From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] powerpc: Fix HMIs on big-endian with CONFIG_RELOCATABLE=y
Date: Mon, 08 Oct 2018 20:53:49 +1100 [thread overview]
Message-ID: <898c4d47e80562b843fcf4c7ba03eb6f4c9c5d5b.camel@kernel.crashing.org> (raw)
In-Reply-To: <20181008170435.0ef2d573@roar.ozlabs.ibm.com>
On Mon, 2018-10-08 at 17:04 +1000, Nicholas Piggin wrote:
> On Mon, 08 Oct 2018 15:08:31 +1100
> Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
>
> > HMIs will crash the kernel due to
> >
> > BRANCH_LINK_TO_FAR(hmi_exception_realmode)
> >
> > Calling into the OPD instead of the actual code.
> >
> > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > ---
> >
> > This hack fixes it for me, but it's not great. Nick, any better idea ?
>
> Is it a hack because the ifdef gunk, or because there's something
> deeper wrong with using the .sym?
I'd say ifdef gunk, also the KVM use doesn't need it bcs the kvm entry
isn't an OPD.
> I guess all those handlers that load label address by hand could have
> the bug silently creep in. Can we have them use the DOTSYM() macro?
The KVM one doesnt have a dotsym does it ?
Also should we load the TOC from the OPD ?
> Thanks,
> Nick
>
> >
> > diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> > index ea04dfb..752709cc8 100644
> > --- a/arch/powerpc/kernel/exceptions-64s.S
> > +++ b/arch/powerpc/kernel/exceptions-64s.S
> > @@ -1119,7 +1119,11 @@ TRAMP_REAL_BEGIN(hmi_exception_early)
> > EXCEPTION_PROLOG_COMMON_2(PACA_EXGEN)
> > EXCEPTION_PROLOG_COMMON_3(0xe60)
> > addi r3,r1,STACK_FRAME_OVERHEAD
> > +#ifdef PPC64_ELF_ABI_v1
> > + BRANCH_LINK_TO_FAR(.hmi_exception_realmode) /* Function call ABI */
> > +#else
> > BRANCH_LINK_TO_FAR(hmi_exception_realmode) /* Function call ABI */
> > +#endif
> > cmpdi cr0,r3,0
> >
> > /* Windup the stack. */
> >
> >
next prev parent reply other threads:[~2018-10-08 9:55 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-08 4:08 [PATCH] powerpc: Fix HMIs on big-endian with CONFIG_RELOCATABLE=y Benjamin Herrenschmidt
2018-10-08 7:04 ` Nicholas Piggin
2018-10-08 9:53 ` Benjamin Herrenschmidt [this message]
2018-10-09 10:37 ` Michael Ellerman
2018-10-09 12:27 ` Benjamin Herrenschmidt
2018-12-23 13:28 ` Michael Ellerman
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