// Rom layout and bios assembler to C interface. // // Copyright (C) 2008,2009 Kevin O'Connor // Copyright (C) 2002 MandrakeSoft S.A. // // This file may be distributed under the terms of the GNU LGPLv3 license. /**************************************************************** * Include of 16bit C code ****************************************************************/ .code16gcc #include "ccode.16.s" #include "config.h" // CONFIG_* #include "ioport.h" // PORT_A20 #include "bregs.h" // CR0_* #include "cmos.h" // CMOS_RESET_CODE #include "asm-offsets.h" // BREGS_* #include "entryfuncs.S" // ENTRY_* /**************************************************************** * Call trampolines ****************************************************************/ // Place CPU into 32bit mode from 16bit mode. // %edx = return location (in 32bit mode) // Clobbers: ecx, flags, segment registers, cr0, idt/gdt DECLFUNC transition32 transition32: movl %eax, %ecx // Disable irqs (and clear direction flag) cli cld // Disable nmi movl $CMOS_RESET_CODE|NMI_DISABLE_BIT, %eax outb %al, $PORT_CMOS_INDEX inb $PORT_CMOS_DATA, %al // enable a20 inb $PORT_A20, %al orb $A20_ENABLE_BIT, %al outb %al, $PORT_A20 // Set segment descriptors lidtw %cs:pmode_IDT_info lgdtw %cs:rombios32_gdt_48 // Enable protected mode movl %cr0, %eax orl $CR0_PE, %eax movl %eax, %cr0 // start 32bit protected mode code ljmpl $SEG32_MODE32_CS, $(BUILD_BIOS_ADDR + 1f) .code32 1: // init data segments movl $SEG32_MODE32_DS, %eax movw %ax, %ds movw %ax, %es movw %ax, %ss movw %ax, %fs movw %ax, %gs movl %ecx, %eax jmpl *%edx // Place CPU into 16bit mode from 32bit mode. // %edx = return location (in 16bit mode) // Clobbers: ecx, flags, segment registers, cr0, idt/gdt DECLFUNC transition16 .global transition16big transition16: movl %eax, %ecx // restore data segment limits to 0xffff movl $SEG32_MODE16_DS, %eax movw %ax, %ds movw %ax, %es movw %ax, %ss movw %ax, %fs movw %ax, %gs #if CONFIG_DISABLE_A20 // disable a20 inb $PORT_A20, %al andb $~A20_ENABLE_BIT, %al outb %al, $PORT_A20 #endif // Jump to 16bit mode ljmpw $SEG32_MODE16_CS, $1f transition16big: movl %eax, %ecx movl $SEG32_MODE16BIG_DS, %eax movw %ax, %ds movw %ax, %es movw %ax, %ss movw %ax, %fs movw %ax, %gs ljmpw $SEG32_MODE16BIG_CS, $1f .code16gcc 1: // Disable protected mode movl %cr0, %eax andl $~CR0_PE, %eax movl %eax, %cr0 // far jump to flush CPU queue after transition to real mode ljmpw $SEG_BIOS, $2f 2: // restore IDT to normal real-mode defaults lidtw %cs:rmode_IDT_info // Clear segment registers xorw %ax, %ax movw %ax, %fs movw %ax, %gs movw %ax, %es movw %ax, %ds movw %ax, %ss // Assume stack is in segment 0 movl %ecx, %eax jmpl *%edx // Call a 16bit function from 16bit mode with a specified cpu register state // %eax = address of struct bregs // Clobbers: %e[bcd]x, %e[ds]i, flags DECLFUNC __call16 __call16: // Save %eax, %ebp pushl %ebp pushl %eax // Setup for iretw call pushw %cs pushw $1f // return point pushw BREGS_flags(%eax) // flags pushl BREGS_code(%eax) // CS:IP // Load calling registers. movl BREGS_edi(%eax), %edi movl BREGS_esi(%eax), %esi movl BREGS_ebp(%eax), %ebp movl BREGS_ebx(%eax), %ebx movl BREGS_edx(%eax), %edx movl BREGS_ecx(%eax), %ecx movw BREGS_es(%eax), %es movw BREGS_ds(%eax), %ds movl %ss:BREGS_eax(%eax), %eax // Invoke call iretw // XXX - just do a lcalll 1: // Store flags, eax, ecx pushfw pushl %eax movl 0x06(%esp), %eax movl %ecx, %ss:BREGS_ecx(%eax) movw %ds, %ss:BREGS_ds(%eax) movw %ss, %cx movw %cx, %ds // Restore %ds == %ss popl %ecx movl %ecx, BREGS_eax(%eax) popw %cx movw %cx, BREGS_flags(%eax) // Store remaining registers movw %es, BREGS_es(%eax) movl %edi, BREGS_edi(%eax) movl %esi, BREGS_esi(%eax) movl %ebp, BREGS_ebp(%eax) movl %ebx, BREGS_ebx(%eax) movl %edx, BREGS_edx(%eax) // Remove %eax, restore %ebp popl %eax popl %ebp retl // Call a 16bit function from 32bit mode. // %eax = address of struct bregs // Clobbers: %e[bcd]x, %e[ds]i, flags, segment registers, idt/gdt DECLFUNC __call16_from32 .global __call16big_from32 .code32 __call16_from32: movl $1f, %edx jmp transition16 __call16big_from32: movl $1f, %edx jmp transition16big // Make call. .code16gcc 1: calll __call16 // Return via transition32 movl $(2f + BUILD_BIOS_ADDR), %edx jmp transition32 .code32 2: retl .code16gcc // IRQ trampolines .macro IRQ_TRAMPOLINE num DECLFUNC irq_trampoline_0x\num irq_trampoline_0x\num : int $0x\num lretw .endm IRQ_TRAMPOLINE 10 IRQ_TRAMPOLINE 13 IRQ_TRAMPOLINE 15 IRQ_TRAMPOLINE 16 IRQ_TRAMPOLINE 18 IRQ_TRAMPOLINE 19 /**************************************************************** * Misc. entry points. ****************************************************************/ // Resume (and reboot) entry point - called from entry_post DECLFUNC entry_resume entry_resume: // Disable interrupts cli cld // Use a stack in EBDA movw $SEG_BDA, %ax movw %ax, %ds movw BDA_ebda_seg, %ax movw %ax, %ds movw %ax, %ss movl $EBDA_OFFSET_TOP_STACK, %esp // Call handler. jmp handle_resume // PMM entry point DECLFUNC entry_pmm entry_pmm: pushl %esp // Backup %esp, then clear high bits movzwl %sp, %esp pushfl // Save registers clobbered by C code cli cld pushl %eax pushl %ecx pushl %edx pushw %es pushw %ds movw %ss, %cx // Move %ss to %ds movw %cx, %ds movl $_cfunc32flat_handle_pmm, %eax // Setup: call32(handle_pmm, args, -1) leal 28(%esp), %edx // %edx points to start of args movl $-1, %ecx calll call32 movw %ax, 12(%esp) // Modify %ax:%dx to return %eax shrl $16, %eax movw %ax, 4(%esp) popw %ds // Restore saved registers popw %es popl %edx popl %ecx popl %eax popfl popl %esp lretw // PnP entry points DECLFUNC entry_pnp_real .global entry_pnp_prot entry_pnp_prot: pushl %esp jmp 1f entry_pnp_real: pushl %esp // Backup %esp, then clear high bits movzwl %sp, %esp 1: pushfl // Save registers clobbered by C code cli cld pushl %eax pushl %ecx pushl %edx pushw %es pushw %ds movw %ss, %cx // Move %ss to %ds movw %cx, %ds leal 28(%esp), %eax // %eax points to start of u16 args calll handle_pnp movw %ax, 12(%esp) // Modify %eax to return %ax popw %ds popw %es popl %edx popl %ecx popl %eax popfl popl %esp lretw // APM entry points DECLFUNC entry_apm16 entry_apm16: pushfw // save flags pushl %eax // dummy ENTRY_ARG handle_apm16 addw $4, %sp // pop dummy popfw // restore flags lretw .code32 DECLFUNC entry_apm32 entry_apm32: pushfl pushl %gs pushl %cs // Move second descriptor after %cs to %gs addl $16, (%esp) popl %gs ENTRY_ARG_ESP _cfunc32seg_handle_apm32 popl %gs popfl lretl // PCI-BIOS 32bit entry point DECLFUNC entry_pcibios32 entry_pcibios32: pushfl pushl %gs // Backup %gs and set %gs=%ds pushl %ds popl %gs ENTRY_ARG_ESP _cfunc32seg_handle_pcibios32 popl %gs popfl lretl // BIOS32 support EXPORTFUNC entry_bios32 entry_bios32: pushfl #if CONFIG_PCIBIOS // Check for PCI-BIOS request cmpl $0x49435024, %eax // $PCI jne 1f movl $BUILD_BIOS_ADDR, %ebx movl $BUILD_BIOS_SIZE, %ecx movl $entry_pcibios32, %edx xorb %al, %al jmp 2f #endif // Unknown request 1: movb $0x80, %al // Return to caller 2: popfl lretl // 32bit elf entry point EXPORTFUNC entry_elf entry_elf: cli cld lidtl (BUILD_BIOS_ADDR + pmode_IDT_info) lgdtl (BUILD_BIOS_ADDR + rombios32_gdt_48) movl $SEG32_MODE32_DS, %eax movw %ax, %ds movw %ax, %es movw %ax, %fs movw %ax, %gs movw %ax, %ss movl $BUILD_STACK_ADDR, %esp ljmpl $SEG32_MODE32_CS, $_cfunc32flat_handle_post .code16gcc /**************************************************************** * Interrupt entry points ****************************************************************/ // Main entry point for interrupts without args DECLFUNC irqentry irqentry: ENTRY_ST iretw // Main entry point for interrupts with args DECLFUNC irqentryarg irqentryarg: ENTRY_ARG_ST iretw // Define an entry point for an interrupt (no args passed). .macro IRQ_ENTRY num .global entry_\num entry_\num : pushl $ handle_\num jmp irqentry .endm .macro DECL_IRQ_ENTRY num DECLFUNC entry_\num IRQ_ENTRY \num .endm // Define an entry point for an interrupt (can read/modify args). .macro IRQ_ENTRY_ARG num .global entry_\num entry_\num : pushl $ handle_\num jmp irqentryarg .endm .macro DECL_IRQ_ENTRY_ARG num DECLFUNC entry_\num IRQ_ENTRY_ARG \num .endm // Various entry points (that don't require a fixed location). DECL_IRQ_ENTRY_ARG 13 DECL_IRQ_ENTRY 76 DECL_IRQ_ENTRY 70 DECL_IRQ_ENTRY 74 DECL_IRQ_ENTRY 75 DECL_IRQ_ENTRY hwpic1 DECL_IRQ_ENTRY hwpic2 // int 18/19 are special - they reset stack and call into 32bit mode. DECLFUNC entry_19 entry_19: ENTRY_INTO32 _cfunc32flat_handle_19 DECLFUNC entry_18 entry_18: ENTRY_INTO32 _cfunc32flat_handle_18 /**************************************************************** * Fixed position entry points ****************************************************************/ // Specify a location in the fixed part of bios area. .macro ORG addr .section .fixedaddr.\addr .endm ORG 0xe05b entry_post: cmpl $0, %cs:HaveRunPost // Check for resume/reboot jnz entry_resume ENTRY_INTO32 _cfunc32flat_handle_post // Normal entry point ORG 0xe2c3 IRQ_ENTRY 02 ORG 0xe3fe .global entry_13_official entry_13_official: jmp entry_13 // 0xe401 - OldFDPT in disk.c ORG 0xe6f2 .global entry_19_official entry_19_official: jmp entry_19 // 0xe6f5 - BIOS_CONFIG_TABLE in misc.c // 0xe729 - BaudTable in serial.c ORG 0xe739 IRQ_ENTRY_ARG 14 ORG 0xe82e IRQ_ENTRY_ARG 16 ORG 0xe987 IRQ_ENTRY 09 ORG 0xec59 IRQ_ENTRY_ARG 40 ORG 0xef57 IRQ_ENTRY 0e // 0xefc7 - diskette_param_table in floppy.c ORG 0xefd2 IRQ_ENTRY_ARG 17 ORG 0xf045 entry_10_0x0f: // XXX - INT 10 Functions 0-Fh Entry Point iretw ORG 0xf065 IRQ_ENTRY_ARG 10 // 0xf0a4 - VideoParams in misc.c ORG 0xf841 IRQ_ENTRY_ARG 12 ORG 0xf84d IRQ_ENTRY_ARG 11 ORG 0xf859 IRQ_ENTRY_ARG 15 // 0xfa6e - vgafont8 in font.c ORG 0xfe6e IRQ_ENTRY_ARG 1a ORG 0xfea5 IRQ_ENTRY 08 // 0xfef3 - InitVectors in misc.c // 0xff00 - BiosCopyright in misc.c ORG 0xff53 .global entry_iret_official entry_iret_official: iretw ORG 0xff54 IRQ_ENTRY_ARG 05 ORG 0xfff0 // Power-up Entry Point .global reset_vector reset_vector: ljmpw $SEG_BIOS, $entry_post // 0xfff5 - BiosDate in misc.c // 0xfffe - BiosModelId in misc.c // 0xffff - BiosChecksum in misc.c .end