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.

1 files changed, 2 insertions, 1 deletions

diff --git a/bfd/elf.c b/bfd/elf.c
index 3ded683..d67b917 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -9908,11 +9908,12 @@ bfd *
 bfd_elf_bfd_from_remote_memory
   (bfd *templ,
    bfd_vma ehdr_vma,
+   size_t size,
    bfd_vma *loadbasep,
    int (*target_read_memory) (bfd_vma, bfd_byte *, bfd_size_type))
 {
   return (*get_elf_backend_data (templ)->elf_backend_bfd_from_remote_memory)
-    (templ, ehdr_vma, loadbasep, target_read_memory);
+    (templ, ehdr_vma, size, loadbasep, target_read_memory);
 }
 
 long