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

["Laszlo Ersek" <lersek@redhat.com>]

On 3/1/24 03:54, Zhou Jianfeng wrote:
> 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.zhou@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Pedro Falcato <pedro.falcato@gmail.com>
> Cc: Zhang Di <di.zhang@intel.com>
> Cc: Tan Dun <dun.tan@intel.com>
> Cc: Michael Brown <mcb30@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;

Reviewed-by: Laszlo Ersek <lersek@redhat.com>




-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#116242): https://edk2.groups.io/g/devel/message/116242
Mute This Topic: https://groups.io/mt/104661494/7686176
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io]
-=-=-=-=-=-=-=-=-=-=-=-