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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __S390_EXTABLE_H
#define __S390_EXTABLE_H
#include <asm/ptrace.h>
#include <linux/compiler.h>
* The exception table consists of three addresses:
* - Address of an instruction that is allowed to fault.
* - Address at which the program should continue.
* - Optional address of handler that takes pt_regs * argument and runs in
* interrupt context.
* No registers are modified, so it is entirely up to the continuation code
* to figure out what to do.
* All the routines below use bits of fixup code that are out of line
* with the main instruction path. This means when everything is well,
* we don't even have to jump over them. Further, they do not intrude
* on our cache or tlb entries.
struct exception_table_entry
int insn, fixup;
long handler;
extern struct exception_table_entry *__start_amode31_ex_table;
extern struct exception_table_entry *__stop_amode31_ex_table;
const struct exception_table_entry *s390_search_extables(unsigned long addr);
static inline unsigned long extable_fixup(const struct exception_table_entry *x)
return (unsigned long)&x->fixup + x->fixup;
typedef bool (*ex_handler_t)(const struct exception_table_entry *,
struct pt_regs *);
static inline ex_handler_t
ex_fixup_handler(const struct exception_table_entry *x)
if (likely(!x->handler))
return NULL;
return (ex_handler_t)((unsigned long)&x->handler + x->handler);
static inline bool ex_handle(const struct exception_table_entry *x,
struct pt_regs *regs)
ex_handler_t handler = ex_fixup_handler(x);
if (unlikely(handler))
return handler(x, regs);
regs->psw.addr = extable_fixup(x);
return true;
static inline void swap_ex_entry_fixup(struct exception_table_entry *a,
struct exception_table_entry *b,
struct exception_table_entry tmp,
int delta)
a->fixup = b->fixup + delta;
b->fixup = tmp.fixup - delta;
a->handler = b->handler + delta;
b->handler = tmp.handler - delta;