From: Lynn Boger <firstname.lastname@example.org> To: Michael Ellerman <email@example.com>, Paul Murphy <firstname.lastname@example.org>, email@example.com Cc: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Subject: Re: Possible regression by ab037dd87a2f (powerpc/vdso: Switch VDSO to generic C implementation.) Date: Mon, 2 Aug 2021 13:14:15 -0500 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> Fixes will be in Go 1.16.7 and 1.15.15. Backports are no longer being done for Go 1.14. On 8/2/21 1:18 AM, Michael Ellerman wrote: > "Paul Murphy" <email@example.com> writes: >> >> (My apologies for however IBM's email client munges this) >> >>> I heard it is going to be in Go 1.16.7, but I do not know much about Go. >>> Maybe the folks in Cc can chime in. >> >> >> We have backports primed and ready for the next point release. They >> are waiting on the release manager to cherrypick them. > OK good, that is still the correct fix in the long run. > >> I think we were aware that our VDSO usage may have exploited some >> peculiarities in how the ppc64 version was constructed (i.e hand >> written assembly which just didn't happen to clobber R30). > Yeah I was "somewhat surprised" that Go thought it could use r30 like > that across a VDSO call :D > > But to be fair the ABI of the VDSO has always been a little fishy, > because the entry points pretend to be a transparent wrapper around > system calls, but then in a case like this are not. > >> Go up to this point has only used the vdso function __kernel_clock_gettime; it >> is the only entry point which would need to explicitly avoid R30 for >> Go's sake. > I thought about limiting the workaround to just that code, but it seemed > silly and likely to come back to bite us. Once the compilers decides to > spill a non-volatile there are plenty of other ones to choose from. > > cheers
prev parent reply other threads:[~2021-08-02 23:40 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-07-27 8:45 Paul Menzel 2021-07-27 23:14 ` Benjamin Herrenschmidt 2021-07-28 8:26 ` Paul Menzel 2021-07-28 12:43 ` Michael Ellerman 2021-07-28 12:53 ` Paul Menzel 2021-07-29 7:41 ` Michael Ellerman 2021-07-29 8:33 ` Paul Menzel 2021-07-29 12:58 ` Michael Ellerman [not found] ` <firstname.lastname@example.org> 2021-07-29 8:48 ` Andreas Schwab 2021-08-02 6:04 ` Michael Ellerman [not found] ` <OF44F7146F.67A4C1C2-ON00258720.004DBF64-00258720.004FCFCC@ibm.com> 2021-08-02 6:18 ` Michael Ellerman 2021-08-02 12:48 ` Benjamin Herrenschmidt 2021-08-02 18:07 ` Segher Boessenkool 2021-08-02 18:14 ` Lynn Boger [this message]
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