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/* ----------------------------------------------------------------------- *
*
* Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
*
* 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>
int syslinux_shuffle_boot_rm(struct syslinux_movelist *fraglist,
struct syslinux_memmap *memmap,
uint16_t bootflags,
struct syslinux_rm_regs *regs)
{
int nd;
com32sys_t ireg;
char *regbuf;
const struct syslinux_rm_regs_alt {
uint16_t seg[6];
uint32_t gpr[8];
uint32_t csip;
} *rp;
int i, rv;
uint8_t handoff_code[5*5+8*6+5], *p;
struct syslinux_memmap *tmap, *tp;
addr_t regstub;
tmap = syslinux_target_memmap(fraglist, memmap);
if (!tmap)
return -1;
/* Search for a good place to put the real-mode register stub.
We prefer to put it as high as possible in the low 640K. */
regstub = 0;
for (tp = tmap; tp->type != SMT_END; tp = tp->next) {
addr_t xend, xlen;
if (tp->start >= 640*1024)
continue;
if (tp->type != SMT_FREE)
continue;
xend = tp->next->start;
if (xend > 640*1024)
xend = 640*1024;
xlen = xend - tp->start;
if (xlen < sizeof handoff_code)
continue;
regstub = xend - sizeof handoff_code; /* Best alternative so far */
}
syslinux_free_memmap(tmap);
/* XXX: it might be possible to do something insane here like
putting the stub in the IRQ vectors... */
if (!regstub)
return -1; /* No space at all */
/* Build register-setting stub */
p = handoff_code;
rp = (const struct syslinux_rm_regs_alt *)regs;
for (i = 0; i < 6; i++) {
if (i != 1) { /* Skip CS */
p[0] = 0xb8; /* MOV AX,imm16 */
*(uint16_t *)(p+1) = rp->seg[i];
*(uint16_t *)(p+3) = 0xc08e + (i << 11); /* MOV seg,AX */
p += 5;
}
}
for (i = 0; i < 8; i++) {
p[0] = 0x66; /* MOV exx,imm32 */
p[1] = 0xb8 + i;
*(uint32_t *)(p+2) = rp->gpr[i];
p += 6;
}
*p++ = 0xea; /* JMP FAR */
*(uint32_t *)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;
/* Convert regstub to a CS:IP entrypoint pair */
regstub = (SEG((void *)regstub) << 16) + OFFS((void *)regstub);
return syslinux_do_shuffle(fraglist, memmap, regstub, 0, bootflags);
}
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