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/* ----------------------------------------------------------------------- *
*
* Copyright 2007-2009 H. Peter Anvin - All Rights Reserved
* Copyright 2009 Intel Corporation; author: H. Peter Anvin
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* shuffle_rm.c
*
* Shuffle and boot to protected mode code
*/
#include <stdlib.h>
#include <inttypes.h>
#include <com32.h>
#include <string.h>
#include <syslinux/movebits.h>
#include <syslinux/bootrm.h>
enum gpr_index { R_AX, R_CX, R_DX, R_BX, R_SP, R_BP, R_SI, R_DI };
enum seg_index { R_ES, R_CS, R_SS, R_DS, R_FS, R_GS };
#define ST8(P,V) \
do { \
uint8_t *_p = (void *)(P); \
*_p++ = (V); \
(P) = (void *)_p; \
} while (0);
#define ST16(P,V) \
do { \
uint16_t *_p = (void *)(P); \
*_p++ = (V); \
(P) = (void *)_p; \
} while (0)
#define ST32(P,V) \
do { \
uint32_t *_p = (void *)(P); \
*_p++ = (V); \
(P) = (void *)_p; \
} while (0)
#define MOV_TO_SEG(P,S,R) \
ST16(P, 0xc08e + ((R) << 8) + ((S) << 11))
#define MOV_TO_R16(P,R,V) \
do { \
ST8(P, 0xb8 + (R)); \
ST16(P, V); \
} while (0)
#define MOV_TO_R32(P,R,V) \
do { \
ST16(P, 0xb866 + ((R) << 8)); \
ST32(P, V); \
} while (0)
int syslinux_shuffle_boot_rm(struct syslinux_movelist *fraglist,
struct syslinux_memmap *memmap,
uint16_t bootflags, struct syslinux_rm_regs *regs)
{
const struct syslinux_rm_regs_alt {
uint16_t seg[6];
uint32_t gpr[8];
uint32_t csip;
bool sti;
} *rp;
int i, rv;
uint8_t handoff_code[8 + 5 * 5 + 8 * 6 + 1 + 5], *p;
uint16_t off;
struct syslinux_memmap *tmap;
addr_t regstub, stublen;
/* Assign GPRs for each sreg, don't use AX and SP */
static const uint8_t gpr_for_seg[6] =
{ R_CX, R_DX, R_BX, R_BP, R_SI, R_DI };
tmap = syslinux_target_memmap(fraglist, memmap);
if (!tmap)
return -1;
/*
* Search for a good place to put the real-mode register stub.
* We prefer it as low as possible above 0x800. KVM barfs horribly
* if we're not aligned to a paragraph boundary, so set the alignment
* appropriately.
*/
regstub = 0x800;
stublen = sizeof handoff_code;
rv = syslinux_memmap_find(tmap, SMT_FREE, ®stub, &stublen, 16);
if (rv || (regstub > 0x100000 - sizeof handoff_code)) {
/*
* Uh-oh. This isn't real-mode accessible memory.
* It might be possible to do something insane here like
* putting the stub in the IRQ vectors, or in the 0x5xx segment.
* This code tries the 0x510-0x7ff range and hopes for the best.
*/
regstub = 0x510; /* Try the 0x5xx segment... */
stublen = sizeof handoff_code;
rv = syslinux_memmap_find(tmap, SMT_FREE, ®stub, &stublen, 16);
if (!rv && (regstub > 0x100000 - sizeof handoff_code))
rv = -1; /* No acceptable memory found */
}
syslinux_free_memmap(tmap);
if (rv)
return -1;
/* Build register-setting stub */
p = handoff_code;
rp = (const struct syslinux_rm_regs_alt *)regs;
/* Set up GPRs with segment registers - don't use AX */
for (i = 0; i < 6; i++) {
if (i != R_CS)
MOV_TO_R16(p, gpr_for_seg[i], rp->seg[i]);
}
/* Actual transition to real mode */
ST32(p, 0xeac0220f); /* MOV CR0,EAX; JMP FAR */
off = (p - handoff_code) + 4;
ST16(p, off); /* Offset */
ST16(p, regstub >> 4); /* Segment */
/* Load SS and ESP immediately */
MOV_TO_SEG(p, R_SS, R_BX);
MOV_TO_R32(p, R_SP, rp->gpr[R_SP]);
/* Load the other segments */
MOV_TO_SEG(p, R_ES, R_CX);
MOV_TO_SEG(p, R_DS, R_BP);
MOV_TO_SEG(p, R_FS, R_SI);
MOV_TO_SEG(p, R_GS, R_DI);
for (i = 0; i < 8; i++) {
if (i != R_SP)
MOV_TO_R32(p, i, rp->gpr[i]);
}
ST8(p, rp->sti ? 0xfb : 0xfa); /* STI/CLI */
ST8(p, 0xea); /* JMP FAR */
ST32(p, rp->csip);
/* Add register-setting stub to shuffle list */
if (syslinux_add_movelist(&fraglist, regstub, (addr_t) handoff_code,
sizeof handoff_code))
return -1;
return syslinux_do_shuffle(fraglist, memmap, regstub, 0, bootflags);
}
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