diff options
| -rw-r--r-- | src/unexelf.c | 290 |
1 files changed, 77 insertions, 213 deletions
diff --git a/src/unexelf.c b/src/unexelf.c index 15a4cdedfc9..4e9c50d5352 100644 --- a/src/unexelf.c +++ b/src/unexelf.c @@ -535,29 +535,6 @@ verify ((! TYPE_SIGNED (ElfW (Half)) /* 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 - */ static void * entry_address (void *section_h, ptrdiff_t idx, ptrdiff_t entsize) @@ -570,23 +547,14 @@ entry_address (void *section_h, ptrdiff_t idx, ptrdiff_t entsize) (*(ElfW (Shdr) *) entry_address (old_section_h, n, old_file_h->e_shentsize)) #define NEW_SECTION_H(n) \ (*(ElfW (Shdr) *) entry_address (new_section_h, n, new_file_h->e_shentsize)) +#define OLD_PROGRAM_H(n) \ + (*(ElfW (Phdr) *) entry_address (old_program_h, n, old_file_h->e_phentsize)) #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; -/* Round X up to a multiple of Y. */ - -static ElfW (Addr) -round_up (ElfW (Addr) x, ElfW (Addr) y) -{ - ElfW (Addr) 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. @@ -650,16 +618,15 @@ unexec (const char *new_name, const char *old_name) /* Point to the section name table in the old file. */ char *old_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 (Word) new_data2_incr; ptrdiff_t n, nn; - ptrdiff_t old_bss_index, old_sbss_index, old_plt_index; - ptrdiff_t old_data_index, new_data2_index; + ptrdiff_t old_bss_index, old_data_index; struct stat stat_buf; off_t old_file_size; @@ -703,54 +670,40 @@ unexec (const char *new_name, const char *old_name) 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. */ - - 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))) + /* Find the PT_LOAD header covering the highest address. This + segment will be where bss sections are located, past p_filesz. */ + old_bss_seg = 0; + for (n = old_file_h->e_phnum; --n >= 0; ) { - 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; + ElfW (Phdr) *seg = &OLD_PROGRAM_H (n); + if (seg->p_type == PT_LOAD + && (old_bss_seg == 0 + || seg->p_vaddr > old_bss_seg->p_vaddr)) + old_bss_seg = seg; } - else + + /* Note that old_bss_addr may be lower than the first bss section + address, since the section may need aligning. */ + old_bss_addr = old_bss_seg->p_vaddr + old_bss_seg->p_filesz; + 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. */ + old_bss_index = -1; + for (n = old_file_h->e_shnum; --n > 0; ) { - 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; + ElfW (Shdr) *shdr = &OLD_SECTION_H (n); + if (shdr->sh_type == SHT_NOBITS + && 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_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. */ @@ -761,13 +714,7 @@ unexec (const char *new_name, const char *old_name) 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_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); + new_data2_offset = old_bss_offset; #ifdef UNEXELF_DEBUG fprintf (stderr, "old_bss_index %td\n", old_bss_index); @@ -778,7 +725,6 @@ unexec (const char *new_name, const char *old_name) DEBUG_LOG (new_data2_addr); DEBUG_LOG (new_data2_size); DEBUG_LOG (new_data2_offset); - DEBUG_LOG (new_data2_incr); #endif if (new_bss_addr < old_bss_addr + old_bss_size) @@ -792,7 +738,7 @@ unexec (const char *new_name, const char *old_name) 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_incr; + new_file_size = old_file_size + old_file_h->e_shentsize + new_data2_size; if (ftruncate (new_file, new_file_size)) fatal ("Can't ftruncate (%s): %s", new_name, strerror (errno)); @@ -811,15 +757,15 @@ unexec (const char *new_name, const char *old_name) /* Fix up file header. We'll add one section. Section header is further away now. */ - new_file_h->e_shoff += new_data2_incr; + 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 + old_file_h->e_phoff); - new_section_h = (ElfW (Shdr) *) - ((byte *) new_base + old_file_h->e_shoff + new_data2_incr); + 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); @@ -831,65 +777,21 @@ unexec (const char *new_name, const char *old_name) fprintf (stderr, "New section count %td\n", (ptrdiff_t) 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. */ + /* Fix up program header. Extend the writable data segment so + that the bss area is covered too. */ - for (n = new_file_h->e_phnum; --n >= 0; ) - { - /* 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", old_name); - - 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", old_name); - - /* 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; --n >= 0; ) - { - 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; + new_bss_seg = new_program_h + (old_bss_seg - old_program_h); + new_bss_seg->p_filesz = new_bss_addr - new_bss_seg->p_vaddr; + new_bss_seg->p_memsz = new_bss_seg->p_filesz; - if (NEW_PROGRAM_H (n).p_offset >= new_data2_offset) - NEW_PROGRAM_H (n).p_offset += new_data2_incr; - } -#endif + /* 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 and new address - is set. data2 section header gets added by copying the existing - .data header and modifying the offset, address and size. */ + 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. */ @@ -900,9 +802,7 @@ unexec (const char *new_name, const char *old_name) ElfW (Shdr) *new_shdr = &NEW_SECTION_H (nn); /* 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) + if (n == old_bss_index) { /* Steal the data section header for this data2 section. */ memcpy (new_shdr, &OLD_SECTION_H (old_data_index), @@ -911,68 +811,43 @@ unexec (const char *new_name, const char *old_name) new_shdr->sh_addr = new_data2_addr; new_shdr->sh_offset = new_data2_offset; new_shdr->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_shdr->sh_addralign = old_shdr->sh_addralign; - - /* Now copy over what we have in the memory now. */ - memcpy (new_shdr->sh_offset + new_base, - (caddr_t) old_shdr->sh_addr, - new_data2_size); + new_shdr->sh_addralign = 1; nn++; new_shdr++; } memcpy (new_shdr, old_shdr, 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 - ) + 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)) { - /* NN should be `old_s?bss_index + 1' at this point. */ - new_shdr->sh_offset = new_data2_offset + new_data2_size; - new_shdr->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_shdr->sh_addralign = OLD_SECTION_H (nn).sh_addralign; + /* 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 + + new_bss_seg->p_offset); + + /* If this is was a SHT_NOBITS .plt section, then it is + probably a PowerPC PLT. If it is PowerPC64 ELFv1 then + glibc ld.so doesn't initialize the toc pointer word. A + non-zero toc pointer word can defeat Power7 thread safety + during lazy update of a PLT entry. This only matters if + emacs becomes multi-threaded. */ + 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_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. + section should now be off by NEW_DATA2_SIZE. */ -> 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_shdr->sh_offset >= old_bss_offset - || (new_shdr->sh_offset + new_shdr->sh_size - > new_data2_offset)) - new_shdr->sh_offset += new_data2_incr; + 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 @@ -992,23 +867,13 @@ temacs: && new_shdr->sh_type != SHT_DYNSYM) PATCH_INDEX (new_shdr->sh_info); - if (old_sbss_index != -1) - if (!strcmp (old_section_names + new_shdr->sh_name, ".sbss")) - { - new_shdr->sh_offset = - round_up (new_shdr->sh_offset, - new_shdr->sh_addralign); - new_shdr->sh_type = SHT_PROGBITS; - } - /* Now, start to copy the content of sections. */ if (new_shdr->sh_type == SHT_NULL || new_shdr->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. */ + /* Some sections are copied from the current process instead of + the old file. */ if (!strcmp (old_section_names + new_shdr->sh_name, ".data") || !strcmp (old_section_names + new_shdr->sh_name, ".sdata") || !strcmp (old_section_names + new_shdr->sh_name, ".lit4") @@ -1037,8 +902,7 @@ temacs: || !strcmp (old_section_names + new_shdr->sh_name, ".got") #endif || !strcmp (old_section_names + new_shdr->sh_name, ".sdata1") - || !strcmp (old_section_names + new_shdr->sh_name, ".data1") - || !strcmp (old_section_names + new_shdr->sh_name, ".sbss")) + || !strcmp (old_section_names + new_shdr->sh_name, ".data1")) src = (caddr_t) old_shdr->sh_addr; else src = old_base + old_shdr->sh_offset; |