[PATCH 34/35] UefiPayloadPkg/BlSupportPei: fix MMCONFIG assignment from XSDT

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

(This patch is unrelated to the rest of this series; its purpose is to
enable building the UefiPayloadPkg DSC files with GCC.)

When building "UefiPayloadPkg/UefiPayloadPkgIa32.dsc" with GCC48 for the
DEBUG target, the compiler reports that "Entry32" may be used
uninitialized in ParseAcpiInfo(), in the XSDT branch.

Code inspection proves the compiler right. In the XSDT branch, the code
from the RSDT branch must have been duplicated, and "Entry32" references
were replaced with "Entry64" -- except where "MmCfgHdr" is assigned.

Fix this bug by introducing a helper variable called "Signature", so that
we have to refer to "Entry32" or "Entry64" only once per loop body.

Cc: Benjamin You <benjamin.you@intel.com>
Cc: Guo Dong <guo.dong@intel.com>
Cc: Maurice Ma <maurice.ma@intel.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---

Notes:
    build-tested only

 UefiPayloadPkg/BlSupportPei/BlSupportPei.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/UefiPayloadPkg/BlSupportPei/BlSupportPei.c b/UefiPayloadPkg/BlSupportPei/BlSupportPei.c
index 90433b609f22..22972453117a 100644
--- a/UefiPayloadPkg/BlSupportPei/BlSupportPei.c
+++ b/UefiPayloadPkg/BlSupportPei/BlSupportPei.c
@@ -164,6 +164,7 @@ ParseAcpiInfo (
   UINT64                                        *Entry64;
   UINTN                                         Entry64Num;
   UINTN                                         Idx;
+  UINT32                                        *Signature;
   EFI_ACPI_MEMORY_MAPPED_CONFIGURATION_BASE_ADDRESS_TABLE_HEADER *MmCfgHdr;
   EFI_ACPI_MEMORY_MAPPED_ENHANCED_CONFIGURATION_SPACE_BASE_ADDRESS_ALLOCATION_STRUCTURE *MmCfgBase;
 
@@ -181,13 +182,14 @@ ParseAcpiInfo (
     Entry32  = (UINT32 *)(Rsdt + 1);
     Entry32Num = (Rsdt->Length - sizeof(EFI_ACPI_DESCRIPTION_HEADER)) >> 2;
     for (Idx = 0; Idx < Entry32Num; Idx++) {
-      if (*(UINT32 *)(UINTN)(Entry32[Idx]) == EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE) {
-        Fadt = (EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *)(UINTN)(Entry32[Idx]);
+      Signature = (UINT32 *)(UINTN)Entry32[Idx];
+      if (*Signature == EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE) {
+        Fadt = (EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *)Signature;
         DEBUG ((DEBUG_INFO, "Found Fadt in Rsdt\n"));
       }
 
-      if (*(UINT32 *)(UINTN)(Entry32[Idx]) == EFI_ACPI_5_0_PCI_EXPRESS_MEMORY_MAPPED_CONFIGURATION_SPACE_BASE_ADDRESS_DESCRIPTION_TABLE_SIGNATURE) {
-        MmCfgHdr = (EFI_ACPI_MEMORY_MAPPED_CONFIGURATION_BASE_ADDRESS_TABLE_HEADER *)(UINTN)(Entry32[Idx]);
+      if (*Signature == EFI_ACPI_5_0_PCI_EXPRESS_MEMORY_MAPPED_CONFIGURATION_SPACE_BASE_ADDRESS_DESCRIPTION_TABLE_SIGNATURE) {
+        MmCfgHdr = (EFI_ACPI_MEMORY_MAPPED_CONFIGURATION_BASE_ADDRESS_TABLE_HEADER *)Signature;
         DEBUG ((DEBUG_INFO, "Found MM config address in Rsdt\n"));
       }
 
@@ -205,13 +207,14 @@ ParseAcpiInfo (
     Entry64  = (UINT64 *)(Xsdt + 1);
     Entry64Num = (Xsdt->Length - sizeof(EFI_ACPI_DESCRIPTION_HEADER)) >> 3;
     for (Idx = 0; Idx < Entry64Num; Idx++) {
-      if (*(UINT32 *)(UINTN)(Entry64[Idx]) == EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE) {
-        Fadt = (EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *)(UINTN)(Entry64[Idx]);
+      Signature = (UINT32 *)(UINTN)Entry64[Idx];
+      if (*Signature == EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE_SIGNATURE) {
+        Fadt = (EFI_ACPI_3_0_FIXED_ACPI_DESCRIPTION_TABLE *)Signature;
         DEBUG ((DEBUG_INFO, "Found Fadt in Xsdt\n"));
       }
 
-      if (*(UINT32 *)(UINTN)(Entry64[Idx]) == EFI_ACPI_5_0_PCI_EXPRESS_MEMORY_MAPPED_CONFIGURATION_SPACE_BASE_ADDRESS_DESCRIPTION_TABLE_SIGNATURE) {
-        MmCfgHdr = (EFI_ACPI_MEMORY_MAPPED_CONFIGURATION_BASE_ADDRESS_TABLE_HEADER *)(UINTN)(Entry32[Idx]);
+      if (*Signature == EFI_ACPI_5_0_PCI_EXPRESS_MEMORY_MAPPED_CONFIGURATION_SPACE_BASE_ADDRESS_DESCRIPTION_TABLE_SIGNATURE) {
+        MmCfgHdr = (EFI_ACPI_MEMORY_MAPPED_CONFIGURATION_BASE_ADDRESS_TABLE_HEADER *)Signature;
         DEBUG ((DEBUG_INFO, "Found MM config address in Xsdt\n"));
       }
 
-- 
2.19.1.3.g30247aa5d201