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From: Kees Cook <keescook@chromium.org>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Ard Biesheuvel <ardb@kernel.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: Don't use cbz/adr with external symbols
Date: Fri, 5 Mar 2021 12:22:36 -0800	[thread overview]
Message-ID: <202103051222.1E08D7D31@keescook> (raw)
In-Reply-To: <20210305202124.3768527-1-samitolvanen@google.com>

On Fri, Mar 05, 2021 at 12:21:24PM -0800, Sami Tolvanen 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):
>   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
> 
> This is because with LTO, the compiler ends up placing hyp_panic()
> more than 1MB away from __guest_enter(). Use an unconditional branch
> and adr_l instead to fix the issue.
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/1317
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Suggested-by: Marc Zyngier <maz@kernel.org>
> Suggested-by: Ard Biesheuvel <ardb@kernel.org>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

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  reply	other threads:[~2021-03-05 20:24 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-05 20:21 [PATCH] KVM: arm64: Don't use cbz/adr with external symbols Sami Tolvanen
2021-03-05 20:22 ` Kees Cook [this message]
2021-03-07  4:35 ` Nathan Chancellor
2021-03-08 14:38 ` Will Deacon
2021-03-09  8:49 ` Marc Zyngier

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