Re: [RFC 0/2] __vdso_findsym

On Sun, Jun 15, 2014 at 12:14:04PM -0700, H. Peter Anvin wrote:

If it doesn't, then you incur an additional indirection penalty. The
strong __vdso symbol allows the libc wrapper to fall back to the
vdso implementation, the weak symbol allows three to be no wrapper
at all. This is good.

No it doesn't. The weak symbol does not implement the interface
contract of the libc function; on error it's required to set errno,
and of course the kernel/vdso cannot do this. Also, there's no way the
symbol versions the kernel provides can match up with userspace symbol
versions that consumers of the function would need. So these features
are just useless.

Rich