blob: 5269ccf97cbe247c5f9537cfc9dc06aab0547ef1 [file] [log] [blame]
// Handler for int 0x15 "system" calls
//
// Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2002 MandrakeSoft S.A.
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
#include "util.h" // memcpy_far
#include "biosvar.h" // BIOS_CONFIG_TABLE
#include "ioport.h" // inb
#include "memmap.h" // E820_RAM
#include "hw/pic.h" // pic_reset
#include "bregs.h" // struct bregs
// Use PS2 System Control port A to set A20 enable
static inline u8
set_a20(u8 cond)
{
// get current setting first
u8 newval, oldval = inb(PORT_A20);
if (cond)
newval = oldval | A20_ENABLE_BIT;
else
newval = oldval & ~A20_ENABLE_BIT;
outb(newval, PORT_A20);
return (oldval & A20_ENABLE_BIT) != 0;
}
static void
handle_152400(struct bregs *regs)
{
set_a20(0);
set_code_success(regs);
}
static void
handle_152401(struct bregs *regs)
{
set_a20(1);
set_code_success(regs);
}
static void
handle_152402(struct bregs *regs)
{
regs->al = (inb(PORT_A20) & A20_ENABLE_BIT) != 0;
set_code_success(regs);
}
static void
handle_152403(struct bregs *regs)
{
regs->bx = 3;
set_code_success(regs);
}
static void
handle_1524XX(struct bregs *regs)
{
set_code_unimplemented(regs, RET_EUNSUPPORTED);
}
static void
handle_1524(struct bregs *regs)
{
switch (regs->al) {
case 0x00: handle_152400(regs); break;
case 0x01: handle_152401(regs); break;
case 0x02: handle_152402(regs); break;
case 0x03: handle_152403(regs); break;
default: handle_1524XX(regs); break;
}
}
// removable media eject
static void
handle_1552(struct bregs *regs)
{
set_code_success(regs);
}
static void
handle_1587(struct bregs *regs)
{
// +++ should probably have descriptor checks
// +++ should have exception handlers
u8 prev_a20_enable = set_a20(1); // enable A20 line
// 128K max of transfer on 386+ ???
// source == destination ???
// ES:SI points to descriptor table
// offset use initially comments
// ==============================================
// 00..07 Unused zeros Null descriptor
// 08..0f GDT zeros filled in by BIOS
// 10..17 source ssssssss source of data
// 18..1f dest dddddddd destination of data
// 20..27 CS zeros filled in by BIOS
// 28..2f SS zeros filled in by BIOS
// check for access rights of source & dest here
// Initialize GDT descriptor
u32 si = regs->si;
u64 *gdt_far = (void*)si;
u16 gdt_seg = regs->es;
u32 loc = (u32)MAKE_FLATPTR(gdt_seg, gdt_far);
SET_FARVAR(gdt_seg, gdt_far[1], GDT_DATA | GDT_LIMIT((6*sizeof(u64))-1)
| GDT_BASE(loc));
// Initialize CS descriptor
SET_FARVAR(gdt_seg, gdt_far[4], GDT_CODE | GDT_LIMIT(BUILD_BIOS_SIZE-1)
| GDT_BASE(BUILD_BIOS_ADDR));
// Initialize SS descriptor
loc = (u32)MAKE_FLATPTR(GET_SEG(SS), 0);
SET_FARVAR(gdt_seg, gdt_far[5], GDT_DATA | GDT_LIMIT(0x0ffff)
| GDT_BASE(loc));
u16 count = regs->cx;
asm volatile(
// Load new descriptor tables
" lgdtw %%es:(1<<3)(%%si)\n"
" lidtw %%cs:pmode_IDT_info\n"
// Enable protected mode
" movl %%cr0, %%eax\n"
" orl $" __stringify(CR0_PE) ", %%eax\n"
" movl %%eax, %%cr0\n"
// far jump to flush CPU queue after transition to protected mode
" ljmpw $(4<<3), $1f\n"
// GDT points to valid descriptor table, now load DS, ES
"1:movw $(2<<3), %%ax\n" // 2nd descriptor in table, TI=GDT, RPL=00
" movw %%ax, %%ds\n"
" movw $(3<<3), %%ax\n" // 3rd descriptor in table, TI=GDT, RPL=00
" movw %%ax, %%es\n"
// move CX words from DS:SI to ES:DI
" xorw %%si, %%si\n"
" xorw %%di, %%di\n"
" rep movsw\n"
// Restore DS and ES segment limits to 0xffff
" movw $(5<<3), %%ax\n" // 5th descriptor in table (SS)
" movw %%ax, %%ds\n"
" movw %%ax, %%es\n"
// Disable protected mode
" movl %%cr0, %%eax\n"
" andl $~" __stringify(CR0_PE) ", %%eax\n"
" movl %%eax, %%cr0\n"
// far jump to flush CPU queue after transition to real mode
" ljmpw $" __stringify(SEG_BIOS) ", $2f\n"
// restore IDT to normal real-mode defaults
"2:lidtw %%cs:rmode_IDT_info\n"
// Restore %ds (from %ss)
" movw %%ss, %%ax\n"
" movw %%ax, %%ds\n"
: "+c"(count), "+S"(si), "+m" (__segment_ES)
: : "eax", "di", "cc");
set_a20(prev_a20_enable);
set_code_success(regs);
}
// Get the amount of extended memory (above 1M)
static void
handle_1588(struct bregs *regs)
{
u32 rs = GET_GLOBAL(LegacyRamSize);
// According to Ralf Brown's interrupt the limit should be 15M,
// but real machines mostly return max. 63M.
if (rs > 64*1024*1024)
regs->ax = 63 * 1024;
else
regs->ax = (rs - 1*1024*1024) / 1024;
set_success(regs);
}
// Switch to protected mode
static void
handle_1589(struct bregs *regs)
{
set_a20(1);
pic_reset(regs->bl, regs->bh);
u64 *gdt_far = (void*)(regs->si + 0);
u16 gdt_seg = regs->es;
SET_FARVAR(gdt_seg, gdt_far[7], GDT_CODE | GDT_LIMIT(BUILD_BIOS_SIZE-1)
| GDT_BASE(BUILD_BIOS_ADDR));
regs->ds = 3<<3; // 3rd gdt descriptor is %ds
regs->es = 4<<3; // 4th gdt descriptor is %es
regs->code.seg = 6<<3; // 6th gdt descriptor is %cs
set_code_success(regs);
asm volatile(
// Load new descriptor tables
" lgdtw %%es:(1<<3)(%%si)\n"
" lidtw %%es:(2<<3)(%%si)\n"
// Enable protected mode
" movl %%cr0, %%eax\n"
" orl $" __stringify(CR0_PE) ", %%eax\n"
" movl %%eax, %%cr0\n"
// far jump to flush CPU queue after transition to protected mode
" ljmpw $(7<<3), $1f\n"
// GDT points to valid descriptor table, now load SS
"1:movw $(5<<3), %%ax\n"
" movw %%ax, %%ds\n"
" movw %%ax, %%ss\n"
:
: "S"(gdt_far), "m" (__segment_ES)
: "eax", "cc");
}
// Device busy interrupt. Called by Int 16h when no key available
static void
handle_1590(struct bregs *regs)
{
}
// Interrupt complete. Called by Int 16h when key becomes available
static void
handle_1591(struct bregs *regs)
{
}
// keyboard intercept
static void
handle_154f(struct bregs *regs)
{
set_invalid_silent(regs);
}
static void
handle_15c0(struct bregs *regs)
{
regs->es = SEG_BIOS;
regs->bx = (u32)&BIOS_CONFIG_TABLE;
set_code_success(regs);
}
static void
handle_15c1(struct bregs *regs)
{
regs->es = get_ebda_seg();
set_success(regs);
}
static void
handle_15e801(struct bregs *regs)
{
// my real system sets ax and bx to 0
// this is confirmed by Ralph Brown list
// but syslinux v1.48 is known to behave
// strangely if ax is set to 0
// regs.u.r16.ax = 0;
// regs.u.r16.bx = 0;
u32 rs = GET_GLOBAL(LegacyRamSize);
// Get the amount of extended memory (above 1M)
if (rs > 16*1024*1024) {
// limit to 15M
regs->cx = 15*1024;
// Get the amount of extended memory above 16M in 64k blocks
regs->dx = (rs - 16*1024*1024) / (64*1024);
} else {
regs->cx = (rs - 1*1024*1024) / 1024;
regs->dx = 0;
}
// Set configured memory equal to extended memory
regs->ax = regs->cx;
regs->bx = regs->dx;
set_success(regs);
}
static void
handle_15e820(struct bregs *regs)
{
int count = GET_GLOBAL(e820_count);
if (regs->edx != 0x534D4150 || regs->bx >= count
|| regs->ecx < sizeof(e820_list[0])) {
set_code_invalid(regs, RET_EUNSUPPORTED);
return;
}
memcpy_far(regs->es, (void*)(regs->di+0)
, get_global_seg(), &e820_list[regs->bx]
, sizeof(e820_list[0]));
if (regs->bx == count-1)
regs->ebx = 0;
else
regs->ebx++;
regs->eax = 0x534D4150;
regs->ecx = sizeof(e820_list[0]);
set_success(regs);
}
static void
handle_15e8XX(struct bregs *regs)
{
set_code_unimplemented(regs, RET_EUNSUPPORTED);
}
static void
handle_15e8(struct bregs *regs)
{
switch (regs->al) {
case 0x01: handle_15e801(regs); break;
case 0x20: handle_15e820(regs); break;
default: handle_15e8XX(regs); break;
}
}
static void
handle_15XX(struct bregs *regs)
{
set_code_unimplemented(regs, RET_EUNSUPPORTED);
}
// INT 15h System Services Entry Point
void VISIBLE16
handle_15(struct bregs *regs)
{
debug_enter(regs, DEBUG_HDL_15);
switch (regs->ah) {
case 0x24: handle_1524(regs); break;
case 0x4f: handle_154f(regs); break;
case 0x52: handle_1552(regs); break;
case 0x53: handle_1553(regs); break;
case 0x5f: handle_155f(regs); break;
case 0x83: handle_1583(regs); break;
case 0x86: handle_1586(regs); break;
case 0x87: handle_1587(regs); break;
case 0x88: handle_1588(regs); break;
case 0x89: handle_1589(regs); break;
case 0x90: handle_1590(regs); break;
case 0x91: handle_1591(regs); break;
case 0xc0: handle_15c0(regs); break;
case 0xc1: handle_15c1(regs); break;
case 0xc2: handle_15c2(regs); break;
case 0xe8: handle_15e8(regs); break;
default: handle_15XX(regs); break;
}
}