2008-08-02 Robert Millan <rmh@aybabtu.com>
* loader/i386/pc/multiboot.c (playground, forward_relocator)
(backward_relocator): New variables. Used to allocate and relocate
the payload, respectively.
(grub_multiboot_load_elf32): Load into heap instead of requested
address, install the appropiate relocator code in each bound of
the payload, and set the entry point such that
grub_multiboot_real_boot() will jump to one of them.
* kern/i386/loader.S (grub_multiboot_payload_size)
(grub_multiboot_payload_orig, grub_multiboot_payload_dest)
(grub_multiboot_payload_entry_offset): New variables.
(grub_multiboot_real_boot): Set cpu context to what the relocator
expects, and jump to the relocator instead of the payload.
* include/grub/i386/loader.h (grub_multiboot_payload_size)
(grub_multiboot_payload_orig, grub_multiboot_payload_dest)
(grub_multiboot_payload_entry_offset): Export.
This commit is contained in:
robertmh
parent
b15d8a0cc6
commit
a927cc7383
4 changed files with 104 additions and 26 deletions
20
ChangeLog
20
ChangeLog
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@ -1,3 +1,23 @@
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2008-08-02 Robert Millan <rmh@aybabtu.com>
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* loader/i386/pc/multiboot.c (playground, forward_relocator)
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(backward_relocator): New variables. Used to allocate and relocate
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the payload, respectively.
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(grub_multiboot_load_elf32): Load into heap instead of requested
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address, install the appropiate relocator code in each bound of
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the payload, and set the entry point such that
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grub_multiboot_real_boot() will jump to one of them.
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* kern/i386/loader.S (grub_multiboot_payload_size)
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(grub_multiboot_payload_orig, grub_multiboot_payload_dest)
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(grub_multiboot_payload_entry_offset): New variables.
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(grub_multiboot_real_boot): Set cpu context to what the relocator
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expects, and jump to the relocator instead of the payload.
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* include/grub/i386/loader.h (grub_multiboot_payload_size)
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(grub_multiboot_payload_orig, grub_multiboot_payload_dest)
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(grub_multiboot_payload_entry_offset): Export.
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2008-08-01 Bean <bean123ch@gmail.com>
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* normal/menu_entry.c (editor_getline): Don't return the original
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@ -43,6 +43,10 @@ void EXPORT_FUNC(grub_multiboot2_real_boot) (grub_addr_t entry,
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void EXPORT_FUNC(grub_unix_real_boot) (grub_addr_t entry, ...)
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__attribute__ ((cdecl,noreturn));
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extern grub_addr_t EXPORT_VAR(grub_multiboot_payload_orig);
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extern grub_addr_t EXPORT_VAR(grub_multiboot_payload_dest);
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extern grub_size_t EXPORT_VAR(grub_multiboot_payload_size);
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extern grub_uint32_t EXPORT_VAR(grub_multiboot_payload_entry_offset);
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/* It is necessary to export these functions, because normal mode commands
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reuse rescue mode commands. */
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@ -123,6 +123,15 @@ linux_setup_seg:
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* This starts the multiboot kernel.
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*/
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VARIABLE(grub_multiboot_payload_size)
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.long 0
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VARIABLE(grub_multiboot_payload_orig)
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.long 0
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VARIABLE(grub_multiboot_payload_dest)
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.long 0
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VARIABLE(grub_multiboot_payload_entry_offset)
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.long 0
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FUNCTION(grub_multiboot_real_boot)
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/* Push the entry address on the stack. */
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pushl %eax
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@ -136,11 +145,16 @@ FUNCTION(grub_multiboot_real_boot)
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/* Interrupts should be disabled. */
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cli
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/* Move the magic value into eax and jump to the kernel. */
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movl $MULTIBOOT_MAGIC2,%eax
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popl %ecx
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jmp *%ecx
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/* Where do we copy what from. */
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movl EXT_C(grub_multiboot_payload_size), %ecx
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movl EXT_C(grub_multiboot_payload_orig), %esi
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movl EXT_C(grub_multiboot_payload_dest), %edi
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movl EXT_C(grub_multiboot_payload_entry_offset), %eax
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/* Jump to the relocator. */
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popl %edx
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jmp *%edx
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/*
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* This starts the multiboot 2 kernel.
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*/
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@ -50,6 +50,33 @@ extern grub_dl_t my_mod;
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static struct grub_multiboot_info *mbi;
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static grub_addr_t entry;
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static char *playground = NULL;
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static grub_uint8_t forward_relocator[] =
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{
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0xfc, /* cld */
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0x89, 0xf2, /* movl %esi, %edx */
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0xf3, 0xa4, /* rep movsb */
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0x01, 0xc2, /* addl %eax, %edx */
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0xb8, 0x02, 0xb0, 0xad, 0x2b, /* movl $MULTIBOOT_MAGIC2, %eax */
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0xff, 0xe2, /* jmp *%edx */
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};
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static grub_uint8_t backward_relocator[] =
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{
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0xfd, /* std */
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0x01, 0xce, /* addl %ecx, %esi */
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0x01, 0xcf, /* addl %ecx, %edi */
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/* backward movsb is implicitly off-by-one. compensate that. */
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0x41, /* incl %ecx */
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0xf3, 0xa4, /* rep movsb */
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/* same problem again. */
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0x47, /* incl %edi */
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0x01, 0xc7, /* addl %eax, %edi */
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0xb8, 0x02, 0xb0, 0xad, 0x2b, /* movl $MULTIBOOT_MAGIC2, %eax */
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0xff, 0xe7, /* jmp *%edi */
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};
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static grub_err_t
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grub_multiboot_boot (void)
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{
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@ -99,6 +126,7 @@ grub_multiboot_load_elf32 (grub_file_t file, void *buffer)
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Elf32_Ehdr *ehdr = (Elf32_Ehdr *) buffer;
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char *phdr_base;
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grub_addr_t physical_entry_addr = 0;
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int lowest_segment = 0, highest_segment = 0;
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int i;
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if (ehdr->e_ident[EI_CLASS] != ELFCLASS32)
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@ -114,50 +142,62 @@ grub_multiboot_load_elf32 (grub_file_t file, void *buffer)
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if (ehdr->e_phoff + ehdr->e_phnum * ehdr->e_phentsize > MULTIBOOT_SEARCH)
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return grub_error (GRUB_ERR_BAD_OS, "program header at a too high offset");
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entry = ehdr->e_entry;
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phdr_base = (char *) buffer + ehdr->e_phoff;
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#define phdr(i) ((Elf32_Phdr *) (phdr_base + (i) * ehdr->e_phentsize))
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for (i = 0; i < ehdr->e_phnum; i++)
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if (phdr(i)->p_type == PT_LOAD)
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{
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if (phdr(i)->p_paddr < phdr(lowest_segment)->p_paddr)
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lowest_segment = i;
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if (phdr(i)->p_paddr > phdr(highest_segment)->p_paddr)
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highest_segment = i;
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}
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grub_multiboot_payload_size = (phdr(highest_segment)->p_paddr + phdr(highest_segment)->p_memsz) - phdr(lowest_segment)->p_paddr;
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grub_multiboot_payload_dest = phdr(lowest_segment)->p_paddr;
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if (playground)
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grub_free (playground);
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playground = grub_malloc (sizeof (forward_relocator) + grub_multiboot_payload_size + sizeof (backward_relocator));
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if (! playground)
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return grub_errno;
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grub_multiboot_payload_orig = playground + sizeof (forward_relocator);
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grub_memmove (playground, forward_relocator, sizeof (forward_relocator));
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grub_memmove (grub_multiboot_payload_orig + grub_multiboot_payload_size, backward_relocator, sizeof (backward_relocator));
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/* Load every loadable segment in memory. */
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for (i = 0; i < ehdr->e_phnum; i++)
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{
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if (phdr(i)->p_type == PT_LOAD)
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{
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/* The segment should fit in the area reserved for the OS. */
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if (phdr(i)->p_paddr < grub_os_area_addr)
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return grub_error (GRUB_ERR_BAD_OS,
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"segment doesn't fit in memory reserved for the OS (0x%lx < 0x%lx)",
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phdr(i)->p_paddr, grub_os_area_addr);
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if (phdr(i)->p_paddr + phdr(i)->p_memsz > grub_os_area_addr + grub_os_area_size)
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return grub_error (GRUB_ERR_BAD_OS,
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"segment doesn't fit in memory reserved for the OS (0x%lx > 0x%lx)",
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phdr(i)->p_paddr + phdr(i)->p_memsz,
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grub_os_area_addr + grub_os_area_size);
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char *load_this_module_at = grub_multiboot_payload_orig + (phdr(i)->p_paddr - phdr(0)->p_paddr);
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if (grub_file_seek (file, (grub_off_t) phdr(i)->p_offset)
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if (grub_file_seek (file, (grub_off_t) phdr(i)->p_offset)
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== (grub_off_t) -1)
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return grub_error (GRUB_ERR_BAD_OS,
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"invalid offset in program header");
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if (grub_file_read (file, (void *) phdr(i)->p_paddr, phdr(i)->p_filesz)
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if (grub_file_read (file, load_this_module_at, phdr(i)->p_filesz)
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!= (grub_ssize_t) phdr(i)->p_filesz)
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return grub_error (GRUB_ERR_BAD_OS,
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"couldn't read segment from file");
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if (phdr(i)->p_filesz < phdr(i)->p_memsz)
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grub_memset ((char *) phdr(i)->p_paddr + phdr(i)->p_filesz, 0,
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grub_memset (load_this_module_at + phdr(i)->p_filesz, 0,
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phdr(i)->p_memsz - phdr(i)->p_filesz);
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if ((entry >= phdr(i)->p_vaddr) &&
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(entry < phdr(i)->p_vaddr + phdr(i)->p_memsz))
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physical_entry_addr = entry + phdr(i)->p_paddr - phdr(i)->p_vaddr;
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}
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}
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grub_multiboot_payload_entry_offset = ehdr->e_entry - phdr(lowest_segment)->p_vaddr;
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#undef phdr
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if (physical_entry_addr)
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entry = physical_entry_addr;
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if (grub_multiboot_payload_dest >= grub_multiboot_payload_orig)
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entry = (grub_addr_t) playground;
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else
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entry = (grub_addr_t) grub_multiboot_payload_orig + grub_multiboot_payload_size;
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return grub_errno;
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}
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