diff --git a/conf/i386.rmk b/conf/i386.rmk index 93f84ce39..33d49b53c 100644 --- a/conf/i386.rmk +++ b/conf/i386.rmk @@ -14,3 +14,9 @@ pkglib_MODULES += vga_text.mod vga_text_mod_SOURCES = term/i386/pc/vga_text.c term/i386/vga_common.c vga_text_mod_CFLAGS = $(COMMON_CFLAGS) vga_text_mod_LDFLAGS = $(COMMON_LDFLAGS) + +pkglib_MODULES += relocator.mod +relocator_mod_SOURCES = lib/i386/relocator.c lib/i386/relocator_asm.S lib/i386/relocator_backward.S +relocator_mod_CFLAGS = $(COMMON_CFLAGS) +relocator_mod_ASFLAGS = $(COMMON_ASFLAGS) +relocator_mod_LDFLAGS = $(COMMON_LDFLAGS) diff --git a/include/grub/i386/multiboot.h b/include/grub/i386/multiboot.h index 2dd7ec008..bd3c573fa 100644 --- a/include/grub/i386/multiboot.h +++ b/include/grub/i386/multiboot.h @@ -27,16 +27,11 @@ void grub_multiboot2_real_boot (grub_addr_t entry, struct grub_multiboot_info *mbi) __attribute__ ((noreturn)); -extern grub_addr_t grub_multiboot_payload_orig; +extern grub_uint32_t grub_multiboot_payload_eip; +extern char *grub_multiboot_payload_orig; extern grub_addr_t grub_multiboot_payload_dest; extern grub_size_t grub_multiboot_payload_size; -extern grub_uint32_t grub_multiboot_payload_entry_offset; -extern grub_uint8_t grub_multiboot_forward_relocator; -extern grub_uint8_t grub_multiboot_forward_relocator_end; -extern grub_uint8_t grub_multiboot_backward_relocator; -extern grub_uint8_t grub_multiboot_backward_relocator_end; - -#define RELOCATOR_SIZEOF(x) (&grub_multiboot_##x##_relocator_end - &grub_multiboot_##x##_relocator) +#define GRUB_MULTIBOOT_STACK_SIZE 4096 #endif /* ! GRUB_MULTIBOOT_CPU_HEADER */ diff --git a/include/grub/i386/relocator.h b/include/grub/i386/relocator.h new file mode 100644 index 000000000..cbc75ed0a --- /dev/null +++ b/include/grub/i386/relocator.h @@ -0,0 +1,40 @@ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2009 Free Software Foundation, Inc. + * + * GRUB 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 3 of the License, or + * (at your option) any later version. + * + * GRUB 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 GRUB. If not, see . + */ + +#ifndef GRUB_RELOCATOR_CPU_HEADER +#define GRUB_RELOCATOR_CPU_HEADER 1 + +struct grub_relocator32_state +{ + grub_uint32_t esp; + grub_uint32_t eax; + grub_uint32_t ebx; + grub_uint32_t ecx; + grub_uint32_t edx; + grub_uint32_t eip; +}; + +void * +grub_relocator32_alloc (grub_size_t size); +grub_err_t +grub_relocator32_boot (void *relocator, grub_uint32_t dest, + struct grub_relocator32_state state); +void +grub_relocator32_free (void *relocator); + +#endif /* ! GRUB_RELOCATOR_CPU_HEADER */ diff --git a/lib/i386/relocator.c b/lib/i386/relocator.c new file mode 100644 index 000000000..7dbdd1597 --- /dev/null +++ b/lib/i386/relocator.c @@ -0,0 +1,148 @@ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2009 Free Software Foundation, Inc. + * + * GRUB 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 3 of the License, or + * (at your option) any later version. + * + * GRUB 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 GRUB. If not, see . + */ + +#include +#include + +#include +#include +#include + +#include + +extern grub_uint8_t grub_relocator32_forward_start; +extern grub_uint8_t grub_relocator32_forward_end; +extern grub_uint8_t grub_relocator32_backward_start; +extern grub_uint8_t grub_relocator32_backward_end; + +extern grub_uint32_t grub_relocator32_backward_dest; +extern grub_uint32_t grub_relocator32_backward_size; +#ifdef __x86_64__ +extern grub_uint64_t grub_relocator32_backward_src; +#else +extern grub_uint32_t grub_relocator32_backward_src; +#endif + +extern grub_uint32_t grub_relocator32_forward_dest; +extern grub_uint32_t grub_relocator32_forward_size; +#ifdef __x86_64__ +extern grub_uint64_t grub_relocator32_forward_src; +#else +extern grub_uint32_t grub_relocator32_forward_src; +#endif + +extern grub_uint32_t grub_relocator32_forward_eax; +extern grub_uint32_t grub_relocator32_forward_ebx; +extern grub_uint32_t grub_relocator32_forward_ecx; +extern grub_uint32_t grub_relocator32_forward_edx; +extern grub_uint32_t grub_relocator32_forward_eip; +extern grub_uint32_t grub_relocator32_forward_esp; + +extern grub_uint32_t grub_relocator32_backward_eax; +extern grub_uint32_t grub_relocator32_backward_ebx; +extern grub_uint32_t grub_relocator32_backward_ecx; +extern grub_uint32_t grub_relocator32_backward_edx; +extern grub_uint32_t grub_relocator32_backward_eip; +extern grub_uint32_t grub_relocator32_backward_esp; + +#define RELOCATOR_SIZEOF(x) (&grub_relocator32_##x##_end - &grub_relocator32_##x##_start) +#define RELOCATOR_ALIGN 16 + +void * +grub_relocator32_alloc (grub_size_t size) +{ + char *playground; + + playground = grub_malloc ((RELOCATOR_SIZEOF(forward) + RELOCATOR_ALIGN) + + size + + (RELOCATOR_SIZEOF(backward) + RELOCATOR_ALIGN)); + if (! playground) + return 0; + + *(grub_size_t *) playground = size; + + return playground + RELOCATOR_SIZEOF(forward); +} + +void +grub_relocator32_free (void *relocator) +{ + if (relocator) + grub_free ((char *) relocator - RELOCATOR_SIZEOF(forward)); +} + + +grub_err_t +grub_relocator32_boot (void *relocator, grub_uint32_t dest, + struct grub_relocator32_state state) +{ + grub_size_t size; + char *playground; + void (*entry) (); + + playground = (char *) relocator - RELOCATOR_SIZEOF(forward); + size = *(grub_size_t *) playground; + + if (UINT_TO_PTR (dest) >= relocator) + { + int overhead; + + overhead = ALIGN_UP (dest - RELOCATOR_SIZEOF(backward) - RELOCATOR_ALIGN, RELOCATOR_ALIGN); + grub_relocator32_backward_dest = dest - overhead; + grub_relocator32_backward_src = PTR_TO_UINT64 (relocator - overhead); + grub_relocator32_backward_size = size + overhead; + + grub_relocator32_backward_eax = state.eax; + grub_relocator32_backward_ebx = state.ebx; + grub_relocator32_backward_ecx = state.ecx; + grub_relocator32_backward_edx = state.edx; + grub_relocator32_backward_eip = state.eip; + grub_relocator32_backward_esp = state.esp; + + grub_memmove (relocator - overhead, + &grub_relocator32_backward_start, + RELOCATOR_SIZEOF(backward)); + entry = (void (*) ()) (relocator - overhead); + } + else + { + int overhead; + + overhead = ALIGN_UP (dest + size, RELOCATOR_ALIGN) + + RELOCATOR_SIZEOF(forward) - (dest + size); + + grub_relocator32_forward_dest = dest; + grub_relocator32_forward_src = PTR_TO_UINT64 (relocator); + grub_relocator32_forward_size = size + overhead; + + grub_relocator32_forward_eax = state.eax; + grub_relocator32_forward_ebx = state.ebx; + grub_relocator32_forward_ecx = state.ecx; + grub_relocator32_forward_edx = state.edx; + grub_relocator32_forward_eip = state.eip; + grub_relocator32_forward_esp = state.esp; + + grub_memmove (relocator + size + overhead - RELOCATOR_SIZEOF(forward), + &grub_relocator32_forward_start, RELOCATOR_SIZEOF(forward)); + entry = (void (*) ()) (relocator + size + overhead - RELOCATOR_SIZEOF(forward)); + } + entry (); + + /* Not reached. */ + return GRUB_ERR_NONE; +} diff --git a/lib/i386/relocator_asm.S b/lib/i386/relocator_asm.S new file mode 100644 index 000000000..3ef1fa083 --- /dev/null +++ b/lib/i386/relocator_asm.S @@ -0,0 +1,269 @@ +/* + * GRUB -- GRand Unified Bootloader + * Copyright (C) 2009 Free Software Foundation, Inc. + * + * GRUB 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 3 of the License, or + * (at your option) any later version. + * + * GRUB 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 GRUB. If not, see . + */ + +#include + +#ifdef BACKWARD +#define RELOCATOR_VARIABLE(x) VARIABLE(grub_relocator32_backward_ ## x) +#else +#define RELOCATOR_VARIABLE(x) VARIABLE(grub_relocator32_forward_ ## x) +#endif + .p2align 4 /* force 16-byte alignment */ + +RELOCATOR_VARIABLE(start) +#ifdef BACKWARD +base: +#endif + cli + +#ifndef __x86_64__ + /* mov imm32, %eax */ + .byte 0xb8 +RELOCATOR_VARIABLE(dest) + .long 0 + mov %eax, %edi + + /* mov imm32, %eax */ + .byte 0xb8 +RELOCATOR_VARIABLE(src) + .long 0 + mov %eax, %esi + + /* mov imm32, %ecx */ + .byte 0xb9 +RELOCATOR_VARIABLE(size) + .long 0 + mov %edi, %eax +#ifndef BACKWARD + add %ecx, %eax +#endif + add $0x3, %ecx + shr $2, %ecx + +#ifdef BACKWARD + /* Backward movsl is implicitly off-by-four. compensate that. */ + subl $4, %esi + subl $4, %edi + + /* Backward copy. */ + std + addl %ecx, %esi + addl %ecx, %edi + + rep + movsl + +#else + /* Forward copy. */ + cld + rep + movsl +#endif + /* %eax contains now our new base. */ + mov %eax, %esi + add $(cont0 - base), %eax + jmp *%eax +cont0: +#else + xorq %rax, %rax + + /* mov imm32, %eax */ + .byte 0xb8 +RELOCATOR_VARIABLE(dest) + .long 0 + mov %eax, %edi + + /* mov imm64, %rax */ + .byte 0xb8 +RELOCATOR_VARIABLE(src) + .long 0, 0 + mov %rax, %rsi + + xorl %rcx, %rcx + /* mov imm32, %ecx */ + .byte 0xb9 +RELOCATOR_VARIABLE(size) + .long 0 + + mov %rdi, %rax +#ifndef BACKWARD + add %rcx, %rax +#endif + add $0x3, %rcx + shr $2, %rcx + +#ifdef BACKWARD + /* Backward movsl is implicitly off-by-four. compensate that. */ + subl $4, %rsi + subl $4, %rdi + + /* Backward copy. */ + std + addl %rcx, %rsi + addl %rcx, %rdi + + rep + movsl + +#else + /* Forward copy. */ + cld + rep + movsl +#endif + + /* %rax contains now our new 'base'. */ + mov %rax, %rsi +#ifdef APPLE_CC + add $(cont0 - base), %eax +#else + add $(cont0 - base), %rax +#endif + jmp *%rax +cont0: +#ifdef APPLE_CC + lea (cont1 - base) (%esi, 1), %eax + mov %eax, (jump_vector - base) (%esi, 1) + + lea (gdt - base) (%esi, 1), %eax + mov %eax, (gdt_addr - base) (%esi, 1) + + /* Switch to compatibility mode. */ + + lgdt (gdtdesc - base) (%esi, 1) + + /* Update %cs. Thanks to David Miller for pointing this mistake out. */ + ljmp *(jump_vector - base) (%esi,1) +#else + lea (cont1 - base) (%rsi, 1), %rax + mov %eax, (jump_vector - base) (%rsi, 1) + + lea (gdt - base) (%rsi, 1), %rax + mov %rax, (gdt_addr - base) (%rsi, 1) + + /* Switch to compatibility mode. */ + + lgdt (gdtdesc - base) (%rsi, 1) + + /* Update %cs. Thanks to David Miller for pointing this mistake out. */ + ljmp *(jump_vector - base) (%rsi, 1) +#endif + +cont1: + .code32 + + /* Update other registers. */ + mov $0x18, %eax + mov %eax, %ds + mov %eax, %es + mov %eax, %fs + mov %eax, %gs + mov %eax, %ss + + /* Disable paging. */ + mov %cr0, %eax + and $0x7fffffff, %eax + mov %eax, %cr0 + + /* Disable amd64. */ + mov $0xc0000080, %ecx + rdmsr + and $0xfffffeff, %eax + wrmsr + + /* Turn off PAE. */ + movl %cr4, %eax + and $0xffffffcf, %eax + mov %eax, %cr4 + + jmp cont2 +cont2: +#endif + .code32 + + /* mov imm32, %eax */ + .byte 0xb8 +RELOCATOR_VARIABLE (esp) + .long 0 + + movl %eax, %esp + + /* mov imm32, %eax */ + .byte 0xb8 +RELOCATOR_VARIABLE (eax) + .long 0 + + /* mov imm32, %ebx */ + .byte 0xbb +RELOCATOR_VARIABLE (ebx) + .long 0 + + /* mov imm32, %ecx */ + .byte 0xb9 +RELOCATOR_VARIABLE (ecx) + .long 0 + + /* mov imm32, %edx */ + .byte 0xba +RELOCATOR_VARIABLE (edx) + .long 0 + + /* Cleared direction flag is of no problem with any current + payload and makes this implementation easier. */ + cld + + .byte 0xea +RELOCATOR_VARIABLE (eip) + .long 0 + .word 0x08 + +#ifdef __x86_64__ + /* GDT. Copied from loader/i386/linux.c. */ + .p2align 4 +gdt: + /* NULL. */ + .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 + + /* Reserved. */ + .byte 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 + + /* Code segment. */ + .byte 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x9A, 0xCF, 0x00 + + /* Data segment. */ + .byte 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x92, 0xCF, 0x00 + +gdtdesc: + .word 31 +gdt_addr: + /* Filled by the code. */ + .quad 0 + + .p2align 4 +jump_vector: + /* Jump location. Is filled by the code */ + .long 0 + .long 0x10 +#endif + +#ifndef BACKWARD +base: +#endif + + +RELOCATOR_VARIABLE(end) diff --git a/lib/i386/relocator_backward.S b/lib/i386/relocator_backward.S new file mode 100644 index 000000000..06913470e --- /dev/null +++ b/lib/i386/relocator_backward.S @@ -0,0 +1,2 @@ +#define BACKWARD +#include "relocator_asm.S" diff --git a/loader/i386/multiboot.c b/loader/i386/multiboot.c index 87ffcae8d..974395f63 100644 --- a/loader/i386/multiboot.c +++ b/loader/i386/multiboot.c @@ -48,18 +48,35 @@ #include #include #endif +#include extern grub_dl_t my_mod; static struct grub_multiboot_info *mbi, *mbi_dest; -static grub_addr_t entry; -static char *playground; static grub_size_t code_size; +char *grub_multiboot_payload_orig; +grub_addr_t grub_multiboot_payload_dest; +grub_size_t grub_multiboot_payload_size; +grub_uint32_t grub_multiboot_payload_eip; +grub_uint32_t grub_multiboot_payload_esp; + static grub_err_t grub_multiboot_boot (void) { - grub_multiboot_real_boot (entry, mbi_dest); + struct grub_relocator32_state state = + { + .eax = MULTIBOOT_MAGIC2, + .ebx = PTR_TO_UINT32 (mbi_dest), + .ecx = 0, + .edx = 0, + .eip = grub_multiboot_payload_eip, + .esp = grub_multiboot_payload_esp + }; + + grub_relocator32_boot (grub_multiboot_payload_orig, + grub_multiboot_payload_dest, + state); /* Not reached. */ return GRUB_ERR_NONE; @@ -248,11 +265,8 @@ grub_multiboot (int argc, char *argv[]) goto fail; } - if (playground) - { - grub_free (playground); - playground = NULL; - } + grub_relocator32_free (grub_multiboot_payload_orig); + grub_multiboot_payload_orig = NULL; mmap_length = grub_get_multiboot_mmap_len (); @@ -267,11 +281,13 @@ grub_multiboot (int argc, char *argv[]) ((void *) ((x) + code_size + cmdline_length)) #define mbi_addr(x) ((void *) ((x) + code_size + cmdline_length + boot_loader_name_length)) #define mmap_addr(x) ((void *) ((x) + code_size + cmdline_length + boot_loader_name_length + sizeof (struct grub_multiboot_info))) +#define stack_addr(x) ((void *) ((x) + code_size + cmdline_length + boot_loader_name_length + sizeof (struct grub_multiboot_info) + mmap_length + GRUB_MULTIBOOT_STACK_SIZE)) grub_multiboot_payload_size = cmdline_length /* boot_loader_name_length might need to grow for mbi,etc to be aligned (see below) */ + boot_loader_name_length + 3 - + sizeof (struct grub_multiboot_info) + mmap_length; + + sizeof (struct grub_multiboot_info) + mmap_length + + GRUB_MULTIBOOT_STACK_SIZE; if (header->flags & MULTIBOOT_AOUT_KLUDGE) { @@ -287,11 +303,12 @@ grub_multiboot (int argc, char *argv[]) grub_multiboot_payload_dest = header->load_addr; grub_multiboot_payload_size += code_size; - playground = grub_malloc (RELOCATOR_SIZEOF(forward) + grub_multiboot_payload_size + RELOCATOR_SIZEOF(backward)); - if (! playground) - goto fail; - grub_multiboot_payload_orig = (long) playground + RELOCATOR_SIZEOF(forward); + grub_multiboot_payload_orig + = grub_relocator32_alloc (grub_multiboot_payload_size); + + if (! grub_multiboot_payload_orig) + goto fail; if ((grub_file_seek (file, offset)) == (grub_off_t) - 1) goto fail; @@ -304,7 +321,7 @@ grub_multiboot (int argc, char *argv[]) grub_memset ((void *) (grub_multiboot_payload_orig + load_size), 0, header->bss_end_addr - header->load_addr - load_size); - grub_multiboot_payload_entry_offset = header->entry_addr - header->load_addr; + grub_multiboot_payload_eip = header->entry_addr; } else if (grub_multiboot_load_elf (file, buffer) != GRUB_ERR_NONE) @@ -325,23 +342,6 @@ grub_multiboot (int argc, char *argv[]) mbi->mmap_addr = (grub_uint32_t) mmap_addr (grub_multiboot_payload_dest); mbi->flags |= MULTIBOOT_INFO_MEM_MAP; - if (grub_multiboot_payload_dest >= grub_multiboot_payload_orig) - { - grub_memmove (playground, &grub_multiboot_forward_relocator, RELOCATOR_SIZEOF(forward)); - entry = (grub_addr_t) playground; - } - else - { - grub_memmove ((char *) (grub_multiboot_payload_orig + grub_multiboot_payload_size), - &grub_multiboot_backward_relocator, RELOCATOR_SIZEOF(backward)); - entry = (grub_addr_t) grub_multiboot_payload_orig + grub_multiboot_payload_size; - } - - grub_dprintf ("multiboot_loader", "dest=%p, size=0x%x, entry_offset=0x%x\n", - (void *) grub_multiboot_payload_dest, - grub_multiboot_payload_size, - grub_multiboot_payload_entry_offset); - /* Convert from bytes to kilobytes. */ mbi->mem_lower = grub_mmap_get_lower () / 1024; mbi->mem_upper = grub_mmap_get_upper () / 1024; @@ -371,6 +371,8 @@ grub_multiboot (int argc, char *argv[]) if (grub_multiboot_get_bootdev (&mbi->boot_device)) mbi->flags |= MULTIBOOT_INFO_BOOTDEV; + grub_multiboot_payload_esp = PTR_TO_UINT32 (stack_addr (grub_multiboot_payload_dest)); + grub_loader_set (grub_multiboot_boot, grub_multiboot_unload, 1); fail: diff --git a/loader/i386/multiboot_elfxx.c b/loader/i386/multiboot_elfxx.c index 77c47118c..0b9820dcc 100644 --- a/loader/i386/multiboot_elfxx.c +++ b/loader/i386/multiboot_elfxx.c @@ -32,6 +32,8 @@ #error "I'm confused" #endif +#include + #define CONCAT(a,b) CONCAT_(a, b) #define CONCAT_(a,b) a ## b @@ -99,11 +101,12 @@ CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer) grub_multiboot_payload_dest = phdr(lowest_segment)->p_paddr; grub_multiboot_payload_size += code_size; - playground = grub_malloc (RELOCATOR_SIZEOF(forward) + grub_multiboot_payload_size + RELOCATOR_SIZEOF(backward)); - if (! playground) - return grub_errno; - grub_multiboot_payload_orig = (long) playground + RELOCATOR_SIZEOF(forward); + grub_multiboot_payload_orig + = grub_relocator32_alloc (grub_multiboot_payload_size); + + if (!grub_multiboot_payload_orig) + return grub_errno; /* Load every loadable segment in memory. */ for (i = 0; i < ehdr->e_phnum; i++) @@ -135,8 +138,7 @@ CONCAT(grub_multiboot_load_elf, XX) (grub_file_t file, void *buffer) if (phdr(i)->p_vaddr <= ehdr->e_entry && phdr(i)->p_vaddr + phdr(i)->p_memsz > ehdr->e_entry) { - grub_multiboot_payload_entry_offset = (ehdr->e_entry - phdr(i)->p_vaddr) - + (phdr(i)->p_paddr - phdr(lowest_segment)->p_paddr); + grub_multiboot_payload_eip = ehdr->e_entry; break; } diff --git a/loader/i386/multiboot_helper.S b/loader/i386/multiboot_helper.S index d1094588b..2f9af778b 100644 --- a/loader/i386/multiboot_helper.S +++ b/loader/i386/multiboot_helper.S @@ -22,81 +22,6 @@ .p2align 2 /* force 4-byte alignment */ -/* - * This starts the multiboot kernel. - */ - -VARIABLE(grub_multiboot_payload_size) - .long 0 -VARIABLE(grub_multiboot_payload_orig) - .long 0 -VARIABLE(grub_multiboot_payload_dest) - .long 0 -VARIABLE(grub_multiboot_payload_entry_offset) - .long 0 - -/* - * The relocators below understand the following parameters: - * ecx: Size of the block to be copied. - * esi: Where to copy from (always lowest address, even if we're relocating - * backwards). - * edi: Where to copy to (likewise). - * edx: Offset of the entry point (relative to the beginning of the block). - */ - -VARIABLE(grub_multiboot_forward_relocator) - /* Add entry offset. */ - addl %edi, %edx - - /* Forward copy. */ - cld - rep - movsb - - jmp *%edx -VARIABLE(grub_multiboot_forward_relocator_end) - -VARIABLE(grub_multiboot_backward_relocator) - /* Add entry offset (before %edi is mangled). */ - addl %edi, %edx - - /* Backward movsb is implicitly off-by-one. compensate that. */ - decl %esi - decl %edi - - /* Backward copy. */ - std - addl %ecx, %esi - addl %ecx, %edi - rep - movsb - - cld - jmp *%edx -VARIABLE(grub_multiboot_backward_relocator_end) - -FUNCTION(grub_multiboot_real_boot) - /* Push the entry address on the stack. */ - pushl %eax - /* Move the address of the multiboot information structure to ebx. */ - movl %edx,%ebx - - /* Interrupts should be disabled. */ - cli - - /* Where do we copy what from. */ - movl EXT_C(grub_multiboot_payload_size), %ecx - movl EXT_C(grub_multiboot_payload_orig), %esi - movl EXT_C(grub_multiboot_payload_dest), %edi - movl EXT_C(grub_multiboot_payload_entry_offset), %edx - - /* Move the magic value into eax. */ - movl $MULTIBOOT_MAGIC2, %eax - - /* Jump to the relocator. */ - popl %ebp - jmp *%ebp - /* * This starts the multiboot 2 kernel. */