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Re: turn off VDSO on glibc side


On Monday 01 July 2013 16:24:14 Ondrej Bilka wrote:
> On Mon, Jul 01, 2013 at 12:58:54PM -0400, Mike Frysinger wrote:
> > On Monday 01 July 2013 11:05:02 heroxbd wrote:
> > > After some STFW, it seems related to
> > > 
> > >       https://bugzilla.redhat.com/show_bug.cgi?id=673616
> > > 
> > > The question is, can I just disable vdso loading in dynamic linker of
> > > glibc instead of requesting SA to upgrade the kernel?
> > 
> > there aren't any configure flags or runtime knobs that i know of on the
> > glibc side of things.  you could edit elf/dl-support.c and try
> > commenting out the parts that handle AT_SYSINFO and AT_SYSINFO_EHDR.  or
> > edit
> > sysdeps/unix/sysv/linux/x86_64/gettimeofday.c and force it to always use
> > the syscall version at the end of the file.
> > 
> > or upgrade your kernel to one that isn't buggy :p
> > 
> > > PS2, the toolchains here are from Gentoo, not sure if it is related to
> > > Gentoo patches.
> > 
> > i doubt it.  but maybe i'm partial :p.
> 
> Another workaround is to write a little library with syscall version of
> gettimeofday and add it to LD_PRELOAD.

that'll catch some calls, but not internal glibc ones since we have a hidden 
one to elide plt jumps.  but maybe that's sufficient for the OP's needs.
-mike

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