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/*
* Copyright (C) 2008 Daniel Verkamp <daniel@drv.nu>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/**
* @file SYSLINUX COM32 helpers
*
*/
FILE_LICENCE ( GPL2_OR_LATER );
#include <stdint.h>
#include <realmode.h>
#include <comboot.h>
#include <assert.h>
#include <gpxe/uaccess.h>
static com32sys_t __bss16 ( com32_regs );
#define com32_regs __use_data16 ( com32_regs )
static uint8_t __bss16 ( com32_int_vector );
#define com32_int_vector __use_data16 ( com32_int_vector )
static uint32_t __bss16 ( com32_farcall_proc );
#define com32_farcall_proc __use_data16 ( com32_farcall_proc )
uint16_t __bss16 ( com32_saved_sp );
/**
* Interrupt call helper
*/
void __asmcall com32_intcall ( uint8_t interrupt, physaddr_t inregs_phys, physaddr_t outregs_phys ) {
memcpy_user ( virt_to_user( &com32_regs ), 0,
phys_to_user ( inregs_phys ), 0,
sizeof(com32sys_t) );
com32_int_vector = interrupt;
__asm__ __volatile__ (
REAL_CODE ( /* Save all registers */
"pushal\n\t"
"pushw %%ds\n\t"
"pushw %%es\n\t"
"pushw %%fs\n\t"
"pushw %%gs\n\t"
/* Mask off unsafe flags */
"movl (com32_regs + 40), %%eax\n\t"
"andl $0x200cd7, %%eax\n\t"
"movl %%eax, (com32_regs + 40)\n\t"
/* Load com32_regs into the actual registers */
"movw %%sp, %%ss:(com32_saved_sp)\n\t"
"movw $com32_regs, %%sp\n\t"
"popw %%gs\n\t"
"popw %%fs\n\t"
"popw %%es\n\t"
"popw %%ds\n\t"
"popal\n\t"
"popfl\n\t"
"movw %%ss:(com32_saved_sp), %%sp\n\t"
/* patch INT instruction */
"pushw %%ax\n\t"
"movb %%ss:(com32_int_vector), %%al\n\t"
"movb %%al, %%cs:(com32_intcall_instr + 1)\n\t"
/* perform a jump to avoid problems with cache
* consistency in self-modifying code on some CPUs (486)
*/
"jmp 1f\n"
"1:\n\t"
"popw %%ax\n\t"
"com32_intcall_instr:\n\t"
/* INT instruction to be patched */
"int $0xFF\n\t"
/* Copy regs back to com32_regs */
"movw %%sp, %%ss:(com32_saved_sp)\n\t"
"movw $(com32_regs + 44), %%sp\n\t"
"pushfl\n\t"
"pushal\n\t"
"pushw %%ds\n\t"
"pushw %%es\n\t"
"pushw %%fs\n\t"
"pushw %%gs\n\t"
"movw %%ss:(com32_saved_sp), %%sp\n\t"
/* Restore registers */
"popw %%gs\n\t"
"popw %%fs\n\t"
"popw %%es\n\t"
"popw %%ds\n\t"
"popal\n\t")
: : );
if ( outregs_phys ) {
memcpy_user ( phys_to_user ( outregs_phys ), 0,
virt_to_user( &com32_regs ), 0,
sizeof(com32sys_t) );
}
}
/**
* Farcall helper
*/
void __asmcall com32_farcall ( uint32_t proc, physaddr_t inregs_phys, physaddr_t outregs_phys ) {
memcpy_user ( virt_to_user( &com32_regs ), 0,
phys_to_user ( inregs_phys ), 0,
sizeof(com32sys_t) );
com32_farcall_proc = proc;
__asm__ __volatile__ (
REAL_CODE ( /* Save all registers */
"pushal\n\t"
"pushw %%ds\n\t"
"pushw %%es\n\t"
"pushw %%fs\n\t"
"pushw %%gs\n\t"
/* Mask off unsafe flags */
"movl (com32_regs + 40), %%eax\n\t"
"andl $0x200cd7, %%eax\n\t"
"movl %%eax, (com32_regs + 40)\n\t"
/* Load com32_regs into the actual registers */
"movw %%sp, %%ss:(com32_saved_sp)\n\t"
"movw $com32_regs, %%sp\n\t"
"popw %%gs\n\t"
"popw %%fs\n\t"
"popw %%es\n\t"
"popw %%ds\n\t"
"popal\n\t"
"popfl\n\t"
"movw %%ss:(com32_saved_sp), %%sp\n\t"
/* Call procedure */
"lcall *%%ss:(com32_farcall_proc)\n\t"
/* Copy regs back to com32_regs */
"movw %%sp, %%ss:(com32_saved_sp)\n\t"
"movw $(com32_regs + 44), %%sp\n\t"
"pushfl\n\t"
"pushal\n\t"
"pushw %%ds\n\t"
"pushw %%es\n\t"
"pushw %%fs\n\t"
"pushw %%gs\n\t"
"movw %%ss:(com32_saved_sp), %%sp\n\t"
/* Restore registers */
"popw %%gs\n\t"
"popw %%fs\n\t"
"popw %%es\n\t"
"popw %%ds\n\t"
"popal\n\t")
: : );
if ( outregs_phys ) {
memcpy_user ( phys_to_user ( outregs_phys ), 0,
virt_to_user( &com32_regs ), 0,
sizeof(com32sys_t) );
}
}
/**
* CDECL farcall helper
*/
int __asmcall com32_cfarcall ( uint32_t proc, physaddr_t stack, size_t stacksz ) {
int32_t eax;
copy_user_to_rm_stack ( phys_to_user ( stack ), stacksz );
com32_farcall_proc = proc;
__asm__ __volatile__ (
REAL_CODE ( "lcall *%%ss:(com32_farcall_proc)\n\t" )
: "=a" (eax)
:
: "ecx", "edx" );
remove_user_from_rm_stack ( 0, stacksz );
return eax;
}
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