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/******************************************************************************
* reloc.c
*
* 32-bit flat memory-map routines for relocating Multiboot structures
* and modules. This is most easily done early with paging disabled.
*
* Copyright (c) 2009, Citrix Systems, Inc.
*
* Authors:
* Keir Fraser <keir@xen.org>
*/
/* entered with %eax = BOOT_TRAMPOLINE */
asm (
" .text \n"
" .globl _start \n"
"_start: \n"
" call 1f \n"
"1: pop %ebx \n"
" mov %eax,alloc-1b(%ebx) \n"
" jmp reloc \n"
);
/* This is our data. Because the code must be relocatable, no BSS is
* allowed. All data is accessed PC-relative with inline assembly.
*/
asm (
"alloc: \n"
" .long 0 \n"
);
typedef unsigned int u32;
#include "../../../include/xen/multiboot.h"
static void *reloc_mbi_struct(void *old, unsigned int bytes)
{
void *new;
asm(
" call 1f \n"
"1: pop %%edx \n"
" mov alloc-1b(%%edx),%0 \n"
" sub %1,%0 \n"
" and $~15,%0 \n"
" mov %0,alloc-1b(%%edx) \n"
" mov %0,%%edi \n"
" rep movsb \n"
: "=&r" (new), "+c" (bytes), "+S" (old)
: : "edx", "edi");
return new;
}
static char *reloc_mbi_string(char *old)
{
char *p;
for ( p = old; *p != '\0'; p++ )
continue;
return reloc_mbi_struct(old, p - old + 1);
}
multiboot_info_t *reloc(multiboot_info_t *mbi_old)
{
multiboot_info_t *mbi = reloc_mbi_struct(mbi_old, sizeof(*mbi));
int i;
if ( mbi->flags & MBI_CMDLINE )
mbi->cmdline = (u32)reloc_mbi_string((char *)mbi->cmdline);
if ( mbi->flags & MBI_MODULES )
{
module_t *mods = reloc_mbi_struct(
(module_t *)mbi->mods_addr, mbi->mods_count * sizeof(module_t));
mbi->mods_addr = (u32)mods;
for ( i = 0; i < mbi->mods_count; i++ )
{
if ( mods[i].string )
mods[i].string = (u32)reloc_mbi_string((char *)mods[i].string);
}
}
if ( mbi->flags & MBI_MEMMAP )
mbi->mmap_addr = (u32)reloc_mbi_struct(
(memory_map_t *)mbi->mmap_addr, mbi->mmap_length);
if ( mbi->flags & MBI_LOADERNAME )
mbi->boot_loader_name = (u32)reloc_mbi_string(
(char *)mbi->boot_loader_name);
/* Mask features we don't understand or don't relocate. */
mbi->flags &= (MBI_MEMLIMITS |
MBI_BOOTDEV |
MBI_CMDLINE |
MBI_MODULES |
MBI_MEMMAP |
MBI_LOADERNAME);
return mbi;
}
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