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/* $OpenBSD: codepatch.h,v 1.4 2017/08/25 19:28:48 guenther Exp $ */
/*
* Copyright (c) 2014-2015 Stefan Fritsch <sf@sfritsch.de>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#ifndef _MACHINE_CODEPATCH_H_
#define _MACHINE_CODEPATCH_H_
#include <machine/param.h>
#ifndef _LOCORE
void *codepatch_maprw(vaddr_t *nva, vaddr_t dest);
void codepatch_unmaprw(vaddr_t nva);
void codepatch_fill_nop(void *caddr, uint16_t len);
void codepatch_nop(uint16_t tag);
void codepatch_replace(uint16_t tag, void *code, size_t len);
void codepatch_call(uint16_t tag, void *func);
#endif /* !_LOCORE */
/*
* Mark the start of some code snippet to be patched.
*/
#define CODEPATCH_START 998:
/*
* Mark the end of some code to be patched, and assign the given tag.
*/
#define CODEPATCH_END(tag) \
999: \
.section .codepatch, "a" ;\
.quad 998b ;\
.short (999b - 998b) ;\
.short tag ;\
.int 0 ;\
.previous
#define CPTAG_STAC 1
#define CPTAG_CLAC 2
#define CPTAG_EOI 3
/*
* As stac/clac SMAP instructions are 3 bytes, we want the fastest
* 3 byte nop sequence possible here. This will be replaced by
* stac/clac instructions if SMAP is detected after booting.
*
* This would be 'nop (%rax)' if binutils could cope.
* Intel documents multi-byte NOP sequences as being available
* on all family 0x6 and 0xf processors (ie 686+)
*/
#define SMAP_NOP .byte 0x0f, 0x1f, 0x00
#define SMAP_STAC CODEPATCH_START ;\
SMAP_NOP ;\
CODEPATCH_END(CPTAG_STAC)
#define SMAP_CLAC CODEPATCH_START ;\
SMAP_NOP ;\
CODEPATCH_END(CPTAG_CLAC)
#endif /* _MACHINE_CODEPATCH_H_ */
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