* On some machines, an existing old_name file is required.
*
*/
-
-/* Even more heavily modified by james@bigtex.cactus.org of Dell Computer Co.
- * ELF support added.
- *
- * Basic theory: the data space of the running process needs to be
- * dumped to the output file. Normally we would just enlarge the size
- * of .data, scooting everything down. But we can't do that in ELF,
- * because there is often something between the .data space and the
- * .bss space.
- *
- * In the temacs dump below, notice that the Global Offset Table
- * (.got) and the Dynamic link data (.dynamic) come between .data1 and
- * .bss. It does not work to overlap .data with these fields.
- *
- * The solution is to create a new .data segment. This segment is
- * filled with data from the current process. Since the contents of
- * various sections refer to sections by index, the new .data segment
- * is made the last in the table to avoid changing any existing index.
-
- * This is an example of how the section headers are changed. "Addr"
- * is a process virtual address. "Offset" is a file offset.
-
-raid:/nfs/raid/src/dist-18.56/src> dump -h temacs
-
-temacs:
-
- **** SECTION HEADER TABLE ****
- [No] Type Flags Addr Offset Size Name
- Link Info Adralgn Entsize
-
- [1] 1 2 0x80480d4 0xd4 0x13 .interp
- 0 0 0x1 0
-
- [2] 5 2 0x80480e8 0xe8 0x388 .hash
- 3 0 0x4 0x4
-
- [3] 11 2 0x8048470 0x470 0x7f0 .dynsym
- 4 1 0x4 0x10
-
- [4] 3 2 0x8048c60 0xc60 0x3ad .dynstr
- 0 0 0x1 0
-
- [5] 9 2 0x8049010 0x1010 0x338 .rel.plt
- 3 7 0x4 0x8
-
- [6] 1 6 0x8049348 0x1348 0x3 .init
- 0 0 0x4 0
-
- [7] 1 6 0x804934c 0x134c 0x680 .plt
- 0 0 0x4 0x4
-
- [8] 1 6 0x80499cc 0x19cc 0x3c56f .text
- 0 0 0x4 0
-
- [9] 1 6 0x8085f3c 0x3df3c 0x3 .fini
- 0 0 0x4 0
-
- [10] 1 2 0x8085f40 0x3df40 0x69c .rodata
- 0 0 0x4 0
-
- [11] 1 2 0x80865dc 0x3e5dc 0xd51 .rodata1
- 0 0 0x4 0
-
- [12] 1 3 0x8088330 0x3f330 0x20afc .data
- 0 0 0x4 0
-
- [13] 1 3 0x80a8e2c 0x5fe2c 0x89d .data1
- 0 0 0x4 0
-
- [14] 1 3 0x80a96cc 0x606cc 0x1a8 .got
- 0 0 0x4 0x4
-
- [15] 6 3 0x80a9874 0x60874 0x80 .dynamic
- 4 0 0x4 0x8
-
- [16] 8 3 0x80a98f4 0x608f4 0x449c .bss
- 0 0 0x4 0
-
- [17] 2 0 0 0x608f4 0x9b90 .symtab
- 18 371 0x4 0x10
-
- [18] 3 0 0 0x6a484 0x8526 .strtab
- 0 0 0x1 0
-
- [19] 3 0 0 0x729aa 0x93 .shstrtab
- 0 0 0x1 0
-
- [20] 1 0 0 0x72a3d 0x68b7 .comment
- 0 0 0x1 0
-
- raid:/nfs/raid/src/dist-18.56/src> dump -h xemacs
-
- xemacs:
-
- **** SECTION HEADER TABLE ****
- [No] Type Flags Addr Offset Size Name
- Link Info Adralgn Entsize
-
- [1] 1 2 0x80480d4 0xd4 0x13 .interp
- 0 0 0x1 0
-
- [2] 5 2 0x80480e8 0xe8 0x388 .hash
- 3 0 0x4 0x4
-
- [3] 11 2 0x8048470 0x470 0x7f0 .dynsym
- 4 1 0x4 0x10
-
- [4] 3 2 0x8048c60 0xc60 0x3ad .dynstr
- 0 0 0x1 0
-
- [5] 9 2 0x8049010 0x1010 0x338 .rel.plt
- 3 7 0x4 0x8
-
- [6] 1 6 0x8049348 0x1348 0x3 .init
- 0 0 0x4 0
-
- [7] 1 6 0x804934c 0x134c 0x680 .plt
- 0 0 0x4 0x4
-
- [8] 1 6 0x80499cc 0x19cc 0x3c56f .text
- 0 0 0x4 0
-
- [9] 1 6 0x8085f3c 0x3df3c 0x3 .fini
- 0 0 0x4 0
-
- [10] 1 2 0x8085f40 0x3df40 0x69c .rodata
- 0 0 0x4 0
-
- [11] 1 2 0x80865dc 0x3e5dc 0xd51 .rodata1
- 0 0 0x4 0
-
- [12] 1 3 0x8088330 0x3f330 0x20afc .data
- 0 0 0x4 0
-
- [13] 1 3 0x80a8e2c 0x5fe2c 0x89d .data1
- 0 0 0x4 0
-
- [14] 1 3 0x80a96cc 0x606cc 0x1a8 .got
- 0 0 0x4 0x4
-
- [15] 6 3 0x80a9874 0x60874 0x80 .dynamic
- 4 0 0x4 0x8
-
- [16] 8 3 0x80c6800 0x7d800 0 .bss
- 0 0 0x4 0
-
- [17] 2 0 0 0x7d800 0x9b90 .symtab
- 18 371 0x4 0x10
-
- [18] 3 0 0 0x87390 0x8526 .strtab
- 0 0 0x1 0
-
- [19] 3 0 0 0x8f8b6 0x93 .shstrtab
- 0 0 0x1 0
-
- [20] 1 0 0 0x8f949 0x68b7 .comment
- 0 0 0x1 0
-
- [21] 1 3 0x80a98f4 0x608f4 0x1cf0c .data
- 0 0 0x4 0
-
- * This is an example of how the file header is changed. "Shoff" is
- * the section header offset within the file. Since that table is
- * after the new .data section, it is moved. "Shnum" is the number of
- * sections, which we increment.
- *
- * "Phoff" is the file offset to the program header. "Phentsize" and
- * "Shentsz" are the program and section header entries sizes respectively.
- * These can be larger than the apparent struct sizes.
-
- raid:/nfs/raid/src/dist-18.56/src> dump -f temacs
-
- temacs:
-
- **** ELF HEADER ****
- Class Data Type Machine Version
- Entry Phoff Shoff Flags Ehsize
- Phentsize Phnum Shentsz Shnum Shstrndx
-
- 1 1 2 3 1
- 0x80499cc 0x34 0x792f4 0 0x34
- 0x20 5 0x28 21 19
-
- raid:/nfs/raid/src/dist-18.56/src> dump -f xemacs
-
- xemacs:
-
- **** ELF HEADER ****
- Class Data Type Machine Version
- Entry Phoff Shoff Flags Ehsize
- Phentsize Phnum Shentsz Shnum Shstrndx
-
- 1 1 2 3 1
- 0x80499cc 0x34 0x96200 0 0x34
- 0x20 5 0x28 22 19
-
- * These are the program headers. "Offset" is the file offset to the
- * segment. "Vaddr" is the memory load address. "Filesz" is the
- * segment size as it appears in the file, and "Memsz" is the size in
- * memory. Below, the third segment is the code and the fourth is the
- * data: the difference between Filesz and Memsz is .bss
-
- raid:/nfs/raid/src/dist-18.56/src> dump -o temacs
-
- temacs:
- ***** PROGRAM EXECUTION HEADER *****
- Type Offset Vaddr Paddr
- Filesz Memsz Flags Align
-
- 6 0x34 0x8048034 0
- 0xa0 0xa0 5 0
-
- 3 0xd4 0 0
- 0x13 0 4 0
-
- 1 0x34 0x8048034 0
- 0x3f2f9 0x3f2f9 5 0x1000
-
- 1 0x3f330 0x8088330 0
- 0x215c4 0x25a60 7 0x1000
-
- 2 0x60874 0x80a9874 0
- 0x80 0 7 0
-
- raid:/nfs/raid/src/dist-18.56/src> dump -o xemacs
-
- xemacs:
- ***** PROGRAM EXECUTION HEADER *****
- Type Offset Vaddr Paddr
- Filesz Memsz Flags Align
-
- 6 0x34 0x8048034 0
- 0xa0 0xa0 5 0
-
- 3 0xd4 0 0
- 0x13 0 4 0
-
- 1 0x34 0x8048034 0
- 0x3f2f9 0x3f2f9 5 0x1000
-
- 1 0x3f330 0x8088330 0
- 0x3e4d0 0x3e4d0 7 0x1000
-
- 2 0x60874 0x80a9874 0
- 0x80 0 7 0
-
-
- */
-\f
-/* Modified by wtien@urbana.mcd.mot.com of Motorola Inc.
- *
- * The above mechanism does not work if the unexeced ELF file is being
- * re-layout by other applications (such as `strip'). All the applications
- * that re-layout the internal of ELF will layout all sections in ascending
- * order of their file offsets. After the re-layout, the data2 section will
- * still be the LAST section in the section header vector, but its file offset
- * is now being pushed far away down, and causes part of it not to be mapped
- * in (ie. not covered by the load segment entry in PHDR vector), therefore
- * causes the new binary to fail.
- *
- * The solution is to modify the unexec algorithm to insert the new data2
- * section header right before the new bss section header, so their file
- * offsets will be in the ascending order. Since some of the section's (all
- * sections AFTER the bss section) indexes are now changed, we also need to
- * modify some fields to make them point to the right sections. This is done
- * by macro PATCH_INDEX. All the fields that need to be patched are:
- *
- * 1. ELF header e_shstrndx field.
- * 2. section header sh_link and sh_info field.
- * 3. symbol table entry st_shndx field.
- *
- * The above example now should look like:
-
- **** SECTION HEADER TABLE ****
- [No] Type Flags Addr Offset Size Name
- Link Info Adralgn Entsize
-
- [1] 1 2 0x80480d4 0xd4 0x13 .interp
- 0 0 0x1 0
-
- [2] 5 2 0x80480e8 0xe8 0x388 .hash
- 3 0 0x4 0x4
-
- [3] 11 2 0x8048470 0x470 0x7f0 .dynsym
- 4 1 0x4 0x10
-
- [4] 3 2 0x8048c60 0xc60 0x3ad .dynstr
- 0 0 0x1 0
-
- [5] 9 2 0x8049010 0x1010 0x338 .rel.plt
- 3 7 0x4 0x8
-
- [6] 1 6 0x8049348 0x1348 0x3 .init
- 0 0 0x4 0
-
- [7] 1 6 0x804934c 0x134c 0x680 .plt
- 0 0 0x4 0x4
-
- [8] 1 6 0x80499cc 0x19cc 0x3c56f .text
- 0 0 0x4 0
-
- [9] 1 6 0x8085f3c 0x3df3c 0x3 .fini
- 0 0 0x4 0
-
- [10] 1 2 0x8085f40 0x3df40 0x69c .rodata
- 0 0 0x4 0
-
- [11] 1 2 0x80865dc 0x3e5dc 0xd51 .rodata1
- 0 0 0x4 0
-
- [12] 1 3 0x8088330 0x3f330 0x20afc .data
- 0 0 0x4 0
-
- [13] 1 3 0x80a8e2c 0x5fe2c 0x89d .data1
- 0 0 0x4 0
-
- [14] 1 3 0x80a96cc 0x606cc 0x1a8 .got
- 0 0 0x4 0x4
-
- [15] 6 3 0x80a9874 0x60874 0x80 .dynamic
- 4 0 0x4 0x8
-
- [16] 1 3 0x80a98f4 0x608f4 0x1cf0c .data
- 0 0 0x4 0
-
- [17] 8 3 0x80c6800 0x7d800 0 .bss
- 0 0 0x4 0
-
- [18] 2 0 0 0x7d800 0x9b90 .symtab
- 19 371 0x4 0x10
-
- [19] 3 0 0 0x87390 0x8526 .strtab
- 0 0 0x1 0
-
- [20] 3 0 0 0x8f8b6 0x93 .shstrtab
- 0 0 0x1 0
-
- [21] 1 0 0 0x8f949 0x68b7 .comment
- 0 0 0x1 0
-
- */
\f
/* We do not use mmap because that fails with NFS.
Instead we read the whole file, modify it, and write it out. */
#define NEW_PROGRAM_H(n) \
(*(ElfW (Phdr) *) entry_address (new_program_h, n, new_file_h->e_phentsize))
-#define PATCH_INDEX(n) ((n) += old_bss_index <= (n))
typedef unsigned char byte;
-/* Return the index of the section named NAME.
- SECTION_NAMES, FILE_NAME and FILE_H give information
- about the file we are looking in.
-
- If we don't find the section NAME, that is a fatal error
- if NOERROR is false; return -1 if NOERROR is true. */
-
-static ptrdiff_t
-find_section (const char *name, const char *section_names, const char *file_name,
- ElfW (Ehdr) *old_file_h, ElfW (Shdr) *old_section_h,
- bool noerror)
-{
- ptrdiff_t idx;
-
- for (idx = 1; idx < old_file_h->e_shnum; idx++)
- {
- char const *found_name = section_names + OLD_SECTION_H (idx).sh_name;
-#ifdef UNEXELF_DEBUG
- fprintf (stderr, "Looking for %s - found %s\n", name, found_name);
-#endif
- if (strcmp (name, found_name) == 0)
- return idx;
- }
-
- if (! noerror)
- fatal ("Can't find %s in %s", name, file_name);
- return -1;
-}
-
/* ****************************************************************
* unexec
*
* driving logic.
*
- * In ELF, this works by replacing the old .bss section with a new
- * .data section, and inserting an empty .bss immediately afterwards.
+ * In ELF, this works by replacing the old bss SHT_NOBITS section with
+ * a new, larger, SHT_PROGBITS section.
*
*/
void
ElfW (Phdr) *old_program_h, *new_program_h;
ElfW (Shdr) *old_section_h, *new_section_h;
- /* Point to the section name table in the old file. */
- char *old_section_names;
+ /* Point to the section name table. */
+ char *old_section_names, *new_section_names;
ElfW (Phdr) *old_bss_seg, *new_bss_seg;
ElfW (Addr) old_bss_addr, new_bss_addr;
ElfW (Word) old_bss_size, new_data2_size;
- ElfW (Off) new_data2_offset;
- ElfW (Addr) new_data2_addr;
- ElfW (Off) old_bss_offset;
+ ElfW (Off) old_bss_offset, new_data2_offset;
- ptrdiff_t n, nn;
- ptrdiff_t old_bss_index, old_data_index;
+ ptrdiff_t n;
+ ptrdiff_t old_bss_index;
struct stat stat_buf;
off_t old_file_size;
old_bss_offset = old_bss_seg->p_offset + old_bss_seg->p_filesz;
old_bss_size = old_bss_seg->p_memsz - old_bss_seg->p_filesz;
- /* Find the first bss style section in the bss segment range. */
+ /* Find the last bss style section in the bss segment range. */
old_bss_index = -1;
for (n = old_file_h->e_shnum; --n > 0; )
{
&& shdr->sh_addr >= old_bss_addr
&& shdr->sh_addr + shdr->sh_size <= old_bss_addr + old_bss_size
&& (old_bss_index == -1
- || OLD_SECTION_H (old_bss_index).sh_addr > shdr->sh_addr))
+ || OLD_SECTION_H (old_bss_index).sh_addr < shdr->sh_addr))
old_bss_index = n;
}
if (old_bss_index == -1)
fatal ("no bss section found");
- /* Find the old .data section. Figure out parameters of
- the new data2 and bss sections. */
-
- old_data_index = find_section (".data", old_section_names,
- old_name, old_file_h, old_section_h, 0);
-
new_break = sbrk (0);
new_bss_addr = (ElfW (Addr)) new_break;
- new_data2_addr = old_bss_addr;
new_data2_size = new_bss_addr - old_bss_addr;
new_data2_offset = old_bss_offset;
DEBUG_LOG (old_bss_size);
DEBUG_LOG (old_bss_offset);
DEBUG_LOG (new_bss_addr);
- DEBUG_LOG (new_data2_addr);
DEBUG_LOG (new_data2_size);
DEBUG_LOG (new_data2_offset);
#endif
if (new_file < 0)
fatal ("Can't creat (%s): %s", new_name, strerror (errno));
- new_file_size = old_file_size + old_file_h->e_shentsize + new_data2_size;
+ new_file_size = old_file_size + new_data2_size;
if (ftruncate (new_file, new_file_size))
fatal ("Can't ftruncate (%s): %s", new_name, strerror (errno));
new_file_h = (ElfW (Ehdr) *) new_base;
memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
- /* Fix up file header. We'll add one section. Section header is
- further away now. */
+ /* Fix up file header. Section header is further away now. */
if (new_file_h->e_shoff >= old_bss_offset)
new_file_h->e_shoff += new_data2_size;
- new_file_h->e_shnum += 1;
-
- /* Modify the e_shstrndx if necessary. */
- PATCH_INDEX (new_file_h->e_shstrndx);
new_program_h = (ElfW (Phdr) *) ((byte *) new_base + new_file_h->e_phoff);
new_section_h = (ElfW (Shdr) *) ((byte *) new_base + new_file_h->e_shoff);
memcpy (new_program_h, old_program_h,
old_file_h->e_phnum * old_file_h->e_phentsize);
+ memcpy (new_section_h, old_section_h,
+ old_file_h->e_shnum * old_file_h->e_shentsize);
#ifdef UNEXELF_DEBUG
DEBUG_LOG (old_file_h->e_shoff);
/* Copy over what we have in memory now for the bss area. */
memcpy (new_base + new_data2_offset, (caddr_t) old_bss_addr, new_data2_size);
- /* Fix up section headers based on new .data2 section. Any section
- whose offset or virtual address is after the new .data2 section
- gets its value adjusted. .bss size becomes zero. data2 section
- header gets added by copying the existing .data header and
- modifying the offset, address and size. */
-
- /* Walk through all section headers, insert the new data2 section right
- before the new bss section. */
- for (n = 1, nn = 1; n < old_file_h->e_shnum; n++, nn++)
+ /* Walk through all section headers, copying data and updating. */
+ for (n = 1; n < old_file_h->e_shnum; n++)
{
caddr_t src;
ElfW (Shdr) *old_shdr = &OLD_SECTION_H (n);
- ElfW (Shdr) *new_shdr = &NEW_SECTION_H (nn);
-
- /* If it is (s)bss section, insert the new data2 section before it. */
- if (n == old_bss_index)
- {
- /* Steal the data section header for this data2 section. */
- memcpy (new_shdr, &OLD_SECTION_H (old_data_index),
- new_file_h->e_shentsize);
-
- new_shdr->sh_addr = new_data2_addr;
- new_shdr->sh_offset = new_data2_offset;
- new_shdr->sh_size = new_data2_size;
- new_shdr->sh_addralign = 1;
- nn++;
- new_shdr++;
- }
-
- memcpy (new_shdr, old_shdr, old_file_h->e_shentsize);
+ ElfW (Shdr) *new_shdr = &NEW_SECTION_H (n);
if (new_shdr->sh_type == SHT_NOBITS
&& new_shdr->sh_addr >= old_bss_addr
&& (new_shdr->sh_addr + new_shdr->sh_size
<= old_bss_addr + old_bss_size))
{
+ /* This section now has file backing. */
+ new_shdr->sh_type = SHT_PROGBITS;
+
/* SHT_NOBITS sections do not need a valid sh_offset, so it
might be incorrect. Write the correct value. */
new_shdr->sh_offset = (new_shdr->sh_addr - new_bss_seg->p_vaddr
if (strcmp (old_section_names + new_shdr->sh_name, ".plt") == 0)
memset (new_shdr->sh_offset + new_base, 0, new_shdr->sh_size);
- /* Set the new bss and sbss section's size to zero, because
- we've already covered this address range by .data2. */
- new_shdr->sh_size = 0;
- }
- else
- {
- /* Any section that was originally placed after the .bss
- section should now be off by NEW_DATA2_SIZE. */
+ /* Extend the size of the last bss section to cover dumped
+ data. */
+ if (n == old_bss_index)
+ new_shdr->sh_size = new_bss_addr - new_shdr->sh_addr;
- if (new_shdr->sh_offset >= old_bss_offset)
- new_shdr->sh_offset += new_data2_size;
-
- /* Any section that was originally placed after the section
- header table should now be off by the size of one section
- header table entry. */
- if (new_shdr->sh_offset > new_file_h->e_shoff)
- new_shdr->sh_offset += new_file_h->e_shentsize;
+ /* We have already copied this section from the current
+ process. */
+ continue;
}
- /* If any section hdr refers to the section after the new .data
- section, make it refer to next one because we have inserted
- a new section in between. */
-
- PATCH_INDEX (new_shdr->sh_link);
- /* For symbol tables, info is a symbol table index,
- so don't change it. */
- if (new_shdr->sh_type != SHT_SYMTAB
- && new_shdr->sh_type != SHT_DYNSYM)
- PATCH_INDEX (new_shdr->sh_info);
+ /* Any section that was originally placed after the .bss
+ section should now be offset by NEW_DATA2_SIZE. */
+ if (new_shdr->sh_offset >= old_bss_offset)
+ new_shdr->sh_offset += new_data2_size;
/* Now, start to copy the content of sections. */
if (new_shdr->sh_type == SHT_NULL
}
}
#endif /* __sgi */
-
- /* Patch st_shndx field of symbol table. */
- if (new_shdr->sh_type == SHT_SYMTAB
- || new_shdr->sh_type == SHT_DYNSYM)
- {
- ptrdiff_t num = new_shdr->sh_size / new_shdr->sh_entsize;
- ElfW (Sym) *sym = (ElfW (Sym) *) (new_shdr->sh_offset + new_base);
- for (; num--; sym++)
- {
- if (sym->st_shndx == SHN_XINDEX)
- fatal ("SHT_SYMTAB_SHNDX unsupported");
- if (sym->st_shndx == SHN_UNDEF
- || sym->st_shndx >= SHN_LORESERVE)
- continue;
-
- PATCH_INDEX (sym->st_shndx);
- }
- }
}
/* Update the symbol values of _edata and _end. */
ElfW (Shdr) *new_shdr = &NEW_SECTION_H (symp->st_shndx);
if (new_shdr->sh_type != SHT_NOBITS)
{
- ElfW (Shdr) *old_shdr;
+ ElfW (Shdr) *old_shdr = &OLD_SECTION_H (symp->st_shndx);
ptrdiff_t reladdr = symp->st_value - new_shdr->sh_addr;
ptrdiff_t newoff = reladdr + new_shdr->sh_offset;
- /* "Unpatch" index. */
- nn = symp->st_shndx;
- if (nn > old_bss_index)
- nn--;
- old_shdr = &OLD_SECTION_H (nn);
if (old_shdr->sh_type == SHT_NOBITS)
memset (new_base + newoff, 0, symp->st_size);
else
}
}
+ /* Modify the names of sections we changed from SHT_NOBITS to
+ SHT_PROGBITS. This is really just cosmetic, but some tools that
+ (wrongly) operate on section names rather than types might be
+ confused by a SHT_PROGBITS .bss section. */
+ new_section_names = ((char *) new_base
+ + NEW_SECTION_H (new_file_h->e_shstrndx).sh_offset);
+ for (n = new_file_h->e_shnum; 0 < --n; )
+ {
+ ElfW (Shdr) *old_shdr = &OLD_SECTION_H (n);
+ ElfW (Shdr) *new_shdr = &NEW_SECTION_H (n);
+
+ /* Replace the leading '.' with ','. When .shstrtab is string
+ merged this will rename both .bss and .rela.bss to ,bss and
+ .rela,bss. */
+ if (old_shdr->sh_type == SHT_NOBITS
+ && new_shdr->sh_type == SHT_PROGBITS)
+ *(new_section_names + new_shdr->sh_name) = ',';
+ }
+
/* This loop seeks out relocation sections for the data section, so
that it can undo relocations performed by the runtime loader. */
for (n = new_file_h->e_shnum; 0 < --n; )
projects / emacs.git / commitdiff