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- /* Copyright (C) 1985, 1986, 1987, 1988 Free Software Foundation, Inc.
-
- This program 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 1, or (at your option)
- any later version.
-
- This program 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 this program; if not, write to the Free Software
- Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
- In other words, you are welcome to use, share and improve this program.
- You are forbidden to forbid anyone else to use, share and improve
- what you give them. Help stamp out software-hoarding! */
-
-
- /*
- * unexec.c - Convert a running program into an a.out file.
- *
- * Author: Spencer W. Thomas
- * Computer Science Dept.
- * University of Utah
- * Date: Tue Mar 2 1982
- * Modified heavily since then.
- *
- * Synopsis:
- * unexec (new_name, a_name, data_start, bss_start, entry_address)
- * char *new_name, *a_name;
- * unsigned data_start, bss_start, entry_address;
- *
- * Takes a snapshot of the program and makes an a.out format file in the
- * file named by the string argument new_name.
- * If a_name is non-NULL, the symbol table will be taken from the given file.
- * On some machines, an existing a_name file is required.
- *
- * The boundaries within the a.out file may be adjusted with the data_start
- * and bss_start arguments. Either or both may be given as 0 for defaults.
- *
- * Data_start gives the boundary between the text segment and the data
- * segment of the program. The text segment can contain shared, read-only
- * program code and literal data, while the data segment is always unshared
- * and unprotected. Data_start gives the lowest unprotected address.
- * The value you specify may be rounded down to a suitable boundary
- * as required by the machine you are using.
- *
- * Specifying zero for data_start means the boundary between text and data
- * should not be the same as when the program was loaded.
- * If NO_REMAP is defined, the argument data_start is ignored and the
- * segment boundaries are never changed.
- *
- * Bss_start indicates how much of the data segment is to be saved in the
- * a.out file and restored when the program is executed. It gives the lowest
- * unsaved address, and is rounded up to a page boundary. The default when 0
- * is given assumes that the entire data segment is to be stored, including
- * the previous data and bss as well as any additional storage allocated with
- * break (2).
- *
- * The new file is set up to start at entry_address.
- *
- * If you make improvements I'd like to get them too.
- * harpo!utah-cs!thomas, thomas@Utah-20
- *
- */
-
- /* 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
-
-
- */
-
- #include <sys/types.h>
- #include <stdio.h>
- #include <sys/stat.h>
- #include <memory.h>
- #include <string.h>
- #include <errno.h>
- #include <unistd.h>
- #include <fcntl.h>
- #include <elf.h>
- #include <sys/mman.h>
-
- #ifndef emacs
- #define fatal(a, b, c) fprintf(stderr, a, b, c), exit(1)
- #else
- extern void fatal(char *, ...);
- #endif
-
- /* Get the address of a particular section or program header entry,
- * accounting for the size of the entries.
- */
-
- #define OLD_SECTION_H(n) \
- (*(Elf32_Shdr *) ((byte *) old_section_h + old_file_h->e_shentsize * (n)))
- #define NEW_SECTION_H(n) \
- (*(Elf32_Shdr *) ((byte *) new_section_h + new_file_h->e_shentsize * (n)))
- #define OLD_PROGRAM_H(n) \
- (*(Elf32_Phdr *) ((byte *) old_program_h + old_file_h->e_phentsize * (n)))
- #define NEW_PROGRAM_H(n) \
- (*(Elf32_Phdr *) ((byte *) new_program_h + new_file_h->e_phentsize * (n)))
-
- typedef unsigned char byte;
-
- /* Round X up to a multiple of Y. */
-
- int
- round_up (x, y)
- int x, y;
- {
- int rem = x % y;
- if (rem == 0)
- return x;
- return x - rem + y;
- }
-
- /* ****************************************************************
- * 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.
- *
- */
- void
- unexec (new_name, old_name, data_start, bss_start, entry_address)
- char *new_name, *old_name;
- unsigned data_start, bss_start, entry_address;
- {
- extern unsigned int bss_end;
- int new_file, old_file, new_file_size;
-
- /* Pointers to the base of the image of the two files. */
- caddr_t old_base, new_base;
-
- /* Pointers to the file, program and section headers for the old and new
- * files.
- */
- Elf32_Ehdr *old_file_h, *new_file_h;
- Elf32_Phdr *old_program_h, *new_program_h;
- Elf32_Shdr *old_section_h, *new_section_h;
-
- /* Point to the section name table in the old file */
- char *old_section_names;
-
- Elf32_Addr old_bss_addr, new_bss_addr;
- Elf32_Word old_bss_size, new_data2_size;
- Elf32_Off new_data2_offset;
- Elf32_Addr new_data2_addr;
-
- int n, old_bss_index, old_data_index, new_data2_index;
- struct stat stat_buf;
-
- /* Open the old file & map it into the address space. */
-
- old_file = open (old_name, O_RDONLY);
-
- if (old_file < 0)
- fatal ("Can't open %s for reading: errno %d\n", old_name, errno);
-
- if (fstat (old_file, &stat_buf) == -1)
- fatal ("Can't fstat(%s): errno %d\n", old_name, errno);
-
- old_base = mmap (0, stat_buf.st_size, PROT_READ, MAP_SHARED, old_file, 0);
-
- if (old_base == (caddr_t) -1)
- fatal ("Can't mmap(%s): errno %d\n", old_name, errno);
-
- #ifdef DEBUG
- fprintf (stderr, "mmap(%s, %x) -> %x\n", old_name, stat_buf.st_size,
- old_base);
- #endif
-
- /* Get pointers to headers & section names */
-
- old_file_h = (Elf32_Ehdr *) old_base;
- old_program_h = (Elf32_Phdr *) ((byte *) old_base + old_file_h->e_phoff);
- old_section_h = (Elf32_Shdr *) ((byte *) old_base + old_file_h->e_shoff);
- old_section_names = (char *) old_base
- + OLD_SECTION_H(old_file_h->e_shstrndx).sh_offset;
-
- /* Find the old .bss section. Figure out parameters of the new
- * data2 and bss sections.
- */
-
- for (old_bss_index = 1; old_bss_index < old_file_h->e_shnum; old_bss_index++)
- {
- #ifdef DEBUG
- fprintf (stderr, "Looking for .bss - found %s\n",
- old_section_names + OLD_SECTION_H(old_bss_index).sh_name);
- #endif
- if (!strcmp (old_section_names + OLD_SECTION_H(old_bss_index).sh_name,
- ".bss"))
- break;
- }
- if (old_bss_index == old_file_h->e_shnum)
- fatal ("Can't find .bss in %s.\n", old_name, 0);
-
- old_bss_addr = OLD_SECTION_H(old_bss_index).sh_addr;
- old_bss_size = OLD_SECTION_H(old_bss_index).sh_size;
- #if defined(emacs) || !defined(DEBUG)
- bss_end = (unsigned int) sbrk (0);
- new_bss_addr = (Elf32_Addr) bss_end;
- #else
- new_bss_addr = old_bss_addr + old_bss_size + 0x1234;
- #endif
- new_data2_addr = old_bss_addr;
- new_data2_size = new_bss_addr - old_bss_addr;
- new_data2_offset = OLD_SECTION_H(old_bss_index).sh_offset;
-
- #ifdef DEBUG
- fprintf (stderr, "old_bss_index %d\n", old_bss_index);
- fprintf (stderr, "old_bss_addr %x\n", old_bss_addr);
- fprintf (stderr, "old_bss_size %x\n", old_bss_size);
- fprintf (stderr, "new_bss_addr %x\n", new_bss_addr);
- fprintf (stderr, "new_data2_addr %x\n", new_data2_addr);
- fprintf (stderr, "new_data2_size %x\n", new_data2_size);
- fprintf (stderr, "new_data2_offset %x\n", new_data2_offset);
- #endif
-
- if ((unsigned) new_bss_addr < (unsigned) old_bss_addr + old_bss_size)
- fatal (".bss shrank when undumping???\n", 0, 0);
-
- /* Set the output file to the right size and mmap(2) it. Set
- * pointers to various interesting objects. stat_buf still has
- * old_file data.
- */
-
- new_file = open (new_name, O_RDWR | O_CREAT, 0666);
- if (new_file < 0)
- fatal ("Can't creat(%s): errno %d\n", new_name, errno);
-
- new_file_size = stat_buf.st_size + old_file_h->e_shentsize + new_data2_size;
-
- if (ftruncate (new_file, new_file_size))
- fatal ("Can't ftruncate(%s): errno %d\n", new_name, errno);
-
- new_base = mmap (0, new_file_size, PROT_READ | PROT_WRITE, MAP_SHARED,
- new_file, 0);
-
- if (new_base == (caddr_t) -1)
- fatal ("Can't mmap(%s): errno %d\n", new_name, errno);
-
- new_file_h = (Elf32_Ehdr *) new_base;
- new_program_h = (Elf32_Phdr *) ((byte *) new_base + old_file_h->e_phoff);
- new_section_h = (Elf32_Shdr *)
- ((byte *) new_base + old_file_h->e_shoff + new_data2_size);
-
- /* Make our new file, program and section headers as copies of the
- * originals.
- */
-
- memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
- 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);
-
- /* Fix up file header. We'll add one section. Section header is
- * further away now.
- */
-
- new_file_h->e_shoff += new_data2_size;
- new_file_h->e_shnum += 1;
-
- #ifdef DEBUG
- fprintf (stderr, "Old section offset %x\n", old_file_h->e_shoff);
- fprintf (stderr, "Old section count %d\n", old_file_h->e_shnum);
- fprintf (stderr, "New section offset %x\n", new_file_h->e_shoff);
- fprintf (stderr, "New section count %d\n", new_file_h->e_shnum);
- #endif
-
- /* Fix up a new program header. Extend the writable data segment so
- * that the bss area is covered too. Find that segment by looking
- * for a segment that ends just before the .bss area. Make sure
- * that no segments are above the new .data2. Put a loop at the end
- * to adjust the offset and address of any segment that is above
- * data2, just in case we decide to allow this later.
- */
-
- for (n = new_file_h->e_phnum - 1; n >= 0; n--)
- {
- /* Compute maximum of all requirements for alignment of section. */
- int alignment = (NEW_PROGRAM_H (n)).p_align;
- if ((OLD_SECTION_H (old_bss_index)).sh_addralign > alignment)
- alignment = OLD_SECTION_H (old_bss_index).sh_addralign;
-
- if (NEW_PROGRAM_H(n).p_vaddr + NEW_PROGRAM_H(n).p_filesz > old_bss_addr)
- fatal ("Program segment above .bss in %s\n", old_name, 0);
-
- if (NEW_PROGRAM_H(n).p_type == PT_LOAD
- && (round_up ((NEW_PROGRAM_H (n)).p_vaddr
- + (NEW_PROGRAM_H (n)).p_filesz,
- alignment)
- == round_up (old_bss_addr, alignment)))
- break;
- }
- if (n < 0)
- fatal ("Couldn't find segment next to .bss in %s\n", old_name, 0);
-
- NEW_PROGRAM_H(n).p_filesz += new_data2_size;
- NEW_PROGRAM_H(n).p_memsz = NEW_PROGRAM_H(n).p_filesz;
-
- #if 0 /* Maybe allow section after data2 - does this ever happen? */
- for (n = new_file_h->e_phnum - 1; n >= 0; n--)
- {
- if (NEW_PROGRAM_H(n).p_vaddr
- && NEW_PROGRAM_H(n).p_vaddr >= new_data2_addr)
- NEW_PROGRAM_H(n).p_vaddr += new_data2_size - old_bss_size;
-
- if (NEW_PROGRAM_H(n).p_offset >= new_data2_offset)
- NEW_PROGRAM_H(n).p_offset += new_data2_size;
- }
- #endif
-
- /* 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 and new address
- * is set. data2 section header gets added by copying the existing
- * .data header and modifying the offset, address and size.
- */
-
- for (n = 1; n < new_file_h->e_shnum; n++)
- {
- if (NEW_SECTION_H(n).sh_offset >= new_data2_offset)
- NEW_SECTION_H(n).sh_offset += new_data2_size;
-
- if (NEW_SECTION_H(n).sh_addr
- && NEW_SECTION_H(n).sh_addr >= new_data2_addr)
- NEW_SECTION_H(n).sh_addr += new_data2_size - old_bss_size;
- }
-
- new_data2_index = old_file_h->e_shnum;
-
- for (old_data_index = 1; old_data_index < old_file_h->e_shnum;
- old_data_index++)
- if (!strcmp (old_section_names + OLD_SECTION_H(old_data_index).sh_name,
- ".data"))
- break;
- if (old_data_index == old_file_h->e_shnum)
- fatal ("Can't find .data in %s.\n", old_name, 0);
-
- memcpy (&NEW_SECTION_H(new_data2_index), &OLD_SECTION_H(old_data_index),
- new_file_h->e_shentsize);
-
- NEW_SECTION_H(new_data2_index).sh_addr = new_data2_addr;
- NEW_SECTION_H(new_data2_index).sh_offset = new_data2_offset;
- NEW_SECTION_H(new_data2_index).sh_size = new_data2_size;
-
- NEW_SECTION_H(old_bss_index).sh_size = 0;
- NEW_SECTION_H(old_bss_index).sh_addr = new_data2_addr + new_data2_size;
-
- /* Write out the sections. .data and .data1 (and data2, called
- * ".data" in the strings table) get copied from the current process
- * instead of the old file.
- */
-
- for (n = new_file_h->e_shnum - 1; n; n--)
- {
- caddr_t src;
-
- if (NEW_SECTION_H(n).sh_type == SHT_NULL
- || NEW_SECTION_H(n).sh_type == SHT_NOBITS)
- continue;
-
- if (!strcmp (old_section_names + NEW_SECTION_H(n).sh_name, ".data")
- || !strcmp ((old_section_names + NEW_SECTION_H(n).sh_name),
- ".data1"))
- src = (caddr_t) NEW_SECTION_H(n).sh_addr;
- else
- src = old_base + OLD_SECTION_H(n).sh_offset;
-
- memcpy (NEW_SECTION_H(n).sh_offset + new_base, src,
- NEW_SECTION_H(n).sh_size);
- }
-
- /* Close the files and make the new file executable */
-
- if (close (old_file))
- fatal ("Can't close(%s): errno %d\n", old_name, errno);
-
- if (close (new_file))
- fatal ("Can't close(%s): errno %d\n", new_name, errno);
-
- if (stat (new_name, &stat_buf) == -1)
- fatal ("Can't stat(%s): errno %d\n", new_name, errno);
-
- n = umask (777);
- umask (n);
- stat_buf.st_mode |= 0111 & ~n;
- if (chmod (new_name, stat_buf.st_mode) == -1)
- fatal ("Can't chmod(%s): errno %d\n", new_name, errno);
- }
-