From: Marc Zyngier <maz@kernel.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: James Morse <james.morse@arm.com>,
Nathan Chancellor <nathan@kernel.org>,
Kees Cook <keescook@chromium.org>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: arm64: Disable LTO in hyp
Date: Thu, 04 Mar 2021 19:15:25 +0000 [thread overview]
Message-ID: <87k0qmzq5u.wl-maz@kernel.org> (raw)
In-Reply-To: <20210304184544.2014171-1-samitolvanen@google.com>
On Thu, 04 Mar 2021 18:45:44 +0000,
Sami Tolvanen <samitolvanen@google.com> wrote:
>
> allmodconfig + CONFIG_LTO_CLANG_THIN=y fails to build due to following
> linker errors:
>
> ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21CC):
I assume this message is only an oddity, right? Because
__guest_enter() is as far as you can imagine from irqbypass.c...
> relocation R_AARCH64_CONDBR19 out of range: 2031220 is not in
> [-1048576, 1048575]; references hyp_panic
> >>> defined in vmlinux.o
>
> ld.lld: error: irqbypass.c:(function __guest_enter: .text+0x21E0):
> relocation R_AARCH64_ADR_PREL_LO21 out of range: 2031200 is not in
> [-1048576, 1048575]; references hyp_panic
> >>> defined in vmlinux.o
>
> As LTO is not really necessary for the hypervisor code, disable it for
> the hyp directory to fix the build.
Can you shed some light on what the problem is exactly?
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1317
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Tested-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
> arch/arm64/kvm/hyp/Makefile | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
> index 687598e41b21..e8116016e6a8 100644
> --- a/arch/arm64/kvm/hyp/Makefile
> +++ b/arch/arm64/kvm/hyp/Makefile
> @@ -11,3 +11,6 @@ subdir-ccflags-y := -I$(incdir) \
> $(DISABLE_STACKLEAK_PLUGIN)
>
> obj-$(CONFIG_KVM) += vhe/ nvhe/ pgtable.o
> +
> +# Disable LTO for the files in this directory
> +KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO), $(KBUILD_CFLAGS))
>
> base-commit: f69d02e37a85645aa90d18cacfff36dba370f797
Can this be reduced to the nvhe part of the tree? The rest of the
hypervisor should support being built with LTO, I'd expect. Or am I
missing something more significant?
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-03-04 19:17 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-04 18:45 [PATCH] KVM: arm64: Disable LTO in hyp Sami Tolvanen
2021-03-04 19:15 ` Marc Zyngier [this message]
2021-03-04 21:25 ` Sami Tolvanen
2021-03-04 22:17 ` Marc Zyngier
2021-03-04 22:34 ` Sami Tolvanen
2021-03-05 2:38 ` Sami Tolvanen
2021-03-05 11:36 ` Marc Zyngier
2021-03-05 14:22 ` Ard Biesheuvel
2021-03-05 16:55 ` Sami Tolvanen
2021-03-05 17:07 ` Marc Zyngier
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