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Subject[PATCH v4 26/26] efi/x86: don't set unsupported memory attributes
From: Peter Jones <>

On platforms where the firmware uses DXE, but which do not implement the
EFI Memory Attribute Protocol, we implement W^X support using DXE's
set_memory_attributes() call. This call will fail without making any
changes if an attribute is set that isn't supported on the platform.

This patch changes efi_adjust_memory_range_protection() to avoid trying
to set any attribute bits that aren't set in the memory region's
capability flags.

Signed-off-by: Peter Jones <>
drivers/firmware/efi/libstub/mem.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
index 50a0b649b75a..b86ea2920d5e 100644
--- a/drivers/firmware/efi/libstub/mem.c
+++ b/drivers/firmware/efi/libstub/mem.c
@@ -195,6 +195,7 @@ static efi_status_t adjust_mem_attrib_dxe(efi_physical_addr_t rounded_start,

desc.attributes &= ~(EFI_MEMORY_RO | EFI_MEMORY_XP);
desc.attributes |= attributes;
+ desc.attributes &= desc.capabilities;

unprotect_start = max(rounded_start, desc.base_address);
unprotect_size = min(rounded_end, next) - unprotect_start;
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