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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 <ipxe/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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