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Diffstat (limited to 'contrib/syslinux-4.02/gpxe/src/arch/i386/prefix/libprefix.S')
| -rw-r--r-- | contrib/syslinux-4.02/gpxe/src/arch/i386/prefix/libprefix.S | 819 |
1 files changed, 819 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/arch/i386/prefix/libprefix.S b/contrib/syslinux-4.02/gpxe/src/arch/i386/prefix/libprefix.S new file mode 100644 index 0000000..9e6ba6f --- /dev/null +++ b/contrib/syslinux-4.02/gpxe/src/arch/i386/prefix/libprefix.S @@ -0,0 +1,819 @@ +/* + * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>. + * + * 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_LICENCE ( GPL2_OR_LATER ) + + .arch i386 + +/** + * High memory temporary load address + * + * Temporary buffer into which to copy (or decompress) our runtime + * image, prior to calling get_memmap() and relocate(). We don't + * actually leave anything here once install() has returned. + * + * We use the start of an even megabyte so that we don't have to worry + * about the current state of the A20 line. + * + * We use 4MB rather than 2MB because some PXE stack / PMM BIOS + * combinations are known to place data required by other UNDI ROMs + * loader around the 2MB mark. + */ + .globl HIGHMEM_LOADPOINT + .equ HIGHMEM_LOADPOINT, ( 4 << 20 ) + +/* Image compression enabled */ +#define COMPRESS 1 + +#define CR0_PE 1 + +/***************************************************************************** + * Utility function: print character (with LF -> LF,CR translation) + * + * Parameters: + * %al : character to print + * %ds:di : output buffer (or %di=0 to print to console) + * Returns: + * %ds:di : next character in output buffer (if applicable) + ***************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl print_character +print_character: + /* Preserve registers */ + pushw %ax + pushw %bx + pushw %bp + /* If %di is non-zero, write character to buffer and exit */ + testw %di, %di + jz 1f + movb %al, %ds:(%di) + incw %di + jmp 3f +1: /* Print character */ + movw $0x0007, %bx /* page 0, attribute 7 (normal) */ + movb $0x0e, %ah /* write char, tty mode */ + cmpb $0x0a, %al /* '\n'? */ + jne 2f + int $0x10 + movb $0x0d, %al +2: int $0x10 + /* Restore registers and return */ +3: popw %bp + popw %bx + popw %ax + ret + .size print_character, . - print_character + +/***************************************************************************** + * Utility function: print a NUL-terminated string + * + * Parameters: + * %ds:si : string to print + * %ds:di : output buffer (or %di=0 to print to console) + * Returns: + * %ds:si : character after terminating NUL + * %ds:di : next character in output buffer (if applicable) + ***************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl print_message +print_message: + /* Preserve registers */ + pushw %ax + /* Print string */ +1: lodsb + testb %al, %al + je 2f + call print_character + jmp 1b +2: /* Restore registers and return */ + popw %ax + ret + .size print_message, . - print_message + +/***************************************************************************** + * Utility functions: print hex digit/byte/word/dword + * + * Parameters: + * %al (low nibble) : digit to print + * %al : byte to print + * %ax : word to print + * %eax : dword to print + * %ds:di : output buffer (or %di=0 to print to console) + * Returns: + * %ds:di : next character in output buffer (if applicable) + ***************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl print_hex_dword +print_hex_dword: + rorl $16, %eax + call print_hex_word + rorl $16, %eax + /* Fall through */ + .size print_hex_dword, . - print_hex_dword + .globl print_hex_word +print_hex_word: + xchgb %al, %ah + call print_hex_byte + xchgb %al, %ah + /* Fall through */ + .size print_hex_word, . - print_hex_word + .globl print_hex_byte +print_hex_byte: + rorb $4, %al + call print_hex_nibble + rorb $4, %al + /* Fall through */ + .size print_hex_byte, . - print_hex_byte + .globl print_hex_nibble +print_hex_nibble: + /* Preserve registers */ + pushw %ax + /* Print digit (technique by Norbert Juffa <norbert.juffa@amd.com> */ + andb $0x0f, %al + cmpb $10, %al + sbbb $0x69, %al + das + call print_character + /* Restore registers and return */ + popw %ax + ret + .size print_hex_nibble, . - print_hex_nibble + +/***************************************************************************** + * Utility function: print PCI bus:dev.fn + * + * Parameters: + * %ax : PCI bus:dev.fn to print + * %ds:di : output buffer (or %di=0 to print to console) + * Returns: + * %ds:di : next character in output buffer (if applicable) + ***************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl print_pci_busdevfn +print_pci_busdevfn: + /* Preserve registers */ + pushw %ax + /* Print bus */ + xchgb %al, %ah + call print_hex_byte + /* Print ":" */ + movb $( ':' ), %al + call print_character + /* Print device */ + movb %ah, %al + shrb $3, %al + call print_hex_byte + /* Print "." */ + movb $( '.' ), %al + call print_character + /* Print function */ + movb %ah, %al + andb $0x07, %al + call print_hex_nibble + /* Restore registers and return */ + popw %ax + ret + .size print_pci_busdevfn, . - print_pci_busdevfn + +/***************************************************************************** + * Utility function: clear current line + * + * Parameters: + * %ds:di : output buffer (or %di=0 to print to console) + * Returns: + * %ds:di : next character in output buffer (if applicable) + ***************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl print_kill_line +print_kill_line: + /* Preserve registers */ + pushw %ax + pushw %cx + /* Print CR */ + movb $( '\r' ), %al + call print_character + /* Print 79 spaces */ + movb $( ' ' ), %al + movw $79, %cx +1: call print_character + loop 1b + /* Print CR */ + movb $( '\r' ), %al + call print_character + /* Restore registers and return */ + popw %cx + popw %ax + ret + .size print_kill_line, . - print_kill_line + +/**************************************************************************** + * pm_call (real-mode near call) + * + * Call routine in 16-bit protected mode for access to extended memory + * + * Parameters: + * %ax : address of routine to call in 16-bit protected mode + * Returns: + * none + * Corrupts: + * %ax + * + * The specified routine is called in 16-bit protected mode, with: + * + * %cs : 16-bit code segment with base matching real-mode %cs + * %ss : 16-bit data segment with base matching real-mode %ss + * %ds,%es,%fs,%gs : 32-bit data segment with zero base and 4GB limit + * + **************************************************************************** + */ + +#ifndef KEEP_IT_REAL + + /* GDT for protected-mode calls */ + .section ".prefix.lib", "awx", @progbits + .align 16 +pm_call_vars: +gdt: +gdt_limit: .word gdt_length - 1 +gdt_base: .long 0 + .word 0 /* padding */ +pm_cs: /* 16-bit protected-mode code segment */ + .equ PM_CS, pm_cs - gdt + .word 0xffff, 0 + .byte 0, 0x9b, 0x00, 0 +pm_ss: /* 16-bit protected-mode stack segment */ + .equ PM_SS, pm_ss - gdt + .word 0xffff, 0 + .byte 0, 0x93, 0x00, 0 +pm_ds: /* 32-bit protected-mode flat data segment */ + .equ PM_DS, pm_ds - gdt + .word 0xffff, 0 + .byte 0, 0x93, 0xcf, 0 +gdt_end: + .equ gdt_length, . - gdt + .size gdt, . - gdt + + .section ".prefix.lib", "awx", @progbits + .align 16 +pm_saved_gdt: + .long 0, 0 + .size pm_saved_gdt, . - pm_saved_gdt + + .equ pm_call_vars_size, . - pm_call_vars +#define PM_CALL_VAR(x) ( -pm_call_vars_size + ( (x) - pm_call_vars ) ) + + .section ".prefix.lib", "awx", @progbits + .code16 +pm_call: + /* Preserve registers, flags, and RM return point */ + pushw %bp + movw %sp, %bp + subw $pm_call_vars_size, %sp + andw $0xfff0, %sp + pushfl + pushw %gs + pushw %fs + pushw %es + pushw %ds + pushw %ss + pushw %cs + pushw $99f + + /* Set up local variable block, and preserve GDT */ + pushw %cx + pushw %si + pushw %di + pushw %ss + popw %es + movw $pm_call_vars, %si + leaw PM_CALL_VAR(pm_call_vars)(%bp), %di + movw $pm_call_vars_size, %cx + cs rep movsb + popw %di + popw %si + popw %cx + sgdt PM_CALL_VAR(pm_saved_gdt)(%bp) + + /* Set up GDT bases */ + pushl %eax + pushl %edi + xorl %eax, %eax + movw %ss, %ax + shll $4, %eax + movzwl %bp, %edi + addr32 leal PM_CALL_VAR(gdt)(%eax, %edi), %eax + movl %eax, PM_CALL_VAR(gdt_base)(%bp) + movw %cs, %ax + movw $PM_CALL_VAR(pm_cs), %di + call set_seg_base + movw %ss, %ax + movw $PM_CALL_VAR(pm_ss), %di + call set_seg_base + popl %edi + popl %eax + + /* Switch CPU to protected mode and load up segment registers */ + pushl %eax + cli + data32 lgdt PM_CALL_VAR(gdt)(%bp) + movl %cr0, %eax + orb $CR0_PE, %al + movl %eax, %cr0 + ljmp $PM_CS, $1f +1: movw $PM_SS, %ax + movw %ax, %ss + movw $PM_DS, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + popl %eax + + /* Call PM routine */ + call *%ax + + /* Set real-mode segment limits on %ds, %es, %fs and %gs */ + movw %ss, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + + /* Return CPU to real mode */ + movl %cr0, %eax + andb $0!CR0_PE, %al + movl %eax, %cr0 + + /* Restore registers and flags */ + lret /* will ljmp to 99f */ +99: popw %ss + popw %ds + popw %es + popw %fs + popw %gs + data32 lgdt PM_CALL_VAR(pm_saved_gdt)(%bp) + popfl + movw %bp, %sp + popw %bp + ret + .size pm_call, . - pm_call + +set_seg_base: + rolw $4, %ax + movw %ax, 2(%bp,%di) + andw $0xfff0, 2(%bp,%di) + movb %al, 4(%bp,%di) + andb $0x0f, 4(%bp,%di) + ret + .size set_seg_base, . - set_seg_base + +#endif /* KEEP_IT_REAL */ + +/**************************************************************************** + * copy_bytes (real-mode or 16-bit protected-mode near call) + * + * Copy bytes + * + * Parameters: + * %ds:esi : source address + * %es:edi : destination address + * %ecx : length + * Returns: + * %ds:esi : next source address + * %es:edi : next destination address + * Corrupts: + * None + **************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 +copy_bytes: + pushl %ecx + rep addr32 movsb + popl %ecx + ret + .size copy_bytes, . - copy_bytes + +/**************************************************************************** + * install_block (real-mode near call) + * + * Install block to specified address + * + * Parameters: + * %esi : source physical address (must be a multiple of 16) + * %edi : destination physical address (must be a multiple of 16) + * %ecx : length of (decompressed) data + * %edx : total length of block (including any uninitialised data portion) + * Returns: + * %esi : next source physical address (will be a multiple of 16) + * Corrupts: + * none + **************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 +install_block: + +#ifdef KEEP_IT_REAL + + /* Preserve registers */ + pushw %ds + pushw %es + pushl %ecx + pushl %edi + + /* Convert %esi and %edi to segment registers */ + shrl $4, %esi + movw %si, %ds + xorw %si, %si + shrl $4, %edi + movw %di, %es + xorw %di, %di + +#else /* KEEP_IT_REAL */ + + /* Call self in protected mode */ + pushw %ax + movw $1f, %ax + call pm_call + popw %ax + ret +1: + /* Preserve registers */ + pushl %ecx + pushl %edi + +#endif /* KEEP_IT_REAL */ + + +#if COMPRESS + /* Decompress source to destination */ + call decompress16 +#else + /* Copy source to destination */ + call copy_bytes +#endif + + /* Zero .bss portion */ + negl %ecx + addl %edx, %ecx + pushw %ax + xorw %ax, %ax + rep addr32 stosb + popw %ax + + /* Round up %esi to start of next source block */ + addl $0xf, %esi + andl $~0xf, %esi + + +#ifdef KEEP_IT_REAL + + /* Convert %ds:esi back to a physical address */ + movzwl %ds, %cx + shll $4, %ecx + addl %ecx, %esi + + /* Restore registers */ + popl %edi + popl %ecx + popw %es + popw %ds + +#else /* KEEP_IT_REAL */ + + /* Restore registers */ + popl %edi + popl %ecx + +#endif + + ret + .size install_block, . - install_block + +/**************************************************************************** + * alloc_basemem (real-mode near call) + * + * Allocate space for .text16 and .data16 from top of base memory. + * Memory is allocated using the BIOS free base memory counter at + * 0x40:13. + * + * Parameters: + * none + * Returns: + * %ax : .text16 segment address + * %bx : .data16 segment address + * Corrupts: + * none + **************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl alloc_basemem +alloc_basemem: + /* Preserve registers */ + pushw %fs + + /* FBMS => %ax as segment address */ + pushw $0x40 + popw %fs + movw %fs:0x13, %ax + shlw $6, %ax + + /* Calculate .data16 segment address */ + subw $_data16_memsz_pgh, %ax + pushw %ax + + /* Calculate .text16 segment address */ + subw $_text16_memsz_pgh, %ax + pushw %ax + + /* Update FBMS */ + shrw $6, %ax + movw %ax, %fs:0x13 + + /* Retrieve .text16 and .data16 segment addresses */ + popw %ax + popw %bx + + /* Restore registers and return */ + popw %fs + ret + .size alloc_basemem, . - alloc_basemem + +/**************************************************************************** + * free_basemem (real-mode near call) + * + * Free space allocated with alloc_basemem. + * + * Parameters: + * %ax : .text16 segment address + * %bx : .data16 segment address + * Returns: + * %ax : 0 if successfully freed + * Corrupts: + * none + **************************************************************************** + */ + .section ".text16", "ax", @progbits + .code16 + .globl free_basemem +free_basemem: + /* Preserve registers */ + pushw %fs + + /* Check FBMS counter */ + pushw %ax + shrw $6, %ax + pushw $0x40 + popw %fs + cmpw %ax, %fs:0x13 + popw %ax + jne 1f + + /* Check hooked interrupt count */ + cmpw $0, %cs:hooked_bios_interrupts + jne 1f + + /* OK to free memory */ + addw $_text16_memsz_pgh, %ax + addw $_data16_memsz_pgh, %ax + shrw $6, %ax + movw %ax, %fs:0x13 + xorw %ax, %ax + +1: /* Restore registers and return */ + popw %fs + ret + .size free_basemem, . - free_basemem + + .section ".text16.data", "aw", @progbits + .globl hooked_bios_interrupts +hooked_bios_interrupts: + .word 0 + .size hooked_bios_interrupts, . - hooked_bios_interrupts + +/**************************************************************************** + * install (real-mode near call) + * + * Install all text and data segments. + * + * Parameters: + * none + * Returns: + * %ax : .text16 segment address + * %bx : .data16 segment address + * Corrupts: + * none + **************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl install +install: + /* Preserve registers */ + pushl %esi + pushl %edi + /* Allocate space for .text16 and .data16 */ + call alloc_basemem + /* Image source = %cs:0000 */ + xorl %esi, %esi + /* Image destination = HIGHMEM_LOADPOINT */ + movl $HIGHMEM_LOADPOINT, %edi + /* Install text and data segments */ + call install_prealloc + /* Restore registers and return */ + popl %edi + popl %esi + ret + .size install, . - install + +/**************************************************************************** + * install_prealloc (real-mode near call) + * + * Install all text and data segments. + * + * Parameters: + * %ax : .text16 segment address + * %bx : .data16 segment address + * %esi : Image source physical address (or zero for %cs:0000) + * %edi : Decompression temporary area physical address + * Corrupts: + * none + **************************************************************************** + */ + .section ".prefix.lib", "awx", @progbits + .code16 + .globl install_prealloc +install_prealloc: + /* Save registers */ + pushal + pushw %ds + pushw %es + + /* Sanity: clear the direction flag asap */ + cld + + /* Calculate physical address of payload (i.e. first source) */ + testl %esi, %esi + jnz 1f + movw %cs, %si + shll $4, %esi +1: addl $_payload_lma, %esi + + /* Install .text16 and .data16 */ + pushl %edi + movzwl %ax, %edi + shll $4, %edi + movl $_text16_memsz, %ecx + movl %ecx, %edx + call install_block /* .text16 */ + movzwl %bx, %edi + shll $4, %edi + movl $_data16_filesz, %ecx + movl $_data16_memsz, %edx + call install_block /* .data16 */ + popl %edi + + /* Set up %ds for access to .data16 */ + movw %bx, %ds + +#ifdef KEEP_IT_REAL + /* Initialise libkir */ + movw %ax, (init_libkir_vector+2) + lcall *init_libkir_vector +#else + /* Install .text and .data to temporary area in high memory, + * prior to reading the E820 memory map and relocating + * properly. + */ + movl $_textdata_filesz, %ecx + movl $_textdata_memsz, %edx + call install_block + + /* Initialise librm at current location */ + movw %ax, (init_librm_vector+2) + lcall *init_librm_vector + + /* Call relocate() to determine target address for relocation. + * relocate() will return with %esi, %edi and %ecx set up + * ready for the copy to the new location. + */ + movw %ax, (prot_call_vector+2) + pushl $relocate + lcall *prot_call_vector + popl %edx /* discard */ + + /* Copy code to new location */ + pushl %edi + pushw %ax + movw $copy_bytes, %ax + call pm_call + popw %ax + popl %edi + + /* Initialise librm at new location */ + lcall *init_librm_vector + +#endif + /* Restore registers */ + popw %es + popw %ds + popal + ret + .size install_prealloc, . - install_prealloc + + /* Vectors for far calls to .text16 functions */ + .section ".data16", "aw", @progbits +#ifdef KEEP_IT_REAL +init_libkir_vector: + .word init_libkir + .word 0 + .size init_libkir_vector, . - init_libkir_vector +#else +init_librm_vector: + .word init_librm + .word 0 + .size init_librm_vector, . - init_librm_vector +prot_call_vector: + .word prot_call + .word 0 + .size prot_call_vector, . - prot_call_vector +#endif + +/**************************************************************************** + * uninstall (real-mode near call) + * + * Uninstall all text and data segments. + * + * Parameters: + * %ax : .text16 segment address + * %bx : .data16 segment address + * Returns: + * none + * Corrupts: + * none + **************************************************************************** + */ + .section ".text16", "ax", @progbits + .code16 + .globl uninstall +uninstall: + call free_basemem + ret + .size uninstall, . - uninstall + + + + /* File split information for the compressor */ +#if COMPRESS + .section ".zinfo", "a", @progbits + .ascii "COPY" + .long _prefix_lma + .long _prefix_filesz + .long _max_align + .ascii "PACK" + .long _text16_lma + .long _text16_filesz + .long _max_align + .ascii "PACK" + .long _data16_lma + .long _data16_filesz + .long _max_align + .ascii "PACK" + .long _textdata_lma + .long _textdata_filesz + .long _max_align +#else /* COMPRESS */ + .section ".zinfo", "a", @progbits + .ascii "COPY" + .long _prefix_lma + .long _filesz + .long _max_align +#endif /* COMPRESS */ |