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From: Paul Menzel <pmenzel@molgen.mpg.de>
Subject: Possible regression by ab037dd87a2f (powerpc/vdso: Switch VDSO to
 generic C implementation.)
To: Michael Ellerman <mpe@ellerman.id.au>,
 Benjamin Herrenschmidt <benh@kernel.crashing.org>,
 Paul Mackerras <paulus@samba.org>,
 Christophe Leroy <christophe.leroy@csgroup.eu>
Message-ID: <a273c619-9258-e29a-24c3-ea47a13c4817@molgen.mpg.de>
Date: Tue, 27 Jul 2021 10:45:48 +0200
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Dear Christophe,


On ppc64le Go 1.16.2 from Ubuntu 21.04 terminates with a segmentation 
fault [1], and it might be related to *[release-branch.go1.16] runtime: 
fix crash during VDSO calls on PowerPC* [2], conjecturing that commit 
ab037dd87a2f (powerpc/vdso: Switch VDSO to generic C implementation.) 
added in Linux 5.11 causes this.

If this is indeed the case, this would be a regression in userspace. Is 
there a generic fix or should the change be reverted?


Kind regards,

Paul


[1]: https://github.com/9elements/converged-security-suite/issues/268
[2]: https://go-review.googlesource.com/c/go/+/334410/
[3]: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ab037dd87a2f946556850e204c06cbd7a2a19390