[tip:efi/core] arm64/efi: Ignore EFI_MEMORY_XP attribute if RP and/or WP are set

[tip-bot for Ard Biesheuvel]

Commit-ID:  1e9de1d2207d67b97bb0b62e38454b663d6542fa
Gitweb: https://git.kernel.org/tip/1e9de1d2207d67b97bb0b62e38454b663d6542fa
Author: Ard Biesheuvel 
AuthorDate: Tue, 2 Jan 2018 18:10:39 +
Committer:  Ingo Molnar 
CommitDate: Wed, 3 Jan 2018 14:03:48 +0100

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: Stephen Boyd 
Tested-by: Stephen Boyd 
Signed-off-by: Ard Biesheuvel 
Cc: Arvind Yadav 
Cc: Linus Torvalds 
Cc: Matt Fleming 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tyler Baicar 
Cc: Vasyl Gomonovych 
Cc: linux-...@vger.kernel.org
Link: http://lkml.kernel.org/r/20180102181042.19074-3-ard.biesheu...@linaro.org
Signed-off-by: Ingo Molnar 
---
 arch/arm64/kernel/efi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 82cd075..f85ac58 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -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 */

[tip:efi/core] arm64/efi: Ignore EFI_MEMORY_XP attribute if RP and/or WP are set

[tip-bot for Ard Biesheuvel]

Commit-ID:  1e9de1d2207d67b97bb0b62e38454b663d6542fa
Gitweb: https://git.kernel.org/tip/1e9de1d2207d67b97bb0b62e38454b663d6542fa
Author: Ard Biesheuvel 
AuthorDate: Tue, 2 Jan 2018 18:10:39 +
Committer:  Ingo Molnar 
CommitDate: Wed, 3 Jan 2018 14:03:48 +0100

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: Stephen Boyd 
Tested-by: Stephen Boyd 
Signed-off-by: Ard Biesheuvel 
Cc: Arvind Yadav 
Cc: Linus Torvalds 
Cc: Matt Fleming 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tyler Baicar 
Cc: Vasyl Gomonovych 
Cc: linux-...@vger.kernel.org
Link: http://lkml.kernel.org/r/20180102181042.19074-3-ard.biesheu...@linaro.org
Signed-off-by: Ingo Molnar 
---
 arch/arm64/kernel/efi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 82cd075..f85ac58 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -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 */