Re: [edk2-devel] [PATCH] UefiCpuPkg:fix issue when splitting paging entry
Reviewed-by: Jiaxin Wu
> -Original Message-
> From: Tan, Dun
> Sent: Friday, May 17, 2024 5:45 PM
> To: devel@edk2.groups.io
> Cc: Ni, Ray ; Kumar, Rahul R ;
> Gerd Hoffmann ; Wu, Jiaxin ;
> Zhou, Jianfeng
> Subject: [PATCH] UefiCpuPkg:fix issue when splitting paging entry
>
> This patch is to fix issue when splitting leaf paging
> entry in CpuPageTableLib code.
>
> In previous code, before we assign the new child paging
> structure address to the content of splitted paging entry,
> PageTableLibSetPnle() is called to make sure the bit7 is
> set to 0, which indicate the previous leaf entry is
> changed to non-leaf entry now. There is a gap between
> we change the bit7 and we assign the new child paging
> structure address to the content of the splitted paging
> entry. If the address of code execution or data access
> happens to be in the range covered by the splitted paging
> entry, this gap may cause issue.
>
> In this patch, we prepare the new paging entry content
> value in a local variable and assign the value to the
> splitted paging entry at once. The volatile keyword
> is used to ensure that no optimization will occur in
> compilation.
>
> Signed-off-by: Dun Tan
> Cc: Ray Ni
> Cc: Rahul Kumar
> Cc: Gerd Hoffmann
> Cc: Jiaxin Wu
> Cc: Zhou Jianfeng
> ---
> UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c | 9 +++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> index b10a3008e4..bdc411338f 100644
> --- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> +++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> @@ -342,6 +342,7 @@ PageTableLibMapInLevel (
>UINT64 PhysicalAddrInAttr;
>IA32_PAGING_ENTRY OriginalParentPagingEntry;
>IA32_PAGING_ENTRY OriginalCurrentPagingEntry;
> + IA32_PAGING_ENTRY TempPagingEntry;
>
>ASSERT (Level != 0);
>ASSERT ((Attribute != NULL) && (Mask != NULL));
> @@ -359,6 +360,8 @@ PageTableLibMapInLevel (
>
>OriginalParentPagingEntry.Uint64 = ParentPagingEntry->Uint64;
>OneOfPagingEntry.Uint64 = 0;
> + TempPagingEntry.Uint64 = 0;
> +
>//
>// RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21)
> or 4K (1 << 12).
>//
> @@ -441,8 +444,10 @@ PageTableLibMapInLevel (
>// Non-leaf entry doesn't have PAT bit. So use
> ~IA32_PE_BASE_ADDRESS_MASK_40 is to make sure PAT bit
>// (bit12) in original big-leaf entry is not assigned to
> PageTableBaseAddress
> field of non-leaf entry.
>//
> - PageTableLibSetPnle (&ParentPagingEntry->Pnle, &NopAttribute,
> &AllOneMask);
> - ParentPagingEntry->Uint64 = ((UINTN)(VOID *)PagingEntry) |
> (ParentPagingEntry->Uint64 & (~IA32_PE_BASE_ADDRESS_MASK_40));
> + TempPagingEntry.Uint64 = ParentPagingEntry->Uint64;
> + PageTableLibSetPnle (&TempPagingEntry.Pnle, &NopAttribute,
> &AllOneMask);
> + TempPagingEntry.Uint64 = ((UINTN)(VOID
> *)PagingEntry) |
> (TempPagingEntry.Uint64 & (~IA32_PE_BASE_ADDRESS_MASK_40));
> + *(volatile UINT64 *)&(ParentPagingEntry->Uint64) =
> TempPagingEntry.Uint64;
> }
>} else {
> //
> --
> 2.31.1.windows.1
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Re: [edk2-devel] [PATCH] UefiCpuPkg:fix issue when splitting paging entry
Reviewed-by: Ray Ni
Thanks,
Ray
From: Tan, Dun
Sent: Friday, May 17, 2024 17:44
To: devel@edk2.groups.io
Cc: Ni, Ray ; Kumar, Rahul R ; Gerd
Hoffmann ; Wu, Jiaxin ; Zhou, Jianfeng
Subject: [PATCH] UefiCpuPkg:fix issue when splitting paging entry
This patch is to fix issue when splitting leaf paging
entry in CpuPageTableLib code.
In previous code, before we assign the new child paging
structure address to the content of splitted paging entry,
PageTableLibSetPnle() is called to make sure the bit7 is
set to 0, which indicate the previous leaf entry is
changed to non-leaf entry now. There is a gap between
we change the bit7 and we assign the new child paging
structure address to the content of the splitted paging
entry. If the address of code execution or data access
happens to be in the range covered by the splitted paging
entry, this gap may cause issue.
In this patch, we prepare the new paging entry content
value in a local variable and assign the value to the
splitted paging entry at once. The volatile keyword
is used to ensure that no optimization will occur in
compilation.
Signed-off-by: Dun Tan
Cc: Ray Ni
Cc: Rahul Kumar
Cc: Gerd Hoffmann
Cc: Jiaxin Wu
Cc: Zhou Jianfeng
---
UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c | 9 +++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
index b10a3008e4..bdc411338f 100644
--- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
+++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
@@ -342,6 +342,7 @@ PageTableLibMapInLevel (
UINT64 PhysicalAddrInAttr;
IA32_PAGING_ENTRY OriginalParentPagingEntry;
IA32_PAGING_ENTRY OriginalCurrentPagingEntry;
+ IA32_PAGING_ENTRY TempPagingEntry;
ASSERT (Level != 0);
ASSERT ((Attribute != NULL) && (Mask != NULL));
@@ -359,6 +360,8 @@ PageTableLibMapInLevel (
OriginalParentPagingEntry.Uint64 = ParentPagingEntry->Uint64;
OneOfPagingEntry.Uint64 = 0;
+ TempPagingEntry.Uint64 = 0;
+
//
// RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21)
or 4K (1 << 12).
//
@@ -441,8 +444,10 @@ PageTableLibMapInLevel (
// Non-leaf entry doesn't have PAT bit. So use
~IA32_PE_BASE_ADDRESS_MASK_40 is to make sure PAT bit
// (bit12) in original big-leaf entry is not assigned to
PageTableBaseAddress field of non-leaf entry.
//
- PageTableLibSetPnle (&ParentPagingEntry->Pnle, &NopAttribute,
&AllOneMask);
- ParentPagingEntry->Uint64 = ((UINTN)(VOID *)PagingEntry) |
(ParentPagingEntry->Uint64 & (~IA32_PE_BASE_ADDRESS_MASK_40));
+ TempPagingEntry.Uint64 = ParentPagingEntry->Uint64;
+ PageTableLibSetPnle (&TempPagingEntry.Pnle, &NopAttribute, &AllOneMask);
+ TempPagingEntry.Uint64 = ((UINTN)(VOID
*)PagingEntry) | (TempPagingEntry.Uint64 & (~IA32_PE_BASE_ADDRESS_MASK_40));
+ *(volatile UINT64 *)&(ParentPagingEntry->Uint64) =
TempPagingEntry.Uint64;
}
} else {
//
--
2.31.1.windows.1
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[edk2-devel] [PATCH] UefiCpuPkg:fix issue when splitting paging entry
This patch is to fix issue when splitting leaf paging
entry in CpuPageTableLib code.
In previous code, before we assign the new child paging
structure address to the content of splitted paging entry,
PageTableLibSetPnle() is called to make sure the bit7 is
set to 0, which indicate the previous leaf entry is
changed to non-leaf entry now. There is a gap between
we change the bit7 and we assign the new child paging
structure address to the content of the splitted paging
entry. If the address of code execution or data access
happens to be in the range covered by the splitted paging
entry, this gap may cause issue.
In this patch, we prepare the new paging entry content
value in a local variable and assign the value to the
splitted paging entry at once. The volatile keyword
is used to ensure that no optimization will occur in
compilation.
Signed-off-by: Dun Tan
Cc: Ray Ni
Cc: Rahul Kumar
Cc: Gerd Hoffmann
Cc: Jiaxin Wu
Cc: Zhou Jianfeng
---
UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c | 9 +++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
index b10a3008e4..bdc411338f 100644
--- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
+++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
@@ -342,6 +342,7 @@ PageTableLibMapInLevel (
UINT64 PhysicalAddrInAttr;
IA32_PAGING_ENTRY OriginalParentPagingEntry;
IA32_PAGING_ENTRY OriginalCurrentPagingEntry;
+ IA32_PAGING_ENTRY TempPagingEntry;
ASSERT (Level != 0);
ASSERT ((Attribute != NULL) && (Mask != NULL));
@@ -359,6 +360,8 @@ PageTableLibMapInLevel (
OriginalParentPagingEntry.Uint64 = ParentPagingEntry->Uint64;
OneOfPagingEntry.Uint64 = 0;
+ TempPagingEntry.Uint64 = 0;
+
//
// RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21)
or 4K (1 << 12).
//
@@ -441,8 +444,10 @@ PageTableLibMapInLevel (
// Non-leaf entry doesn't have PAT bit. So use
~IA32_PE_BASE_ADDRESS_MASK_40 is to make sure PAT bit
// (bit12) in original big-leaf entry is not assigned to
PageTableBaseAddress field of non-leaf entry.
//
- PageTableLibSetPnle (&ParentPagingEntry->Pnle, &NopAttribute,
&AllOneMask);
- ParentPagingEntry->Uint64 = ((UINTN)(VOID *)PagingEntry) |
(ParentPagingEntry->Uint64 & (~IA32_PE_BASE_ADDRESS_MASK_40));
+ TempPagingEntry.Uint64 = ParentPagingEntry->Uint64;
+ PageTableLibSetPnle (&TempPagingEntry.Pnle, &NopAttribute, &AllOneMask);
+ TempPagingEntry.Uint64 = ((UINTN)(VOID
*)PagingEntry) | (TempPagingEntry.Uint64 & (~IA32_PE_BASE_ADDRESS_MASK_40));
+ *(volatile UINT64 *)&(ParentPagingEntry->Uint64) =
TempPagingEntry.Uint64;
}
} else {
//
--
2.31.1.windows.1
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