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Provide __bss_start and _end symbols in grub-mkimage.

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For this ensure that all bss sections are merged.

We need this to correctly prelink non-PE relocatable images.
This commit is contained in:
Vladimir Serbinenko 2016-02-18 20:57:21 +01:00
parent 73a9c742fe
commit df21fff504
2 changed files with 89 additions and 50 deletions
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2
include/grub/util/mkimage.h
View file

@ -33,6 +33,8 @@ struct grub_mkimage_layout
grub_size_t ia64_got_off;
grub_size_t got_size;
unsigned ia64jmpnum;
Elf_Addr bss_start;
Elf_Addr end;
};
/* Private header. Use only in mkimage-related sources. */

119
util/grub-mkimagexx.c
View file

@ -490,6 +490,7 @@ SUFFIX (relocate_symbols) (Elf_Ehdr *e, Elf_Shdr *sections,
Elf_Shdr *symtab_section, Elf_Addr *section_addresses,
Elf_Half section_entsize, Elf_Half num_sections,
void *jumpers, Elf_Addr jumpers_addr,
Elf_Addr bss_start, Elf_Addr end,
const struct grub_install_image_target_desc *image_target)
{
Elf_Word symtab_size, sym_size, num_syms;
@ -528,16 +529,22 @@ SUFFIX (relocate_symbols) (Elf_Ehdr *e, Elf_Shdr *sections,
}
else if (cur_index == STN_UNDEF)
{
if (sym->st_name)
if (sym->st_name && grub_strcmp (name, "__bss_start"))
sym->st_value = bss_start;
else if (sym->st_name && grub_strcmp (name, "__end"))
sym->st_value = end;
else if (sym->st_name)
grub_util_error ("undefined symbol %s", name);
else
continue;
}
else if (cur_index >= num_sections)
grub_util_error ("section %d does not exist", cur_index);
else
{
sym->st_value = (grub_target_to_host (sym->st_value)
+ section_addresses[cur_index]);
}
if (image_target->elf_target == EM_IA_64 && ELF_ST_TYPE (sym->st_info)
== STT_FUNC)
@ -1462,9 +1469,7 @@ SUFFIX (is_text_section) (Elf_Shdr *s, const struct grub_install_image_target_de
== (SHF_EXECINSTR | SHF_ALLOC));
}
/* Determine if this section is a data section. This assumes that
BSS is also a data section, since the converter initializes BSS
when producing PE32 to avoid a bug in EFI implementations. */
/* Determine if this section is a data section. */
static int
SUFFIX (is_data_section) (Elf_Shdr *s, const struct grub_install_image_target_desc *image_target)
{
@ -1472,7 +1477,16 @@ SUFFIX (is_data_section) (Elf_Shdr *s, const struct grub_install_image_target_de
&& grub_target_to_host32 (s->sh_type) != SHT_PROGBITS)
return 0;
return ((grub_target_to_host (s->sh_flags) & (SHF_EXECINSTR | SHF_ALLOC))
== SHF_ALLOC);
== SHF_ALLOC) && !(grub_target_to_host32 (s->sh_type) == SHT_NOBITS);
}
static int
SUFFIX (is_bss_section) (Elf_Shdr *s, const struct grub_install_image_target_desc *image_target)
{
if (!is_relocatable (image_target))
return 0;
return ((grub_target_to_host (s->sh_flags) & (SHF_EXECINSTR | SHF_ALLOC))
== SHF_ALLOC) && (grub_target_to_host32 (s->sh_type) == SHT_NOBITS);
}
/* Return if the ELF header is valid. */
@ -1492,6 +1506,32 @@ SUFFIX (check_elf_header) (Elf_Ehdr *e, size_t size, const struct grub_install_i
return 1;
}
static Elf_Addr
SUFFIX (put_section) (Elf_Shdr *s, int i,
Elf_Addr current_address,
Elf_Addr *section_addresses,
const char *strtab,
const struct grub_install_image_target_desc *image_target)
{
Elf_Word align = grub_host_to_target_addr (s->sh_addralign);
const char *name = strtab + grub_host_to_target32 (s->sh_name);
if (align)
current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
align)
- image_target->vaddr_offset;
grub_util_info ("locating the section %s at 0x%"
GRUB_HOST_PRIxLONG_LONG,
name, (unsigned long long) current_address);
if (!is_relocatable (image_target))
current_address = grub_host_to_target_addr (s->sh_addr)
- image_target->link_addr;
section_addresses[i] = current_address;
current_address += grub_host_to_target_addr (s->sh_size);
return current_address;
}
/* Locate section addresses by merging code sections and data sections
into .text and .data, respectively. Return the array of section
addresses. */
@ -1531,20 +1571,13 @@ SUFFIX (locate_sections) (const char *kernel_path,
i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
if (SUFFIX (is_text_section) (s, image_target))
{
Elf_Word align = grub_host_to_target_addr (s->sh_addralign);
const char *name = strtab + grub_host_to_target32 (s->sh_name);
if (align)
current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
align) - image_target->vaddr_offset;
grub_util_info ("locating the section %s at 0x%"
GRUB_HOST_PRIxLONG_LONG,
name, (unsigned long long) current_address);
if (image_target->id != IMAGE_EFI)
{
current_address = grub_host_to_target_addr (s->sh_addr)
- image_target->link_addr;
if (grub_host_to_target_addr (s->sh_addr)
!= image_target->link_addr)
current_address = SUFFIX (put_section) (s, i,
current_address,
section_addresses,
strtab,
image_target);
if (!is_relocatable (image_target) &&
grub_host_to_target_addr (s->sh_addr) != image_target->link_addr)
{
char *msg
= grub_xasprintf (_("`%s' is miscompiled: its start address is 0x%llx"
@ -1555,9 +1588,6 @@ SUFFIX (locate_sections) (const char *kernel_path,
grub_util_error ("%s", msg);
}
}
section_addresses[i] = current_address;
current_address += grub_host_to_target_addr (s->sh_size);
}
current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
image_target->section_align)
@ -1569,27 +1599,31 @@ SUFFIX (locate_sections) (const char *kernel_path,
i < num_sections;
i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
if (SUFFIX (is_data_section) (s, image_target))
{
Elf_Word align = grub_host_to_target_addr (s->sh_addralign);
const char *name = strtab + grub_host_to_target32 (s->sh_name);
if (align)
current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
align)
- image_target->vaddr_offset;
grub_util_info ("locating the section %s at 0x%"
GRUB_HOST_PRIxLONG_LONG,
name, (unsigned long long) current_address);
if (image_target->id != IMAGE_EFI)
current_address = grub_host_to_target_addr (s->sh_addr)
- image_target->link_addr;
section_addresses[i] = current_address;
current_address += grub_host_to_target_addr (s->sh_size);
}
current_address = SUFFIX (put_section) (s, i,
current_address,
section_addresses,
strtab,
image_target);
current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
image_target->section_align) - image_target->vaddr_offset;
layout->bss_start = current_address;
/* .bss */
for (i = 0, s = sections;
i < num_sections;
i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
if (SUFFIX (is_bss_section) (s, image_target))
current_address = SUFFIX (put_section) (s, i,
current_address,
section_addresses,
strtab,
image_target);
current_address = ALIGN_UP (current_address + image_target->vaddr_offset,
image_target->section_align) - image_target->vaddr_offset;
layout->end = current_address;
layout->kernel_size = current_address;
return section_addresses;
}
@ -1789,8 +1823,11 @@ SUFFIX (grub_mkimage_load_image) (const char *kernel_path,
i < num_sections;
i++, s = (Elf_Shdr *) ((char *) s + section_entsize))
if (SUFFIX (is_data_section) (s, image_target)
|| SUFFIX (is_bss_section) (s, image_target)
|| SUFFIX (is_text_section) (s, image_target))
{
/* Explicitly initialize BSS
when producing PE32 to avoid a bug in EFI implementations. */
if (grub_target_to_host32 (s->sh_type) == SHT_NOBITS)
memset (out_img + section_addresses[i], 0,
grub_host_to_target_addr (s->sh_size));