diff options
Diffstat (limited to 'stand/i386/btx/btx/btx.S')
| -rw-r--r-- | stand/i386/btx/btx/btx.S | 1082 |
1 files changed, 1082 insertions, 0 deletions
diff --git a/stand/i386/btx/btx/btx.S b/stand/i386/btx/btx/btx.S new file mode 100644 index 0000000000000..87d09a5a1e179 --- /dev/null +++ b/stand/i386/btx/btx/btx.S @@ -0,0 +1,1082 @@ +/* + * 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> + +/* + * Memory layout. + */ + .set MEM_BTX,0x1000 # Start of BTX memory + .set MEM_ESP0,0x1800 # Supervisor stack + .set MEM_BUF,0x1800 # Scratch buffer + .set MEM_ESPR,0x5e00 # Real mode stack + .set MEM_IDT,0x5e00 # IDT + .set MEM_TSS,0x5f98 # TSS + .set MEM_MAP,0x6000 # I/O bit map + .set MEM_TSS_END,0x7fff # End of TSS + .set MEM_ORG,0x9000 # BTX code + .set MEM_USR,0xa000 # Start of user memory +/* + * Paging control. + */ + .set PAG_SIZ,0x1000 # Page size + .set PAG_CNT,0x1000 # Pages to map +/* + * Fields in %eflags. + */ + .set PSL_RESERVED_DEFAULT,0x00000002 + .set PSL_T,0x00000100 # Trap flag + .set PSL_I,0x00000200 # Interrupt enable flag + .set PSL_D,0x00000400 # String instruction direction + .set PSL_NT,0x00004000 # Nested task flag + .set PSL_VM,0x00020000 # Virtual 8086 mode flag + .set PSL_AC,0x00040000 # Alignment check flag +/* + * Segment selectors. + */ + .set SEL_SCODE,0x8 # Supervisor code + .set SEL_SDATA,0x10 # Supervisor data + .set SEL_RCODE,0x18 # Real mode code + .set SEL_RDATA,0x20 # Real mode data + .set SEL_UCODE,0x28|3 # User code + .set SEL_UDATA,0x30|3 # User data + .set SEL_TSS,0x38 # TSS +/* + * Task state segment fields. + */ + .set TSS_ESP0,0x4 # PL 0 ESP + .set TSS_SS0,0x8 # PL 0 SS + .set TSS_MAP,0x66 # I/O bit map base +/* + * System calls. + */ + .set SYS_EXIT,0x0 # Exit + .set SYS_EXEC,0x1 # Exec +/* + * Fields in V86 interface structure. + */ + .set V86_CTL,0x0 # Control flags + .set V86_ADDR,0x4 # Int number/address + .set V86_ES,0x8 # V86 ES + .set V86_DS,0xc # V86 DS + .set V86_FS,0x10 # V86 FS + .set V86_GS,0x14 # V86 GS +/* + * V86 control flags. + */ + .set V86F_ADDR,0x10000 # Segment:offset address + .set V86F_CALLF,0x20000 # Emulate far call + .set V86F_FLAGS,0x40000 # Return flags +/* + * Dump format control bytes. + */ + .set DMP_X16,0x1 # Word + .set DMP_X32,0x2 # Long + .set DMP_MEM,0x4 # Memory + .set DMP_EOL,0x8 # End of line +/* + * Screen defaults and assumptions. + */ + .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 + .set BDA_BOOT,0x472 # Boot howto flag +/* + * Derivations, for brevity. + */ + .set _ESP0H,MEM_ESP0>>0x8 # Byte 1 of ESP0 + .set _TSSIO,MEM_MAP-MEM_TSS # TSS I/O base + .set _TSSLM,MEM_TSS_END-MEM_TSS # TSS limit + .set _IDTLM,MEM_TSS-MEM_IDT-1 # IDT limit +/* + * Code segment. + */ + .globl start + .code16 +start: # Start of code +/* + * BTX header. + */ +btx_hdr: .byte 0xeb # Machine ID + .byte 0xe # Header size + .ascii "BTX" # Magic + .byte 0x1 # Major version + .byte 0x2 # Minor version + .byte BTX_FLAGS # Flags + .word PAG_CNT-MEM_ORG>>0xc # Paging control + .word break-start # Text size + .long 0x0 # Entry address +/* + * Initialization routine. + */ +init: cli # Disable interrupts + xor %ax,%ax # Zero/segment + mov %ax,%ss # Set up + mov $MEM_ESP0,%sp # stack + mov %ax,%es # Address + mov %ax,%ds # data + pushl $0x2 # Clear + popfl # flags +/* + * Initialize memory. + */ + mov $MEM_IDT,%di # Memory to initialize + mov $(MEM_ORG-MEM_IDT)/2,%cx # Words to zero + rep # Zero-fill + stosw # memory +/* + * Update real mode IDT for reflecting hardware interrupts. + */ + mov $intr20,%bx # Address first handler + mov $0x10,%cx # Number of handlers + mov $0x20*4,%di # First real mode IDT entry +init.0: mov %bx,(%di) # Store IP + inc %di # Address next + inc %di # entry + stosw # Store CS + add $4,%bx # Next handler + loop init.0 # Next IRQ +/* + * Create IDT. + */ + mov $MEM_IDT,%di + mov $idtctl,%si # Control string +init.1: lodsb # Get entry + cbw # count + xchg %ax,%cx # as word + jcxz init.4 # If done + lodsb # Get segment + xchg %ax,%dx # P:DPL:type + lodsw # Get control + xchg %ax,%bx # set + lodsw # Get handler offset + mov $SEL_SCODE,%dh # Segment selector +init.2: shr %bx # Handle this int? + jnc init.3 # No + mov %ax,(%di) # Set handler offset + mov %dh,0x2(%di) # and selector + mov %dl,0x5(%di) # Set P:DPL:type + add $0x4,%ax # Next handler +init.3: lea 0x8(%di),%di # Next entry + loop init.2 # Till set done + jmp init.1 # Continue +/* + * Initialize TSS. + */ +init.4: movb $_ESP0H,TSS_ESP0+1(%di) # Set ESP0 + movb $SEL_SDATA,TSS_SS0(%di) # Set SS0 + movb $_TSSIO,TSS_MAP(%di) # Set I/O bit map base +/* + * Bring up the system. + */ + mov $0x2820,%bx # Set protected mode + callw setpic # IRQ offsets + lidt idtdesc # Set IDT + lgdt gdtdesc # Set GDT + mov %cr0,%eax # Switch to protected + inc %ax # mode + mov %eax,%cr0 # + ljmp $SEL_SCODE,$init.8 # To 32-bit code + .code32 +init.8: xorl %ecx,%ecx # Zero + movb $SEL_SDATA,%cl # To 32-bit + movw %cx,%ss # stack +/* + * Launch user task. + */ + movb $SEL_TSS,%cl # Set task + ltr %cx # register + movl $MEM_USR,%edx # User base address + movzwl %ss:BDA_MEM,%eax # Get free memory + shll $0xa,%eax # To bytes + subl $ARGSPACE,%eax # Less arg space + subl %edx,%eax # Less base + movb $SEL_UDATA,%cl # User data selector + pushl %ecx # Set SS + pushl %eax # Set ESP + push $0x202 # Set flags (IF set) + push $SEL_UCODE # Set CS + pushl btx_hdr+0xc # Set EIP + pushl %ecx # Set GS + pushl %ecx # Set FS + pushl %ecx # Set DS + pushl %ecx # Set ES + pushl %edx # Set EAX + movb $0x7,%cl # Set remaining +init.9: push $0x0 # general + loop init.9 # registers +#ifdef BTX_SERIAL + call sio_init # setup the serial console +#endif + popa # and initialize + popl %es # Initialize + popl %ds # user + popl %fs # segment + popl %gs # registers + iret # To user mode +/* + * Exit routine. + */ +exit: cli # Disable interrupts + movl $MEM_ESP0,%esp # Clear stack +/* + * Turn off paging. + */ + movl %cr0,%eax # Get CR0 + andl $~0x80000000,%eax # Disable + movl %eax,%cr0 # paging + xorl %ecx,%ecx # Zero + movl %ecx,%cr3 # Flush TLB +/* + * Restore the GDT in case we caught a kernel trap. + */ + lgdt %cs:gdtdesc # Set GDT +/* + * To 16 bits. + */ + ljmpw $SEL_RCODE,$exit.1 # Reload CS + .code16 +exit.1: mov $SEL_RDATA,%cl # 16-bit selector + mov %cx,%ss # Reload SS + mov %cx,%ds # Load + mov %cx,%es # remaining + mov %cx,%fs # segment + mov %cx,%gs # registers +/* + * To real-address mode. + */ + dec %ax # Switch to + mov %eax,%cr0 # real mode + ljmp $0x0,$exit.2 # Reload CS +exit.2: xor %ax,%ax # Real mode segment + mov %ax,%ss # Reload SS + mov %ax,%ds # Address data + mov $0x7008,%bx # Set real mode + callw setpic # IRQ offsets + lidt ivtdesc # Set IVT +/* + * Reboot or await reset. + */ + sti # Enable interrupts + testb $0x1,btx_hdr+0x7 # Reboot? +exit.3: jz exit.3 # No + movw $0x1234, BDA_BOOT # Do a warm boot + ljmp $0xf000,$0xfff0 # reboot the machine +/* + * Set IRQ offsets by reprogramming 8259A PICs. + */ +setpic: in $0x21,%al # Save master + push %ax # IMR + in $0xa1,%al # Save slave + push %ax # IMR + movb $0x11,%al # ICW1 to + outb %al,$0x20 # master, + outb %al,$0xa0 # slave + movb %bl,%al # ICW2 to + outb %al,$0x21 # master + movb %bh,%al # ICW2 to + outb %al,$0xa1 # slave + movb $0x4,%al # ICW3 to + outb %al,$0x21 # master + movb $0x2,%al # ICW3 to + outb %al,$0xa1 # slave + movb $0x1,%al # ICW4 to + outb %al,$0x21 # master, + outb %al,$0xa1 # slave + pop %ax # Restore slave + outb %al,$0xa1 # IMR + pop %ax # Restore master + outb %al,$0x21 # IMR + retw # To caller + .code32 +/* + * Exception jump table. + */ +intx00: push $0x0 # Int 0x0: #DE + jmp ex_noc # Divide error + push $0x1 # Int 0x1: #DB + jmp ex_noc # Debug + push $0x3 # Int 0x3: #BP + jmp ex_noc # Breakpoint + push $0x4 # Int 0x4: #OF + jmp ex_noc # Overflow + push $0x5 # Int 0x5: #BR + jmp ex_noc # BOUND range exceeded + push $0x6 # Int 0x6: #UD + jmp ex_noc # Invalid opcode + push $0x7 # Int 0x7: #NM + jmp ex_noc # Device not available + push $0x8 # Int 0x8: #DF + jmp except # Double fault + push $0xa # Int 0xa: #TS + jmp except # Invalid TSS + push $0xb # Int 0xb: #NP + jmp except # Segment not present + push $0xc # Int 0xc: #SS + jmp except # Stack segment fault + push $0xd # Int 0xd: #GP + jmp except # General protection + push $0xe # Int 0xe: #PF + jmp except # Page fault +intx10: push $0x10 # Int 0x10: #MF + jmp ex_noc # Floating-point error +/* + * Save a zero error code. + */ +ex_noc: pushl (%esp,1) # Duplicate int no + movb $0x0,0x4(%esp,1) # Fake error code +/* + * Handle exception. + */ +except: cld # String ops inc + pushl %ds # Save + pushl %es # most + pusha # registers + pushl %gs # Set GS + pushl %fs # Set FS + pushl %ds # Set DS + pushl %es # Set ES + cmpw $SEL_SCODE,0x44(%esp,1) # Supervisor mode? + jne except.1 # No + pushl %ss # Set SS + jmp except.2 # Join common code +except.1: pushl 0x50(%esp,1) # Set SS +except.2: pushl 0x50(%esp,1) # Set ESP + push $SEL_SDATA # Set up + popl %ds # to + pushl %ds # address + popl %es # data + movl %esp,%ebx # Stack frame + movl $dmpfmt,%esi # Dump format string + movl $MEM_BUF,%edi # Buffer + pushl %edi # Dump to + call dump # buffer + popl %esi # and + call putstr # display + leal 0x18(%esp,1),%esp # Discard frame + popa # Restore + popl %es # registers + popl %ds # saved + cmpb $0x3,(%esp,1) # Breakpoint? + je except.3 # Yes + cmpb $0x1,(%esp,1) # Debug? + jne except.2a # No + testl $PSL_T,0x10(%esp,1) # Trap flag set? + jnz except.3 # Yes +except.2a: jmp exit # Exit +except.3: leal 0x8(%esp,1),%esp # Discard err, int no + iret # From interrupt + +/* + * Reboot the machine by setting the reboot flag and exiting + */ +reboot: orb $0x1,btx_hdr+0x7 # Set the reboot flag + jmp exit # Terminate BTX and reboot + +/* + * Protected Mode Hardware interrupt jump table. + */ +intx20: push $0x8 # Int 0x20: IRQ0 + jmp int_hw # V86 int 0x8 + push $0x9 # Int 0x21: IRQ1 + jmp int_hw # V86 int 0x9 + push $0xa # Int 0x22: IRQ2 + jmp int_hw # V86 int 0xa + push $0xb # Int 0x23: IRQ3 + jmp int_hw # V86 int 0xb + push $0xc # Int 0x24: IRQ4 + jmp int_hw # V86 int 0xc + push $0xd # Int 0x25: IRQ5 + jmp int_hw # V86 int 0xd + push $0xe # Int 0x26: IRQ6 + jmp int_hw # V86 int 0xe + push $0xf # Int 0x27: IRQ7 + jmp int_hw # V86 int 0xf + push $0x70 # Int 0x28: IRQ8 + jmp int_hw # V86 int 0x70 + push $0x71 # Int 0x29: IRQ9 + jmp int_hw # V86 int 0x71 + push $0x72 # Int 0x2a: IRQ10 + jmp int_hw # V86 int 0x72 + push $0x73 # Int 0x2b: IRQ11 + jmp int_hw # V86 int 0x73 + push $0x74 # Int 0x2c: IRQ12 + jmp int_hw # V86 int 0x74 + push $0x75 # Int 0x2d: IRQ13 + jmp int_hw # V86 int 0x75 + push $0x76 # Int 0x2e: IRQ14 + jmp int_hw # V86 int 0x76 + push $0x77 # Int 0x2f: IRQ15 + jmp int_hw # V86 int 0x77 + +/* + * Invoke real mode interrupt/function call from user mode with arguments. + */ +intx31: pushl $-1 # Dummy int no for btx_v86 +/* + * Invoke real mode interrupt/function call from protected mode. + * + * We place a trampoline on the user stack that will return to rret_tramp + * which will reenter protected mode and then finally return to the user + * client. + * + * Kernel frame %esi points to: Real mode stack frame at MEM_ESPR: + * + * -0x00 user %ss -0x04 kernel %esp (with full frame) + * -0x04 user %esp -0x08 btx_v86 pointer + * -0x08 user %eflags -0x0c flags (only used if interrupt) + * -0x0c user %cs -0x10 real mode CS:IP return trampoline + * -0x10 user %eip -0x12 real mode flags + * -0x14 int no -0x16 real mode CS:IP (target) + * -0x18 %eax + * -0x1c %ecx + * -0x20 %edx + * -0x24 %ebx + * -0x28 %esp + * -0x2c %ebp + * -0x30 %esi + * -0x34 %edi + * -0x38 %gs + * -0x3c %fs + * -0x40 %ds + * -0x44 %es + * -0x48 zero %eax (hardware int only) + * -0x4c zero %ecx (hardware int only) + * -0x50 zero %edx (hardware int only) + * -0x54 zero %ebx (hardware int only) + * -0x58 zero %esp (hardware int only) + * -0x5c zero %ebp (hardware int only) + * -0x60 zero %esi (hardware int only) + * -0x64 zero %edi (hardware int only) + * -0x68 zero %gs (hardware int only) + * -0x6c zero %fs (hardware int only) + * -0x70 zero %ds (hardware int only) + * -0x74 zero %es (hardware int only) + */ +int_hw: cld # String ops inc + pusha # Save gp regs + pushl %gs # Save + pushl %fs # seg + pushl %ds # regs + pushl %es + push $SEL_SDATA # Set up + popl %ds # to + pushl %ds # address + popl %es # data + leal 0x44(%esp,1),%esi # Base of frame + movl %esp,MEM_ESPR-0x04 # Save kernel stack pointer + movl -0x14(%esi),%eax # Get Int no + cmpl $-1,%eax # Hardware interrupt? + jne intusr.1 # Yes +/* + * v86 calls save the btx_v86 pointer on the real mode stack and read + * the address and flags from the btx_v86 structure. For interrupt + * handler invocations (VM86 INTx requests), disable interrupts, + * tracing, and alignment checking while the handler runs. + */ + movl $MEM_USR,%ebx # User base + movl %ebx,%edx # address + addl -0x4(%esi),%ebx # User ESP + movl (%ebx),%ebp # btx_v86 pointer + addl %ebp,%edx # Flatten btx_v86 ptr + movl %edx,MEM_ESPR-0x08 # Save btx_v86 ptr + movl V86_ADDR(%edx),%eax # Get int no/address + movl V86_CTL(%edx),%edx # Get control flags + movl -0x08(%esi),%ebx # Save user flags in %ebx + testl $V86F_ADDR,%edx # Segment:offset? + jnz intusr.4 # Yes + andl $~(PSL_I|PSL_T|PSL_AC),%ebx # Disable interrupts, tracing, + # and alignment checking for + # interrupt handler + jmp intusr.3 # Skip hardware interrupt +/* + * Hardware interrupts store a NULL btx_v86 pointer and use the + * address (interrupt number) from the stack with empty flags. Also, + * push a dummy frame of zeros onto the stack for all the general + * purpose and segment registers and clear %eflags. This gives the + * hardware interrupt handler a clean slate. + */ +intusr.1: xorl %edx,%edx # Control flags + movl %edx,MEM_ESPR-0x08 # NULL btx_v86 ptr + movl $12,%ecx # Frame is 12 dwords +intusr.2: pushl $0x0 # Fill frame + loop intusr.2 # with zeros + movl $PSL_RESERVED_DEFAULT,%ebx # Set clean %eflags +/* + * Look up real mode IDT entry for hardware interrupts and VM86 INTx + * requests. + */ +intusr.3: shll $0x2,%eax # Scale + movl (%eax),%eax # Load int vector + jmp intusr.5 # Skip CALLF test +/* + * Panic if V86F_CALLF isn't set with V86F_ADDR. + */ +intusr.4: testl $V86F_CALLF,%edx # Far call? + jnz intusr.5 # Ok + movl %edx,0x30(%esp,1) # Place VM86 flags in int no + movl $badvm86,%esi # Display bad + call putstr # VM86 call + popl %es # Restore + popl %ds # seg + popl %fs # regs + popl %gs + popal # Restore gp regs + jmp ex_noc # Panic +/* + * %eax now holds the segment:offset of the function. + * %ebx now holds the %eflags to pass to real mode. + * %edx now holds the V86F_* flags. + */ +intusr.5: movw %bx,MEM_ESPR-0x12 # Pass user flags to real mode + # target +/* + * If this is a v86 call, copy the seg regs out of the btx_v86 structure. + */ + movl MEM_ESPR-0x08,%ecx # Get btx_v86 ptr + jecxz intusr.6 # Skip for hardware ints + leal -0x44(%esi),%edi # %edi => kernel stack seg regs + pushl %esi # Save + leal V86_ES(%ecx),%esi # %esi => btx_v86 seg regs + movl $4,%ecx # Copy seg regs + rep # from btx_v86 + movsl # to kernel stack + popl %esi # Restore +intusr.6: movl -0x08(%esi),%ebx # Copy user flags to real + movl %ebx,MEM_ESPR-0x0c # mode return trampoline + movl $rret_tramp,%ebx # Set return trampoline + movl %ebx,MEM_ESPR-0x10 # CS:IP + movl %eax,MEM_ESPR-0x16 # Real mode target CS:IP + ljmpw $SEL_RCODE,$intusr.7 # Change to 16-bit segment + .code16 +intusr.7: movl %cr0,%eax # Leave + dec %al # protected + movl %eax,%cr0 # mode + ljmpw $0x0,$intusr.8 +intusr.8: xorw %ax,%ax # Reset %ds + movw %ax,%ds # and + movw %ax,%ss # %ss + lidt ivtdesc # Set IVT + popl %es # Restore + popl %ds # seg + popl %fs # regs + popl %gs + popal # Restore gp regs + movw $MEM_ESPR-0x16,%sp # Switch to real mode stack + iret # Call target routine +/* + * For the return to real mode we setup a stack frame like this on the real + * mode stack. Note that callf calls won't pop off the flags, but we just + * ignore that by repositioning %sp to be just above the btx_v86 pointer + * so it is aligned. The stack is relative to MEM_ESPR. + * + * -0x04 kernel %esp + * -0x08 btx_v86 + * -0x0c %eax + * -0x10 %ecx + * -0x14 %edx + * -0x18 %ebx + * -0x1c %esp + * -0x20 %ebp + * -0x24 %esi + * -0x28 %edi + * -0x2c %gs + * -0x30 %fs + * -0x34 %ds + * -0x38 %es + * -0x3c %eflags + */ +rret_tramp: movw $MEM_ESPR-0x08,%sp # Reset stack pointer + pushal # Save gp regs + pushl %gs # Save + pushl %fs # seg + pushl %ds # regs + pushl %es + pushfl # Save %eflags + pushl $PSL_RESERVED_DEFAULT|PSL_D # Use clean %eflags with + popfl # string ops dec + xorw %ax,%ax # Reset seg + movw %ax,%ds # regs + movw %ax,%es # (%ss is already 0) + lidt idtdesc # Set IDT + lgdt gdtdesc # Set GDT + mov %cr0,%eax # Switch to protected + inc %ax # mode + mov %eax,%cr0 # + ljmp $SEL_SCODE,$rret_tramp.1 # To 32-bit code + .code32 +rret_tramp.1: xorl %ecx,%ecx # Zero + movb $SEL_SDATA,%cl # Setup + movw %cx,%ss # 32-bit + movw %cx,%ds # seg + movw %cx,%es # regs + movl MEM_ESPR-0x04,%esp # Switch to kernel stack + leal 0x44(%esp,1),%esi # Base of frame + andb $~0x2,tss_desc+0x5 # Clear TSS busy + movb $SEL_TSS,%cl # Set task + ltr %cx # register +/* + * Now we are back in protected mode. The kernel stack frame set up + * before entering real mode is still intact. For hardware interrupts, + * leave the frame unchanged. + */ + cmpl $0,MEM_ESPR-0x08 # Leave saved regs unchanged + jz rret_tramp.3 # for hardware ints +/* + * For V86 calls, copy the registers off of the real mode stack onto + * the kernel stack as we want their updated values. Also, initialize + * the segment registers on the kernel stack. + * + * Note that the %esp in the kernel stack after this is garbage, but popa + * ignores it, so we don't have to fix it up. + */ + leal -0x18(%esi),%edi # Kernel stack GP regs + pushl %esi # Save + movl $MEM_ESPR-0x0c,%esi # Real mode stack GP regs + movl $8,%ecx # Copy GP regs from + rep # real mode stack + movsl # to kernel stack + movl $SEL_UDATA,%eax # Selector for data seg regs + movl $4,%ecx # Initialize %ds, + rep # %es, %fs, and + stosl # %gs +/* + * For V86 calls, copy the saved seg regs on the real mode stack back + * over to the btx_v86 structure. Also, conditionally update the + * saved eflags on the kernel stack based on the flags from the user. + */ + movl MEM_ESPR-0x08,%ecx # Get btx_v86 ptr + leal V86_GS(%ecx),%edi # %edi => btx_v86 seg regs + leal MEM_ESPR-0x2c,%esi # %esi => real mode seg regs + xchgl %ecx,%edx # Save btx_v86 ptr + movl $4,%ecx # Copy seg regs + rep # from real mode stack + movsl # to btx_v86 + popl %esi # Restore + movl V86_CTL(%edx),%edx # Read V86 control flags + testl $V86F_FLAGS,%edx # User wants flags? + jz rret_tramp.3 # No + movl MEM_ESPR-0x3c,%eax # Read real mode flags + andl $~(PSL_T|PSL_NT),%eax # Clear unsafe flags + movw %ax,-0x08(%esi) # Update user flags (low 16) +/* + * Return to the user task + */ +rret_tramp.3: popl %es # Restore + popl %ds # seg + popl %fs # regs + popl %gs + popal # Restore gp regs + addl $4,%esp # Discard int no + iret # Return to user mode + +/* + * System Call. + */ +intx30: cmpl $SYS_EXEC,%eax # Exec system call? + jne intx30.1 # No + pushl %ss # Set up + popl %es # all + pushl %es # segment + popl %ds # registers + pushl %ds # for the + popl %fs # program + pushl %fs # we're + popl %gs # invoking + movl $MEM_USR,%eax # User base address + addl 0xc(%esp,1),%eax # Change to user + leal 0x4(%eax),%esp # stack + popl %eax # Call + call *%eax # program +intx30.1: orb $0x1,%ss:btx_hdr+0x7 # Flag reboot + jmp exit # Exit +/* + * Dump structure [EBX] to [EDI], using format string [ESI]. + */ +dump.0: stosb # Save char +dump: lodsb # Load char + testb %al,%al # End of string? + jz dump.10 # Yes + testb $0x80,%al # Control? + jz dump.0 # No + movb %al,%ch # Save control + movb $'=',%al # Append + stosb # '=' + lodsb # Get offset + pushl %esi # Save + movsbl %al,%esi # To + addl %ebx,%esi # pointer + testb $DMP_X16,%ch # Dump word? + jz dump.1 # No + lodsw # Get and + call hex16 # dump it +dump.1: testb $DMP_X32,%ch # Dump long? + jz dump.2 # No + lodsl # Get and + call hex32 # dump it +dump.2: testb $DMP_MEM,%ch # Dump memory? + jz dump.8 # No + pushl %ds # Save + testl $PSL_VM,0x50(%ebx) # V86 mode? + jnz dump.3 # Yes + verr 0x4(%esi) # Readable selector? + jnz dump.3 # No + ldsl (%esi),%esi # Load pointer + jmp dump.4 # Join common code +dump.3: lodsl # Set offset + xchgl %eax,%edx # Save + lodsl # Get segment + shll $0x4,%eax # * 0x10 + addl %edx,%eax # + offset + xchgl %eax,%esi # Set pointer +dump.4: movb $2,%dl # Num lines +dump.4a: movb $0x10,%cl # Bytes to dump +dump.5: lodsb # Get byte and + call hex8 # dump it + decb %cl # Keep count + jz dump.6a # If done + movb $'-',%al # Separator + cmpb $0x8,%cl # Half way? + je dump.6 # Yes + movb $' ',%al # Use space +dump.6: stosb # Save separator + jmp dump.5 # Continue +dump.6a: decb %dl # Keep count + jz dump.7 # If done + movb $0xa,%al # Line feed + stosb # Save one + movb $7,%cl # Leading + movb $' ',%al # spaces +dump.6b: stosb # Dump + decb %cl # spaces + jnz dump.6b + jmp dump.4a # Next line +dump.7: popl %ds # Restore +dump.8: popl %esi # Restore + movb $0xa,%al # Line feed + testb $DMP_EOL,%ch # End of line? + jnz dump.9 # Yes + movb $' ',%al # Use spaces + stosb # Save one +dump.9: jmp dump.0 # Continue +dump.10: stosb # Terminate string + 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) +/* + * Output zero-terminated string [ESI] to the console. + */ +putstr.0: call putchr # Output char +putstr: lodsb # Load char + testb %al,%al # End of string? + jnz putstr.0 # No + ret # To caller +#ifdef BTX_SERIAL + .set SIO_PRT,SIOPRT # Base port + .set SIO_FMT,SIOFMT # 8N1 + .set SIO_DIV,(115200/SIOSPD) # 115200 / SPD + +/* + * int sio_init(void) + */ +sio_init: movw $SIO_PRT+0x3,%dx # Data format reg + movb $SIO_FMT|0x80,%al # Set format + outb %al,(%dx) # and DLAB + pushl %edx # Save + subb $0x3,%dl # Divisor latch reg + movw $SIO_DIV,%ax # Set + outw %ax,(%dx) # BPS + popl %edx # Restore + movb $SIO_FMT,%al # Clear + outb %al,(%dx) # DLAB + incl %edx # Modem control reg + movb $0x3,%al # Set RTS, + outb %al,(%dx) # DTR + incl %edx # Line status reg + call sio_getc.1 # Get character + +/* + * int sio_flush(void) + */ +sio_flush: xorl %eax,%eax # Return value + xorl %ecx,%ecx # Timeout + movb $0x80,%ch # counter +sio_flush.1: call sio_ischar # Check for character + jz sio_flush.2 # Till none + loop sio_flush.1 # or counter is zero + movb $1, %al # Exhausted all tries +sio_flush.2: ret # To caller + +/* + * void sio_putc(int c) + */ +sio_putc: movw $SIO_PRT+0x5,%dx # Line status reg + xor %ecx,%ecx # Timeout + movb $0x40,%ch # counter +sio_putc.1: inb (%dx),%al # Transmitter + testb $0x20,%al # buffer empty? + loopz sio_putc.1 # No + jz sio_putc.2 # If timeout + movb 0x4(%esp,1),%al # Get character + subb $0x5,%dl # Transmitter hold reg + outb %al,(%dx) # Write character +sio_putc.2: ret $0x4 # To caller + +/* + * int sio_getc(void) + */ +sio_getc: call sio_ischar # Character available? + jz sio_getc # No +sio_getc.1: subb $0x5,%dl # Receiver buffer reg + inb (%dx),%al # Read character + ret # To caller + +/* + * int sio_ischar(void) + */ +sio_ischar: movw $SIO_PRT+0x5,%dx # Line status register + xorl %eax,%eax # Zero + inb (%dx),%al # Received data + andb $0x1,%al # ready? + ret # To caller + +/* + * Output character AL to the serial console. + */ +putchr: pusha # Save + cmpb $10, %al # is it a newline? + jne putchr.1 # no?, then leave + push $13 # output a carriage + call sio_putc # return first + movb $10, %al # restore %al +putchr.1: pushl %eax # Push the character + # onto the stack + call sio_putc # Output the character + popa # Restore + ret # To caller +#else +/* + * Output character AL to the console. + */ +putchr: 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 $0x20,%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 + ret # To caller +#endif + + .code16 +/* + * Real Mode Hardware interrupt jump table. + */ +intr20: push $0x8 # Int 0x20: IRQ0 + jmp int_hwr # V86 int 0x8 + push $0x9 # Int 0x21: IRQ1 + jmp int_hwr # V86 int 0x9 + push $0xa # Int 0x22: IRQ2 + jmp int_hwr # V86 int 0xa + push $0xb # Int 0x23: IRQ3 + jmp int_hwr # V86 int 0xb + push $0xc # Int 0x24: IRQ4 + jmp int_hwr # V86 int 0xc + push $0xd # Int 0x25: IRQ5 + jmp int_hwr # V86 int 0xd + push $0xe # Int 0x26: IRQ6 + jmp int_hwr # V86 int 0xe + push $0xf # Int 0x27: IRQ7 + jmp int_hwr # V86 int 0xf + push $0x70 # Int 0x28: IRQ8 + jmp int_hwr # V86 int 0x70 + push $0x71 # Int 0x29: IRQ9 + jmp int_hwr # V86 int 0x71 + push $0x72 # Int 0x2a: IRQ10 + jmp int_hwr # V86 int 0x72 + push $0x73 # Int 0x2b: IRQ11 + jmp int_hwr # V86 int 0x73 + push $0x74 # Int 0x2c: IRQ12 + jmp int_hwr # V86 int 0x74 + push $0x75 # Int 0x2d: IRQ13 + jmp int_hwr # V86 int 0x75 + push $0x76 # Int 0x2e: IRQ14 + jmp int_hwr # V86 int 0x76 + push $0x77 # Int 0x2f: IRQ15 + jmp int_hwr # V86 int 0x77 +/* + * Reflect hardware interrupts in real mode. + */ +int_hwr: push %ax # Save + push %ds # Save + push %bp # Save + mov %sp,%bp # Address stack frame + xchg %bx,6(%bp) # Swap BX, int no + xor %ax,%ax # Set %ds:%bx to + shl $2,%bx # point to + mov %ax,%ds # IDT entry + mov (%bx),%ax # Load IP + mov 2(%bx),%bx # Load CS + xchg %ax,4(%bp) # Swap saved %ax,%bx with + xchg %bx,6(%bp) # CS:IP of handler + pop %bp # Restore + pop %ds # Restore + lret # Jump to handler + + .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 + .word 0xffff,MEM_USR,0xfa00,0xcf# SEL_UCODE + .word 0xffff,MEM_USR,0xf200,0xcf# SEL_UDATA +tss_desc: .word _TSSLM,MEM_TSS,0x8900,0x0 # SEL_TSS +gdt.1: +/* + * Pseudo-descriptors. + */ +gdtdesc: .word gdt.1-gdt-1,gdt,0x0 # GDT +idtdesc: .word _IDTLM,MEM_IDT,0x0 # IDT +ivtdesc: .word 0x400-0x0-1,0x0,0x0 # IVT +/* + * IDT construction control string. + */ +idtctl: .byte 0x10, 0x8e # Int 0x0-0xf + .word 0x7dfb,intx00 # (exceptions) + .byte 0x10, 0x8e # Int 0x10 + .word 0x1, intx10 # (exception) + .byte 0x10, 0x8e # Int 0x20-0x2f + .word 0xffff,intx20 # (hardware) + .byte 0x1, 0xee # int 0x30 + .word 0x1, intx30 # (system call) + .byte 0x2, 0xee # Int 0x31-0x32 + .word 0x1, intx31 # (V86, null) + .byte 0x0 # End of string +/* + * Dump format string. + */ +dmpfmt: .byte '\n' # "\n" + .ascii "int" # "int=" + .byte 0x80|DMP_X32, 0x40 # "00000000 " + .ascii "err" # "err=" + .byte 0x80|DMP_X32, 0x44 # "00000000 " + .ascii "efl" # "efl=" + .byte 0x80|DMP_X32, 0x50 # "00000000 " + .ascii "eip" # "eip=" + .byte 0x80|DMP_X32|DMP_EOL,0x48 # "00000000\n" + .ascii "eax" # "eax=" + .byte 0x80|DMP_X32, 0x34 # "00000000 " + .ascii "ebx" # "ebx=" + .byte 0x80|DMP_X32, 0x28 # "00000000 " + .ascii "ecx" # "ecx=" + .byte 0x80|DMP_X32, 0x30 # "00000000 " + .ascii "edx" # "edx=" + .byte 0x80|DMP_X32|DMP_EOL,0x2c # "00000000\n" + .ascii "esi" # "esi=" + .byte 0x80|DMP_X32, 0x1c # "00000000 " + .ascii "edi" # "edi=" + .byte 0x80|DMP_X32, 0x18 # "00000000 " + .ascii "ebp" # "ebp=" + .byte 0x80|DMP_X32, 0x20 # "00000000 " + .ascii "esp" # "esp=" + .byte 0x80|DMP_X32|DMP_EOL,0x0 # "00000000\n" + .ascii "cs" # "cs=" + .byte 0x80|DMP_X16, 0x4c # "0000 " + .ascii "ds" # "ds=" + .byte 0x80|DMP_X16, 0xc # "0000 " + .ascii "es" # "es=" + .byte 0x80|DMP_X16, 0x8 # "0000 " + .ascii " " # " " + .ascii "fs" # "fs=" + .byte 0x80|DMP_X16, 0x10 # "0000 " + .ascii "gs" # "gs=" + .byte 0x80|DMP_X16, 0x14 # "0000 " + .ascii "ss" # "ss=" + .byte 0x80|DMP_X16|DMP_EOL,0x4 # "0000\n" + .ascii "cs:eip" # "cs:eip=" + .byte 0x80|DMP_MEM|DMP_EOL,0x48 # "00 00 ... 00 00\n" + .ascii "ss:esp" # "ss:esp=" + .byte 0x80|DMP_MEM|DMP_EOL,0x0 # "00 00 ... 00 00\n" + .asciz "BTX halted\n" # End +/* + * Bad VM86 call panic + */ +badvm86: .asciz "Invalid VM86 Request\n" + +/* + * End of BTX memory. + */ + .p2align 4 +break: |