/* Copyright (C) 1985, 1986, 1987, 1988, 1990, 1992, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. This file is part of GNU Emacs. GNU Emacs 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 3 of the License, or (at your option) any later version. GNU Emacs 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 GNU Emacs. If not, see . */ /* 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, old_name, data_start, bss_start, entry_address) * char *new_name, *old_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 old_name is non-NULL, the symbol table will be taken from the given file. * On some machines, an existing old_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. * * 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. * */ /* 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 */ /* 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 */ /* We do not use mmap because that fails with NFS. Instead we read the whole file, modify it, and write it out. */ #ifndef emacs #define fatal(a, b, c) fprintf (stderr, a, b, c), exit (1) #include #else #include extern void fatal (const char *msgid, ...); #endif #include #include #include #include #include #include #include #if !defined (__NetBSD__) && !defined (__OpenBSD__) #include #endif #include #if defined (_SYSTYPE_SYSV) #include #include #endif /* _SYSTYPE_SYSV */ #if __sgi #include /* for HDRR declaration */ #endif /* __sgi */ #ifndef MAP_ANON #ifdef MAP_ANONYMOUS #define MAP_ANON MAP_ANONYMOUS #else #define MAP_ANON 0 #endif #endif #ifndef MAP_FAILED #define MAP_FAILED ((void *) -1) #endif #if defined (__alpha__) && !defined (__NetBSD__) && !defined (__OpenBSD__) /* Declare COFF debugging symbol table. This used to be in /usr/include/sym.h, but this file is no longer included in Red Hat 5.0 and presumably in any other glibc 2.x based distribution. */ typedef struct { short magic; short vstamp; int ilineMax; int idnMax; int ipdMax; int isymMax; int ioptMax; int iauxMax; int issMax; int issExtMax; int ifdMax; int crfd; int iextMax; long cbLine; long cbLineOffset; long cbDnOffset; long cbPdOffset; long cbSymOffset; long cbOptOffset; long cbAuxOffset; long cbSsOffset; long cbSsExtOffset; long cbFdOffset; long cbRfdOffset; long cbExtOffset; } HDRR, *pHDRR; #define cbHDRR sizeof(HDRR) #define hdrNil ((pHDRR)0) #endif #ifdef __NetBSD__ /* * NetBSD does not have normal-looking user-land ELF support. */ # if defined __alpha__ || defined __sparc_v9__ # define ELFSIZE 64 # else # define ELFSIZE 32 # endif # include # ifndef PT_LOAD # define PT_LOAD Elf_pt_load # if 0 /* was in pkgsrc patches for 20.7 */ # define SHT_PROGBITS Elf_sht_progbits # endif # define SHT_SYMTAB Elf_sht_symtab # define SHT_DYNSYM Elf_sht_dynsym # define SHT_NULL Elf_sht_null # define SHT_NOBITS Elf_sht_nobits # define SHT_REL Elf_sht_rel # define SHT_RELA Elf_sht_rela # define SHN_UNDEF Elf_eshn_undefined # define SHN_ABS Elf_eshn_absolute # define SHN_COMMON Elf_eshn_common # endif /* !PT_LOAD */ # ifdef __alpha__ # include # define HDRR struct ecoff_symhdr # define pHDRR HDRR * # endif /* __alpha__ */ #ifdef __mips__ /* was in pkgsrc patches for 20.7 */ # define SHT_MIPS_DEBUG DT_MIPS_FLAGS # define HDRR struct Elf_Shdr #endif /* __mips__ */ #endif /* __NetBSD__ */ #ifdef __OpenBSD__ # include #endif #if __GNU_LIBRARY__ - 0 >= 6 # include /* get ElfW etc */ #endif #ifndef ElfW # ifdef __STDC__ # define ElfBitsW(bits, type) Elf##bits##_##type # else # define ElfBitsW(bits, type) Elf/**/bits/**/_/**/type # endif # ifdef _LP64 # define ELFSIZE 64 # else # define ELFSIZE 32 # endif /* This macro expands `bits' before invoking ElfBitsW. */ # define ElfExpandBitsW(bits, type) ElfBitsW (bits, type) # define ElfW(type) ElfExpandBitsW (ELFSIZE, type) #endif #ifndef ELF_BSS_SECTION_NAME #define ELF_BSS_SECTION_NAME ".bss" #endif /* Get the address of a particular section or program header entry, * accounting for the size of the entries. */ /* On PPC Reference Platform running Solaris 2.5.1 the plt section is also of type NOBI like the bss section. (not really stored) and therefore sections after the bss section start at the plt offset. The plt section is always the one just before the bss section. Thus, we modify the test from if (NEW_SECTION_H (nn).sh_offset >= new_data2_offset) to if (NEW_SECTION_H (nn).sh_offset >= OLD_SECTION_H (old_bss_index-1).sh_offset) This is just a hack. We should put the new data section before the .plt section. And we should not have this routine at all but use the libelf library to read the old file and create the new file. The changed code is minimal and depends on prep set in m/prep.h Erik Deumens Quantum Theory Project University of Florida deumens@qtp.ufl.edu Apr 23, 1996 */ #define OLD_SECTION_H(n) \ (*(ElfW(Shdr) *) ((byte *) old_section_h + old_file_h->e_shentsize * (n))) #define NEW_SECTION_H(n) \ (*(ElfW(Shdr) *) ((byte *) new_section_h + new_file_h->e_shentsize * (n))) #define OLD_PROGRAM_H(n) \ (*(ElfW(Phdr) *) ((byte *) old_program_h + old_file_h->e_phentsize * (n))) #define NEW_PROGRAM_H(n) \ (*(ElfW(Phdr) *) ((byte *) new_program_h + new_file_h->e_phentsize * (n))) #define PATCH_INDEX(n) \ do { \ if ((int) (n) >= old_bss_index) \ (n)++; } while (0) typedef unsigned char byte; /* Round X up to a multiple of Y. */ static ElfW(Addr) round_up (x, y) ElfW(Addr) x, y; { int rem = x % y; if (rem == 0) return x; return x - rem + y; } /* 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 0; we return -1 if NOERROR is nonzero. */ static int find_section (name, section_names, file_name, old_file_h, old_section_h, noerror) char *name; char *section_names; char *file_name; ElfW(Ehdr) *old_file_h; ElfW(Shdr) *old_section_h; int noerror; { int idx; for (idx = 1; idx < old_file_h->e_shnum; idx++) { #ifdef DEBUG fprintf (stderr, "Looking for %s - found %s\n", name, section_names + OLD_SECTION_H (idx).sh_name); #endif if (!strcmp (section_names + OLD_SECTION_H (idx).sh_name, name)) break; } if (idx == old_file_h->e_shnum) { if (noerror) return -1; else fatal ("Can't find %s in %s.\n", name, file_name); } return idx; } /* **************************************************************** * 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; { 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; #if MAP_ANON == 0 int mmap_fd; #else # define mmap_fd -1 #endif /* Pointers to the file, program and section headers for the old and new files. */ ElfW(Ehdr) *old_file_h, *new_file_h; 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; 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(Word) new_data2_incr; int n, nn; int old_bss_index, old_sbss_index, old_plt_index; int old_data_index, new_data2_index; int old_mdebug_index; struct stat stat_buf; int old_file_size; /* Open the old file, allocate a buffer of the right size, and read in the file contents. */ 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); #if MAP_ANON == 0 mmap_fd = open ("/dev/zero", O_RDONLY); if (mmap_fd < 0) fatal ("Can't open /dev/zero for reading: errno %d\n", errno, 0); #endif /* We cannot use malloc here because that may use sbrk. If it does, we'd dump our temporary buffers with Emacs, and we'd have to be extra careful to use the correct value of sbrk(0) after allocating all buffers in the code below, which we aren't. */ old_file_size = stat_buf.st_size; old_base = mmap (NULL, old_file_size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, mmap_fd, 0); if (old_base == MAP_FAILED) fatal ("Can't allocate buffer for %s\n", old_name, 0); if (read (old_file, old_base, stat_buf.st_size) != stat_buf.st_size) fatal ("Didn't read all of %s: errno %d\n", old_name, errno); /* Get pointers to headers & section names */ old_file_h = (ElfW(Ehdr) *) old_base; old_program_h = (ElfW(Phdr) *) ((byte *) old_base + old_file_h->e_phoff); old_section_h = (ElfW(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 mdebug section, if any. */ old_mdebug_index = find_section (".mdebug", old_section_names, old_name, old_file_h, old_section_h, 1); /* Find the old .bss section. Figure out parameters of the new data2 and bss sections. */ old_bss_index = find_section (".bss", old_section_names, old_name, old_file_h, old_section_h, 0); old_sbss_index = find_section (".sbss", old_section_names, old_name, old_file_h, old_section_h, 1); if (old_sbss_index != -1) if (OLD_SECTION_H (old_sbss_index).sh_type != SHT_NOBITS) old_sbss_index = -1; /* PowerPC64 has .plt in the BSS section. */ old_plt_index = find_section (".plt", old_section_names, old_name, old_file_h, old_section_h, 1); if (old_plt_index != -1) if (OLD_SECTION_H (old_plt_index).sh_type != SHT_NOBITS) old_plt_index = -1; if (old_sbss_index == -1 && old_plt_index == -1) { old_bss_addr = OLD_SECTION_H (old_bss_index).sh_addr; old_bss_size = OLD_SECTION_H (old_bss_index).sh_size; old_bss_offset = OLD_SECTION_H (old_bss_index).sh_offset; new_data2_index = old_bss_index; } else if (old_plt_index != -1 && (old_sbss_index == -1 || (OLD_SECTION_H (old_sbss_index).sh_addr > OLD_SECTION_H (old_plt_index).sh_addr))) { old_bss_addr = OLD_SECTION_H (old_plt_index).sh_addr; old_bss_size = OLD_SECTION_H (old_bss_index).sh_size + OLD_SECTION_H (old_plt_index).sh_size; if (old_sbss_index != -1) old_bss_size += OLD_SECTION_H (old_sbss_index).sh_size; old_bss_offset = OLD_SECTION_H (old_plt_index).sh_offset; new_data2_index = old_plt_index; } else { old_bss_addr = OLD_SECTION_H (old_sbss_index).sh_addr; old_bss_size = OLD_SECTION_H (old_bss_index).sh_size + OLD_SECTION_H (old_sbss_index).sh_size; old_bss_offset = OLD_SECTION_H (old_sbss_index).sh_offset; new_data2_index = old_sbss_index; } /* 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); #if defined (emacs) || !defined (DEBUG) new_bss_addr = (ElfW(Addr)) sbrk (0); #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_data_index).sh_offset + (new_data2_addr - OLD_SECTION_H (old_data_index).sh_addr); /* This is the amount by which the sections following the bss sections must be shifted in the image. It can differ from new_data2_size if the end of the old .data section (and thus the offset of the .bss section) was unaligned. */ new_data2_incr = new_data2_size + (new_data2_offset - old_bss_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, "old_bss_offset %x\n", old_bss_offset); 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); fprintf (stderr, "new_data2_incr %x\n", new_data2_incr); #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. Allocate a buffer to hold the image of the new file. 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_incr; if (ftruncate (new_file, new_file_size)) fatal ("Can't ftruncate (%s): errno %d\n", new_name, errno); new_base = mmap (NULL, new_file_size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, mmap_fd, 0); if (new_base == MAP_FAILED) fatal ("Can't allocate buffer for %s\n", old_name, 0); new_file_h = (ElfW(Ehdr) *) new_base; new_program_h = (ElfW(Phdr) *) ((byte *) new_base + old_file_h->e_phoff); new_section_h = (ElfW(Shdr) *) ((byte *) new_base + old_file_h->e_shoff + new_data2_incr); /* 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); /* Modify the e_shstrndx if necessary. */ PATCH_INDEX (new_file_h->e_shstrndx); /* Fix up file header. We'll add one section. Section header is further away now. */ new_file_h->e_shoff += new_data2_incr; 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. */ ElfW(Word) 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; #ifdef __sgi /* According to r02kar@x4u2.desy.de (Karsten Kuenne) and oliva@gnu.org (Alexandre Oliva), on IRIX 5.2, we always get "Program segment above .bss" when dumping when the executable doesn't have an sbss section. */ if (old_sbss_index != -1) #endif /* __sgi */ if (NEW_PROGRAM_H (n).p_vaddr + NEW_PROGRAM_H (n).p_filesz > (old_sbss_index == -1 ? old_bss_addr : round_up (old_bss_addr, alignment))) 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); /* Make sure that the size includes any padding before the old .bss section. */ NEW_PROGRAM_H (n).p_filesz = new_bss_addr - NEW_PROGRAM_H (n).p_vaddr; 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_incr; } #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. */ /* Walk through all section headers, insert the new data2 section right before the new bss section. */ for (n = 1, nn = 1; n < (int) old_file_h->e_shnum; n++, nn++) { caddr_t src; /* If it is (s)bss section, insert the new data2 section before it. */ /* new_data2_index is the index of either old_sbss or old_bss, that was chosen as a section for new_data2. */ if (n == new_data2_index) { /* Steal the data section header for this data2 section. */ memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (old_data_index), new_file_h->e_shentsize); NEW_SECTION_H (nn).sh_addr = new_data2_addr; NEW_SECTION_H (nn).sh_offset = new_data2_offset; NEW_SECTION_H (nn).sh_size = new_data2_size; /* Use the bss section's alignment. This will assure that the new data2 section always be placed in the same spot as the old bss section by any other application. */ NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (n).sh_addralign; /* Now copy over what we have in the memory now. */ memcpy (NEW_SECTION_H (nn).sh_offset + new_base, (caddr_t) OLD_SECTION_H (n).sh_addr, new_data2_size); nn++; } memcpy (&NEW_SECTION_H (nn), &OLD_SECTION_H (n), old_file_h->e_shentsize); if (n == old_bss_index /* The new bss and sbss section's size is zero, and its file offset and virtual address should be off by NEW_DATA2_SIZE. */ || n == old_sbss_index || n == old_plt_index ) { /* NN should be `old_s?bss_index + 1' at this point. */ NEW_SECTION_H (nn).sh_offset = new_data2_offset + new_data2_size; NEW_SECTION_H (nn).sh_addr = new_data2_addr + new_data2_size; /* Let the new bss section address alignment be the same as the section address alignment followed the old bss section, so this section will be placed in exactly the same place. */ NEW_SECTION_H (nn).sh_addralign = OLD_SECTION_H (nn).sh_addralign; NEW_SECTION_H (nn).sh_size = 0; } else { /* Any section that was originally placed after the .bss section should now be off by NEW_DATA2_INCR. If a section overlaps the .bss section, consider it to be placed after the .bss section. Overlap can occur if the section just before .bss has less-strict alignment; this was observed between .symtab and .bss on Solaris 2.5.1 (sparc) with GCC snapshot 960602. > dump -h temacs temacs: **** SECTION HEADER TABLE **** [No] Type Flags Addr Offset Size Name Link Info Adralgn Entsize [22] 1 3 0x335150 0x315150 0x4 .data.rel.local 0 0 0x4 0 [23] 8 3 0x335158 0x315158 0x42720 .bss 0 0 0x8 0 [24] 2 0 0 0x315154 0x1c9d0 .symtab 25 1709 0x4 0x10 */ if (NEW_SECTION_H (nn).sh_offset >= old_bss_offset || (NEW_SECTION_H (nn).sh_offset + NEW_SECTION_H (nn).sh_size > new_data2_offset)) NEW_SECTION_H (nn).sh_offset += new_data2_incr; /* 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_SECTION_H (nn).sh_offset > new_file_h->e_shoff) NEW_SECTION_H (nn).sh_offset += new_file_h->e_shentsize; } /* 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_SECTION_H (nn).sh_link); /* For symbol tables, info is a symbol table index, so don't change it. */ if (NEW_SECTION_H (nn).sh_type != SHT_SYMTAB && NEW_SECTION_H (nn).sh_type != SHT_DYNSYM) PATCH_INDEX (NEW_SECTION_H (nn).sh_info); if (old_sbss_index != -1) if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".sbss")) { NEW_SECTION_H (nn).sh_offset = round_up (NEW_SECTION_H (nn).sh_offset, NEW_SECTION_H (nn).sh_addralign); NEW_SECTION_H (nn).sh_type = SHT_PROGBITS; } /* Now, start to copy the content of sections. */ if (NEW_SECTION_H (nn).sh_type == SHT_NULL || NEW_SECTION_H (nn).sh_type == SHT_NOBITS) continue; /* 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. */ if (!strcmp (old_section_names + NEW_SECTION_H (n).sh_name, ".data") || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name), ".sdata") || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name), ".lit4") || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name), ".lit8") /* The conditional bit below was in Oliva's original code (1999-08-25) and seems to have been dropped by mistake subsequently. It prevents a crash at startup under X in `IRIX64 6.5 6.5.17m', whether compiled on that relase or an earlier one. It causes no trouble on the other ELF platforms I could test (Irix 6.5.15m, Solaris 8, Debian Potato x86, Debian Woody SPARC); however, it's reported to cause crashes under some version of GNU/Linux. It's not yet clear what's changed in that Irix version to cause the problem, or why the fix sometimes fails under GNU/Linux. There's probably no good reason to have something Irix-specific here, but this will have to do for now. IRIX6_5 is the most specific macro we have to test. -- fx 2002-10-01 The issue _looks_ as though it's gone away on 6.5.18m, but maybe it's still lurking, to be triggered by some change in the binary. It appears to concern the dynamic loader, but I never got anywhere with an SGI support call seeking clues. -- fx 2002-11-29. */ #ifdef IRIX6_5 || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name), ".got") #endif || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name), ".sdata1") || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name), ".data1") || !strcmp ((old_section_names + NEW_SECTION_H (n).sh_name), ".sbss")) src = (caddr_t) OLD_SECTION_H (n).sh_addr; else src = old_base + OLD_SECTION_H (n).sh_offset; memcpy (NEW_SECTION_H (nn).sh_offset + new_base, src, NEW_SECTION_H (nn).sh_size); #ifdef __alpha__ /* Update Alpha COFF symbol table: */ if (strcmp (old_section_names + OLD_SECTION_H (n).sh_name, ".mdebug") == 0) { pHDRR symhdr = (pHDRR) (NEW_SECTION_H (nn).sh_offset + new_base); symhdr->cbLineOffset += new_data2_size; symhdr->cbDnOffset += new_data2_size; symhdr->cbPdOffset += new_data2_size; symhdr->cbSymOffset += new_data2_size; symhdr->cbOptOffset += new_data2_size; symhdr->cbAuxOffset += new_data2_size; symhdr->cbSsOffset += new_data2_size; symhdr->cbSsExtOffset += new_data2_size; symhdr->cbFdOffset += new_data2_size; symhdr->cbRfdOffset += new_data2_size; symhdr->cbExtOffset += new_data2_size; } #endif /* __alpha__ */ #if defined (_SYSTYPE_SYSV) if (NEW_SECTION_H (nn).sh_type == SHT_MIPS_DEBUG && old_mdebug_index != -1) { int diff = NEW_SECTION_H(nn).sh_offset - OLD_SECTION_H(old_mdebug_index).sh_offset; HDRR *phdr = (HDRR *)(NEW_SECTION_H (nn).sh_offset + new_base); if (diff) { phdr->cbLineOffset += diff; phdr->cbDnOffset += diff; phdr->cbPdOffset += diff; phdr->cbSymOffset += diff; phdr->cbOptOffset += diff; phdr->cbAuxOffset += diff; phdr->cbSsOffset += diff; phdr->cbSsExtOffset += diff; phdr->cbFdOffset += diff; phdr->cbRfdOffset += diff; phdr->cbExtOffset += diff; } } #endif /* _SYSTYPE_SYSV */ #if __sgi /* Adjust the HDRR offsets in .mdebug and copy the line data if it's in its usual 'hole' in the object. Makes the new file debuggable with dbx. patches up two problems: the absolute file offsets in the HDRR record of .mdebug (see /usr/include/syms.h), and the ld bug that gets the line table in a hole in the elf file rather than in the .mdebug section proper. David Anderson. davea@sgi.com Jan 16,1994. */ if (n == old_mdebug_index) { #define MDEBUGADJUST(__ct,__fileaddr) \ if (n_phdrr->__ct > 0) \ { \ n_phdrr->__fileaddr += movement; \ } HDRR * o_phdrr = (HDRR *)((byte *)old_base + OLD_SECTION_H (n).sh_offset); HDRR * n_phdrr = (HDRR *)((byte *)new_base + NEW_SECTION_H (nn).sh_offset); unsigned movement = new_data2_size; MDEBUGADJUST (idnMax, cbDnOffset); MDEBUGADJUST (ipdMax, cbPdOffset); MDEBUGADJUST (isymMax, cbSymOffset); MDEBUGADJUST (ioptMax, cbOptOffset); MDEBUGADJUST (iauxMax, cbAuxOffset); MDEBUGADJUST (issMax, cbSsOffset); MDEBUGADJUST (issExtMax, cbSsExtOffset); MDEBUGADJUST (ifdMax, cbFdOffset); MDEBUGADJUST (crfd, cbRfdOffset); MDEBUGADJUST (iextMax, cbExtOffset); /* The Line Section, being possible off in a hole of the object, requires special handling. */ if (n_phdrr->cbLine > 0) { if (o_phdrr->cbLineOffset > (OLD_SECTION_H (n).sh_offset + OLD_SECTION_H (n).sh_size)) { /* line data is in a hole in elf. do special copy and adjust for this ld mistake. */ n_phdrr->cbLineOffset += movement; memcpy (n_phdrr->cbLineOffset + new_base, o_phdrr->cbLineOffset + old_base, n_phdrr->cbLine); } else { /* somehow line data is in .mdebug as it is supposed to be. */ MDEBUGADJUST (cbLine, cbLineOffset); } } } #endif /* __sgi */ /* If it is the symbol table, its st_shndx field needs to be patched. */ if (NEW_SECTION_H (nn).sh_type == SHT_SYMTAB || NEW_SECTION_H (nn).sh_type == SHT_DYNSYM) { ElfW(Shdr) *spt = &NEW_SECTION_H (nn); unsigned int num = spt->sh_size / spt->sh_entsize; ElfW(Sym) * sym = (ElfW(Sym) *) (NEW_SECTION_H (nn).sh_offset + new_base); for (; num--; sym++) { if ((sym->st_shndx == SHN_UNDEF) || (sym->st_shndx == SHN_ABS) || (sym->st_shndx == SHN_COMMON)) continue; PATCH_INDEX (sym->st_shndx); } } } /* Update the symbol values of _edata and _end. */ for (n = new_file_h->e_shnum - 1; n; n--) { byte *symnames; ElfW(Sym) *symp, *symendp; if (NEW_SECTION_H (n).sh_type != SHT_DYNSYM && NEW_SECTION_H (n).sh_type != SHT_SYMTAB) continue; symnames = ((byte *) new_base + NEW_SECTION_H (NEW_SECTION_H (n).sh_link).sh_offset); symp = (ElfW(Sym) *) (NEW_SECTION_H (n).sh_offset + new_base); symendp = (ElfW(Sym) *) ((byte *)symp + NEW_SECTION_H (n).sh_size); for (; symp < symendp; symp ++) { if (strcmp ((char *) (symnames + symp->st_name), "_end") == 0 || strcmp ((char *) (symnames + symp->st_name), "end") == 0 || strcmp ((char *) (symnames + symp->st_name), "_edata") == 0 || strcmp ((char *) (symnames + symp->st_name), "edata") == 0) memcpy (&symp->st_value, &new_bss_addr, sizeof (new_bss_addr)); /* Strictly speaking, #ifdef below is not necessary. But we keep it to indicate that this kind of change may also be necessary for other unexecs to support GNUstep. */ #ifdef NS_IMPL_GNUSTEP /* ObjC runtime modifies the values of some data structures such as classes and selectors in the .data section after loading. As the dump process copies the .data section from the current process, that causes problems when the modified classes are reinitialized in the dumped executable. We copy such data from the old file, not from the current process. */ if (strncmp ((char *) (symnames + symp->st_name), "_OBJC_", sizeof ("_OBJC_") - 1) == 0) { caddr_t old, new; new = ((symp->st_value - NEW_SECTION_H (symp->st_shndx).sh_addr) + NEW_SECTION_H (symp->st_shndx).sh_offset + new_base); /* "Unpatch" index. */ nn = symp->st_shndx; if (nn > old_bss_index) nn--; old = ((symp->st_value - NEW_SECTION_H (symp->st_shndx).sh_addr) + OLD_SECTION_H (nn).sh_offset + old_base); memcpy (new, old, symp->st_size); } #endif } } /* This loop seeks out relocation sections for the data section, so that it can undo relocations performed by the runtime linker. */ for (n = new_file_h->e_shnum - 1; n; n--) { ElfW(Shdr) section = NEW_SECTION_H (n); /* Cause a compilation error if anyone uses n instead of nn below. */ struct {int a;} n; (void)n.a; /* Prevent `unused variable' warnings. */ switch (section.sh_type) { default: break; case SHT_REL: case SHT_RELA: /* This code handles two different size structs, but there should be no harm in that provided that r_offset is always the first member. */ nn = section.sh_info; if (!strcmp (old_section_names + NEW_SECTION_H (nn).sh_name, ".data") || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name), ".sdata") || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name), ".lit4") || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name), ".lit8") #ifdef IRIX6_5 /* see above */ || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name), ".got") #endif || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name), ".sdata1") || !strcmp ((old_section_names + NEW_SECTION_H (nn).sh_name), ".data1")) { ElfW(Addr) offset = (NEW_SECTION_H (nn).sh_addr - NEW_SECTION_H (nn).sh_offset); caddr_t reloc = old_base + section.sh_offset, end; for (end = reloc + section.sh_size; reloc < end; reloc += section.sh_entsize) { ElfW(Addr) addr = ((ElfW(Rel) *) reloc)->r_offset - offset; #ifdef __alpha__ /* The Alpha ELF binutils currently have a bug that sometimes results in relocs that contain all zeroes. Work around this for now... */ if (((ElfW(Rel) *) reloc)->r_offset == 0) continue; #endif memcpy (new_base + addr, old_base + addr, sizeof(ElfW(Addr))); } } break; } } /* Write out new_file, and free the buffers. */ if (write (new_file, new_base, new_file_size) != new_file_size) #ifndef emacs fatal ("Didn't write %d bytes: errno %d\n", new_file_size, errno); #else fatal ("Didn't write %d bytes to %s: errno %d\n", new_file_size, new_name, errno); #endif munmap (old_base, old_file_size); munmap (new_base, new_file_size); /* Close the files and make the new file executable. */ #if MAP_ANON == 0 close (mmap_fd); #endif 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); } /* arch-tag: e02e1512-95e2-4ef0-bba7-b6bce658f1e3 (do not change this comment) */