// Handler for int 0x15 "system" calls // // Copyright (C) 2008 Kevin O'Connor // Copyright (C) 2002 MandrakeSoft S.A. // // This file may be distributed under the terms of the GNU LGPLv3 license. #include "biosvar.h" // GET_GLOBAL #include "bregs.h" // struct bregs #include "hw/pic.h" // pic_reset #include "hw/ps2port.h" // PORT_A20 #include "malloc.h" // LegacyRamSize #include "memmap.h" // E820_RAM #include "output.h" // debug_enter #include "string.h" // memcpy_far #include "util.h" // handle_1553 #include "x86.h" // inb // 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 u64 lim = GDT_LIMIT(0x0ffff); if (in_post()) lim = GDT_GRANLIMIT(0xffffffff); SET_FARVAR(gdt_seg, gdt_far[4], GDT_CODE | lim | 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 | lim | 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 void VISIBLE16 handle_1589(struct bregs *regs) { debug_enter(regs, DEBUG_HDL_15); 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 0x7f: handle_157f(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 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; } }