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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 12 Jan 2021 14:57:58 -0800
Message-ID: <CAKwvOd=U1bpjbCeTjB_P+F3BYPD6THricJ5fpfjF9CgNRvJFMg@mail.gmail.com>
Subject: Re: [PATCH] compiler.h: Raise minimum version of GCC to 5.1 for arm64
To:     Will Deacon <will@kernel.org>
Cc:     Linux ARM <linux-arm-kernel@lists.infradead.org>,
        kernel-team <kernel-team@android.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "Theodore Ts'o" <tytso@mit.edu>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Florian Weimer <fweimer@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Russell King <linux@armlinux.org.uk>,
        Arnd Bergmann <arnd@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>
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On Tue, Jan 12, 2021 at 2:48 PM Will Deacon <will@kernel.org> wrote:
>
> GCC versions >= 4.9 and < 5.1 have been shown to emit memory references
> beyond the stack pointer, resulting in memory corruption if an interrupt
> is taken after the stack pointer has been adjusted but before the
> reference has been executed. This leads to subtle, infrequent data
> corruption such as the EXT4 problems reported by Russell King at the
> link below.
>
> Life is too short for buggy compilers, so raise the minimum GCC version
> required by arm64 to 5.1.
>
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Florian Weimer <fweimer@redhat.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Reported-by: Russell King <linux@armlinux.org.uk>
> Suggested-by: Arnd Bergmann <arnd@kernel.org>
> Link: https://lore.kernel.org/r/20210105154726.GD1551@shell.armlinux.org.uk
> Signed-off-by: Will Deacon <will@kernel.org>

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
>  include/linux/compiler-gcc.h | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
> index 74c6c0486eed..555ab0fddbef 100644
> --- a/include/linux/compiler-gcc.h
> +++ b/include/linux/compiler-gcc.h
> @@ -13,6 +13,12 @@
>  /* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 */
>  #if GCC_VERSION < 40900
>  # error Sorry, your version of GCC is too old - please use 4.9 or newer.
> +#elif defined(CONFIG_ARM64) && GCC_VERSION < 50100
> +/*
> + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293
> + * https://lore.kernel.org/r/20210107111841.GN1551@shell.armlinux.org.uk
> + */
> +# error Sorry, your version of GCC is too old - please use 5.1 or newer.
>  #endif
>
>  /*
> --
> 2.30.0.284.gd98b1dd5eaa7-goog
>


-- 
Thanks,
~Nick Desaulniers