[compiler-rt] Fixing Linux compile error due to use of clone

[Andy Jost]

I should also mention that the system in question, is not *that* old.  It was brand-new in 2009.

I don't know much about the Linux kernel, but uname -r reports "2.6.9-89.ELlargesmp".

I don't know how that relates to "Linux version 2.4," but I can see from the definition of clone in /usr/include/bits/sched.h that the extra three arguments are not accepted.

-Andy

From: Andy Jost
Sent: Thursday, July 11, 2013 9:13 AM
To: Alexey Samsonov; Andy Jost
Cc: Reid Kleckner; llvm-commits at cs.uiuc.edu
Subject: RE: [compiler-rt] Fixing Linux compile error due to use of clone

I'm using autoconf.

From: Alexey Samsonov [mailto:samsonov at google.com]<mailto:[mailto:samsonov at google.com]>
Sent: Thursday, July 11, 2013 7:20 AM
To: Andy Jost
Cc: Reid Kleckner; llvm-commits at cs.uiuc.edu<mailto:llvm-commits at cs.uiuc.edu>
Subject: Re: [compiler-rt] Fixing Linux compile error due to use of clone

On Thu, Jul 11, 2013 at 8:03 AM, Andy Jost <Andrew.Jost at synopsys.com<mailto:Andrew.Jost at synopsys.com>> wrote:
> I'd honestly be surprised if the sanitizers work at all on Linux 2.4 with just this change

That may be, but I don't need the sanitizer and this change is required just to make compiler-rt.

How do I check if this was committed?

-Andy

From: Reid Kleckner [mailto:rnk at google.com<mailto:rnk at google.com>]
Sent: Wednesday, July 10, 2013 3:49 PM
To: Andy Jost
Cc: llvm-commits at cs.uiuc.edu<mailto:llvm-commits at cs.uiuc.edu>
Subject: Re: [compiler-rt] Fixing Linux compile error due to use of clone

This change is probably fine.  I think those args are only accessed if certain flags are set.
That said, I'd honestly be surprised if the sanitizers work at all on Linux 2.4 with just this change.  I doubt anyone is testing it.

I think we should just disable building all the sanitizers on old Linux kernels.

Andy, what build system do you use (CMake or autoconf/make)?

On Wed, Jul 10, 2013 at 6:33 PM, Andy Jost <Andrew.Jost at synopsys.com<mailto:Andrew.Jost at synopsys.com>> wrote:
First post to llvm-commits, so I may not know the process.  I'm hoping someone will review and submit this for me.

The attached patch fixes an unsafe use of clone in projects/compiler-rt/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc.

>From the clone man page:
In Linux 2.4 and earlier, clone() does not take arguments ptid, tls, and ctid.

Those last three arguments are unused in this case, anyway, so I just removed them.  This fixes the build of compiler-rt on my machine.

Is a testcase needed?  If so, where should I look to get started?

-Andy

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--
Alexey Samsonov, MSK
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