arch/s390/include/asm/extable.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __S390_EXTABLE_H
   3 #define __S390_EXTABLE_H
   4
   5 #include <asm/ptrace.h>
   6 #include <linux/compiler.h>
   7
   8 /*
   9  * The exception table consists of three addresses:
  10  *
  11  * - Address of an instruction that is allowed to fault.
  12  * - Address at which the program should continue.
  13  * - Optional address of handler that takes pt_regs * argument and runs in
  14  *   interrupt context.
  15  *
  16  * No registers are modified, so it is entirely up to the continuation code
  17  * to figure out what to do.
  18  *
  19  * All the routines below use bits of fixup code that are out of line
  20  * with the main instruction path.  This means when everything is well,
  21  * we don't even have to jump over them.  Further, they do not intrude
  22  * on our cache or tlb entries.
  23  */
  24
  25 struct exception_table_entry
  26 {
  27         int insn, fixup;
  28         long handler;
  29 };
  30
  31 extern struct exception_table_entry *__start_dma_ex_table;
  32 extern struct exception_table_entry *__stop_dma_ex_table;
  33
  34 const struct exception_table_entry *s390_search_extables(unsigned long addr);
  35
  36 static inline unsigned long extable_fixup(const struct exception_table_entry *x)
  37 {
  38         return (unsigned long)&x->fixup + x->fixup;
  39 }
  40
  41 typedef bool (*ex_handler_t)(const struct exception_table_entry *,
  42                              struct pt_regs *);
  43
  44 static inline ex_handler_t
  45 ex_fixup_handler(const struct exception_table_entry *x)
  46 {
  47         if (likely(!x->handler))
  48                 return NULL;
  49         return (ex_handler_t)((unsigned long)&x->handler + x->handler);
  50 }
  51
  52 static inline bool ex_handle(const struct exception_table_entry *x,
  53                              struct pt_regs *regs)
  54 {
  55         ex_handler_t handler = ex_fixup_handler(x);
  56
  57         if (unlikely(handler))
  58                 return handler(x, regs);
  59         regs->psw.addr = extable_fixup(x);
  60         return true;
  61 }
  62
  63 #define ARCH_HAS_RELATIVE_EXTABLE
  64
  65 static inline void swap_ex_entry_fixup(struct exception_table_entry *a,
  66                                        struct exception_table_entry *b,
  67                                        struct exception_table_entry tmp,
  68                                        int delta)
  69 {
  70         a->fixup = b->fixup + delta;
  71         b->fixup = tmp.fixup - delta;
  72         a->handler = b->handler + delta;
  73         b->handler = tmp.handler - delta;
  74 }
  75
  76 #endif