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| author | Ard Biesheuvel <workofard@gmail.com> | 2024-06-13 19:44:43 +0200 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2024-06-13 19:44:43 +0200 |
| commit | 26873a4bf8d12bc5bc292c51030559e8ed353599 (patch) | |
| tree | e9ec5dffb4478cf8031b1e9a75b02840a4d29e1c | |
| parent | b6c7ca95341290805a72f355682a78d0a174cb70 (diff) | |
| download | edk2-revert-5714-devel/ovmf-rdrand-pedro.zip edk2-revert-5714-devel/ovmf-rdrand-pedro.tar.gz edk2-revert-5714-devel/ovmf-rdrand-pedro.tar.bz2 | |
Revert "MdePkg/BaseRngLib: Add a smoketest for RDRAND and check CPUID"revert-5714-devel/ovmf-rdrand-pedro
This reverts commit c3a8ca7b54a9fd17acdf16c6282a92cc989fa92a.
| -rw-r--r-- | MdePkg/Library/BaseRngLib/Rand/RdRand.c | 99 |
1 files changed, 8 insertions, 91 deletions
diff --git a/MdePkg/Library/BaseRngLib/Rand/RdRand.c b/MdePkg/Library/BaseRngLib/Rand/RdRand.c index 06d2a6f..9bd6835 100644 --- a/MdePkg/Library/BaseRngLib/Rand/RdRand.c +++ b/MdePkg/Library/BaseRngLib/Rand/RdRand.c @@ -3,7 +3,6 @@ to provide high-quality random numbers.
Copyright (c) 2023, Arm Limited. All rights reserved.<BR>
-Copyright (c) 2022, Pedro Falcato. All rights reserved.<BR>
Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>
@@ -25,88 +24,6 @@ SPDX-License-Identifier: BSD-2-Clause-Patent STATIC BOOLEAN mRdRandSupported;
-//
-// Intel SDM says 10 tries is good enough for reliable RDRAND usage.
-//
-#define RDRAND_RETRIES 10
-
-#define RDRAND_TEST_SAMPLES 8
-
-#define RDRAND_MIN_CHANGE 5
-
-//
-// Add a define for native-word RDRAND, just for the test.
-//
-#ifdef MDE_CPU_X64
-#define ASM_RDRAND AsmRdRand64
-#else
-#define ASM_RDRAND AsmRdRand32
-#endif
-
-/**
- Tests RDRAND for broken implementations.
-
- @retval TRUE RDRAND is reliable (and hopefully safe).
- @retval FALSE RDRAND is unreliable and should be disabled, despite CPUID.
-
-**/
-STATIC
-BOOLEAN
-TestRdRand (
- VOID
- )
-{
- //
- // Test for notoriously broken rdrand implementations that always return the same
- // value, like the Zen 3 uarch (all-1s) or other several AMD families on suspend/resume (also all-1s).
- // Note that this should be expanded to extensively test for other sorts of possible errata.
- //
-
- //
- // Our algorithm samples rdrand $RDRAND_TEST_SAMPLES times and expects
- // a different result $RDRAND_MIN_CHANGE times for reliable RDRAND usage.
- //
- UINTN Prev;
- UINT8 Idx;
- UINT8 TestIteration;
- UINT32 Changed;
-
- Changed = 0;
-
- for (TestIteration = 0; TestIteration < RDRAND_TEST_SAMPLES; TestIteration++) {
- UINTN Sample;
- //
- // Note: We use a retry loop for rdrand. Normal users get this in BaseRng.c
- // Any failure to get a random number will assume RDRAND does not work.
- //
- for (Idx = 0; Idx < RDRAND_RETRIES; Idx++) {
- if (ASM_RDRAND (&Sample)) {
- break;
- }
- }
-
- if (Idx == RDRAND_RETRIES) {
- DEBUG ((DEBUG_ERROR, "BaseRngLib/x86: CPU BUG: Failed to get an RDRAND random number - disabling\n"));
- return FALSE;
- }
-
- if (TestIteration != 0) {
- Changed += Sample != Prev;
- }
-
- Prev = Sample;
- }
-
- if (Changed < RDRAND_MIN_CHANGE) {
- DEBUG ((DEBUG_ERROR, "BaseRngLib/x86: CPU BUG: RDRAND not reliable - disabling\n"));
- return FALSE;
- }
-
- return TRUE;
-}
-
-#undef ASM_RDRAND
-
/**
The constructor function checks whether or not RDRAND instruction is supported
by the host hardware.
@@ -131,13 +48,10 @@ BaseRngLibConstructor ( // CPUID. A value of 1 indicates that processor support RDRAND instruction.
//
AsmCpuid (1, 0, 0, &RegEcx, 0);
+ ASSERT ((RegEcx & RDRAND_MASK) == RDRAND_MASK);
mRdRandSupported = ((RegEcx & RDRAND_MASK) == RDRAND_MASK);
- if (mRdRandSupported) {
- mRdRandSupported = TestRdRand ();
- }
-
return EFI_SUCCESS;
}
@@ -156,7 +70,6 @@ ArchGetRandomNumber16 ( OUT UINT16 *Rand
)
{
- ASSERT (mRdRandSupported);
return AsmRdRand16 (Rand);
}
@@ -175,7 +88,6 @@ ArchGetRandomNumber32 ( OUT UINT32 *Rand
)
{
- ASSERT (mRdRandSupported);
return AsmRdRand32 (Rand);
}
@@ -194,7 +106,6 @@ ArchGetRandomNumber64 ( OUT UINT64 *Rand
)
{
- ASSERT (mRdRandSupported);
return AsmRdRand64 (Rand);
}
@@ -211,7 +122,13 @@ ArchIsRngSupported ( VOID
)
{
- return mRdRandSupported;
+ /*
+ Existing software depends on this always returning TRUE, so for
+ now hard-code it.
+
+ return mRdRandSupported;
+ */
+ return TRUE;
}
/**
|