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[x86/Linux] Add UMThunkStub #8627

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Dec 19, 2016
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[x86/Linux] Add UMThunkStub #8627

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2 changes: 1 addition & 1 deletion src/vm/amd64/umthunkstub.S
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Original file line number Diff line number Diff line change
Expand Up @@ -83,7 +83,7 @@ LOCAL_LABEL(HaveThread):

mov r12, rax // r12 <- Thread*

//FailFast if a native callable method invoked via ldftn and calli.
//FailFast if a native callable method is invoked via ldftn and calli.
cmp dword ptr [r12 + OFFSETOF__Thread__m_fPreemptiveGCDisabled], 1
jz LOCAL_LABEL(InvalidTransition)

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18 changes: 18 additions & 0 deletions src/vm/i386/asmconstants.h
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Expand Up @@ -449,6 +449,24 @@ ASMCONSTANTS_C_ASSERT(CallDescrData__fpReturnSize == offsetof(CallDescrD
ASMCONSTANTS_C_ASSERT(CallDescrData__pTarget == offsetof(CallDescrData, pTarget))
ASMCONSTANTS_C_ASSERT(CallDescrData__returnValue == offsetof(CallDescrData, returnValue))

#define UMEntryThunk__m_pUMThunkMarshInfo 0x0C
ASMCONSTANTS_C_ASSERT(UMEntryThunk__m_pUMThunkMarshInfo == offsetof(UMEntryThunk, m_pUMThunkMarshInfo))

#define UMEntryThunk__m_dwDomainId 0x10
ASMCONSTANTS_C_ASSERT(UMEntryThunk__m_dwDomainId == offsetof(UMEntryThunk, m_dwDomainId))

#define UMThunkMarshInfo__m_pILStub 0x00
ASMCONSTANTS_C_ASSERT(UMThunkMarshInfo__m_pILStub == offsetof(UMThunkMarshInfo, m_pILStub))

#define UMThunkMarshInfo__m_cbActualArgSize 0x04
ASMCONSTANTS_C_ASSERT(UMThunkMarshInfo__m_cbActualArgSize == offsetof(UMThunkMarshInfo, m_cbActualArgSize))

#ifndef CROSSGEN_COMPILE
#define Thread__m_pDomain 0x14
ASMCONSTANTS_C_ASSERT(Thread__m_pDomain == offsetof(Thread, m_pDomain));

#endif

#undef ASMCONSTANTS_C_ASSERT
#undef ASMCONSTANTS_RUNTIME_ASSERT

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151 changes: 148 additions & 3 deletions src/vm/i386/umthunkstub.S
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Expand Up @@ -14,9 +14,10 @@ NESTED_ENTRY TheUMEntryPrestub, _TEXT, UnhandledExceptionHandlerUnix
push ecx
push edx

push eax
push eax // UMEntryThunk*
call C_FUNC(TheUMEntryPrestubWorker)
pop edx
// eax = PCODE

// Restore argument registers
pop edx
Expand All @@ -25,8 +26,152 @@ NESTED_ENTRY TheUMEntryPrestub, _TEXT, UnhandledExceptionHandlerUnix
jmp eax // Tail Jmp
NESTED_END TheUMEntryPrestub, _TEXT


//
// eax: UMEntryThunk*
//
NESTED_ENTRY UMThunkStub, _TEXT, UnhandledExceptionHandlerUnix
int 3 // implement here

#define UMThunkStub_SAVEDREG (3*4) // ebx, esi, edi
#define UMThunkStub_LOCALVARS (2*4) // UMEntryThunk*, Thread*
#define UMThunkStub_INT_ARG_SPILL (2*4) // for save ecx, edx
#define UMThunkStub_UMENTRYTHUNK_OFFSET (UMThunkStub_SAVEDREG+4)
#define UMThunkStub_THREAD_OFFSET (UMThunkStub_UMENTRYTHUNK_OFFSET+4)
#define UMThunkStub_INT_ARG_OFFSET (UMThunkStub_THREAD_OFFSET+4)
#define UMThunkStub_FIXEDALLOCSIZE (UMThunkStub_LOCALVARS+UMThunkStub_INT_ARG_SPILL)

// return address <-- entry ESP
// saved ebp <-- EBP
// saved ebx
// saved esi
// saved edi
// UMEntryThunk*
// Thread*
// save ecx
// save edx
// {optional stack args passed to callee} <-- new esp

PROLOG_BEG
PROLOG_PUSH ebx
PROLOG_PUSH esi
PROLOG_PUSH edi
PROLOG_END
sub esp, UMThunkStub_FIXEDALLOCSIZE

mov dword ptr [ebp - UMThunkStub_INT_ARG_OFFSET], ecx
mov dword ptr [ebp - UMThunkStub_INT_ARG_OFFSET - 0x04], edx

mov dword ptr [ebp - UMThunkStub_UMENTRYTHUNK_OFFSET], eax

call C_FUNC(GetThread)
test eax, eax
jz LOCAL_LABEL(DoThreadSetup)

LOCAL_LABEL(HaveThread):

mov dword ptr [ebp - UMThunkStub_THREAD_OFFSET], eax

// FailFast if a native callable method is invoked via ldftn and calli.
cmp dword ptr [eax + Thread_m_fPreemptiveGCDisabled], 1
jz LOCAL_LABEL(InvalidTransition)

// disable preemptive GC
mov dword ptr [eax + Thread_m_fPreemptiveGCDisabled], 1

// catch returning thread here if a GC is in progress
PREPARE_EXTERNAL_VAR g_TrapReturningThreads, eax
cmp eax, 0
jnz LOCAL_LABEL(DoTrapReturningThreadsTHROW)

LOCAL_LABEL(InCooperativeMode):

#if _DEBUG
mov eax, dword ptr [ebp - UMThunkStub_THREAD_OFFSET]
mov eax, dword ptr [eax + Thread__m_pDomain]
mov esi, dword ptr [eax + AppDomain__m_dwId]

mov eax, dword ptr [ebp - UMThunkStub_UMENTRYTHUNK_OFFSET]
mov edi, dword ptr [eax + UMEntryThunk__m_dwDomainId]
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@seanshpark I am sorry, I don't know how I could have missed the fact that you are actually using esi adn edi in this function. That means that we need to push them in the prolog and pop them in the epilog to preserve them as they are callee saved registers and we cannot destroy them otherwise we would break our callers that might have something in those registers and expect them being preserved. The same is true for ebx.

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Thank you for the comment :)


cmp esi, edi
jne LOCAL_LABEL(WrongAppDomain)
#endif

mov eax, dword ptr [ebp - UMThunkStub_UMENTRYTHUNK_OFFSET]
mov ebx, dword ptr [eax + UMEntryThunk__m_pUMThunkMarshInfo]
mov eax, dword ptr [ebx + UMThunkMarshInfo__m_cbActualArgSize]
test eax, eax
jnz LOCAL_LABEL(UMThunkStub_CopyStackArgs)

LOCAL_LABEL(UMThunkStub_ArgumentsSetup):

mov ecx, dword ptr [ebp - UMThunkStub_INT_ARG_OFFSET]
mov edx, dword ptr [ebp - UMThunkStub_INT_ARG_OFFSET - 0x04]

mov eax, dword ptr [ebp - UMThunkStub_UMENTRYTHUNK_OFFSET]
mov ebx, dword ptr [eax + UMEntryThunk__m_pUMThunkMarshInfo]
mov ebx, dword ptr [ebx + UMThunkMarshInfo__m_pILStub]

call ebx

LOCAL_LABEL(PostCall):

mov ebx, dword ptr [ebp - UMThunkStub_THREAD_OFFSET]
mov dword ptr [ebx + Thread_m_fPreemptiveGCDisabled], 0

lea esp, [ebp - UMThunkStub_SAVEDREG] // deallocate arguments
EPILOG_BEG
EPILOG_POP edi
EPILOG_POP esi
EPILOG_POP ebx
EPILOG_END
ret

LOCAL_LABEL(DoThreadSetup):

call C_FUNC(CreateThreadBlockThrow)
jmp LOCAL_LABEL(HaveThread)

LOCAL_LABEL(InvalidTransition):

//No arguments to setup , ReversePInvokeBadTransition will failfast
call C_FUNC(ReversePInvokeBadTransition)

LOCAL_LABEL(DoTrapReturningThreadsTHROW):

// extern "C" VOID STDCALL UMThunkStubRareDisableWorker(Thread *pThread, UMEntryThunk *pUMEntryThunk)
mov eax, dword ptr [ebp - UMThunkStub_UMENTRYTHUNK_OFFSET]
push eax
mov eax, dword ptr [ebp - UMThunkStub_THREAD_OFFSET]
push eax
call C_FUNC(UMThunkStubRareDisableWorker)

jmp LOCAL_LABEL(InCooperativeMode)

LOCAL_LABEL(UMThunkStub_CopyStackArgs):

// eax = m_cbActualArgSize
sub esp, eax
and esp, -16 // align with 16 byte
lea esi, [ebp + 0x08]
lea edi, [esp]

LOCAL_LABEL(CopyLoop):

// eax = number of bytes
// esi = src
// edi = dest
// edx = sratch

add eax, -4
mov edx, dword ptr [esi + eax]
mov dword ptr [edi + eax], edx
jnz LOCAL_LABEL(CopyLoop)

jmp LOCAL_LABEL(UMThunkStub_ArgumentsSetup)

#if _DEBUG
LOCAL_LABEL(WrongAppDomain):
int3
#endif

NESTED_END UMThunkStub, _TEXT
2 changes: 1 addition & 1 deletion src/vm/stackwalk.cpp
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Expand Up @@ -2677,7 +2677,7 @@ StackWalkAction StackFrameIterator::NextRaw(void)

// We are transitioning from unmanaged code to managed code... lets do some validation of our
// EH mechanism on platforms that we can.
#if defined(_DEBUG) && !defined(DACCESS_COMPILE) && defined(_TARGET_X86_)
#if defined(_DEBUG) && !defined(DACCESS_COMPILE) && (defined(_TARGET_X86_) && !defined(FEATURE_STUBS_AS_IL))
VerifyValidTransitionFromManagedCode(m_crawl.pThread, &m_crawl);
#endif // _DEBUG && !DACCESS_COMPILE && _TARGET_X86_
}
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