UNLOZE/sm-ext-dhooks2
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Fix detour of functions returning a float

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Floats are always returned in FPU register st0. Since the value in st0 doesn't matter in a pre-hook before the function was executed, don't try to save and restore the value of the FPU stack top for a pre-hook.
Only replace st0 after a post hook.
This commit is contained in:
Peace-Maker 2018-08-18 12:54:30 +02:00
parent 6a98d26307
commit a89eb67124
3 changed files with 29 additions and 11 deletions
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34
DynamicHooks/hook.cpp
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@ -227,7 +227,7 @@ void* CHook::CreateBridge()
masm.cmpb(r8_al, ReturnAction_Supercede); masm.cmpb(r8_al, ReturnAction_Supercede);
// Restore the previously saved registers, so any changes will be applied // Restore the previously saved registers, so any changes will be applied
Write_RestoreRegisters(masm); Write_RestoreRegisters(masm, HOOKTYPE_PRE);
masm.j(equal, &label_supercede); masm.j(equal, &label_supercede);
@ -293,7 +293,7 @@ void* CHook::CreatePostCallback()
Write_CallHandler(masm, HOOKTYPE_POST); Write_CallHandler(masm, HOOKTYPE_POST);
// Restore the previously saved registers, so any changes will be applied // Restore the previously saved registers, so any changes will be applied
Write_RestoreRegisters(masm); Write_RestoreRegisters(masm, HOOKTYPE_POST);
// Save scratch registers that are used by GetReturnAddress // Save scratch registers that are used by GetReturnAddress
static void* pEAX = NULL; static void* pEAX = NULL;
@ -337,16 +337,19 @@ void CHook::Write_CallHandler(sp::MacroAssembler& masm, HookType_t type)
ReturnAction_t (__cdecl CHook::*HookHandler)(HookType_t) = &CHook::HookHandler; ReturnAction_t (__cdecl CHook::*HookHandler)(HookType_t) = &CHook::HookHandler;
// Save the registers so that we can access them in our handlers // Save the registers so that we can access them in our handlers
Write_SaveRegisters(masm); Write_SaveRegisters(masm, type);
// Align the stack to 16 bytes.
masm.subl(esp, 8);
// Call the global hook handler // Call the global hook handler
masm.push(type); masm.push(type);
masm.push(intptr_t(this)); masm.push(intptr_t(this));
masm.call(ExternalAddress((void *&)HookHandler)); masm.call(ExternalAddress((void *&)HookHandler));
masm.addl(esp, 8); masm.addl(esp, 16);
} }
void CHook::Write_SaveRegisters(sp::MacroAssembler& masm) void CHook::Write_SaveRegisters(sp::MacroAssembler& masm, HookType_t type)
{ {
ke::Vector<Register_t> vecRegistersToSave = m_pCallingConvention->GetRegisters(); ke::Vector<Register_t> vecRegistersToSave = m_pCallingConvention->GetRegisters();
for(size_t i = 0; i < vecRegistersToSave.length(); i++) for(size_t i = 0; i < vecRegistersToSave.length(); i++)
@ -394,7 +397,12 @@ void CHook::Write_SaveRegisters(sp::MacroAssembler& masm)
// ======================================================================== // ========================================================================
// >> 80-bit FPU registers // >> 80-bit FPU registers
// ======================================================================== // ========================================================================
case ST0: masm.fst32(Operand(ExternalAddress(m_pRegisters->m_st0->m_pAddress))); break; case ST0:
// Don't mess with the FPU stack in a pre-hook. The float return is returned in st0,
// so only load it in a post hook to avoid writing back NaN.
if (type == HOOKTYPE_POST)
masm.fst32(Operand(ExternalAddress(m_pRegisters->m_st0->m_pAddress)));
break;
//case ST1: masm.movl(tword_ptr_abs(Ptr(m_pRegisters->m_st1->m_pAddress)), st1); break; //case ST1: masm.movl(tword_ptr_abs(Ptr(m_pRegisters->m_st1->m_pAddress)), st1); break;
//case ST2: masm.movl(tword_ptr_abs(Ptr(m_pRegisters->m_st2->m_pAddress)), st2); break; //case ST2: masm.movl(tword_ptr_abs(Ptr(m_pRegisters->m_st2->m_pAddress)), st2); break;
//case ST3: masm.movl(tword_ptr_abs(Ptr(m_pRegisters->m_st3->m_pAddress)), st3); break; //case ST3: masm.movl(tword_ptr_abs(Ptr(m_pRegisters->m_st3->m_pAddress)), st3); break;
@ -408,7 +416,7 @@ void CHook::Write_SaveRegisters(sp::MacroAssembler& masm)
} }
} }
void CHook::Write_RestoreRegisters(sp::MacroAssembler& masm) void CHook::Write_RestoreRegisters(sp::MacroAssembler& masm, HookType_t type)
{ {
ke::Vector<Register_t> vecRegistersToSave = m_pCallingConvention->GetRegisters(); ke::Vector<Register_t> vecRegistersToSave = m_pCallingConvention->GetRegisters();
for (size_t i = 0; i < vecRegistersToSave.length(); i++) for (size_t i = 0; i < vecRegistersToSave.length(); i++)
@ -456,7 +464,17 @@ void CHook::Write_RestoreRegisters(sp::MacroAssembler& masm)
// ======================================================================== // ========================================================================
// >> 80-bit FPU registers // >> 80-bit FPU registers
// ======================================================================== // ========================================================================
case ST0: masm.fld32(Operand(ExternalAddress(m_pRegisters->m_st0->m_pAddress))); break; case ST0:
if (type == HOOKTYPE_POST) {
// Replace the top of the FPU stack.
// Copy st0 to st0 and pop -> just pop the FPU stack.
masm.fstp(st0);
// Push a value to the FPU stack.
// TODO: Only write back when changed? Save full 80bits for that case.
// Avoid truncation of the data if it's unchanged.
masm.fld32(Operand(ExternalAddress(m_pRegisters->m_st0->m_pAddress)));
}
break;
//case ST1: masm.movl(st1, tword_ptr_abs(Ptr(m_pRegisters->m_st1->m_pAddress))); break; //case ST1: masm.movl(st1, tword_ptr_abs(Ptr(m_pRegisters->m_st1->m_pAddress))); break;
//case ST2: masm.movl(st2, tword_ptr_abs(Ptr(m_pRegisters->m_st2->m_pAddress))); break; //case ST2: masm.movl(st2, tword_ptr_abs(Ptr(m_pRegisters->m_st2->m_pAddress))); break;
//case ST3: masm.movl(st3, tword_ptr_abs(Ptr(m_pRegisters->m_st3->m_pAddress))); break; //case ST3: masm.movl(st3, tword_ptr_abs(Ptr(m_pRegisters->m_st3->m_pAddress))); break;

4
DynamicHooks/hook.h
View File

@ -174,8 +174,8 @@ private:
void Write_ModifyReturnAddress(sp::MacroAssembler& masm); void Write_ModifyReturnAddress(sp::MacroAssembler& masm);
void Write_CallHandler(sp::MacroAssembler& masm, HookType_t type); void Write_CallHandler(sp::MacroAssembler& masm, HookType_t type);
void Write_SaveRegisters(sp::MacroAssembler& masm); void Write_SaveRegisters(sp::MacroAssembler& masm, HookType_t type);
void Write_RestoreRegisters(sp::MacroAssembler& masm); void Write_RestoreRegisters(sp::MacroAssembler& masm, HookType_t type);
void* CreatePostCallback(); void* CreatePostCallback();

2
dynhooks_sourcepawn.cpp
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@ -387,7 +387,7 @@ ReturnAction_t HandleDetour(HookType_t hookType, CHook* pDetour)
} }
else if (pWrapper->returnType == ReturnType_Float) else if (pWrapper->returnType == ReturnType_Float)
{ {
*(float *)tempRetBuf = *(float *)returnStruct->newResult; *(float *)&tempRetBuf = *(float *)returnStruct->newResult;
} }
else else
{ {