sydney/q3-sydney-qvm
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Allow unaligned load/store in QVM interpreter/x86 compiler

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constructions like (dataMask & ~3) was used to protect against out-of-bound load/store when address is 4-byte closer to dataMask
 but at the same time it effectively cut low address bits for ALL load/store operations which is totally wrong in terms of conformance to ALLOWED (i.e. generated by q3lcc from C sources) low-level operations like packed binary data parsing
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ec- authored and Tim Angus committed 2017-05-25 09:44:18 +01:00
1 parent abce15055c
commit 566fb0edfc
4 files changed
+17 -14
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code/qcommon/vm_x86.c
+4 -4
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@@ -790,7 +790,7 @@ qboolean ConstOptimize(vm_t *vm, int callProcOfsSyscall)
return qtrue;
case OP_STORE4:
EmitMovEAXStack(vm, (vm->dataMask & ~3));
EmitMovEAXStack(vm, vm->dataMask);
#if idx64
EmitRexString(0x41, "C7 04 01"); // mov dword ptr [r9 + eax], 0x12345678
Emit4(Constant4());
@@ -805,7 +805,7 @@ qboolean ConstOptimize(vm_t *vm, int callProcOfsSyscall)
return qtrue;
case OP_STORE2:
EmitMovEAXStack(vm, (vm->dataMask & ~1));
EmitMovEAXStack(vm, vm->dataMask);
#if idx64
Emit1(0x66); // mov word ptr [r9 + eax], 0x1234
EmitRexString(0x41, "C7 04 01");
@@ -1377,7 +1377,7 @@ void VM_Compile(vm_t *vm, vmHeader_t *header)
case OP_STORE4:
EmitMovEAXStack(vm, 0);
EmitString("8B 54 9F FC"); // mov edx, dword ptr -4[edi + ebx * 4]
MASK_REG("E2", vm->dataMask & ~3); // and edx, 0x12345678
MASK_REG("E2", vm->dataMask); // and edx, 0x12345678
#if idx64
EmitRexString(0x41, "89 04 11"); // mov dword ptr [r9 + edx], eax
#else
@@ -1389,7 +1389,7 @@ void VM_Compile(vm_t *vm, vmHeader_t *header)
case OP_STORE2:
EmitMovEAXStack(vm, 0);
EmitString("8B 54 9F FC"); // mov edx, dword ptr -4[edi + ebx * 4]
MASK_REG("E2", vm->dataMask & ~1); // and edx, 0x12345678
MASK_REG("E2", vm->dataMask); // and edx, 0x12345678
#if idx64
Emit1(0x66); // mov word ptr [r9 + edx], eax
EmitRexString(0x41, "89 04 11");