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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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d5caa4dbf9
Use a brcl 0,2 instruction for jump label nops during compile time, so we don't mix up the different nops during mcount/hotpatch call site detection. The initial jump label code instruction replacement will exchange these instructions with either a branch or a brcl 0,0 instruction. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
106 lines
2.4 KiB
C
106 lines
2.4 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 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_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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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, &old);
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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);
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}
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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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