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 77