107 lines
2.4 KiB
C
107 lines
2.4 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/stop_machine.h>
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#include <linux/jump_label.h>
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#include <asm/ipl.h>
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#ifdef HAVE_JUMP_LABEL
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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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struct insn_args {
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struct jump_entry *entry;
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enum jump_label_type type;
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};
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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 0,0 */
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insn->opcode = 0xc004;
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insn->offset = 0;
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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 = (entry->target - entry->code) >> 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 *)entry->code;
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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 [%p]\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 struct insn orignop = {
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.opcode = 0xc004,
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.offset = JUMP_LABEL_NOP_OFFSET >> 1,
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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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int init)
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{
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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 (init) {
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if (memcmp((void *)entry->code, &orignop, sizeof(orignop)))
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jump_label_bug(entry, &orignop, &new);
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} else {
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if (memcmp((void *)entry->code, &old, sizeof(old)))
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jump_label_bug(entry, &old, &new);
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}
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s390_kernel_write((void *)entry->code, &new, sizeof(new));
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}
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static int __sm_arch_jump_label_transform(void *data)
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{
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struct insn_args *args = data;
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__jump_label_transform(args->entry, args->type, 0);
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return 0;
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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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struct insn_args args;
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args.entry = entry;
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args.type = type;
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stop_machine_cpuslocked(__sm_arch_jump_label_transform, &args, NULL);
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}
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void arch_jump_label_transform_static(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, 1);
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}
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#endif
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