MdePkg/BaseRngLib: Prefer ArmReadIdAA64Isar0Reg() over ArmReadIdIsar0()

A ArmReadIdAA64Isar0Reg() function was recently added to BaseLib. Use it instead of its ArmReadIdIsar0() equivalent, which was private to the BaseRngLib library. This also allows to avoid the confusion between the following registers: - ID_ISAR0_EL1: allows to probe for Divide instructions, Debug instructions, ... - ID_AA64ISAR0_EL1: AARCH64 specific register allowing to probe for AESE, RNDR, ... instructions Signed-off-by: Pierre Gondois <[email protected]>
microsoft · Oct 2, 2024 · dba9c25 · dba9c25
1 parent 93481df
commit dba9c25
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Showing 5 changed files with 2 additions and 82 deletions.
diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.S b/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.S
diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.asm b/MdePkg/Library/BaseRngLib/AArch64/ArmReadIdIsar0.asm
diff --git a/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h b/MdePkg/Library/BaseRngLib/AArch64/ArmRng.h
@@ -27,16 +27,4 @@ ArmRndr (
   OUT UINT64  *Rand
   );
 
-/**
-  Reads the ID_AA64ISAR0 Register.
-
-  @return The contents of the ID_AA64ISAR0 register.
-
-**/
-UINT64
-EFIAPI
-ArmReadIdIsar0 (
-  VOID
-  );
-
 #endif /* ARM_RNG_H_ */
diff --git a/MdePkg/Library/BaseRngLib/AArch64/Rndr.c b/MdePkg/Library/BaseRngLib/AArch64/Rndr.c
@@ -21,11 +21,6 @@
 
 STATIC BOOLEAN  mRndrSupported;
 
-//
-// Bit mask used to determine if RNDR instruction is supported.
-//
-#define RNDR_MASK  ((UINT64)MAX_UINT16 << 60U)
-
 /**
   The constructor function checks whether or not RNDR instruction is supported
   by the host hardware.
@@ -49,9 +44,8 @@ BaseRngLibConstructor (
   // Determine RNDR support by examining bits 63:60 of the ISAR0 register returned by
   // MSR. A non-zero value indicates that the processor supports the RNDR instruction.
   //
-  Isar0 = ArmReadIdIsar0 ();
-
-  mRndrSupported = ((Isar0 & RNDR_MASK) != 0);
+  Isar0          = ArmReadIdAA64Isar0Reg ();
+  mRndrSupported = !!((Isar0 >> ARM_ID_AA64ISAR0_EL1_RNDR_SHIFT) & ARM_ID_AA64ISAR0_EL1_RNDR_MASK);
 
   return EFI_SUCCESS;
 }

diff --git a/MdePkg/Library/BaseRngLib/BaseRngLib.inf b/MdePkg/Library/BaseRngLib/BaseRngLib.inf
@@ -38,10 +38,8 @@
   AArch64/Rndr.c
   AArch64/ArmRng.h
 
-  AArch64/ArmReadIdIsar0.S   | GCC
   AArch64/ArmRng.S           | GCC
 
-  AArch64/ArmReadIdIsar0.asm | MSFT
   AArch64/ArmRng.asm         | MSFT
 
 [Guids.AARCH64]