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JIT into scratch buffer (#53173)
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* Generate JITted code into a scratch buffer

Copy it to the final location after the JITing is done.

* Put also the code header and real code header into the buffer

* Disable the scratch buffer usage until we enable W^X
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@janvorli
janvorli committed May 26, 2021
1 parent b0f0868 commit dc5a1c8
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Showing 4 changed files with 182 additions and 77 deletions.
86 changes: 56 additions & 30 deletions src/coreclr/vm/codeman.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2592,18 +2592,20 @@ void* EEJitManager::allocCodeRaw(CodeHeapRequestInfo *pInfo,
RETURN(mem);
}

CodeHeader* EEJitManager::allocCode(MethodDesc* pMD, size_t blockSize, size_t reserveForJumpStubs, CorJitAllocMemFlag flag
void EEJitManager::allocCode(MethodDesc* pMD, size_t blockSize, size_t reserveForJumpStubs, CorJitAllocMemFlag flag, CodeHeader** ppCodeHeader, CodeHeader** ppCodeHeaderRW,
size_t* pAllocatedSize, HeapList** ppCodeHeap
#ifdef USE_INDIRECT_CODEHEADER
, BYTE** ppRealHeader
#endif
#ifdef FEATURE_EH_FUNCLETS
, UINT nUnwindInfos
, TADDR * pModuleBase
, UINT nUnwindInfos
#endif
)
)
{
CONTRACT(CodeHeader *) {
CONTRACTL {
THROWS;
GC_NOTRIGGER;
POSTCONDITION(CheckPointer(RETVAL));
} CONTRACT_END;
} CONTRACTL_END;

//
// Alignment
Expand Down Expand Up @@ -2636,6 +2638,7 @@ CodeHeader* EEJitManager::allocCode(MethodDesc* pMD, size_t blockSize, size_t re
SIZE_T totalSize = blockSize;

CodeHeader * pCodeHdr = NULL;
CodeHeader * pCodeHdrRW = NULL;

CodeHeapRequestInfo requestInfo(pMD);
#if defined(FEATURE_JIT_PITCHING)
Expand Down Expand Up @@ -2663,11 +2666,9 @@ CodeHeader* EEJitManager::allocCode(MethodDesc* pMD, size_t blockSize, size_t re
{
CrstHolder ch(&m_CodeHeapCritSec);

HeapList *pCodeHeap = NULL;

TADDR pCode = (TADDR) allocCodeRaw(&requestInfo, sizeof(CodeHeader), totalSize, alignment, &pCodeHeap);

_ASSERTE(pCodeHeap);
*ppCodeHeap = NULL;
TADDR pCode = (TADDR) allocCodeRaw(&requestInfo, sizeof(CodeHeader), totalSize, alignment, ppCodeHeap);
_ASSERTE(*ppCodeHeap);

if (pMD->IsLCGMethod())
{
Expand All @@ -2676,40 +2677,53 @@ CodeHeader* EEJitManager::allocCode(MethodDesc* pMD, size_t blockSize, size_t re

_ASSERTE(IS_ALIGNED(pCode, alignment));

// Initialize the CodeHeader *BEFORE* we publish this code range via the nibble
// map so that we don't have to harden readers against uninitialized data.
// However because we hold the lock, this initialization should be fast and cheap!

pCodeHdr = ((CodeHeader *)pCode) - 1;

*pAllocatedSize = sizeof(CodeHeader) + totalSize;
#ifdef FEATURE_WXORX
pCodeHdrRW = (CodeHeader *)new BYTE[*pAllocatedSize];
#else
pCodeHdrRW = pCodeHdr;
#endif

#ifdef USE_INDIRECT_CODEHEADER
if (requestInfo.IsDynamicDomain())
{
pCodeHdr->SetRealCodeHeader((BYTE*)pCode + ALIGN_UP(blockSize, sizeof(void*)));
// Set the real code header to the writeable mapping so that we can set its members via the CodeHeader methods below
pCodeHdrRW->SetRealCodeHeader((BYTE *)(pCodeHdrRW + 1) + ALIGN_UP(blockSize, sizeof(void*)));
}
else
{
// TODO: think about the CodeHeap carrying around a RealCodeHeader chunking mechanism
//
// allocate the real header in the low frequency heap
BYTE* pRealHeader = (BYTE*)(void*)pMD->GetLoaderAllocator()->GetLowFrequencyHeap()->AllocMem(S_SIZE_T(realHeaderSize));
pCodeHdr->SetRealCodeHeader(pRealHeader);
pCodeHdrRW->SetRealCodeHeader(pRealHeader);
}
#endif

pCodeHdr->SetDebugInfo(NULL);
pCodeHdr->SetEHInfo(NULL);
pCodeHdr->SetGCInfo(NULL);
pCodeHdr->SetMethodDesc(pMD);
pCodeHdrRW->SetDebugInfo(NULL);
pCodeHdrRW->SetEHInfo(NULL);
pCodeHdrRW->SetGCInfo(NULL);
pCodeHdrRW->SetMethodDesc(pMD);
#ifdef FEATURE_EH_FUNCLETS
pCodeHdr->SetNumberOfUnwindInfos(nUnwindInfos);
*pModuleBase = pCodeHeap->GetModuleBase();
pCodeHdrRW->SetNumberOfUnwindInfos(nUnwindInfos);
#endif

NibbleMapSet(pCodeHeap, pCode, TRUE);
#ifdef USE_INDIRECT_CODEHEADER
if (requestInfo.IsDynamicDomain())
{
*ppRealHeader = (BYTE*)pCode + ALIGN_UP(blockSize, sizeof(void*));
}
else
{
*ppRealHeader = NULL;
}
#endif // USE_INDIRECT_CODEHEADER
}

RETURN(pCodeHdr);
*ppCodeHeader = pCodeHdr;
*ppCodeHeaderRW = pCodeHdrRW;
}

EEJitManager::DomainCodeHeapList *EEJitManager::GetCodeHeapList(CodeHeapRequestInfo *pInfo, LoaderAllocator *pAllocator, BOOL fDynamicOnly)
Expand Down Expand Up @@ -2995,7 +3009,7 @@ JumpStubBlockHeader * EEJitManager::allocJumpStubBlock(MethodDesc* pMD, DWORD n
CodeHeader * pCodeHdr = (CodeHeader *) (mem - sizeof(CodeHeader));
pCodeHdr->SetStubCodeBlockKind(STUB_CODE_BLOCK_JUMPSTUB);

NibbleMapSet(pCodeHeap, mem, TRUE);
NibbleMapSetUnlocked(pCodeHeap, mem, TRUE);

pBlock = (JumpStubBlockHeader *)mem;

Expand Down Expand Up @@ -3046,7 +3060,7 @@ void * EEJitManager::allocCodeFragmentBlock(size_t blockSize, unsigned alignment
CodeHeader * pCodeHdr = (CodeHeader *) (mem - sizeof(CodeHeader));
pCodeHdr->SetStubCodeBlockKind(kind);

NibbleMapSet(pCodeHeap, mem, TRUE);
NibbleMapSetUnlocked(pCodeHeap, mem, TRUE);

// Record the jump stub reservation
pCodeHeap->reserveForJumpStubs += requestInfo.getReserveForJumpStubs();
Expand Down Expand Up @@ -3224,7 +3238,7 @@ void EEJitManager::RemoveJitData (CodeHeader * pCHdr, size_t GCinfo_len, size_t
if (pHp == NULL)
return;

NibbleMapSet(pHp, (TADDR)(pCHdr + 1), FALSE);
NibbleMapSetUnlocked(pHp, (TADDR)(pCHdr + 1), FALSE);
}

// Backout the GCInfo
Expand Down Expand Up @@ -3386,7 +3400,7 @@ void EEJitManager::FreeCodeMemory(HostCodeHeap *pCodeHeap, void * codeStart)
// so pCodeHeap can only be a HostCodeHeap.

// clean up the NibbleMap
NibbleMapSet(pCodeHeap->m_pHeapList, (TADDR)codeStart, FALSE);
NibbleMapSetUnlocked(pCodeHeap->m_pHeapList, (TADDR)codeStart, FALSE);

// The caller of this method doesn't call HostCodeHeap->FreeMemForCode
// directly because the operation should be protected by m_CodeHeapCritSec.
Expand Down Expand Up @@ -3850,13 +3864,25 @@ TADDR EEJitManager::FindMethodCode(RangeSection * pRangeSection, PCODE currentPC
}

#if !defined(DACCESS_COMPILE)

void EEJitManager::NibbleMapSet(HeapList * pHp, TADDR pCode, BOOL bSet)
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
} CONTRACTL_END;

CrstHolder ch(&m_CodeHeapCritSec);
NibbleMapSetUnlocked(pHp, pCode, bSet);
}

void EEJitManager::NibbleMapSetUnlocked(HeapList * pHp, TADDR pCode, BOOL bSet)
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
} CONTRACTL_END;

// Currently all callers to this method ensure EEJitManager::m_CodeHeapCritSec
// is held.
_ASSERTE(m_CodeHeapCritSec.OwnedByCurrentThread());
Expand Down
18 changes: 11 additions & 7 deletions src/coreclr/vm/codeman.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -461,9 +461,9 @@ class CodeHeap
// The number of code heaps at which we increase the size of new code heaps.
#define CODE_HEAP_SIZE_INCREASE_THRESHOLD 5

typedef DPTR(struct _HeapList) PTR_HeapList;
typedef DPTR(struct HeapList) PTR_HeapList;

typedef struct _HeapList
struct HeapList
{
PTR_HeapList hpNext;

Expand Down Expand Up @@ -497,7 +497,7 @@ typedef struct _HeapList
void SetNext(PTR_HeapList next)
{ hpNext = next; }

} HeapList;
};

//-----------------------------------------------------------------------------
// Implementation of the standard CodeHeap.
Expand Down Expand Up @@ -974,12 +974,15 @@ class EEJitManager : public IJitManager

BOOL LoadJIT();

CodeHeader* allocCode(MethodDesc* pFD, size_t blockSize, size_t reserveForJumpStubs, CorJitAllocMemFlag flag
void allocCode(MethodDesc* pFD, size_t blockSize, size_t reserveForJumpStubs, CorJitAllocMemFlag flag, CodeHeader** ppCodeHeader, CodeHeader** ppCodeHeaderRW,
size_t* pAllocatedSize, HeapList** ppCodeHeap
#ifdef USE_INDIRECT_CODEHEADER
, BYTE** ppRealHeader
#endif
#ifdef FEATURE_EH_FUNCLETS
, UINT nUnwindInfos
, TADDR * pModuleBase
, UINT nUnwindInfos
#endif
);
);
BYTE * allocGCInfo(CodeHeader* pCodeHeader, DWORD blockSize, size_t * pAllocationSize);
EE_ILEXCEPTION* allocEHInfo(CodeHeader* pCodeHeader, unsigned numClauses, size_t * pAllocationSize);
JumpStubBlockHeader* allocJumpStubBlock(MethodDesc* pMD, DWORD numJumps,
Expand Down Expand Up @@ -1024,6 +1027,7 @@ class EEJitManager : public IJitManager
#ifndef DACCESS_COMPILE
// Heap Management functions
void NibbleMapSet(HeapList * pHp, TADDR pCode, BOOL bSet);
void NibbleMapSetUnlocked(HeapList * pHp, TADDR pCode, BOOL bSet);
#endif // !DACCESS_COMPILE

static TADDR FindMethodCode(RangeSection * pRangeSection, PCODE currentPC);
Expand Down
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