/* 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)
(*(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.
/* 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;
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. */
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);
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)
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));
/* 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);
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. */
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),
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
&& 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")
|| !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;
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