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5c6497c50f
Add sanity checks to verify that only expected code will be replaced. If the code patterns do not match print the code patterns and panic, since something went terribly wrong. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
98 lines
2.2 KiB
C
98 lines
2.2 KiB
C
/*
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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/module.h>
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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 *insn)
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{
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unsigned char *ipc = (unsigned char *)entry->code;
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unsigned char *ipe = (unsigned char *)insn;
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pr_emerg("Jump label code mismatch at %pS [%p]\n", ipc, ipc);
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pr_emerg("Found: %02x %02x %02x %02x %02x %02x\n",
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ipc[0], ipc[1], ipc[2], ipc[3], ipc[4], ipc[5]);
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pr_emerg("Expected: %02x %02x %02x %02x %02x %02x\n",
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ipe[0], ipe[1], ipe[2], ipe[3], ipe[4], ipe[5]);
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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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int init)
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{
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struct insn old, new;
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if (type == JUMP_LABEL_ENABLE) {
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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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if (init)
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jump_label_make_nop(entry, &old);
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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((void *)entry->code, &old, sizeof(old)))
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jump_label_bug(entry, &old);
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probe_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(__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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