From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Alexander Potapenko <glider@google.com>
Cc: dave.hansen@linux.intel.com, mingo@kernel.org,
kirill.shutemov@linux.intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, mka@chromium.org,
dvyukov@google.com, md@google.com
Subject: Re: [PATCH v3] x86/boot/64/clang: Use fixup_pointer() to access '__supported_pte_mask'
Date: Fri, 11 May 2018 10:43:37 +0300 [thread overview]
Message-ID: <20180511074337.3fa5htarfcsbeeqy@kshutemo-mobl1> (raw)
In-Reply-To: <20180509091822.191810-1-glider@google.com>
On Wed, May 09, 2018 at 11:18:22AM +0200, Alexander Potapenko wrote:
> Clang builds with defconfig started crashing after commit fb43d6cb91ef
> ("x86/mm: Do not auto-massage page protections")
> This was caused by introducing a new global access in __startup_64().
>
> Code in __startup_64() can be relocated during execution, but the compiler
> doesn't have to generate PC-relative relocations when accessing globals
> from that function. Clang actually does not generate them, which leads
> to boot-time crashes. To work around this problem, every global pointer
> must be adjusted using fixup_pointer().
>
> Signed-off-by: Alexander Potapenko <glider@google.com>
> Fixes: fb43d6cb91ef ("x86/mm: Do not auto-massage page protections")
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
prev parent reply other threads:[~2018-05-15 20:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-09 9:18 [PATCH v3] x86/boot/64/clang: Use fixup_pointer() to access '__supported_pte_mask' Alexander Potapenko
2018-05-11 7:43 ` Kirill A. Shutemov [this message]
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