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EmbeddedPkg: NonCoherentDmaLib: Set EFI_MEMORY_XP Capability on DMA Buffer 

Commit 8984fba2f2 added setting the
EFI_MEMORY_XP attribute on DMA buffers. However, it did not ensure
that the XP capability was set on that region.

This patch adds setting the XP capability before attempting to set
the attribute. If setting the capability fails, it defaults to the
old behavior of not setting the XP bit.

Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com>
This commit is contained in:
Oliver Smith-Denny 2024-07-29 09:29:14 -07:00 committed by mergify[bot]
parent be1d408773
commit 909abd7104
1 changed files with 32 additions and 4 deletions
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36
EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.c
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@ -500,10 +500,12 @@ DmaAllocateAlignedBuffer (
{
EFI_GCD_MEMORY_SPACE_DESCRIPTOR GcdDescriptor;
VOID *Allocation;
UINT64 MemType;
UINT64 Attributes;
UNCACHED_ALLOCATION *Alloc;
EFI_STATUS Status;
Attributes = EFI_MEMORY_XP;
if (Alignment == 0) {
Alignment = EFI_PAGE_SIZE;
}
@ -534,9 +536,9 @@ DmaAllocateAlignedBuffer (
// Choose a suitable uncached memory type that is supported by the region
if (GcdDescriptor.Capabilities & EFI_MEMORY_WC) {
MemType = EFI_MEMORY_WC;
Attributes |= EFI_MEMORY_WC;
} else if (GcdDescriptor.Capabilities & EFI_MEMORY_UC) {
MemType = EFI_MEMORY_UC;
Attributes |= EFI_MEMORY_UC;
} else {
Status = EFI_UNSUPPORTED;
goto FreeBuffer;
@ -553,11 +555,37 @@ DmaAllocateAlignedBuffer (
InsertHeadList (&UncachedAllocationList, &Alloc->Link);
// Ensure that EFI_MEMORY_XP is in the capability set
if ((GcdDescriptor.Capabilities & EFI_MEMORY_XP) != EFI_MEMORY_XP) {
Status = gDS->SetMemorySpaceCapabilities (
(PHYSICAL_ADDRESS)(UINTN)Allocation,
EFI_PAGES_TO_SIZE (Pages),
GcdDescriptor.Capabilities | EFI_MEMORY_XP
);
// if we were to fail setting the capability, this would indicate an internal failure of the GCD code. We should
// assert here to let a platform know something went crazy, but for a release build we can let the allocation occur
// without the EFI_MEMORY_XP bit set, as that was the existing behavior
if (EFI_ERROR (Status)) {
DEBUG ((
DEBUG_ERROR,
"%a failed to set EFI_MEMORY_XP capability on 0x%llx for length 0x%llx. Attempting to allocate without XP set.\n",
__func__,
Allocation,
EFI_PAGES_TO_SIZE (Pages)
));
ASSERT_EFI_ERROR (Status);
Attributes &= ~EFI_MEMORY_XP;
}
}
// Remap the region with the new attributes and mark it non-executable
Status = gDS->SetMemorySpaceAttributes (
(PHYSICAL_ADDRESS)(UINTN)Allocation,
EFI_PAGES_TO_SIZE (Pages),
MemType | EFI_MEMORY_XP
Attributes
);
if (EFI_ERROR (Status)) {
goto FreeAlloc;