Handle VDSO section headers past end of page
When a VDSO gets large enough that it doesn't entirely fit in one page, but not so large that the part described by the program header exceeds one page, then gdb/BFD doesn't read the section headers and symbol table information. This patch cures that by passing the size of the vdso to BFD, and fixes a number of other issues in the BFD code. bfd/ * elfcode.h (bfd_from_remote_memory): Add "size" parameter. Consolidate code handling possible section headers past end of segment. Don't use p_align for page size guess, instead use minpagesize. Take note of ld.so clearing section headers when p_memsz > p_filesz. Handle file header specifying no section headers. Handle zero p_align throughout. Default loadbase to zero. Add comments. Rename contents_size to high_offset, and make it a bfd_vma. Delete unnecessary bfd_set_error calls. * bfd-in.h (bfd_elf_bfd_from_remote_memory): Update prototpe. * elf-bfd.h (struct elf_backend_data <elf_backend_from_remote_memory>): Likewise. (_bfd_elf32_bfd_from_remote_memory): Likewise. (_bfd_elf64_bfd_from_remote_memory): Likewise. * elf.c (bfd_elf_bfd_from_remote_memory): Adjust. * bfd-in2.h: Regnerate. gdb/ * symfile-mem.c (symbol_file_add_from_memory): Add size parameter. Pass to bfd_elf_bfd_from_remote_memory. Adjust all callers. (struct symbol_file_add_from_memory_args): Add size field. (find_vdso_size): New function. (add_vsyscall_page): Attempt to find vdso size.
This commit is contained in:
Alan Modra
parent
cf2a3e9905
commit
5979d6b69b
8 changed files with 180 additions and 94 deletions
149
bfd/elfcode.h
149
bfd/elfcode.h
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@ -1587,37 +1587,40 @@ elf_debug_file (Elf_Internal_Ehdr *ehdrp)
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#endif
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/* Create a new BFD as if by bfd_openr. Rather than opening a file,
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reconstruct an ELF file by reading the segments out of remote memory
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based on the ELF file header at EHDR_VMA and the ELF program headers it
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points to. If not null, *LOADBASEP is filled in with the difference
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between the VMAs from which the segments were read, and the VMAs the
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file headers (and hence BFD's idea of each section's VMA) put them at.
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reconstruct an ELF file by reading the segments out of remote
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memory based on the ELF file header at EHDR_VMA and the ELF program
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headers it points to. If non-zero, SIZE is the known extent of the
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object. If not null, *LOADBASEP is filled in with the difference
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between the VMAs from which the segments were read, and the VMAs
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the file headers (and hence BFD's idea of each section's VMA) put
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them at.
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The function TARGET_READ_MEMORY is called to copy LEN bytes from the
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remote memory at target address VMA into the local buffer at MYADDR; it
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should return zero on success or an `errno' code on failure. TEMPL must
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be a BFD for a target with the word size and byte order found in the
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remote memory. */
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The function TARGET_READ_MEMORY is called to copy LEN bytes from
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the remote memory at target address VMA into the local buffer at
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MYADDR; it should return zero on success or an `errno' code on
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failure. TEMPL must be a BFD for a target with the word size and
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byte order found in the remote memory. */
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bfd *
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NAME(_bfd_elf,bfd_from_remote_memory)
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(bfd *templ,
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bfd_vma ehdr_vma,
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size_t size,
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bfd_vma *loadbasep,
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int (*target_read_memory) (bfd_vma, bfd_byte *, bfd_size_type))
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{
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Elf_External_Ehdr x_ehdr; /* Elf file header, external form */
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Elf_Internal_Ehdr i_ehdr; /* Elf file header, internal form */
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Elf_External_Phdr *x_phdrs;
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Elf_Internal_Phdr *i_phdrs, *last_phdr;
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Elf_Internal_Phdr *i_phdrs, *last_phdr, *first_phdr;
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bfd *nbfd;
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struct bfd_in_memory *bim;
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int contents_size;
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bfd_byte *contents;
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int err;
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unsigned int i;
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bfd_vma high_offset;
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bfd_vma shdr_end;
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bfd_vma loadbase;
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bfd_boolean loadbase_set;
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/* Read in the ELF header in external format. */
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err = target_read_memory (ehdr_vma, (bfd_byte *) &x_ehdr, sizeof x_ehdr);
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@ -1677,10 +1680,7 @@ NAME(_bfd_elf,bfd_from_remote_memory)
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x_phdrs = (Elf_External_Phdr *)
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bfd_malloc (i_ehdr.e_phnum * (sizeof *x_phdrs + sizeof *i_phdrs));
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if (x_phdrs == NULL)
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{
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bfd_set_error (bfd_error_no_memory);
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return NULL;
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}
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return NULL;
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err = target_read_memory (ehdr_vma + i_ehdr.e_phoff, (bfd_byte *) x_phdrs,
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i_ehdr.e_phnum * sizeof x_phdrs[0]);
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if (err)
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@ -1692,34 +1692,44 @@ NAME(_bfd_elf,bfd_from_remote_memory)
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}
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i_phdrs = (Elf_Internal_Phdr *) &x_phdrs[i_ehdr.e_phnum];
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contents_size = 0;
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high_offset = 0;
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loadbase = 0;
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first_phdr = NULL;
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last_phdr = NULL;
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loadbase = ehdr_vma;
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loadbase_set = FALSE;
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for (i = 0; i < i_ehdr.e_phnum; ++i)
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{
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elf_swap_phdr_in (templ, &x_phdrs[i], &i_phdrs[i]);
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if (i_phdrs[i].p_type == PT_LOAD)
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{
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bfd_vma segment_end;
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segment_end = (i_phdrs[i].p_offset + i_phdrs[i].p_filesz
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+ i_phdrs[i].p_align - 1) & -i_phdrs[i].p_align;
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if (segment_end > (bfd_vma) contents_size)
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contents_size = segment_end;
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bfd_vma segment_end = i_phdrs[i].p_offset + i_phdrs[i].p_filesz;
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/* LOADADDR is the `Base address' from the gELF specification:
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`lowest p_vaddr value for a PT_LOAD segment' is P_VADDR from the
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first PT_LOAD as PT_LOADs are ordered by P_VADDR. */
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if (!loadbase_set && (i_phdrs[i].p_offset & -i_phdrs[i].p_align) == 0)
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if (segment_end > high_offset)
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{
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loadbase = ehdr_vma - (i_phdrs[i].p_vaddr & -i_phdrs[i].p_align);
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loadbase_set = TRUE;
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high_offset = segment_end;
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last_phdr = &i_phdrs[i];
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}
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last_phdr = &i_phdrs[i];
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/* If this program header covers offset zero, where the file
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header sits, then we can figure out the loadbase. */
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if (first_phdr == NULL)
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{
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bfd_vma p_offset = i_phdrs[i].p_offset;
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bfd_vma p_vaddr = i_phdrs[i].p_vaddr;
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if (i_phdrs[i].p_align > 1)
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{
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p_offset &= -i_phdrs[i].p_align;
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p_vaddr &= -i_phdrs[i].p_align;
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}
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if (p_offset == 0)
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{
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loadbase = ehdr_vma - p_vaddr;
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first_phdr = &i_phdrs[i];
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}
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}
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}
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}
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if (last_phdr == NULL)
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if (high_offset == 0)
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{
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/* There were no PT_LOAD segments, so we don't have anything to read. */
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free (x_phdrs);
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@ -1727,40 +1737,64 @@ NAME(_bfd_elf,bfd_from_remote_memory)
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return NULL;
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}
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/* Trim the last segment so we don't bother with zeros in the last page
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that are off the end of the file. However, if the extra bit in that
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page includes the section headers, keep them. */
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if ((bfd_vma) contents_size > last_phdr->p_offset + last_phdr->p_filesz
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&& (bfd_vma) contents_size >= (i_ehdr.e_shoff
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+ i_ehdr.e_shnum * i_ehdr.e_shentsize))
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shdr_end = 0;
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if (i_ehdr.e_shoff != 0 && i_ehdr.e_shnum != 0 && i_ehdr.e_shentsize != 0)
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{
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contents_size = last_phdr->p_offset + last_phdr->p_filesz;
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if ((bfd_vma) contents_size < (i_ehdr.e_shoff
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+ i_ehdr.e_shnum * i_ehdr.e_shentsize))
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contents_size = i_ehdr.e_shoff + i_ehdr.e_shnum * i_ehdr.e_shentsize;
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shdr_end = i_ehdr.e_shoff + i_ehdr.e_shnum * i_ehdr.e_shentsize;
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if (last_phdr->p_filesz != last_phdr->p_memsz)
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{
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/* If the last PT_LOAD header has a bss area then ld.so will
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have cleared anything past p_filesz, zapping the section
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headers. */
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}
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else if (size >= shdr_end)
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high_offset = shdr_end;
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else
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{
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bfd_vma page_size = get_elf_backend_data (templ)->minpagesize;
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bfd_vma segment_end = last_phdr->p_offset + last_phdr->p_filesz;
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/* Assume we loaded full pages, allowing us to sometimes see
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section headers. */
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if (page_size > 1 && shdr_end > segment_end)
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{
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bfd_vma page_end = (segment_end + page_size - 1) & -page_size;
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if (page_end >= shdr_end)
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/* Whee, section headers covered. */
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high_offset = shdr_end;
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}
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}
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}
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else
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contents_size = last_phdr->p_offset + last_phdr->p_filesz;
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/* Now we know the size of the whole image we want read in. */
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contents = (bfd_byte *) bfd_zmalloc (contents_size);
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contents = (bfd_byte *) bfd_zmalloc (high_offset);
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if (contents == NULL)
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{
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free (x_phdrs);
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bfd_set_error (bfd_error_no_memory);
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return NULL;
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}
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for (i = 0; i < i_ehdr.e_phnum; ++i)
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if (i_phdrs[i].p_type == PT_LOAD)
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{
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bfd_vma start = i_phdrs[i].p_offset & -i_phdrs[i].p_align;
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bfd_vma end = (i_phdrs[i].p_offset + i_phdrs[i].p_filesz
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+ i_phdrs[i].p_align - 1) & -i_phdrs[i].p_align;
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if (end > (bfd_vma) contents_size)
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end = contents_size;
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err = target_read_memory ((loadbase + i_phdrs[i].p_vaddr)
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& -i_phdrs[i].p_align,
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bfd_vma start = i_phdrs[i].p_offset;
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bfd_vma end = start + i_phdrs[i].p_filesz;
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bfd_vma vaddr = i_phdrs[i].p_vaddr;
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/* Extend the beginning of the first pt_load to cover file
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header and program headers, if we proved earlier that its
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aligned offset is 0. */
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if (first_phdr == &i_phdrs[i])
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{
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vaddr -= start;
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start = 0;
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}
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/* Extend the end of the last pt_load to cover section headers. */
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if (last_phdr == &i_phdrs[i])
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end = high_offset;
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err = target_read_memory (loadbase + vaddr,
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contents + start, end - start);
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if (err)
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{
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@ -1775,8 +1809,7 @@ NAME(_bfd_elf,bfd_from_remote_memory)
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/* If the segments visible in memory didn't include the section headers,
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then clear them from the file header. */
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if ((bfd_vma) contents_size < (i_ehdr.e_shoff
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+ i_ehdr.e_shnum * i_ehdr.e_shentsize))
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if (high_offset < shdr_end)
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{
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memset (&x_ehdr.e_shoff, 0, sizeof x_ehdr.e_shoff);
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memset (&x_ehdr.e_shnum, 0, sizeof x_ehdr.e_shnum);
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@ -1792,7 +1825,6 @@ NAME(_bfd_elf,bfd_from_remote_memory)
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if (bim == NULL)
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{
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free (contents);
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bfd_set_error (bfd_error_no_memory);
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return NULL;
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}
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nbfd = _bfd_new_bfd ();
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@ -1800,12 +1832,11 @@ NAME(_bfd_elf,bfd_from_remote_memory)
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{
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free (bim);
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free (contents);
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bfd_set_error (bfd_error_no_memory);
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return NULL;
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}
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nbfd->filename = xstrdup ("<in-memory>");
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nbfd->xvec = templ->xvec;
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bim->size = contents_size;
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bim->size = high_offset;
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bim->buffer = contents;
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nbfd->iostream = bim;
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nbfd->flags = BFD_IN_MEMORY;
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