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|
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
.intel_syntax noprefix
#include "unixasmmacros.inc"
#include "asmconstants.h"
// ***
// JIT_WriteBarrier* - GC write barrier helper
//
// Purpose:
// Helper calls in order to assign an object to a field
// Enables book-keeping of the GC.
//
// Entry:
// EDX - address of ref-field (assigned to)
// the resp. other reg - RHS of assignment
//
// Exit:
//
// Uses:
// EDX is destroyed.
//
// Exceptions:
//
// *******************************************************************************
// The code here is tightly coupled with AdjustContextForWriteBarrier, if you change
// anything here, you might need to change AdjustContextForWriteBarrier as well
.macro WriteBarrierHelper rg
.align 4
// The entry point is the fully 'safe' one in which we check if EDX (the REF
// begin updated) is actually in the GC heap
NESTED_ENTRY JIT_CheckedWriteBarrier\rg, _TEXT, NoHandler
// check in the REF being updated is in the GC heap
push eax
PREPARE_EXTERNAL_VAR g_lowest_address, eax
cmp edx, [eax]
pop eax
jb LOCAL_LABEL(WriteBarrier_NotInHeap_\rg)
push eax
PREPARE_EXTERNAL_VAR g_highest_address, eax
cmp edx, [eax]
pop eax
jae LOCAL_LABEL(WriteBarrier_NotInHeap_\rg)
// fall through to unchecked routine
// note that its entry point also happens to be aligned
#ifdef WRITE_BARRIER_CHECK
// This entry point is used when you know the REF pointer being updated
// is in the GC heap
PATCH_LABEL JIT_DebugWriteBarrier\rg
#endif // WRITE_BARRIER_CHECK
#ifdef _DEBUG
push edx
push ecx
push eax
push \rg
push edx
call C_FUNC(WriteBarrierAssert)
pop eax
pop ecx
pop edx
#endif // _DEBUG
// in the !WRITE_BARRIER_CHECK case this will be the move for all
// addresses in the GCHeap, addresses outside the GCHeap will get
// taken care of below at WriteBarrier_NotInHeap_&rg
#ifndef WRITE_BARRIER_CHECK
mov DWORD PTR [edx], \rg
#endif // !WRITE_BARRIER_CHECK
#ifdef WRITE_BARRIER_CHECK
// Test dest here so if it is bad AV would happen before we change register/stack
// status. This makes job of AdjustContextForWriteBarrier easier.
cmp BYTE PTR [edx], 0
// ALSO update the shadow GC heap if that is enabled
// Make ebp into the temporary src register. We need to do this so that we can use ecx
// in the calculation of the shadow GC address, but still have access to the src register
push ecx
push ebp
mov ebp, \rg
// if g_GCShadow is 0, don't perform the check
push eax
PREPARE_EXTERNAL_VAR g_GCShadow, eax
cmp DWORD PTR [eax], 0
pop eax
je LOCAL_LABEL(WriteBarrier_NoShadow_\rg)
mov ecx, edx
push eax
PREPARE_EXTERNAL_VAR g_lowest_address, eax
sub ecx, [eax]
pop eax
jb LOCAL_LABEL(WriteBarrier_NoShadow_\rg)
push edx
PREPARE_EXTERNAL_VAR g_GCShadow, edx
mov [edx], edx
add ecx, [edx]
PREPARE_EXTERNAL_VAR g_GCShadowEnd, edx
mov [edx], edx
cmp ecx, [edx]
pop edx
ja LOCAL_LABEL(WriteBarrier_NoShadow_\rg)
// TODO: In Orcas timeframe if we move to P4+ only on X86 we should enable
// mfence barriers on either side of these two writes to make sure that
// they stay as close together as possible
// edx contains address in GC
// ecx contains address in ShadowGC
// ebp temporarially becomes the src register
// When we're writing to the shadow GC heap we want to be careful to minimize
// the risk of a race that can occur here where the GC and ShadowGC don't match
mov DWORD PTR [edx], ebp
mov DWORD PTR [ecx], ebp
// We need a scratch register to verify the shadow heap. We also need to
// construct a memory barrier so that the write to the shadow heap happens
// before the read from the GC heap. We can do both by using SUB/XCHG
// rather than PUSH.
//
// TODO: Should be changed to a push if the mfence described above is added.
//
sub esp, 4
xchg [esp], eax
// As part of our race avoidance (see above) we will now check whether the values
// in the GC and ShadowGC match. There is a possibility that we're wrong here but
// being overaggressive means we might mask a case where someone updates GC refs
// without going to a write barrier, but by its nature it will be indeterminant
// and we will find real bugs whereas the current implementation is indeterminant
// but only leads to investigations that find that this code is fundamentally flawed
mov eax, [edx]
cmp [ecx], eax
je LOCAL_LABEL(WriteBarrier_CleanupShadowCheck_\rg)
mov DWORD PTR [ecx], INVALIDGCVALUE
LOCAL_LABEL(WriteBarrier_CleanupShadowCheck_\rg):
pop eax
jmp LOCAL_LABEL(WriteBarrier_ShadowCheckEnd_\rg)
LOCAL_LABEL(WriteBarrier_NoShadow_\rg):
// If we come here then we haven't written the value to the GC and need to.
// ebp contains rg
// We restore ebp/ecx immediately after this, and if either of them is the src
// register it will regain its value as the src register.
mov DWORD PTR [edx], ebp
LOCAL_LABEL(WriteBarrier_ShadowCheckEnd_\rg):
pop ebp
pop ecx
#endif // WRITE_BARRIER_CHECK
push eax
push ebx
mov eax, \rg
PREPARE_EXTERNAL_VAR g_ephemeral_low, ebx
cmp eax, [ebx]
pop ebx
pop eax
jb LOCAL_LABEL(WriteBarrier_NotInEphemeral_\rg)
push eax
push ebx
mov eax, \rg
PREPARE_EXTERNAL_VAR g_ephemeral_high, ebx
cmp eax, [ebx]
pop ebx
pop eax
jae LOCAL_LABEL(WriteBarrier_NotInEphemeral_\rg)
shr edx, 10
push eax
PREPARE_EXTERNAL_VAR g_card_table, eax
add edx, [eax]
pop eax
cmp BYTE PTR [edx], 0FFh
jne LOCAL_LABEL(WriteBarrier_UpdateCardTable_\rg)
ret
LOCAL_LABEL(WriteBarrier_UpdateCardTable_\rg):
mov BYTE PTR [edx], 0FFh
ret
LOCAL_LABEL(WriteBarrier_NotInHeap_\rg):
// If it wasn't in the heap then we haven't updated the dst in memory yet
mov DWORD PTR [edx], \rg
LOCAL_LABEL(WriteBarrier_NotInEphemeral_\rg):
// If it is in the GC Heap but isn't in the ephemeral range we've already
// updated the Heap with the Object*.
ret
NESTED_END JIT_CheckedWriteBarrier\rg, _TEXT
.endm
// ***
// JIT_ByRefWriteBarrier* - GC write barrier helper
//
// Purpose:
// Helper calls in order to assign an object to a byref field
// Enables book-keeping of the GC.
//
// Entry:
// EDI - address of ref-field (assigned to)
// ESI - address of the data (source)
// ECX can be trashed
//
// Exit:
//
// Uses:
// EDI and ESI are incremented by a DWORD
//
// Exceptions:
//
// *******************************************************************************
//
// The code here is tightly coupled with AdjustContextForWriteBarrier, if you change
// anything here, you might need to change AdjustContextForWriteBarrier as well
//
.macro ByRefWriteBarrierHelper
.align 4
LEAF_ENTRY JIT_ByRefWriteBarrier, _TEXT
// test for dest in range
mov ecx, [esi]
push eax
PREPARE_EXTERNAL_VAR g_lowest_address, eax
cmp edi, [eax]
pop eax
jb LOCAL_LABEL(ByRefWriteBarrier_NotInHeap)
push eax
PREPARE_EXTERNAL_VAR g_highest_address, eax
cmp edi, [eax]
pop eax
jae LOCAL_LABEL(ByRefWriteBarrier_NotInHeap)
#ifndef WRITE_BARRIER_CHECK
// write barrier
mov [edi], ecx
#endif // !WRITE_BARRIER_CHECK
#ifdef WRITE_BARRIER_CHECK
// Test dest here so if it is bad AV would happen before we change register/stack
// status. This makes job of AdjustContextForWriteBarrier easier.
cmp BYTE PTR [edi], 0
// ALSO update the shadow GC heap if that is enabled
// use edx for address in GC Shadow,
push edx
// if g_GCShadow is 0, don't do the update
push ebx
PREPARE_EXTERNAL_VAR g_GCShadow, ebx
cmp DWORD PTR [ebx], 0
pop ebx
je LOCAL_LABEL(ByRefWriteBarrier_NoShadow)
mov edx, edi
push ebx
PREPARE_EXTERNAL_VAR g_lowest_address, ebx
sub edx, [ebx] // U/V
pop ebx
jb LOCAL_LABEL(ByRefWriteBarrier_NoShadow)
push eax
PREPARE_EXTERNAL_VAR g_GCShadow, eax
mov eax, [eax]
add edx, [eax]
PREPARE_EXTERNAL_VAR g_GCShadowEnd, eax
mov eax, [eax]
cmp edx, [eax]
pop eax
ja LOCAL_LABEL(ByRefWriteBarrier_NoShadow)
// TODO: In Orcas timeframe if we move to P4+ only on X86 we should enable
// mfence barriers on either side of these two writes to make sure that
// they stay as close together as possible
// edi contains address in GC
// edx contains address in ShadowGC
// ecx is the value to assign
// When we're writing to the shadow GC heap we want to be careful to minimize
// the risk of a race that can occur here where the GC and ShadowGC don't match
mov DWORD PTR [edi], ecx
mov DWORD PTR [edx], ecx
// We need a scratch register to verify the shadow heap. We also need to
// construct a memory barrier so that the write to the shadow heap happens
// before the read from the GC heap. We can do both by using SUB/XCHG
// rather than PUSH.
//
// TODO: Should be changed to a push if the mfence described above is added.
//
sub esp, 4
xchg [esp], eax
// As part of our race avoidance (see above) we will now check whether the values
// in the GC and ShadowGC match. There is a possibility that we're wrong here but
// being overaggressive means we might mask a case where someone updates GC refs
// without going to a write barrier, but by its nature it will be indeterminant
// and we will find real bugs whereas the current implementation is indeterminant
// but only leads to investigations that find that this code is fundamentally flawed
mov eax, [edi]
cmp [edx], eax
je LOCAL_LABEL(ByRefWriteBarrier_CleanupShadowCheck)
mov DWORD PTR [edx], INVALIDGCVALUE
LOCAL_LABEL(ByRefWriteBarrier_CleanupShadowCheck):
pop eax
jmp LOCAL_LABEL(ByRefWriteBarrier_ShadowCheckEnd)
LOCAL_LABEL(ByRefWriteBarrier_NoShadow):
// If we come here then we haven't written the value to the GC and need to.
mov DWORD PTR [edi], ecx
LOCAL_LABEL(ByRefWriteBarrier_ShadowCheckEnd):
pop edx
#endif // WRITE_BARRIER_CHECK
// test for *src in ephemeral segement
push eax
PREPARE_EXTERNAL_VAR g_ephemeral_low, eax
cmp ecx, [eax]
pop eax
jb LOCAL_LABEL(ByRefWriteBarrier_NotInEphemeral)
push eax
PREPARE_EXTERNAL_VAR g_ephemeral_high, eax
cmp ecx, [eax]
pop eax
jae LOCAL_LABEL(ByRefWriteBarrier_NotInEphemeral)
mov ecx, edi
add esi, 4
add edi, 4
shr ecx, 10
push eax
PREPARE_EXTERNAL_VAR g_card_table, eax
add ecx, [eax]
pop eax
cmp BYTE PTR [ecx], 0FFh
jne LOCAL_LABEL(ByRefWriteBarrier_UpdateCardTable)
ret
LOCAL_LABEL(ByRefWriteBarrier_UpdateCardTable):
mov BYTE PTR [ecx], 0FFh
ret
LOCAL_LABEL(ByRefWriteBarrier_NotInHeap):
// If it wasn't in the heap then we haven't updated the dst in memory yet
mov [edi], ecx
LOCAL_LABEL(ByRefWriteBarrier_NotInEphemeral):
// If it is in the GC Heap but isn't in the ephemeral range we've already
// updated the Heap with the Object*.
add esi, 4
add edi, 4
ret
NESTED_END JIT_ByRefWriteBarrier, _TEXT
.endm
// JIT_WriteBarrierGroup and JIT_WriteBarrierGroup_End are used
// to determine bounds of WriteBarrier functions so can determine if got AV in them.
//
LEAF_ENTRY JIT_WriteBarrierGroup, _TEXT
ret
LEAF_END JIT_WriteBarrierGroup, _TEXT
#ifdef FEATURE_USE_ASM_GC_WRITE_BARRIERS
// *******************************************************************************
// Write barrier wrappers with fcall calling convention
//
.macro UniversalWriteBarrierHelper name
.align 4
LEAF_ENTRY JIT_\name, _TEXT
mov eax, edx
mov edx, ecx
jmp C_FUNC(JIT_\name\()EAX)
LEAF_END JIT_\name, _TEXT
.endm
// Only define these if we're using the ASM GC write barriers; if this flag is not defined,
// we'll use C++ versions of these write barriers.
UniversalWriteBarrierHelper CheckedWriteBarrier
UniversalWriteBarrierHelper WriteBarrier
#endif // FEATURE_USE_ASM_GC_WRITE_BARRIERS
WriteBarrierHelper EAX
WriteBarrierHelper EBX
WriteBarrierHelper ECX
WriteBarrierHelper ESI
WriteBarrierHelper EDI
WriteBarrierHelper EBP
ByRefWriteBarrierHelper
// This is the first function outside the "keep together range". Used by BBT scripts.
LEAF_ENTRY JIT_WriteBarrierGroup_End, _TEXT
ret
LEAF_END JIT_WriteBarrierGroup_End, _TEXT
// *********************************************************************/
// In cases where we support it we have an optimized GC Poll callback.
// Normall (when we're not trying to suspend for GC, the CORINFO_HELP_POLL_GC
// helper points to this nop routine. When we're ready to suspend for GC,
// we whack the Jit Helper table entry to point to the real helper. When we're
// done with GC we whack it back.
LEAF_ENTRY JIT_PollGC_Nop, _TEXT
ret
LEAF_END JIT_PollGC_Nop, _TEXT
// *********************************************************************/
// llshl - long shift left
//
// Purpose:
// Does a Long Shift Left (signed and unsigned are identical)
// Shifts a long left any number of bits.
//
// NOTE: This routine has been adapted from the Microsoft CRTs.
//
// Entry:
// EDX:EAX - long value to be shifted
// ECX - number of bits to shift by
//
// Exit:
// EDX:EAX - shifted value
//
.align 16
LEAF_ENTRY JIT_LLsh, _TEXT
cmp ecx, 32
jae LOCAL_LABEL(LLshMORE32)
// Handle shifts of between bits 0 and 31
shld edx, eax, cl
shl eax, cl
ret
LOCAL_LABEL(LLshMORE32):
// Handle shifts of between bits 32 and 63
// The x86 shift instructions only use the lower 5 bits.
mov edx, eax
xor eax, eax
shl edx, cl
ret
LEAF_END JIT_LLsh, _TEXT
// *********************************************************************/
// LRsh - long shift right
//
// Purpose:
// Does a signed Long Shift Right
// Shifts a long right any number of bits.
//
// NOTE: This routine has been adapted from the Microsoft CRTs.
//
// Entry:
// EDX:EAX - long value to be shifted
// ECX - number of bits to shift by
//
// Exit:
// EDX:EAX - shifted value
//
.align 16
LEAF_ENTRY JIT_LRsh, _TEXT
cmp ecx, 32
jae LOCAL_LABEL(LRshMORE32)
// Handle shifts of between bits 0 and 31
shrd eax, edx, cl
sar edx, cl
ret
LOCAL_LABEL(LRshMORE32):
// Handle shifts of between bits 32 and 63
// The x86 shift instructions only use the lower 5 bits.
mov eax, edx
sar edx, 31
sar eax, cl
ret
LEAF_END JIT_LRsh, _TEXT
// *********************************************************************/
// LRsz:
// Purpose:
// Does a unsigned Long Shift Right
// Shifts a long right any number of bits.
//
// NOTE: This routine has been adapted from the Microsoft CRTs.
//
// Entry:
// EDX:EAX - long value to be shifted
// ECX - number of bits to shift by
//
// Exit:
// EDX:EAX - shifted value
//
.align 16
LEAF_ENTRY JIT_LRsz, _TEXT
cmp ecx, 32
jae LOCAL_LABEL(LRszMORE32)
// Handle shifts of between bits 0 and 31
shrd eax, edx, cl
shr edx, cl
ret
LOCAL_LABEL(LRszMORE32):
// Handle shifts of between bits 32 and 63
// The x86 shift instructions only use the lower 5 bits.
mov eax, edx
xor edx, edx
shr eax, cl
ret
LEAF_END JIT_LRsz, _TEXT
// *********************************************************************/
// JIT_Dbl2LngP4x87
//
// Purpose:
// converts a double to a long truncating toward zero (C semantics)
//
// uses stdcall calling conventions
//
// This code is faster on a P4 than the Dbl2Lng code above, but is
// slower on a PIII. Hence we choose this code when on a P4 or above.
//
LEAF_ENTRY JIT_Dbl2LngP4x87, _TEXT
// get some local space
sub esp, 8
#define arg1 [esp + 0Ch]
fld QWORD PTR arg1 // fetch arg
fnstcw WORD PTR arg1 // store FPCW
movzx eax, WORD PTR arg1 // zero extend - wide
or ah, 0Ch // turn on OE and DE flags
mov DWORD PTR [esp], eax // store new FPCW bits
fldcw WORD PTR [esp] // reload FPCW with new bits
fistp QWORD PTR [esp] // convert
// reload FP result
mov eax, DWORD PTR [esp]
mov edx, DWORD PTR [esp + 4]
// reload original FPCW value
fldcw WORD PTR arg1
#undef arg1
// restore stack
add esp, 8
ret
LEAF_END JIT_Dbl2LngP4x87, _TEXT
// *********************************************************************/
// JIT_Dbl2LngSSE3
//
// Purpose:
// converts a double to a long truncating toward zero (C semantics)
//
// uses stdcall calling conventions
//
// This code is faster than the above P4 x87 code for Intel processors
// equal or later than Core2 and Atom that have SSE3 support
//
LEAF_ENTRY JIT_Dbl2LngSSE3, _TEXT
// get some local space
sub esp, 8
fld QWORD PTR [esp + 0Ch] // fetch arg
fisttp QWORD PTR [esp] // convert
mov eax, DWORD PTR [esp] // reload FP result
mov edx, DWORD PTR [esp + 4]
// restore stack
add esp, 8
ret
LEAF_END JIT_Dbl2LngSSE3, _TEXT
// *********************************************************************/
// JIT_Dbl2IntSSE2
//
// Purpose:
// converts a double to a long truncating toward zero (C semantics)
//
// uses stdcall calling conventions
//
// This code is even faster than the P4 x87 code for Dbl2LongP4x87,
// but only returns a 32 bit value (only good for int).
//
LEAF_ENTRY JIT_Dbl2IntSSE2, _TEXT
movsd xmm0, [esp + 4]
cvttsd2si eax, xmm0
ret
LEAF_END JIT_Dbl2IntSSE2, _TEXT
// *********************************************************************/
// This is the small write barrier thunk we use when we know the
// ephemeral generation is higher in memory than older generations.
// The 0x0F0F0F0F values are bashed by the two functions above.
// This the generic version - wherever the code says ECX,
// the specific register is patched later into a copy
// Note: do not replace ECX by EAX - there is a smaller encoding for
// the compares just for EAX, which won't work for other registers.
//
// READ THIS!!!!!!
// it is imperative that the addresses of of the values that we overwrite
// (card table, ephemeral region ranges, etc) are naturally aligned since
// there are codepaths that will overwrite these values while the EE is running.
//
LEAF_ENTRY JIT_WriteBarrierReg_PreGrow, _TEXT
mov DWORD PTR [edx], ecx
cmp ecx, 0F0F0F0F0h
jb LOCAL_LABEL(NoWriteBarrierPre)
shr edx, 10
nop // padding for alignment of constant
cmp BYTE PTR [edx + 0F0F0F0F0h], 0FFh
jne LOCAL_LABEL(WriteBarrierPre)
LOCAL_LABEL(NoWriteBarrierPre):
ret
nop // padding for alignment of constant
nop // padding for alignment of constant
LOCAL_LABEL(WriteBarrierPre):
mov BYTE PTR [edx+0F0F0F0F0h], 0FFh
ret
LEAF_END JIT_WriteBarrierReg_PreGrow, _TEXT
// *********************************************************************/
// This is the larger write barrier thunk we use when we know that older
// generations may be higher in memory than the ephemeral generation
// The 0x0F0F0F0F values are bashed by the two functions above.
// This the generic version - wherever the code says ECX,
// the specific register is patched later into a copy
// Note: do not replace ECX by EAX - there is a smaller encoding for
// the compares just for EAX, which won't work for other registers.
// NOTE: we need this aligned for our validation to work properly
.align 4
LEAF_ENTRY JIT_WriteBarrierReg_PostGrow, _TEXT
mov DWORD PTR [edx], ecx
cmp ecx, 0F0F0F0F0h
jb LOCAL_LABEL(NoWriteBarrierPost)
cmp ecx, 0F0F0F0F0h
jae LOCAL_LABEL(NoWriteBarrierPost)
shr edx, 10
nop // padding for alignment of constant
cmp BYTE PTR [edx + 0F0F0F0F0h], 0FFh
jne LOCAL_LABEL(WriteBarrierPost)
LOCAL_LABEL(NoWriteBarrierPost):
ret
nop // padding for alignment of constant
nop // padding for alignment of constant
LOCAL_LABEL(WriteBarrierPost):
mov BYTE PTR [edx + 0F0F0F0F0h], 0FFh
ret
LEAF_END JIT_WriteBarrierReg_PostGrow,_TEXT
// PatchedCodeStart and PatchedCodeEnd are used to determine bounds of patched code.
//
LEAF_ENTRY JIT_PatchedCodeStart, _TEXT
ret
LEAF_END JIT_PatchedCodeStart, _TEXT
// **********************************************************************
// Write barriers generated at runtime
LEAF_ENTRY JIT_PatchedWriteBarrierGroup, _TEXT
ret
LEAF_END JIT_PatchedWriteBarrierGroup, _TEXT
.macro PatchedWriteBarrierHelper rg
.align 8
LEAF_ENTRY JIT_WriteBarrier\rg, _TEXT
// Just allocate space that will be filled in at runtime
.space 0CCH, 48
LEAF_END JIT_WriteBarrier\rg, _TEXT
.endm
PatchedWriteBarrierHelper EAX
PatchedWriteBarrierHelper EBX
PatchedWriteBarrierHelper ECX
PatchedWriteBarrierHelper ESI
PatchedWriteBarrierHelper EDI
PatchedWriteBarrierHelper EBP
// This is the first function outside the "keep together range". Used by BBT scripts.
LEAF_ENTRY JIT_PatchedWriteBarrierGroup_End, _TEXT
ret
LEAF_END JIT_PatchedWriteBarrierGroup_End, _TEXT
LEAF_ENTRY JIT_PatchedCodeLast, _TEXT
ret
LEAF_END JIT_PatchedCodeLast, _TEXT
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