirror of
https://github.com/torvalds/linux
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7e6b9db27d
Instead of defaulting to patching NOP opcodes at init time, and leaving it to the architectures to override this if this is not needed, switch to a model where doing nothing is the default. This is the common case by far, as only MIPS requires NOP patching at init time. On all other architectures, the correct encodings are emitted by the compiler and so no initial patching is needed. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220615154142.1574619-4-ardb@kernel.org
83 lines
2 KiB
C
83 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Jump label s390 support
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*
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* Copyright IBM Corp. 2011
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* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#include <linux/uaccess.h>
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#include <linux/jump_label.h>
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#include <linux/module.h>
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#include <asm/text-patching.h>
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#include <asm/ipl.h>
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struct insn {
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u16 opcode;
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s32 offset;
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} __packed;
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static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn)
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{
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/* brcl 0,offset */
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insn->opcode = 0xc004;
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insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
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}
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static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn)
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{
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/* brcl 15,offset */
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insn->opcode = 0xc0f4;
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insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1;
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}
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static void jump_label_bug(struct jump_entry *entry, struct insn *expected,
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struct insn *new)
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{
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unsigned char *ipc = (unsigned char *)jump_entry_code(entry);
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unsigned char *ipe = (unsigned char *)expected;
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unsigned char *ipn = (unsigned char *)new;
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pr_emerg("Jump label code mismatch at %pS [%px]\n", ipc, ipc);
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pr_emerg("Found: %6ph\n", ipc);
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pr_emerg("Expected: %6ph\n", ipe);
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pr_emerg("New: %6ph\n", ipn);
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panic("Corrupted kernel text");
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}
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static void jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type)
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{
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void *code = (void *)jump_entry_code(entry);
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struct insn old, new;
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if (type == JUMP_LABEL_JMP) {
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jump_label_make_nop(entry, &old);
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jump_label_make_branch(entry, &new);
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} else {
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jump_label_make_branch(entry, &old);
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jump_label_make_nop(entry, &new);
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}
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if (memcmp(code, &old, sizeof(old)))
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jump_label_bug(entry, &old, &new);
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s390_kernel_write(code, &new, sizeof(new));
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}
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void arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type)
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{
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jump_label_transform(entry, type);
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text_poke_sync();
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}
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bool arch_jump_label_transform_queue(struct jump_entry *entry,
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enum jump_label_type type)
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{
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jump_label_transform(entry, type);
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return true;
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}
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void arch_jump_label_transform_apply(void)
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{
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text_poke_sync();
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}
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