Fully stripping the vDSO has other unfortunate side effects:
- binutils is unable to find ELF notes without a SHT_NOTE section.
- Even elfutils has trouble: it can find ELF notes without a section
table at all, but if a section table is present, it won't look for
PT_NOTE.
- gdb wants section names to match between stripped DSOs and their
symbols; otherwise it will corrupt symbol addresses.
We're also breaking the rules: section 0 is supposed to be SHT_NULL.
Fix these problems by building a better fake section table. While
we're at it, we might as well let buggy Go versions keep working well
by giving the SHT_DYNSYM entry the correct size.
This is a bit unfortunate: it adds quite a bit of size to the vdso
image.
If/when binutils improves and the improved versions become widespread,
it would be worth considering dropping most of this.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/0e546a5eeaafdf1840e6ee654a55c1e727c26663.1403129369.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Drop the legacy weak symbols that don't carry the __vdso prefix from
the x32 VDSO. This is a new ABI and we don't need to support that
legacy; the actual libc will export the proper symbols.
Suggested-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/4F42E171.9080005@mit.edu
Cc: H. J. Lu <hjl.tools@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Add support for the x32 VDSO. The x32 VDSO takes advantage of the
similarity between the x86-64 and the x32 ABIs to contain the same
content, only the container is different, as the x32 VDSO obviously is
an x32 shared object.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Andy Lutomirski