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Validate CPU virtual addresses on access (#1987)

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* Enable PTE null checks again

* Do address validation on EmitPtPointerLoad, and make it branchless

* PTC version increment

* Mask of pointer tag for exclusive access

* Move mask to the correct place

Co-authored-by: LDj3SNuD <35856442+LDj3SNuD@users.noreply.github.com>
This commit is contained in:
gdkchan 2021-02-16 15:04:19 -03:00 • committed by GitHub
parent 6f1d964801
commit 715b605e95
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GPG key ID: 4AEE18F83AFDEB23
4 changed files with 52 additions and 122 deletions
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31
ARMeilleure/Instructions/InstEmitMemoryExHelper.cs
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@ -19,19 +19,8 @@ namespace ARMeilleure.Instructions
if (size == 4)
{
Operand isUnalignedAddr = InstEmitMemoryHelper.EmitAddressCheck(context, address, size);
Operand lblFastPath = Label();
context.BranchIfFalse(lblFastPath, isUnalignedAddr);
// The call is not expected to return (it should throw).
context.Call(typeof(NativeInterface).GetMethod(nameof(NativeInterface.ThrowInvalidMemoryAccess)), address);
context.MarkLabel(lblFastPath);
// Only 128-bit CAS is guaranteed to have a atomic load.
Operand physAddr = InstEmitMemoryHelper.EmitPtPointerLoad(context, address, null, write: false);
Operand physAddr = InstEmitMemoryHelper.EmitPtPointerLoad(context, address, null, write: false, 4);
Operand zero = context.VectorZero();
@ -119,20 +108,8 @@ namespace ARMeilleure.Instructions
context.BranchIfTrue(lblExit, exFailed);
// STEP 2: We have exclusive access, make sure that the address is valid.
Operand isUnalignedAddr = InstEmitMemoryHelper.EmitAddressCheck(context, address, size);
Operand lblFastPath = Label();
context.BranchIfFalse(lblFastPath, isUnalignedAddr);
// The call is not expected to return (it should throw).
context.Call(typeof(NativeInterface).GetMethod(nameof(NativeInterface.ThrowInvalidMemoryAccess)), address);
// STEP 3: We have exclusive access and the address is valid, attempt the store using CAS.
context.MarkLabel(lblFastPath);
Operand physAddr = InstEmitMemoryHelper.EmitPtPointerLoad(context, address, null, write: true);
// STEP 2: We have exclusive access and the address is valid, attempt the store using CAS.
Operand physAddr = InstEmitMemoryHelper.EmitPtPointerLoad(context, address, null, write: true, size);
Operand exValuePtr = context.Add(arg0, Const((long)NativeContext.GetExclusiveValueOffset()));
Operand exValue = size switch
@ -151,7 +128,7 @@ namespace ARMeilleure.Instructions
_ => context.CompareAndSwap(physAddr, exValue, value)
};
// STEP 4: Check if we succeeded by comparing expected and in-memory values.
// STEP 3: Check if we succeeded by comparing expected and in-memory values.
Operand storeFailed;
if (size == 4)