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05a68e892e
This is a s390 port of commit 548acf1923 ("x86/mm: Expand the
exception table logic to allow new handling options"), which is needed
for implementing BPF_PROBE_MEM on s390.
The new handler field is made 64-bit in order to allow pointing from
dynamically allocated entries to handlers in kernel text. Unlike on x86,
NULL is used instead of ex_handler_default. This is because exception
tables are used by boot/text_dma.S, and it would be a pain to preserve
ex_handler_default.
The new infrastructure is ignored in early_pgm_check_handler, since
there is no pt_regs.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
77 lines
2.0 KiB
C
77 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __S390_EXTABLE_H
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#define __S390_EXTABLE_H
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#include <asm/ptrace.h>
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#include <linux/compiler.h>
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/*
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* The exception table consists of three addresses:
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*
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* - Address of an instruction that is allowed to fault.
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* - Address at which the program should continue.
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* - Optional address of handler that takes pt_regs * argument and runs in
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* interrupt context.
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*
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* No registers are modified, so it is entirely up to the continuation code
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* to figure out what to do.
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*
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* All the routines below use bits of fixup code that are out of line
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* with the main instruction path. This means when everything is well,
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* we don't even have to jump over them. Further, they do not intrude
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* on our cache or tlb entries.
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*/
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struct exception_table_entry
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{
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int insn, fixup;
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long handler;
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};
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extern struct exception_table_entry *__start_dma_ex_table;
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extern struct exception_table_entry *__stop_dma_ex_table;
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const struct exception_table_entry *s390_search_extables(unsigned long addr);
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static inline unsigned long extable_fixup(const struct exception_table_entry *x)
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{
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return (unsigned long)&x->fixup + x->fixup;
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}
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typedef bool (*ex_handler_t)(const struct exception_table_entry *,
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struct pt_regs *);
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static inline ex_handler_t
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ex_fixup_handler(const struct exception_table_entry *x)
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{
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if (likely(!x->handler))
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return NULL;
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return (ex_handler_t)((unsigned long)&x->handler + x->handler);
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}
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static inline bool ex_handle(const struct exception_table_entry *x,
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struct pt_regs *regs)
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{
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ex_handler_t handler = ex_fixup_handler(x);
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if (unlikely(handler))
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return handler(x, regs);
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regs->psw.addr = extable_fixup(x);
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return true;
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}
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#define ARCH_HAS_RELATIVE_EXTABLE
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static inline void swap_ex_entry_fixup(struct exception_table_entry *a,
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struct exception_table_entry *b,
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struct exception_table_entry tmp,
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int delta)
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{
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a->fixup = b->fixup + delta;
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b->fixup = tmp.fixup - delta;
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a->handler = b->handler + delta;
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b->handler = tmp.handler - delta;
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}
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#endif
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