diff options
Diffstat (limited to 'sys/boot/i386/btx/btxldr/btxldr.S')
| -rw-r--r-- | sys/boot/i386/btx/btxldr/btxldr.S | 409 |
1 files changed, 409 insertions, 0 deletions
diff --git a/sys/boot/i386/btx/btxldr/btxldr.S b/sys/boot/i386/btx/btxldr/btxldr.S new file mode 100644 index 000000000000..1a0f5f40ff07 --- /dev/null +++ b/sys/boot/i386/btx/btxldr/btxldr.S @@ -0,0 +1,409 @@ +/* + * Copyright (c) 1998 Robert Nordier + * All rights reserved. + * + * Redistribution and use in source and binary forms are freely + * permitted provided that the above copyright notice and this + * paragraph and the following disclaimer are duplicated in all + * such forms. + * + * This software is provided "AS IS" and without any express or + * implied warranties, including, without limitation, the implied + * warranties of merchantability and fitness for a particular + * purpose. + * + * $FreeBSD$ + */ + +#include <bootargs.h> + +#define RBX_MUTE 0x10 /* -m */ +#define OPT_SET(opt) (1 << (opt)) + +/* + * Prototype BTX loader program, written in a couple of hours. The + * real thing should probably be more flexible, and in C. + */ + +/* + * Memory locations. + */ + .set MEM_STUB,0x600 # Real mode stub + .set MEM_ESP,0x1000 # New stack pointer + .set MEM_TBL,0x5000 # BTX page tables + .set MEM_ENTRY,0x9010 # BTX entry point + .set MEM_DATA,start+0x1000 # Data segment +/* + * Segment selectors. + */ + .set SEL_SCODE,0x8 # 4GB code + .set SEL_SDATA,0x10 # 4GB data + .set SEL_RCODE,0x18 # 64K code + .set SEL_RDATA,0x20 # 64K data +/* + * Paging constants. + */ + .set PAG_SIZ,0x1000 # Page size + .set PAG_ENT,0x4 # Page entry size +/* + * Screen constants. + */ + .set SCR_MAT,0x7 # Mode/attribute + .set SCR_COL,0x50 # Columns per row + .set SCR_ROW,0x19 # Rows per screen +/* + * BIOS Data Area locations. + */ + .set BDA_MEM,0x413 # Free memory + .set BDA_SCR,0x449 # Video mode + .set BDA_POS,0x450 # Cursor position +/* + * Required by aout gas inadequacy. + */ + .set SIZ_STUB,0x1a # Size of stub +/* + * We expect to be loaded by boot2 at the origin defined in ./Makefile. + */ + .globl start +/* + * BTX program loader for ELF clients. + */ +start: cld # String ops inc + testl $OPT_SET(RBX_MUTE), 4(%esp) # Check first argument + setnz muted # for RBX_MUTE, set flag + movl $m_logo,%esi # Identify + call putstr # ourselves + movzwl BDA_MEM,%eax # Get base memory + shll $0xa,%eax # in bytes + movl %eax,%ebp # Base of user stack +#ifdef BTXLDR_VERBOSE + movl $m_mem,%esi # Display + call hexout # amount of + call putstr # base memory +#endif + lgdt gdtdesc # Load new GDT +/* + * Relocate caller's arguments. + */ +#ifdef BTXLDR_VERBOSE + movl $m_esp,%esi # Display + movl %esp,%eax # caller + call hexout # stack + call putstr # pointer + movl $m_args,%esi # Format string + leal 0x4(%esp),%ebx # First argument + movl $0x6,%ecx # Count +start.1: movl (%ebx),%eax # Get argument and + addl $0x4,%ebx # bump pointer + call hexout # Display it + loop start.1 # Till done + call putstr # End message +#endif + movl BA_BOOTINFO+4(%esp),%esi # Source: bootinfo + cmpl $0x0, %esi # If the bootinfo pointer + je start_null_bi # is null, don't copy it + movl BI_SIZE(%esi),%ecx # Allocate space + subl %ecx,%ebp # for bootinfo + movl %ebp,%edi # Destination + rep # Copy + movsb # it + movl %ebp,BA_BOOTINFO+4(%esp) # Update pointer + movl %edi,%ebp # Restore base pointer +#ifdef BTXLDR_VERBOSE + movl $m_rel_bi,%esi # Display + movl %ebp,%eax # bootinfo + call hexout # relocation + call putstr # message +#endif +start_null_bi: movl $BOOTARGS_SIZE,%ecx # Fixed size of arguments + testl $KARGS_FLAGS_EXTARG, BA_BOOTFLAGS+4(%esp) # Check for extra data + jz start_fixed # Skip if the flag is not set + addl BOOTARGS_SIZE+4(%esp),%ecx # Add size of variable args +start_fixed: subl $ARGOFF,%ebp # Place args at fixed offset + leal 0x4(%esp),%esi # Source + movl %ebp,%edi # Destination + rep # Copy + movsb # them +#ifdef BTXLDR_VERBOSE + movl $m_rel_args,%esi # Display + movl %ebp,%eax # argument + call hexout # relocation + call putstr # message +#endif +/* + * Set up BTX kernel. + */ + movl $MEM_ESP,%esp # Set up new stack + movl $MEM_DATA,%ebx # Data segment + movl $m_vers,%esi # Display BTX + call putstr # version message + movb 0x5(%ebx),%al # Get major version + addb $'0',%al # Display + call putchr # it + movb $'.',%al # And a + call putchr # dot + movb 0x6(%ebx),%al # Get minor + xorb %ah,%ah # version + movb $0xa,%dl # Divide + divb %dl,%al # by 10 + addb $'0',%al # Display + call putchr # tens + movb %ah,%al # Get units + addb $'0',%al # Display + call putchr # units + call putstr # End message + movl %ebx,%esi # BTX image + movzwl 0x8(%ebx),%edi # Compute + orl $PAG_SIZ/PAG_ENT-1,%edi # the + incl %edi # BTX + shll $0x2,%edi # load + addl $MEM_TBL,%edi # address + pushl %edi # Save load address + movzwl 0xa(%ebx),%ecx # Image size +#ifdef BTXLDR_VERBOSE + pushl %ecx # Save image size +#endif + rep # Relocate + movsb # BTX + movl %esi,%ebx # Keep place +#ifdef BTXLDR_VERBOSE + movl $m_rel_btx,%esi # Restore + popl %eax # parameters + call hexout # and +#endif + popl %ebp # display +#ifdef BTXLDR_VERBOSE + movl %ebp,%eax # the + call hexout # relocation + call putstr # message +#endif + addl $PAG_SIZ,%ebp # Display +#ifdef BTXLDR_VERBOSE + movl $m_base,%esi # the + movl %ebp,%eax # user + call hexout # base + call putstr # address +#endif +/* + * Set up ELF-format client program. + */ + cmpl $0x464c457f,(%ebx) # ELF magic number? + je start.3 # Yes + movl $e_fmt,%esi # Display error + call putstr # message +start.2: jmp start.2 # Hang +start.3: +#ifdef BTXLDR_VERBOSE + movl $m_elf,%esi # Display ELF + call putstr # message + movl $m_segs,%esi # Format string +#endif + movl 0x1c(%ebx),%edx # Get e_phoff + addl %ebx,%edx # To pointer + movzwl 0x2c(%ebx),%ecx # Get e_phnum +start.4: cmpl $0x1,(%edx) # Is p_type PT_LOAD? + jne start.6 # No +#ifdef BTXLDR_VERBOSE + movl 0x4(%edx),%eax # Display + call hexout # p_offset + movl 0x8(%edx),%eax # Display + call hexout # p_vaddr + movl 0x10(%edx),%eax # Display + call hexout # p_filesz + movl 0x14(%edx),%eax # Display + call hexout # p_memsz + call putstr # End message +#endif + pushl %esi # Save + pushl %ecx # working registers + movl 0x4(%edx),%esi # Get p_offset + addl %ebx,%esi # as pointer + movl 0x8(%edx),%edi # Get p_vaddr + addl %ebp,%edi # as pointer + movl 0x10(%edx),%ecx # Get p_filesz + rep # Set up + movsb # segment + movl 0x14(%edx),%ecx # Any bytes + subl 0x10(%edx),%ecx # to zero? + jz start.5 # No + xorb %al,%al # Then + rep # zero + stosb # them +start.5: popl %ecx # Restore + popl %esi # registers +start.6: addl $0x20,%edx # To next entry + loop start.4 # Till done +#ifdef BTXLDR_VERBOSE + movl $m_done,%esi # Display done + call putstr # message +#endif + movl $start.8,%esi # Real mode stub + movl $MEM_STUB,%edi # Destination + movl $start.9-start.8,%ecx # Size + rep # Relocate + movsb # it + ljmp $SEL_RCODE,$MEM_STUB # To 16-bit code + .code16 +start.8: xorw %ax,%ax # Data + movb $SEL_RDATA,%al # selector + movw %ax,%ss # Reload SS + movw %ax,%ds # Reset + movw %ax,%es # other + movw %ax,%fs # segment + movw %ax,%gs # limits + movl %cr0,%eax # Switch to + decw %ax # real + movl %eax,%cr0 # mode + ljmp $0,$MEM_ENTRY # Jump to BTX entry point +start.9: + .code32 +/* + * Output message [ESI] followed by EAX in hex. + */ +hexout: pushl %eax # Save + call putstr # Display message + popl %eax # Restore + pushl %esi # Save + pushl %edi # caller's + movl $buf,%edi # Buffer + pushl %edi # Save + call hex32 # To hex + xorb %al,%al # Terminate + stosb # string + popl %esi # Restore +hexout.1: lodsb # Get a char + cmpb $'0',%al # Leading zero? + je hexout.1 # Yes + testb %al,%al # End of string? + jne hexout.2 # No + decl %esi # Undo +hexout.2: decl %esi # Adjust for inc + call putstr # Display hex + popl %edi # Restore + popl %esi # caller's + ret # To caller +/* + * Output zero-terminated string [ESI] to the console. + */ +putstr.0: call putchr # Output char +putstr: lodsb # Load char + testb %al,%al # End of string? + jne putstr.0 # No + ret # To caller +/* + * Output character AL to the console. + */ +putchr: testb $1,muted # Check muted + jnz putchr.5 # do a nop + pusha # Save + xorl %ecx,%ecx # Zero for loops + movb $SCR_MAT,%ah # Mode/attribute + movl $BDA_POS,%ebx # BDA pointer + movw (%ebx),%dx # Cursor position + movl $0xb8000,%edi # Regen buffer (color) + cmpb %ah,BDA_SCR-BDA_POS(%ebx) # Mono mode? + jne putchr.1 # No + xorw %di,%di # Regen buffer (mono) +putchr.1: cmpb $0xa,%al # New line? + je putchr.2 # Yes + xchgl %eax,%ecx # Save char + movb $SCR_COL,%al # Columns per row + mulb %dh # * row position + addb %dl,%al # + column + adcb $0x0,%ah # position + shll %eax # * 2 + xchgl %eax,%ecx # Swap char, offset + movw %ax,(%edi,%ecx,1) # Write attr:char + incl %edx # Bump cursor + cmpb $SCR_COL,%dl # Beyond row? + jb putchr.3 # No +putchr.2: xorb %dl,%dl # Zero column + incb %dh # Bump row +putchr.3: cmpb $SCR_ROW,%dh # Beyond screen? + jb putchr.4 # No + leal 2*SCR_COL(%edi),%esi # New top line + movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move + rep # Scroll + movsl # screen + movb $' ',%al # Space + movb $SCR_COL,%cl # Columns to clear + rep # Clear + stosw # line + movb $SCR_ROW-1,%dh # Bottom line +putchr.4: movw %dx,(%ebx) # Update position + popa # Restore +putchr.5: ret # To caller +/* + * Convert EAX, AX, or AL to hex, saving the result to [EDI]. + */ +hex32: pushl %eax # Save + shrl $0x10,%eax # Do upper + call hex16 # 16 + popl %eax # Restore +hex16: call hex16.1 # Do upper 8 +hex16.1: xchgb %ah,%al # Save/restore +hex8: pushl %eax # Save + shrb $0x4,%al # Do upper + call hex8.1 # 4 + popl %eax # Restore +hex8.1: andb $0xf,%al # Get lower 4 + cmpb $0xa,%al # Convert + sbbb $0x69,%al # to hex + das # digit + orb $0x20,%al # To lower case + stosb # Save char + ret # (Recursive) + + .data + .p2align 4 +/* + * Global descriptor table. + */ +gdt: .word 0x0,0x0,0x0,0x0 # Null entry + .word 0xffff,0x0,0x9a00,0xcf # SEL_SCODE + .word 0xffff,0x0,0x9200,0xcf # SEL_SDATA + .word 0xffff,0x0,0x9a00,0x0 # SEL_RCODE + .word 0xffff,0x0,0x9200,0x0 # SEL_RDATA +gdt.1: +gdtdesc: .word gdt.1-gdt-1 # Limit + .long gdt # Base +/* + * Messages. + */ +m_logo: .asciz " \nBTX loader 1.00 " +m_vers: .asciz "BTX version is \0\n" +e_fmt: .asciz "Error: Client format not supported\n" +#ifdef BTXLDR_VERBOSE +m_mem: .asciz "Starting in protected mode (base mem=\0)\n" +m_esp: .asciz "Arguments passed (esp=\0):\n" +m_args: .asciz "<howto=" + .asciz " bootdev=" + .asciz " junk=" + .asciz " " + .asciz " " + .asciz " bootinfo=\0>\n" +m_rel_bi: .asciz "Relocated bootinfo (size=48) to \0\n" +m_rel_args: .asciz "Relocated arguments (size=18) to \0\n" +m_rel_btx: .asciz "Relocated kernel (size=\0) to \0\n" +m_base: .asciz "Client base address is \0\n" +m_elf: .asciz "Client format is ELF\n" +m_segs: .asciz "text segment: offset=" + .asciz " vaddr=" + .asciz " filesz=" + .asciz " memsz=\0\n" + .asciz "data segment: offset=" + .asciz " vaddr=" + .asciz " filesz=" + .asciz " memsz=\0\n" +m_done: .asciz "Loading complete\n" +#endif + +/* + * Flags + */ +muted: .byte 0x0 + +/* + * Uninitialized data area. + */ +buf: # Scratch buffer |