[edk2-devel] [PATCH] UefiCpuPkg/CpuPageTableLib: qualify page table accesses as volatile

[Zhou Jianfeng]

Add volatile qualifier to page table related variable to prevent
compiler from optimizing away the variables which may lead to
unexpected result.

Signed-off-by: Zhou Jianfeng <jianfeng.z...@intel.com>
Cc: Ray Ni <ray...@intel.com>
Cc: Laszlo Ersek <ler...@redhat.com>
Cc: Rahul Kumar <rahul1.ku...@intel.com>
Cc: Gerd Hoffmann <kra...@redhat.com>
Cc: Pedro Falcato <pedro.falc...@gmail.com>
Cc: Zhang Di <di.zh...@intel.com>
Cc: Tan Dun <dun....@intel.com>
Cc: Michael Brown <mc...@ipxe.org>
---
 .../Library/CpuPageTableLib/CpuPageTableMap.c | 36 +++++++++----------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c 
b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
index c4e46a6d74..0a380a04cb 100644
--- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
+++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
@@ -20,17 +20,17 @@
 **/
 VOID
 PageTableLibSetPte4K (
-  IN OUT IA32_PTE_4K         *Pte4K,
-  IN UINT64                  Offset,
-  IN IA32_MAP_ATTRIBUTE      *Attribute,
-  IN IA32_MAP_ATTRIBUTE      *Mask
+  IN OUT volatile IA32_PTE_4K  *Pte4K,
+  IN UINT64                    Offset,
+  IN IA32_MAP_ATTRIBUTE        *Attribute,
+  IN IA32_MAP_ATTRIBUTE        *Mask
   )
 {
   IA32_PTE_4K  LocalPte4K;

   LocalPte4K.Uint64 = Pte4K->Uint64;
   if (Mask->Bits.PageTableBaseAddressLow || 
Mask->Bits.PageTableBaseAddressHigh) {
-    LocalPte4K.Uint64 = (IA32_MAP_ATTRIBUTE_PAGE_TABLE_BASE_ADDRESS 
(Attribute) + Offset) | (Pte4K->Uint64 & ~IA32_PE_BASE_ADDRESS_MASK_40);
+    LocalPte4K.Uint64 = (IA32_MAP_ATTRIBUTE_PAGE_TABLE_BASE_ADDRESS 
(Attribute) + Offset) | (LocalPte4K.Uint64 & ~IA32_PE_BASE_ADDRESS_MASK_40);
   }

   if (Mask->Bits.Present) {
@@ -94,17 +94,17 @@ PageTableLibSetPte4K (
 **/
 VOID
 PageTableLibSetPleB (
-  IN OUT IA32_PAGE_LEAF_ENTRY_BIG_PAGESIZE  *PleB,
-  IN UINT64                                 Offset,
-  IN IA32_MAP_ATTRIBUTE                     *Attribute,
-  IN IA32_MAP_ATTRIBUTE                     *Mask
+  IN OUT volatile IA32_PAGE_LEAF_ENTRY_BIG_PAGESIZE  *PleB,
+  IN UINT64                                          Offset,
+  IN IA32_MAP_ATTRIBUTE                              *Attribute,
+  IN IA32_MAP_ATTRIBUTE                              *Mask
   )
 {
   IA32_PAGE_LEAF_ENTRY_BIG_PAGESIZE  LocalPleB;

   LocalPleB.Uint64 = PleB->Uint64;
   if (Mask->Bits.PageTableBaseAddressLow || 
Mask->Bits.PageTableBaseAddressHigh) {
-    LocalPleB.Uint64 = (IA32_MAP_ATTRIBUTE_PAGE_TABLE_BASE_ADDRESS (Attribute) 
+ Offset) | (PleB->Uint64 & ~IA32_PE_BASE_ADDRESS_MASK_39);
+    LocalPleB.Uint64 = (IA32_MAP_ATTRIBUTE_PAGE_TABLE_BASE_ADDRESS (Attribute) 
+ Offset) | (LocalPleB.Uint64 & ~IA32_PE_BASE_ADDRESS_MASK_39);
   }

   LocalPleB.Bits.MustBeOne = 1;
@@ -171,11 +171,11 @@ PageTableLibSetPleB (
 **/
 VOID
 PageTableLibSetPle (
-  IN UINTN                   Level,
-  IN OUT IA32_PAGING_ENTRY   *Ple,
-  IN UINT64                  Offset,
-  IN IA32_MAP_ATTRIBUTE      *Attribute,
-  IN IA32_MAP_ATTRIBUTE      *Mask
+  IN UINTN                            Level,
+  IN OUT volatile IA32_PAGING_ENTRY   *Ple,
+  IN UINT64                           Offset,
+  IN IA32_MAP_ATTRIBUTE               *Attribute,
+  IN IA32_MAP_ATTRIBUTE               *Mask
   )
 {
   if (Level == 1) {
@@ -195,9 +195,9 @@ PageTableLibSetPle (
 **/
 VOID
 PageTableLibSetPnle (
-  IN OUT IA32_PAGE_NON_LEAF_ENTRY  *Pnle,
-  IN IA32_MAP_ATTRIBUTE            *Attribute,
-  IN IA32_MAP_ATTRIBUTE            *Mask
+  IN OUT volatile IA32_PAGE_NON_LEAF_ENTRY  *Pnle,
+  IN IA32_MAP_ATTRIBUTE                     *Attribute,
+  IN IA32_MAP_ATTRIBUTE                     *Mask
   )
 {
   IA32_PAGE_NON_LEAF_ENTRY  LocalPnle;
--
2.31.1.windows.1



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