Commit 1e9de1d2 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Ingo Molnar

arm64/efi: Ignore EFI_MEMORY_XP attribute if RP and/or WP are set

The UEFI memory map is a bit vague about how to interpret the
EFI_MEMORY_XP attribute when it is combined with EFI_MEMORY_RP and/or
EFI_MEMORY_WP, which have retroactively been redefined as cacheability
attributes rather than permission attributes.

So let's ignore EFI_MEMORY_XP if _RP and/or _WP are also set. In this
case, it is likely that they are being used to describe the capability
of the region (i.e., whether it has the controls to reconfigure it as
non-executable) rather than the nature of the contents of the region
(i.e., whether it contains data that we will never attempt to execute)
Reported-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Tested-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Yadav <arvind.yadav.cs@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tyler Baicar <tbaicar@codeaurora.org>
Cc: Vasyl Gomonovych <gomonovych@gmail.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20180102181042.19074-3-ard.biesheuvel@linaro.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 76ad9dff
......@@ -48,7 +48,9 @@ static __init pteval_t create_mapping_protection(efi_memory_desc_t *md)
return pgprot_val(PAGE_KERNEL_ROX);
/* RW- */
if (attr & EFI_MEMORY_XP || type != EFI_RUNTIME_SERVICES_CODE)
if (((attr & (EFI_MEMORY_RP | EFI_MEMORY_WP | EFI_MEMORY_XP)) ==
EFI_MEMORY_XP) ||
type != EFI_RUNTIME_SERVICES_CODE)
return pgprot_val(PAGE_KERNEL);
/* RWX */
......
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