diff options
Diffstat (limited to 'roms/ipxe/src/arch/i386/transitions')
| -rw-r--r-- | roms/ipxe/src/arch/i386/transitions/liba20.S | 309 | ||||
| -rw-r--r-- | roms/ipxe/src/arch/i386/transitions/libkir.S | 256 | ||||
| -rw-r--r-- | roms/ipxe/src/arch/i386/transitions/libpm.S | 0 | ||||
| -rw-r--r-- | roms/ipxe/src/arch/i386/transitions/librm.S | 671 | ||||
| -rw-r--r-- | roms/ipxe/src/arch/i386/transitions/librm_mgmt.c | 158 | ||||
| -rw-r--r-- | roms/ipxe/src/arch/i386/transitions/librm_test.c | 117 |
6 files changed, 1511 insertions, 0 deletions
diff --git a/roms/ipxe/src/arch/i386/transitions/liba20.S b/roms/ipxe/src/arch/i386/transitions/liba20.S new file mode 100644 index 00000000..68469752 --- /dev/null +++ b/roms/ipxe/src/arch/i386/transitions/liba20.S @@ -0,0 +1,309 @@ +/* + * Copyright (C) 2010 Michael Brown <mbrown@fensystems.co.uk>. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ) + + .arch i386 + +/**************************************************************************** + * test_a20_short, test_a20_long + * + * Check to see if A20 line is enabled + * + * Parameters: + * none + * Returns: + * CF set if A20 line is not enabled + * Corrupts: + * none + **************************************************************************** + */ +#define TEST_A20_SHORT_MAX_RETRIES 0x20 +#define TEST_A20_LONG_MAX_RETRIES 0x200000 + .section ".text16.early", "awx", @progbits + .code16 +test_a20_short: + pushl %ecx + movl $TEST_A20_SHORT_MAX_RETRIES, %ecx + jmp 1f + .size test_a20_short, . - test_a20_short +test_a20_long: + pushl %ecx + movl $TEST_A20_LONG_MAX_RETRIES, %ecx +1: pushw %ax + pushw %ds + pushw %es + + /* Set up segment registers for access across the 1MB boundary */ + xorw %ax, %ax + movw %ax, %ds + decw %ax + movw %ax, %es + +2: /* Modify and check test pattern; succeed if we see a difference */ + pushfw + cli + xchgw %ds:0, %cx + movw %es:0x10, %ax + xchgw %ds:0, %cx + popfw + cmpw %ax, %cx + clc + jnz 99f + + /* Delay and retry */ + outb %al, $0x80 + addr32 loop 2b + stc + +99: /* Restore registers and return */ + popw %es + popw %ds + popw %ax + popl %ecx + ret + .size test_a20_long, . - test_a20_long + +/**************************************************************************** + * enable_a20_bios + * + * Try enabling A20 line via BIOS + * + * Parameters: + * none + * Returns: + * CF set if A20 line is not enabled + * Corrupts: + * none + **************************************************************************** + */ + .section ".text16.early", "awx", @progbits + .code16 +enable_a20_bios: + + /* Preserve registers. Be very paranoid, since some BIOSes + * are reported to clobber %ebx + */ + pushal + + /* Attempt INT 15,2401 */ + movw $0x2401, %ax + int $0x15 + jc 99f + + /* Check that success was really successful */ + call test_a20_short + +99: /* Restore registers and return */ + popal + ret + .size enable_a20_bios, . - enable_a20_bios + +/**************************************************************************** + * enable_a20_kbc + * + * Try enabling A20 line via keyboard controller + * + * Parameters: + * none + * Returns: + * CF set if A20 line is not enabled + * Corrupts: + * none + **************************************************************************** + */ +#define KC_RDWR 0x60 +#define KC_RDWR_SET_A20 0xdf +#define KC_CMD 0x64 +#define KC_CMD_WOUT 0xd1 +#define KC_CMD_NULL 0xff +#define KC_STATUS 0x64 +#define KC_STATUS_OBUF_FULL 0x01 +#define KC_STATUS_IBUF_FULL 0x02 +#define KC_MAX_RETRIES 100000 + .section ".text16.early", "awx", @progbits + .code16 +enable_a20_kbc: + /* Preserve registers */ + pushw %ax + + /* Try keyboard controller */ + call empty_kbc + movb $KC_CMD_WOUT, %al + outb %al, $KC_CMD + call empty_kbc + movb $KC_RDWR_SET_A20, %al + outb %al, $KC_RDWR + call empty_kbc + movb $KC_CMD_NULL, %al + outb %al, $KC_CMD + call empty_kbc + + /* Check to see if it worked */ + call test_a20_long + + /* Restore registers and return */ + popw %ax + ret + .size enable_a20_kbc, . - enable_a20_kbc + + .section ".text16.early", "awx", @progbits + .code16 +empty_kbc: + /* Preserve registers */ + pushl %ecx + pushw %ax + + /* Wait for KBC to become empty */ + movl $KC_MAX_RETRIES, %ecx +1: outb %al, $0x80 + inb $KC_STATUS, %al + testb $( KC_STATUS_OBUF_FULL | KC_STATUS_IBUF_FULL ), %al + jz 99f + testb $KC_STATUS_OBUF_FULL, %al + jz 2f + outb %al, $0x80 + inb $KC_RDWR, %al +2: addr32 loop 1b + +99: /* Restore registers and return */ + popw %ax + popl %ecx + ret + .size empty_kbc, . - empty_kbc + +/**************************************************************************** + * enable_a20_fast + * + * Try enabling A20 line via "Fast Gate A20" + * + * Parameters: + * none + * Returns: + * CF set if A20 line is not enabled + * Corrupts: + * none + **************************************************************************** + */ +#define SCP_A 0x92 + .section ".text16.early", "awx", @progbits + .code16 +enable_a20_fast: + /* Preserve registers */ + pushw %ax + + /* Try "Fast Gate A20" */ + inb $SCP_A, %al + orb $0x02, %al + andb $~0x01, %al + outb %al, $SCP_A + + /* Check to see if it worked */ + call test_a20_long + + /* Restore registers and return */ + popw %ax + ret + .size enable_a20_fast, . - enable_a20_fast + +/**************************************************************************** + * enable_a20 + * + * Try enabling A20 line via any available method + * + * Parameters: + * none + * Returns: + * CF set if A20 line is not enabled + * Corrupts: + * none + **************************************************************************** + */ +#define ENABLE_A20_RETRIES 255 + .section ".text16.early", "awx", @progbits + .code16 + .globl enable_a20 +enable_a20: + /* Preserve registers */ + pushl %ecx + pushw %ax + + /* Check to see if A20 is already enabled */ + call test_a20_short + jnc 99f + + /* Use known working method, if we have one */ + movw %cs:enable_a20_method, %ax + testw %ax, %ax + jz 1f + call *%ax + jmp 99f +1: + /* Try all methods in turn until one works */ + movl $ENABLE_A20_RETRIES, %ecx +2: movw $enable_a20_bios, %ax + movw %ax, %cs:enable_a20_method + call *%ax + jnc 99f + movw $enable_a20_kbc, %ax + movw %ax, %cs:enable_a20_method + call *%ax + jnc 99f + movw $enable_a20_fast, %ax + movw %ax, %cs:enable_a20_method + call *%ax + jnc 99f + addr32 loop 2b + /* Failure; exit with carry set */ + movw $0, %cs:enable_a20_method + stc + +99: /* Restore registers and return */ + popw %ax + popl %ecx + ret + + .section ".text16.early.data", "aw", @progbits + .align 2 +enable_a20_method: + .word 0 + .size enable_a20_method, . - enable_a20_method + +/**************************************************************************** + * access_highmem (real mode far call) + * + * Open up access to high memory with A20 enabled + * + * Parameters: + * none + * Returns: + * CF set if high memory could not be accessed + * Corrupts: + * none + **************************************************************************** + */ + .section ".text16.early", "awx", @progbits + .code16 + .globl access_highmem +access_highmem: + /* Enable A20 line */ + call enable_a20 + lret + .size access_highmem, . - access_highmem diff --git a/roms/ipxe/src/arch/i386/transitions/libkir.S b/roms/ipxe/src/arch/i386/transitions/libkir.S new file mode 100644 index 00000000..1176fcce --- /dev/null +++ b/roms/ipxe/src/arch/i386/transitions/libkir.S @@ -0,0 +1,256 @@ +/* + * libkir: a transition library for -DKEEP_IT_REAL + * + * Michael Brown <mbrown@fensystems.co.uk> + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ) + +/**************************************************************************** + * This file defines libkir: an interface between external and + * internal environments when -DKEEP_IT_REAL is used, so that both + * internal and external environments are in real mode. It deals with + * switching data segments and the stack. It provides the following + * functions: + * + * ext_to_kir & switch between external and internal (kir) + * kir_to_ext environments, preserving all non-segment + * registers + * + * kir_call issue a call to an internal routine from external + * code + * + * libkir is written to avoid assuming that segments are anything + * other than opaque data types, and also avoids assuming that the + * stack pointer is 16-bit. This should enable it to run just as well + * in 16:16 or 16:32 protected mode as in real mode. + **************************************************************************** + */ + +/* Breakpoint for when debugging under bochs */ +#define BOCHSBP xchgw %bx, %bx + + .text + .arch i386 + .section ".text16", "awx", @progbits + .code16 + +/**************************************************************************** + * init_libkir (real-mode or 16:xx protected-mode far call) + * + * Initialise libkir ready for transitions to the kir environment + * + * Parameters: + * %cs : .text16 segment + * %ds : .data16 segment + **************************************************************************** + */ + .globl init_libkir +init_libkir: + /* Record segment registers */ + pushw %ds + popw %cs:kir_ds + lret + +/**************************************************************************** + * ext_to_kir (real-mode or 16:xx protected-mode near call) + * + * Switch from external stack and segment registers to internal stack + * and segment registers. %ss:sp is restored from the saved kir_ds + * and kir_sp. %ds, %es, %fs and %gs are all restored from the saved + * kir_ds. All other registers are preserved. + * + * %cs:0000 must point to the start of the runtime image code segment + * on entry. + * + * Parameters: none + **************************************************************************** + */ + + .globl ext_to_kir +ext_to_kir: + /* Record external segment registers */ + movw %ds, %cs:ext_ds + pushw %cs + popw %ds /* Set %ds = %cs for easier access to variables */ + movw %es, %ds:ext_es + movw %fs, %ds:ext_fs + movw %gs, %ds:ext_fs + + /* Preserve registers */ + movw %ax, %ds:save_ax + + /* Extract near return address from stack */ + popw %ds:save_retaddr + + /* Record external %ss:esp */ + movw %ss, %ds:ext_ss + movl %esp, %ds:ext_esp + + /* Load internal segment registers and stack pointer */ + movw %ds:kir_ds, %ax + movw %ax, %ss + movzwl %ds:kir_sp, %esp + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs +1: + + /* Place return address on new stack */ + pushw %cs:save_retaddr + + /* Restore registers and return */ + movw %cs:save_ax, %ax + ret + +/**************************************************************************** + * kir_to_ext (real-mode or 16:xx protected-mode near call) + * + * Switch from internal stack and segment registers to external stack + * and segment registers. %ss:%esp is restored from the saved ext_ss + * and ext_esp. Other segment registers are restored from the + * corresponding locations. All other registers are preserved. + * + * Note that it is actually %ss that is recorded as kir_ds, on the + * assumption that %ss == %ds when kir_to_ext is called. + * + * Parameters: none + **************************************************************************** + */ + + .globl kir_to_ext +kir_to_ext: + /* Record near return address */ + pushw %cs + popw %ds /* Set %ds = %cs for easier access to variables */ + popw %ds:save_retaddr + + /* Record internal segment registers and %sp */ + movw %ss, %ds:kir_ds + movw %sp, %ds:kir_sp + + /* Load external segment registers and stack pointer */ + movw %ds:ext_ss, %ss + movl %ds:ext_esp, %esp + movw %ds:ext_gs, %gs + movw %ds:ext_fs, %fs + movw %ds:ext_es, %es + movw %ds:ext_ds, %ds + + /* Return */ + pushw %cs:save_retaddr + ret + +/**************************************************************************** + * kir_call (real-mode or 16:xx protected-mode far call) + * + * Call a specific C function in the internal code. The prototype of + * the C function must be + * void function ( struct i386_all_resg *ix86 ); + * ix86 will point to a struct containing the real-mode registers + * at entry to kir_call. + * + * All registers will be preserved across kir_call(), unless the C + * function explicitly overwrites values in ix86. Interrupt status + * will also be preserved. + * + * Parameters: + * function : (32-bit) virtual address of C function to call + * + * Example usage: + * pushl $pxe_api_call + * lcall $UNDI_CS, $kir_call + * addw $4, %sp + * to call in to the C function + * void pxe_api_call ( struct i386_all_regs *ix86 ); + **************************************************************************** + */ + + .globl kir_call +kir_call: + /* Preserve flags. Must do this before any operation that may + * affect flags. + */ + pushfl + popl %cs:save_flags + + /* Disable interrupts. We do funny things with the stack, and + * we're not re-entrant. + */ + cli + + /* Extract address of internal routine from stack. We must do + * this without using (%bp), because we may be called with + * either a 16-bit or a 32-bit stack segment. + */ + popl %cs:save_retaddr /* Scratch location */ + popl %cs:save_function + subl $8, %esp /* Restore %esp */ + + /* Switch to internal stack. Note that the external stack is + * inaccessible once we're running internally (since we have + * no concept of 48-bit far pointers) + */ + call ext_to_kir + + /* Store external registers on internal stack */ + pushl %cs:save_flags + pushal + pushl %cs:ext_fs_and_gs + pushl %cs:ext_ds_and_es + pushl %cs:ext_cs_and_ss + + /* Push &ix86 on stack and call function */ + sti + pushl %esp + data32 call *%cs:save_function + popl %eax /* discard */ + + /* Restore external registers from internal stack */ + popl %cs:ext_cs_and_ss + popl %cs:ext_ds_and_es + popl %cs:ext_fs_and_gs + popal + popl %cs:save_flags + + /* Switch to external stack */ + call kir_to_ext + + /* Restore flags */ + pushl %cs:save_flags + popfl + + /* Return */ + lret + +/**************************************************************************** + * Stored internal and external stack and segment registers + **************************************************************************** + */ + +ext_cs_and_ss: +ext_cs: .word 0 +ext_ss: .word 0 +ext_ds_and_es: +ext_ds: .word 0 +ext_es: .word 0 +ext_fs_and_gs: +ext_fs: .word 0 +ext_gs: .word 0 +ext_esp: .long 0 + + .globl kir_ds +kir_ds: .word 0 + .globl kir_sp +kir_sp: .word _estack + +/**************************************************************************** + * Temporary variables + **************************************************************************** + */ +save_ax: .word 0 +save_retaddr: .long 0 +save_flags: .long 0 +save_function: .long 0 diff --git a/roms/ipxe/src/arch/i386/transitions/libpm.S b/roms/ipxe/src/arch/i386/transitions/libpm.S new file mode 100644 index 00000000..e69de29b --- /dev/null +++ b/roms/ipxe/src/arch/i386/transitions/libpm.S diff --git a/roms/ipxe/src/arch/i386/transitions/librm.S b/roms/ipxe/src/arch/i386/transitions/librm.S new file mode 100644 index 00000000..2e447b03 --- /dev/null +++ b/roms/ipxe/src/arch/i386/transitions/librm.S @@ -0,0 +1,671 @@ +/* + * librm: a library for interfacing to real-mode code + * + * Michael Brown <mbrown@fensystems.co.uk> + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ) + +/* Drag in local definitions */ +#include "librm.h" + +/* For switches to/from protected mode */ +#define CR0_PE 1 + +/* Size of various C data structures */ +#define SIZEOF_I386_SEG_REGS 12 +#define SIZEOF_I386_REGS 32 +#define SIZEOF_REAL_MODE_REGS ( SIZEOF_I386_SEG_REGS + SIZEOF_I386_REGS ) +#define SIZEOF_I386_FLAGS 4 +#define SIZEOF_I386_ALL_REGS ( SIZEOF_REAL_MODE_REGS + SIZEOF_I386_FLAGS ) + + .arch i386 + +/**************************************************************************** + * Global descriptor table + * + * Call init_librm to set up the GDT before attempting to use any + * protected-mode code. + * + * NOTE: This must be located before prot_to_real, otherwise gas + * throws a "can't handle non absolute segment in `ljmp'" error due to + * not knowing the value of REAL_CS when the ljmp is encountered. + * + * Note also that putting ".word gdt_end - gdt - 1" directly into + * gdt_limit, rather than going via gdt_length, will also produce the + * "non absolute segment" error. This is most probably a bug in gas. + **************************************************************************** + */ + .section ".data16", "aw", @progbits + .align 16 +gdt: +gdtr: /* The first GDT entry is unused, the GDTR can fit here. */ +gdt_limit: .word gdt_length - 1 +gdt_base: .long 0 + .word 0 /* padding */ + + .org gdt + VIRTUAL_CS, 0 +virtual_cs: /* 32 bit protected mode code segment, virtual addresses */ + .word 0xffff, 0 + .byte 0, 0x9f, 0xcf, 0 + + .org gdt + VIRTUAL_DS, 0 +virtual_ds: /* 32 bit protected mode data segment, virtual addresses */ + .word 0xffff, 0 + .byte 0, 0x93, 0xcf, 0 + + .org gdt + PHYSICAL_CS, 0 +physical_cs: /* 32 bit protected mode code segment, physical addresses */ + .word 0xffff, 0 + .byte 0, 0x9f, 0xcf, 0 + + .org gdt + PHYSICAL_DS, 0 +physical_ds: /* 32 bit protected mode data segment, physical addresses */ + .word 0xffff, 0 + .byte 0, 0x93, 0xcf, 0 + + .org gdt + REAL_CS, 0 +real_cs: /* 16 bit real mode code segment */ + .word 0xffff, 0 + .byte 0, 0x9b, 0x00, 0 + + .org gdt + REAL_DS +real_ds: /* 16 bit real mode data segment */ + .word 0xffff, ( REAL_DS << 4 ) + .byte 0, 0x93, 0x00, 0 + +gdt_end: + .equ gdt_length, gdt_end - gdt + +/**************************************************************************** + * init_librm (real-mode far call, 16-bit real-mode far return address) + * + * Initialise the GDT ready for transitions to protected mode. + * + * Parameters: + * %cs : .text16 segment + * %ds : .data16 segment + * %edi : Physical base of protected-mode code (virt_offset) + **************************************************************************** + */ + .section ".text16", "ax", @progbits + .code16 + .globl init_librm +init_librm: + /* Preserve registers */ + pushl %eax + pushl %ebx + + /* Store virt_offset and set up virtual_cs and virtual_ds segments */ + movl %edi, %eax + movw $virtual_cs, %bx + call set_seg_base + movw $virtual_ds, %bx + call set_seg_base + movl %edi, rm_virt_offset + + /* Negate virt_offset */ + negl %edi + + /* Store rm_cs and text16, set up real_cs segment */ + xorl %eax, %eax + movw %cs, %ax + movw %ax, %cs:rm_cs + shll $4, %eax + movw $real_cs, %bx + call set_seg_base + addr32 leal (%eax, %edi), %ebx + movl %ebx, rm_text16 + + /* Store rm_ds and data16 */ + xorl %eax, %eax + movw %ds, %ax + movw %ax, %cs:rm_ds + shll $4, %eax + addr32 leal (%eax, %edi), %ebx + movl %ebx, rm_data16 + + /* Set GDT base */ + movl %eax, gdt_base + addl $gdt, gdt_base + + /* Initialise IDT */ + pushl $init_idt + pushw %cs + call prot_call + popl %eax /* discard */ + + /* Restore registers */ + negl %edi + popl %ebx + popl %eax + lret + + .section ".text16", "ax", @progbits + .code16 +set_seg_base: +1: movw %ax, 2(%bx) + rorl $16, %eax + movb %al, 4(%bx) + movb %ah, 7(%bx) + roll $16, %eax + ret + +/**************************************************************************** + * real_to_prot (real-mode near call, 32-bit virtual return address) + * + * Switch from 16-bit real-mode to 32-bit protected mode with virtual + * addresses. The real-mode %ss:sp is stored in rm_ss and rm_sp, and + * the protected-mode %esp is restored from the saved pm_esp. + * Interrupts are disabled. All other registers may be destroyed. + * + * The return address for this function should be a 32-bit virtual + * address. + * + * Parameters: + * %ecx : number of bytes to move from RM stack to PM stack + * + **************************************************************************** + */ + .section ".text16", "ax", @progbits + .code16 +real_to_prot: + /* Enable A20 line */ + call enable_a20 + /* A failure at this point is fatal, and there's nothing we + * can do about it other than lock the machine to make the + * problem immediately visible. + */ +1: jc 1b + + /* Make sure we have our data segment available */ + movw %cs:rm_ds, %ax + movw %ax, %ds + + /* Add virt_offset, text16 and data16 to stack to be + * copied, and also copy the return address. + */ + pushl rm_virt_offset + pushl rm_text16 + pushl rm_data16 + addw $16, %cx /* %ecx must be less than 64kB anyway */ + + /* Real-mode %ss:%sp => %ebp:%edx and virtual address => %esi */ + xorl %ebp, %ebp + movw %ss, %bp + movzwl %sp, %edx + movl %ebp, %eax + shll $4, %eax + addr32 leal (%eax,%edx), %esi + subl rm_virt_offset, %esi + + /* Load protected-mode global descriptor table */ + data32 lgdt gdtr + + /* Zero segment registers. This wastes around 12 cycles on + * real hardware, but saves a substantial number of emulated + * instructions under KVM. + */ + xorw %ax, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + movw %ax, %ss + + /* Switch to protected mode */ + cli + movl %cr0, %eax + orb $CR0_PE, %al + movl %eax, %cr0 + data32 ljmp $VIRTUAL_CS, $r2p_pmode + .section ".text", "ax", @progbits + .code32 +r2p_pmode: + /* Set up protected-mode data segments and stack pointer */ + movw $VIRTUAL_DS, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + movw %ax, %ss + movl pm_esp, %esp + + /* Load protected-mode interrupt descriptor table */ + lidt idtr + + /* Record real-mode %ss:sp (after removal of data) */ + movw %bp, rm_ss + addl %ecx, %edx + movw %dx, rm_sp + + /* Move data from RM stack to PM stack */ + subl %ecx, %esp + movl %esp, %edi + rep movsb + + /* Publish virt_offset, text16 and data16 for PM code to use */ + popl data16 + popl text16 + popl virt_offset + + /* Return to virtual address */ + ret + +/**************************************************************************** + * prot_to_real (protected-mode near call, 32-bit real-mode return address) + * + * Switch from 32-bit protected mode with virtual addresses to 16-bit + * real mode. The protected-mode %esp is stored in pm_esp and the + * real-mode %ss:sp is restored from the saved rm_ss and rm_sp. The + * high word of the real-mode %esp is set to zero. All real-mode data + * segment registers are loaded from the saved rm_ds. Interrupts are + * *not* enabled, since we want to be able to use prot_to_real in an + * ISR. All other registers may be destroyed. + * + * The return address for this function should be a 32-bit (sic) + * real-mode offset within .code16. + * + * Parameters: + * %ecx : number of bytes to move from PM stack to RM stack + * %esi : real-mode global and interrupt descriptor table registers + * + **************************************************************************** + */ + .section ".text", "ax", @progbits + .code32 +prot_to_real: + /* Copy real-mode global descriptor table register to RM code segment */ + movl text16, %edi + leal rm_gdtr(%edi), %edi + movsw + movsl + + /* Load real-mode interrupt descriptor table register */ + lidt (%esi) + + /* Add return address to data to be moved to RM stack */ + addl $4, %ecx + + /* Real-mode %ss:sp => %ebp:edx and virtual address => %edi */ + movzwl rm_ss, %ebp + movzwl rm_sp, %edx + subl %ecx, %edx + movl %ebp, %eax + shll $4, %eax + leal (%eax,%edx), %edi + subl virt_offset, %edi + + /* Move data from PM stack to RM stack */ + movl %esp, %esi + rep movsb + + /* Record protected-mode %esp (after removal of data) */ + movl %esi, pm_esp + + /* Load real-mode segment limits */ + movw $REAL_DS, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + movw %ax, %ss + ljmp $REAL_CS, $p2r_rmode + .section ".text16", "ax", @progbits + .code16 +p2r_rmode: + /* Load real-mode GDT */ + data32 lgdt %cs:rm_gdtr + /* Switch to real mode */ + movl %cr0, %eax + andb $0!CR0_PE, %al + movl %eax, %cr0 +p2r_ljmp_rm_cs: + ljmp $0, $1f +1: + /* Set up real-mode data segments and stack pointer */ + movw %cs:rm_ds, %ax + movw %ax, %ds + movw %ax, %es + movw %ax, %fs + movw %ax, %gs + movw %bp, %ss + movl %edx, %esp + + /* Return to real-mode address */ + data32 ret + + + /* Real-mode code and data segments. Assigned by the call to + * init_librm. rm_cs doubles as the segment part of the jump + * instruction used by prot_to_real. Both are located in + * .text16 rather than .data16: rm_cs since it forms part of + * the jump instruction within the code segment, and rm_ds + * since real-mode code needs to be able to locate the data + * segment with no other reference available. + */ + .globl rm_cs + .equ rm_cs, ( p2r_ljmp_rm_cs + 3 ) + + .section ".text16.data", "aw", @progbits + .globl rm_ds +rm_ds: .word 0 + + /* Real-mode global and interrupt descriptor table registers */ + .section ".text16.data", "aw", @progbits +rm_gdtr: + .word 0 /* Limit */ + .long 0 /* Base */ + +/**************************************************************************** + * prot_call (real-mode far call, 16-bit real-mode far return address) + * + * Call a specific C function in the protected-mode code. The + * prototype of the C function must be + * void function ( struct i386_all_regs *ix86 ); + * ix86 will point to a struct containing the real-mode registers + * at entry to prot_call. + * + * All registers will be preserved across prot_call(), unless the C + * function explicitly overwrites values in ix86. Interrupt status + * and GDT will also be preserved. Gate A20 will be enabled. + * + * Note that prot_call() does not rely on the real-mode stack + * remaining intact in order to return, since everything relevant is + * copied to the protected-mode stack for the duration of the call. + * In particular, this means that a real-mode prefix can make a call + * to main() which will return correctly even if the prefix's stack + * gets vapourised during the Etherboot run. (The prefix cannot rely + * on anything else on the stack being preserved, so should move any + * critical data to registers before calling main()). + * + * Parameters: + * function : virtual address of protected-mode function to call + * + * Example usage: + * pushl $pxe_api_call + * call prot_call + * addw $4, %sp + * to call in to the C function + * void pxe_api_call ( struct i386_all_regs *ix86 ); + **************************************************************************** + */ + +#define PC_OFFSET_GDT ( 0 ) +#define PC_OFFSET_IDT ( PC_OFFSET_GDT + 6 ) +#define PC_OFFSET_IX86 ( PC_OFFSET_IDT + 6 ) +#define PC_OFFSET_RETADDR ( PC_OFFSET_IX86 + SIZEOF_I386_ALL_REGS ) +#define PC_OFFSET_FUNCTION ( PC_OFFSET_RETADDR + 4 ) +#define PC_OFFSET_END ( PC_OFFSET_FUNCTION + 4 ) + + .section ".text16", "ax", @progbits + .code16 + .globl prot_call +prot_call: + /* Preserve registers, flags and GDT on external RM stack */ + pushfl + pushal + pushw %gs + pushw %fs + pushw %es + pushw %ds + pushw %ss + pushw %cs + subw $PC_OFFSET_IX86, %sp + movw %sp, %bp + sidt PC_OFFSET_IDT(%bp) + sgdt PC_OFFSET_GDT(%bp) + + /* For sanity's sake, clear the direction flag as soon as possible */ + cld + + /* Switch to protected mode and move register dump to PM stack */ + movl $PC_OFFSET_END, %ecx + pushl $pc_pmode + jmp real_to_prot + .section ".text", "ax", @progbits + .code32 +pc_pmode: + /* Call function */ + leal PC_OFFSET_IX86(%esp), %eax + pushl %eax + call *(PC_OFFSET_FUNCTION+4)(%esp) + popl %eax /* discard */ + + /* Switch to real mode and move register dump back to RM stack */ + movl $PC_OFFSET_END, %ecx + movl %esp, %esi + pushl $pc_rmode + jmp prot_to_real + .section ".text16", "ax", @progbits + .code16 +pc_rmode: + /* Restore registers and flags and return */ + addw $( PC_OFFSET_IX86 + 4 /* also skip %cs and %ss */ ), %sp + popw %ds + popw %es + popw %fs + popw %gs + popal + /* popal skips %esp. We therefore want to do "movl -20(%sp), + * %esp", but -20(%sp) is not a valid 80386 expression. + * Fortunately, prot_to_real() zeroes the high word of %esp, so + * we can just use -20(%esp) instead. + */ + addr32 movl -20(%esp), %esp + popfl + lret + +/**************************************************************************** + * real_call (protected-mode near call, 32-bit virtual return address) + * + * Call a real-mode function from protected-mode code. + * + * The non-segment register values will be passed directly to the + * real-mode code. The segment registers will be set as per + * prot_to_real. The non-segment register values set by the real-mode + * function will be passed back to the protected-mode caller. A + * result of this is that this routine cannot be called directly from + * C code, since it clobbers registers that the C ABI expects the + * callee to preserve. + * + * librm.h defines a convenient macro REAL_CODE() for using real_call. + * See librm.h and realmode.h for details and examples. + * + * Parameters: + * (32-bit) near pointer to real-mode function to call + * + * Returns: none + **************************************************************************** + */ + +#define RC_OFFSET_PRESERVE_REGS ( 0 ) +#define RC_OFFSET_RETADDR ( RC_OFFSET_PRESERVE_REGS + SIZEOF_I386_REGS ) +#define RC_OFFSET_FUNCTION ( RC_OFFSET_RETADDR + 4 ) +#define RC_OFFSET_END ( RC_OFFSET_FUNCTION + 4 ) + + .section ".text", "ax", @progbits + .code32 + .globl real_call +real_call: + /* Create register dump and function pointer copy on PM stack */ + pushal + pushl RC_OFFSET_FUNCTION(%esp) + + /* Switch to real mode and move register dump to RM stack */ + movl $( RC_OFFSET_RETADDR + 4 /* function pointer copy */ ), %ecx + pushl $rc_rmode + movl $rm_default_gdtr_idtr, %esi + jmp prot_to_real + .section ".text16", "ax", @progbits + .code16 +rc_rmode: + /* Call real-mode function */ + popl rc_function + popal + call *rc_function + pushal + + /* For sanity's sake, clear the direction flag as soon as possible */ + cld + + /* Switch to protected mode and move register dump back to PM stack */ + movl $RC_OFFSET_RETADDR, %ecx + pushl $rc_pmode + jmp real_to_prot + .section ".text", "ax", @progbits + .code32 +rc_pmode: + /* Restore registers and return */ + popal + ret + + + /* Function vector, used because "call xx(%sp)" is not a valid + * 16-bit expression. + */ + .section ".data16", "aw", @progbits +rc_function: .word 0, 0 + + /* Default real-mode global and interrupt descriptor table registers */ + .section ".data", "aw", @progbits +rm_default_gdtr_idtr: + .word 0 /* Global descriptor table limit */ + .long 0 /* Global descriptor table base */ + .word 0x03ff /* Interrupt descriptor table limit */ + .long 0 /* Interrupt descriptor table base */ + +/**************************************************************************** + * flatten_real_mode (real-mode near call) + * + * Switch to flat real mode + * + **************************************************************************** + */ + .section ".text16", "ax", @progbits + .code16 + .globl flatten_real_mode +flatten_real_mode: + /* Modify GDT to use flat real mode */ + movb $0x8f, real_cs + 6 + movb $0x8f, real_ds + 6 + /* Call dummy protected-mode function */ + pushl $flatten_dummy + pushw %cs + call prot_call + addw $4, %sp + /* Restore GDT */ + movb $0x00, real_cs + 6 + movb $0x00, real_ds + 6 + /* Return */ + ret + + .section ".text", "ax", @progbits + .code32 +flatten_dummy: + ret + +/**************************************************************************** + * Interrupt wrapper + * + * Used by the protected-mode interrupt vectors to call the + * interrupt() function. + * + * May be entered with either physical or virtual stack segment. + **************************************************************************** + */ + .globl interrupt_wrapper +interrupt_wrapper: + /* Preserve segment registers and original %esp */ + pushl %ds + pushl %es + pushl %fs + pushl %gs + pushl %ss + pushl %esp + + /* Switch to virtual addressing */ + call _intr_to_virt + + /* Expand IRQ number to whole %eax register */ + movzbl %al, %eax + + /* Call interrupt handler */ + call interrupt + + /* Restore original stack and segment registers */ + lss (%esp), %esp + popl %ss + popl %gs + popl %fs + popl %es + popl %ds + + /* Restore registers and return */ + popal + iret + +/**************************************************************************** + * Stored real-mode and protected-mode stack pointers + * + * The real-mode stack pointer is stored here whenever real_to_prot + * is called and restored whenever prot_to_real is called. The + * converse happens for the protected-mode stack pointer. + * + * Despite initial appearances this scheme is, in fact re-entrant, + * because program flow dictates that we always return via the point + * we left by. For example: + * PXE API call entry + * 1 real => prot + * ... + * Print a text string + * ... + * 2 prot => real + * INT 10 + * 3 real => prot + * ... + * ... + * 4 prot => real + * PXE API call exit + * + * At point 1, the RM mode stack value, say RPXE, is stored in + * rm_ss,sp. We want this value to still be present in rm_ss,sp when + * we reach point 4. + * + * At point 2, the RM stack value is restored from RPXE. At point 3, + * the RM stack value is again stored in rm_ss,sp. This *does* + * overwrite the RPXE that we have stored there, but it's the same + * value, since the code between points 2 and 3 has managed to return + * to us. + **************************************************************************** + */ + .section ".data", "aw", @progbits + .globl rm_sp +rm_sp: .word 0 + .globl rm_ss +rm_ss: .word 0 +pm_esp: .long _estack + +/**************************************************************************** + * Virtual address offsets + * + * These are used by the protected-mode code to map between virtual + * and physical addresses, and to access variables in the .text16 or + * .data16 segments. + **************************************************************************** + */ + /* Internal copies, created by init_librm (which runs in real mode) */ + .section ".data16", "aw", @progbits +rm_virt_offset: .long 0 +rm_text16: .long 0 +rm_data16: .long 0 + + /* Externally-visible copies, created by real_to_prot */ + .section ".data", "aw", @progbits + .globl virt_offset +virt_offset: .long 0 + .globl text16 +text16: .long 0 + .globl data16 +data16: .long 0 diff --git a/roms/ipxe/src/arch/i386/transitions/librm_mgmt.c b/roms/ipxe/src/arch/i386/transitions/librm_mgmt.c new file mode 100644 index 00000000..cc4765de --- /dev/null +++ b/roms/ipxe/src/arch/i386/transitions/librm_mgmt.c @@ -0,0 +1,158 @@ +/* + * librm: a library for interfacing to real-mode code + * + * Michael Brown <mbrown@fensystems.co.uk> + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +#include <stdint.h> +#include <ipxe/profile.h> +#include <realmode.h> +#include <pic8259.h> + +/* + * This file provides functions for managing librm. + * + */ + +/** The interrupt wrapper */ +extern char interrupt_wrapper[]; + +/** The interrupt vectors */ +static struct interrupt_vector intr_vec[NUM_INT]; + +/** The interrupt descriptor table */ +struct interrupt_descriptor idt[NUM_INT] __attribute__ (( aligned ( 16 ) )); + +/** The interrupt descriptor table register */ +struct idtr idtr = { + .limit = ( sizeof ( idt ) - 1 ), +}; + +/** Timer interrupt profiler */ +static struct profiler timer_irq_profiler __profiler = { .name = "irq.timer" }; + +/** Other interrupt profiler */ +static struct profiler other_irq_profiler __profiler = { .name = "irq.other" }; + +/** + * Allocate space on the real-mode stack and copy data there from a + * user buffer + * + * @v data User buffer + * @v size Size of stack data + * @ret sp New value of real-mode stack pointer + */ +uint16_t copy_user_to_rm_stack ( userptr_t data, size_t size ) { + userptr_t rm_stack; + rm_sp -= size; + rm_stack = real_to_user ( rm_ss, rm_sp ); + memcpy_user ( rm_stack, 0, data, 0, size ); + return rm_sp; +}; + +/** + * Deallocate space on the real-mode stack, optionally copying back + * data to a user buffer. + * + * @v data User buffer + * @v size Size of stack data + */ +void remove_user_from_rm_stack ( userptr_t data, size_t size ) { + if ( data ) { + userptr_t rm_stack = real_to_user ( rm_ss, rm_sp ); + memcpy_user ( rm_stack, 0, data, 0, size ); + } + rm_sp += size; +}; + +/** + * Set interrupt vector + * + * @v intr Interrupt number + * @v vector Interrupt vector, or NULL to disable + */ +void set_interrupt_vector ( unsigned int intr, void *vector ) { + struct interrupt_descriptor *idte; + + idte = &idt[intr]; + idte->segment = VIRTUAL_CS; + idte->attr = ( vector ? ( IDTE_PRESENT | IDTE_TYPE_IRQ32 ) : 0 ); + idte->low = ( ( ( uint32_t ) vector ) & 0xffff ); + idte->high = ( ( ( uint32_t ) vector ) >> 16 ); +} + +/** + * Initialise interrupt descriptor table + * + */ +void init_idt ( void ) { + struct interrupt_vector *vec; + unsigned int intr; + + /* Initialise the interrupt descriptor table and interrupt vectors */ + for ( intr = 0 ; intr < NUM_INT ; intr++ ) { + vec = &intr_vec[intr]; + vec->pushal = PUSHAL_INSN; + vec->movb = MOVB_INSN; + vec->intr = intr; + vec->jmp = JMP_INSN; + vec->offset = ( ( uint32_t ) interrupt_wrapper - + ( uint32_t ) vec->next ); + set_interrupt_vector ( intr, vec ); + } + DBGC ( &intr_vec[0], "INTn vector at %p+%xn (phys %#lx+%xn)\n", + intr_vec, sizeof ( intr_vec[0] ), + virt_to_phys ( intr_vec ), sizeof ( intr_vec[0] ) ); + + /* Initialise the interrupt descriptor table register */ + idtr.base = virt_to_phys ( idt ); +} + +/** + * Determine interrupt profiler (for debugging) + * + * @v intr Interrupt number + * @ret profiler Profiler + */ +static struct profiler * interrupt_profiler ( int intr ) { + + switch ( intr ) { + case IRQ_INT ( 0 ) : + return &timer_irq_profiler; + default: + return &other_irq_profiler; + } +} + +/** + * Interrupt handler + * + * @v intr Interrupt number + */ +void __attribute__ (( cdecl, regparm ( 1 ) )) interrupt ( int intr ) { + struct profiler *profiler = interrupt_profiler ( intr ); + uint32_t discard_eax; + + /* Reissue interrupt in real mode */ + profile_start ( profiler ); + __asm__ __volatile__ ( REAL_CODE ( "movb %%al, %%cs:(1f + 1)\n\t" + "\n1:\n\t" + "int $0x00\n\t" ) + : "=a" ( discard_eax ) : "0" ( intr ) ); + profile_stop ( profiler ); + profile_exclude ( profiler ); +} + +PROVIDE_UACCESS_INLINE ( librm, phys_to_user ); +PROVIDE_UACCESS_INLINE ( librm, user_to_phys ); +PROVIDE_UACCESS_INLINE ( librm, virt_to_user ); +PROVIDE_UACCESS_INLINE ( librm, user_to_virt ); +PROVIDE_UACCESS_INLINE ( librm, userptr_add ); +PROVIDE_UACCESS_INLINE ( librm, memcpy_user ); +PROVIDE_UACCESS_INLINE ( librm, memmove_user ); +PROVIDE_UACCESS_INLINE ( librm, memset_user ); +PROVIDE_UACCESS_INLINE ( librm, strlen_user ); +PROVIDE_UACCESS_INLINE ( librm, memchr_user ); diff --git a/roms/ipxe/src/arch/i386/transitions/librm_test.c b/roms/ipxe/src/arch/i386/transitions/librm_test.c new file mode 100644 index 00000000..e07cfccd --- /dev/null +++ b/roms/ipxe/src/arch/i386/transitions/librm_test.c @@ -0,0 +1,117 @@ +/* + * Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of the + * License, or any later version. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA + * 02110-1301, USA. + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +/** @file + * + * Real mode transition self-tests + * + * This file allows for easy measurement of the time taken to perform + * real mode transitions, which may have a substantial overhead when + * running under a hypervisor. + * + */ + +/* Forcibly enable assertions */ +#undef NDEBUG + +#include <ipxe/test.h> +#include <ipxe/profile.h> +#include <realmode.h> + +/** Number of sample iterations for profiling */ +#define PROFILE_COUNT 4096 + +/** Protected-to-real mode transition profiler */ +static struct profiler p2r_profiler __profiler = { .name = "p2r" }; + +/** Real-to-protected mode transition profiler */ +static struct profiler r2p_profiler __profiler = { .name = "r2p" }; + +/** Real-mode call profiler */ +static struct profiler real_call_profiler __profiler = { .name = "real_call" }; + +/** Protected-mode call profiler */ +static struct profiler prot_call_profiler __profiler = { .name = "prot_call" }; + +/** + * Dummy protected-mode function + */ +static void librm_test_prot_call ( void ) { + /* Do nothing */ +} + +/** + * Perform real mode transition self-tests + * + */ +static void librm_test_exec ( void ) { + unsigned int i; + unsigned long timestamp; + unsigned long started; + unsigned long stopped; + unsigned int discard_d; + + /* Profile mode transitions. We want to profile each + * direction of the transition separately, so perform an RDTSC + * while in real mode and tweak the profilers' start/stop + * times appropriately. + */ + for ( i = 0 ; i < PROFILE_COUNT ; i++ ) { + profile_start ( &p2r_profiler ); + __asm__ __volatile__ ( REAL_CODE ( "rdtsc\n\t" ) + : "=a" ( timestamp ), "=d" ( discard_d ) + : ); + profile_start_at ( &r2p_profiler, timestamp ); + profile_stop ( &r2p_profiler ); + profile_stop_at ( &p2r_profiler, timestamp ); + } + + /* Profile complete real-mode call cycle */ + for ( i = 0 ; i < PROFILE_COUNT ; i++ ) { + profile_start ( &real_call_profiler ); + __asm__ __volatile__ ( REAL_CODE ( "" ) : : ); + profile_stop ( &real_call_profiler ); + } + + /* Profile complete protected-mode call cycle */ + for ( i = 0 ; i < PROFILE_COUNT ; i++ ) { + __asm__ __volatile__ ( REAL_CODE ( "rdtsc\n\t" + "movl %0, %2\n\t" + "pushl %3\n\t" + "pushw %%cs\n\t" + "call prot_call\n\t" + "addw $4, %%sp\n\t" + "rdtsc\n\t" ) + : "=a" ( stopped ), "=d" ( discard_d ), + "=r" ( started ) + : "i" ( librm_test_prot_call ) ); + profile_start_at ( &prot_call_profiler, started ); + profile_stop_at ( &prot_call_profiler, stopped ); + } +} + +/** Real mode transition self-test */ +struct self_test librm_test __self_test = { + .name = "librm", + .exec = librm_test_exec, +}; + +REQUIRE_OBJECT ( test ); |