/* $Id: PGMHandler.cpp 23 2007-01-15 14:08:28Z vboxsync $ */ /** @file * PGM - Page Manager / Monitor, Access Handlers. */ /* * Copyright (C) 2006 InnoTek Systemberatung GmbH * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License as published by the Free Software Foundation, * in version 2 as it comes in the "COPYING" file of the VirtualBox OSE * distribution. VirtualBox OSE is distributed in the hope that it will * be useful, but WITHOUT ANY WARRANTY of any kind. * * If you received this file as part of a commercial VirtualBox * distribution, then only the terms of your commercial VirtualBox * license agreement apply instead of the previous paragraph. */ /******************************************************************************* * Header Files * *******************************************************************************/ #define LOG_GROUP LOG_GROUP_PGM #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "PGMInternal.h" #include #include #include #include #include #include #include #include #include #include #include /******************************************************************************* * Internal Functions * *******************************************************************************/ static DECLCALLBACK(int) pgmR3HandlerPhysicalOneClear(PAVLROGCPHYSNODECORE pNode, void *pvUser); static DECLCALLBACK(int) pgmR3HandlerPhysicalOneSet(PAVLROGCPHYSNODECORE pNode, void *pvUser); static DECLCALLBACK(int) pgmR3InfoHandlersPhysicalOne(PAVLROGCPHYSNODECORE pNode, void *pvUser); static DECLCALLBACK(int) pgmR3InfoHandlersVirtualOne(PAVLROGCPTRNODECORE pNode, void *pvUser); /** * Register a access handler for a physical range. * * @returns VBox status code. * @param pVM VM handle. * @param enmType Handler type. Any of the PGMPHYSHANDLERTYPE_PHYSICAL* enums. * @param GCPhys Start physical address. * @param GCPhysLast Last physical address. (inclusive) * @param pfnHandlerR3 The R3 handler. * @param pvUserR3 User argument to the R3 handler. * @param pszModR0 The R0 handler module. NULL means default R0 module. * @param pszHandlerR0 The R0 handler symbol name. * @param pvUserR0 User argument to the R0 handler. * @param pszModGC The GC handler module. NULL means default GC module. * @param pszHandlerGC The GC handler symbol name. * @param pvUserGC User argument to the GC handler. * This must be a GC pointer because it will be relocated! * @param pszDesc Pointer to description string. This must not be freed. */ PGMR3DECL(int) PGMR3HandlerPhysicalRegister(PVM pVM, PGMPHYSHANDLERTYPE enmType, RTGCPHYS GCPhys, RTGCPHYS GCPhysLast, PFNPGMR3PHYSHANDLER pfnHandlerR3, void *pvUserR3, const char *pszModR0, const char *pszHandlerR0, RTHCPTR pvUserR0, const char *pszModGC, const char *pszHandlerGC, RTGCPTR pvUserGC, const char *pszDesc) { LogFlow(("PGMR3HandlerPhysicalRegister: enmType=%d GCPhys=%VGv GCPhysLast=%VGv pfnHandlerR3=%VHv pvUserHC=%VHv pszModGC=%p:{%s} pszHandlerGC=%p:{%s} pvUser=%VGv pszDesc=%s\n", enmType, GCPhys, GCPhysLast, pfnHandlerR3, pvUserR3, pszModGC, pszModGC, pszHandlerGC, pszHandlerGC, pvUserGC, pszDesc)); /* * Validate input. */ if (!pszModGC) pszModGC = VMMGC_MAIN_MODULE_NAME; if (!pszModR0) pszModR0 = VMMR0_MAIN_MODULE_NAME; if ( !pszModGC || !*pszModGC || !pszHandlerGC || !*pszHandlerGC || !pszModR0 || !*pszModR0 || !pszHandlerR0 || !*pszHandlerR0) { AssertMsgFailed(("pfnHandlerGC or/and pszModGC is missing\n")); return VERR_INVALID_PARAMETER; } /* * Resolve the R0 handler. */ R0PTRTYPE(PFNPGMR0PHYSHANDLER) pfnHandlerR0 = NIL_RTR0PTR; int rc = VINF_SUCCESS; if (HWACCMR3IsAllowed(pVM)) rc = PDMR3GetSymbolR0Lazy(pVM, pszModR0, pszHandlerR0, (void **)&pfnHandlerR0); if (VBOX_SUCCESS(rc)) { /* * Resolve the GC handler. */ RTGCPTR pfnHandlerGC; rc = PDMR3GetSymbolGCLazy(pVM, pszModGC, pszHandlerGC, &pfnHandlerGC); if (VBOX_SUCCESS(rc)) return PGMHandlerPhysicalRegisterEx(pVM, enmType, GCPhys, GCPhysLast, pfnHandlerR3, pvUserR3, pfnHandlerR0, pvUserR0, pfnHandlerGC, pvUserGC, pszDesc); AssertMsgFailed(("Failed to resolve %s.%s, rc=%Vrc.\n", pszModGC, pszHandlerGC, rc)); } else AssertMsgFailed(("Failed to resolve %s.%s, rc=%Vrc.\n", pszModR0, pszHandlerR0, rc)); return rc; } /** * Updates the physical page access handlers. * * @param pVM VM handle. * @remark Only used when restoring a saved state. */ void pgmR3HandlerPhysicalUpdateAll(PVM pVM) { LogFlow(("pgmHandlerPhysicalUpdateAll:\n")); /* * Clear and set. * (the right -> left on the setting pass is just bird speculating on cache hits) */ pgmLock(pVM); RTAvlroGCPhysDoWithAll(&pVM->pgm.s.CTXSUFF(pTrees)->PhysHandlers, true, pgmR3HandlerPhysicalOneClear, pVM); RTAvlroGCPhysDoWithAll(&pVM->pgm.s.CTXSUFF(pTrees)->PhysHandlers, false, pgmR3HandlerPhysicalOneSet, pVM); pgmUnlock(pVM); } /** * Clears all the page level flags for one physical handler range. * * @returns 0 * @param pNode Pointer to a PGMPHYSHANDLER. * @param pvUser VM handle. */ static DECLCALLBACK(int) pgmR3HandlerPhysicalOneClear(PAVLROGCPHYSNODECORE pNode, void *pvUser) { PPGMPHYSHANDLER pCur = (PPGMPHYSHANDLER)pNode; PPGMRAMRANGE pRamHint = NULL; RTGCPHYS GCPhys = pCur->Core.Key; RTUINT cPages = pCur->cPages; PPGM pPGM = &((PVM)pvUser)->pgm.s; for (;;) { PGMRamFlagsClearByGCPhysWithHint(pPGM, GCPhys, MM_RAM_FLAGS_PHYSICAL_HANDLER | MM_RAM_FLAGS_PHYSICAL_WRITE | MM_RAM_FLAGS_PHYSICAL_ALL, &pRamHint); if (--cPages == 0) return 0; GCPhys += PAGE_SIZE; } } /** * Sets all the page level flags for one physical handler range. * * @returns 0 * @param pNode Pointer to a PGMPHYSHANDLER. * @param pvUser VM handle. */ static DECLCALLBACK(int) pgmR3HandlerPhysicalOneSet(PAVLROGCPHYSNODECORE pNode, void *pvUser) { PPGMPHYSHANDLER pCur = (PPGMPHYSHANDLER)pNode; unsigned fFlags = pgmHandlerPhysicalCalcFlags(pCur); PPGMRAMRANGE pRamHint = NULL; RTGCPHYS GCPhys = pCur->Core.Key; RTUINT cPages = pCur->cPages; PPGM pPGM = &((PVM)pvUser)->pgm.s; for (;;) { PGMRamFlagsSetByGCPhysWithHint(pPGM, GCPhys, fFlags, &pRamHint); if (--cPages == 0) return 0; GCPhys += PAGE_SIZE; } } /** * Register a access handler for a virtual range. * * @returns VBox status code. * @param pVM VM handle. * @param enmType Handler type. Any of the PGMVIRTHANDLERTYPE_* enums. * @param GCPtr Start address. * @param GCPtrLast Last address (inclusive). * @param pfnInvalidateHC The HC invalidate callback (can be 0) * @param pfnHandlerHC The HC handler. * @param pszHandlerGC The GC handler symbol name. * @param pszModGC The GC handler module. * @param pszDesc Pointer to description string. This must not be freed. */ /** @todo rename this function to PGMR3HandlerVirtualRegister */ PGMR3DECL(int) PGMR3HandlerVirtualRegister(PVM pVM, PGMVIRTHANDLERTYPE enmType, RTGCPTR GCPtr, RTGCPTR GCPtrLast, PFNPGMHCVIRTINVALIDATE pfnInvalidateHC, PFNPGMHCVIRTHANDLER pfnHandlerHC, const char *pszHandlerGC, const char *pszModGC, const char *pszDesc) { LogFlow(("PGMR3HandlerVirtualRegisterEx: enmType=%d GCPtr=%VGv GCPtrLast=%VGv pszHandlerGC=%p:{%s} pszModGC=%p:{%s} pszDesc=%s\n", enmType, GCPtr, GCPtrLast, pszHandlerGC, pszHandlerGC, pszModGC, pszModGC, pszDesc)); /* * Validate input. */ if (!pszModGC) pszModGC = VMMGC_MAIN_MODULE_NAME; if (!pszModGC || !*pszModGC || !pszHandlerGC || !*pszHandlerGC) { AssertMsgFailed(("pfnHandlerGC or/and pszModGC is missing\n")); return VERR_INVALID_PARAMETER; } /* * Resolve the GC handler. */ RTGCPTR pfnHandlerGC; int rc = PDMR3GetSymbolGCLazy(pVM, pszModGC, pszHandlerGC, &pfnHandlerGC); if (VBOX_SUCCESS(rc)) return PGMHandlerVirtualRegisterEx(pVM, enmType, GCPtr, GCPtrLast, pfnInvalidateHC, pfnHandlerHC, pfnHandlerGC, pszDesc); AssertMsgFailed(("Failed to resolve %s.%s, rc=%Vrc.\n", pszModGC, pszHandlerGC, rc)); return rc; } /** * Register an access handler for a virtual range. * * @returns VBox status code. * @param pVM VM handle. * @param enmType Handler type. Any of the PGMVIRTHANDLERTYPE_* enums. * @param GCPtr Start address. * @param GCPtrLast Last address (inclusive). * @param pfnInvalidateHC The HC invalidate callback (can be 0) * @param pfnHandlerHC The HC handler. * @param pfnHandlerGC The GC handler. * @param pszDesc Pointer to description string. This must not be freed. */ /** @todo rename this to PGMR3HandlerVirtualRegisterEx. */ PGMDECL(int) PGMHandlerVirtualRegisterEx(PVM pVM, PGMVIRTHANDLERTYPE enmType, RTGCPTR GCPtr, RTGCPTR GCPtrLast, PFNPGMHCVIRTINVALIDATE pfnInvalidateHC, PFNPGMHCVIRTHANDLER pfnHandlerHC, RTGCPTR pfnHandlerGC, HCPTRTYPE(const char *) pszDesc) { Log(("PGMR3HandlerVirtualRegister: enmType=%d GCPtr=%RGv GCPtrLast=%RGv pfnHandlerGC=%RGv pszDesc=%s\n", enmType, GCPtr, GCPtrLast, pfnHandlerGC, pszDesc)); /* * Validate input. */ switch (enmType) { case PGMVIRTHANDLERTYPE_NORMAL: case PGMVIRTHANDLERTYPE_ALL: case PGMVIRTHANDLERTYPE_WRITE: case PGMVIRTHANDLERTYPE_EIP: if (!pfnHandlerHC) { AssertMsgFailed(("No HC handler specified!!\n")); return VERR_INVALID_PARAMETER; } break; case PGMVIRTHANDLERTYPE_HYPERVISOR: if (pfnHandlerHC) { AssertMsgFailed(("HC handler specified for hypervisor range!?!\n")); return VERR_INVALID_PARAMETER; } break; default: AssertMsgFailed(("Invalid enmType! enmType=%d\n", enmType)); return VERR_INVALID_PARAMETER; } if (GCPtrLast < GCPtr) { AssertMsgFailed(("GCPtrLast < GCPtr (%#x < %#x)\n", GCPtrLast, GCPtr)); return VERR_INVALID_PARAMETER; } if (!pfnHandlerGC) { AssertMsgFailed(("pfnHandlerGC is missing\n")); return VERR_INVALID_PARAMETER; } /* * Allocate and initialize a new entry. */ unsigned cPages = (RT_ALIGN((RTGCUINTPTR)GCPtrLast + 1, PAGE_SIZE) - ((RTGCUINTPTR)GCPtr & PAGE_BASE_GC_MASK)) >> PAGE_SHIFT; PPGMVIRTHANDLER pNew; int rc = MMHyperAlloc(pVM, RT_OFFSETOF(PGMVIRTHANDLER, aPhysToVirt[cPages]), 0, MM_TAG_PGM_HANDLERS, (void **)&pNew); /** @todo r=bird: incorrect member name PhysToVirt? */ if (VBOX_FAILURE(rc)) return rc; pNew->Core.Key = GCPtr; pNew->Core.KeyLast = GCPtrLast; pNew->enmType = enmType; pNew->pfnInvalidateHC = pfnInvalidateHC; pNew->pfnHandlerGC = pfnHandlerGC; pNew->pfnHandlerHC = pfnHandlerHC; pNew->pszDesc = pszDesc; pNew->GCPtr = GCPtr; pNew->GCPtrLast = GCPtrLast; pNew->cb = GCPtrLast - GCPtr + 1; pNew->cPages = cPages; /* Will be synced at next guest execution attempt. */ while (cPages-- > 0) { pNew->aPhysToVirt[cPages].Core.Key = NIL_RTGCPHYS; pNew->aPhysToVirt[cPages].Core.KeyLast = NIL_RTGCPHYS; pNew->aPhysToVirt[cPages].offVirtHandler = -RT_OFFSETOF(PGMVIRTHANDLER, aPhysToVirt[cPages]); pNew->aPhysToVirt[cPages].offNextAlias = 0; } /* * Try to insert it into the tree. * * The current implementation doesn't allow multiple handlers for * the same range this makes everything much simpler and faster. */ pgmLock(pVM); if (pVM->pgm.s.pTreesHC->VirtHandlers != 0) { PPGMVIRTHANDLER pCur = (PPGMVIRTHANDLER)RTAvlroGCPtrGetBestFit(&pVM->pgm.s.CTXSUFF(pTrees)->VirtHandlers, pNew->Core.Key, true); if (pCur && GCPtr <= pCur->GCPtrLast && GCPtrLast >= pCur->GCPtr) { /* * The LDT sometimes conflicts with the IDT and LDT ranges while being * updated on linux. So, we don't assert simply log it. */ Log(("PGMR3HandlerVirtualRegister: Conflict with existing range %RGv-%RGv (%s), req. %RGv-%RGv (%s)\n", pCur->GCPtr, pCur->GCPtrLast, pCur->pszDesc, GCPtr, GCPtrLast, pszDesc)); MMHyperFree(pVM, pNew); pgmUnlock(pVM); return VERR_PGM_HANDLER_VIRTUAL_CONFLICT; } } if (RTAvlroGCPtrInsert(&pVM->pgm.s.CTXSUFF(pTrees)->VirtHandlers, &pNew->Core)) { if (enmType != PGMVIRTHANDLERTYPE_HYPERVISOR) { pVM->pgm.s.fPhysCacheFlushPending = true; pVM->pgm.s.fSyncFlags |= PGM_SYNC_UPDATE_PAGE_BIT_VIRTUAL | PGM_SYNC_CLEAR_PGM_POOL; VM_FF_SET(pVM, VM_FF_PGM_SYNC_CR3); } pgmUnlock(pVM); #ifdef VBOX_WITH_STATISTICS char szPath[256]; RTStrPrintf(szPath, sizeof(szPath), "/PGM/VirtHandler/Calls/%VGv-%VGv", pNew->GCPtr, pNew->GCPtrLast); rc = STAMR3Register(pVM, &pNew->Stat, STAMTYPE_PROFILE, STAMVISIBILITY_USED, szPath, STAMUNIT_TICKS_PER_CALL, pszDesc); AssertRC(rc); #endif return VINF_SUCCESS; } pgmUnlock(pVM); AssertFailed(); MMHyperFree(pVM, pNew); return VERR_PGM_HANDLER_VIRTUAL_CONFLICT; } /** * Modify the page invalidation callback handler for a registered virtual range * (add more when needed) * * @returns VBox status code. * @param pVM VM handle. * @param GCPtr Start address. * @param pfnInvalidateHC The HC invalidate callback (can be 0) */ PGMDECL(int) PGMHandlerVirtualChangeInvalidateCallback(PVM pVM, RTGCPTR GCPtr, PFNPGMHCVIRTINVALIDATE pfnInvalidateHC) { pgmLock(pVM); PPGMVIRTHANDLER pCur = (PPGMVIRTHANDLER)RTAvlroGCPtrGet(&pVM->pgm.s.pTreesHC->VirtHandlers, GCPtr); if (pCur) { pCur->pfnInvalidateHC = pfnInvalidateHC; pgmUnlock(pVM); return VINF_SUCCESS; } pgmUnlock(pVM); AssertMsgFailed(("Range %#x not found!\n", GCPtr)); return VERR_INVALID_PARAMETER; } /** * Deregister an access handler for a virtual range. * * @returns VBox status code. * @param pVM VM handle. * @param GCPtr Start address. */ PGMDECL(int) PGMHandlerVirtualDeregister(PVM pVM, RTGCPTR GCPtr) { /* * Find the handler. * We naturally assume GCPtr is a unique specification. */ pgmLock(pVM); PPGMVIRTHANDLER pCur = (PPGMVIRTHANDLER)RTAvlroGCPtrRemove(&pVM->pgm.s.CTXSUFF(pTrees)->VirtHandlers, GCPtr); if (pCur) { Log(("PGMR3HandlerVirtualDeregister: Removing Virtual (%d) Range %#x-%#x %s\n", pCur->enmType, pCur->GCPtr, pCur->GCPtrLast, pCur->pszDesc)); /* * Reset the flags and remove phys2virt nodes. */ PPGM pPGM = &pVM->pgm.s; for (unsigned iPage = 0; iPage < pCur->cPages; iPage++) if (pCur->aPhysToVirt[iPage].offNextAlias & PGMPHYS2VIRTHANDLER_IN_TREE) pgmHandlerVirtualClearPage(pPGM, pCur, iPage); /* * Schedule CR3 sync (if required) and the memory. */ STAM_DEREG(pVM, &pCur->Stat); if (pCur->enmType != PGMVIRTHANDLERTYPE_HYPERVISOR) { pVM->pgm.s.fSyncFlags |= PGM_SYNC_UPDATE_PAGE_BIT_VIRTUAL | PGM_SYNC_CLEAR_PGM_POOL; VM_FF_SET(pVM, VM_FF_PGM_SYNC_CR3); } MMHyperFree(pVM, pCur); pgmUnlock(pVM); return VINF_SUCCESS; } pgmUnlock(pVM); AssertMsgFailed(("Range %#x not found!\n", GCPtr)); return VERR_INVALID_PARAMETER; } /** * Arguments for pgmR3InfoHandlersPhysicalOne and pgmR3InfoHandlersVirtualOne. */ typedef struct PGMHANDLERINFOARG { /** The output helpers.*/ PCDBGFINFOHLP pHlp; /** Set if statistics should be dumped. */ bool fStats; } PGMHANDLERINFOARG, *PPGMHANDLERINFOARG; /** * Info callback for 'pgmhandlers'. * * @param pHlp The output helpers. * @param pszArgs The arguments. phys or virt. */ DECLCALLBACK(void) pgmR3InfoHandlers(PVM pVM, PCDBGFINFOHLP pHlp, const char *pszArgs) { /* * Test input. */ PGMHANDLERINFOARG Args = { pHlp, true }; bool fPhysical = !pszArgs || !*pszArgs; bool fVirtual = fPhysical; if (!fPhysical) { fPhysical = strstr(pszArgs, "phys") != NULL; fVirtual = strstr(pszArgs, "virt") != NULL; Args.fStats = strstr(pszArgs, "nost") == NULL; } /* * Dump the handlers. */ if (fPhysical) { pHlp->pfnPrintf(pHlp, "Physical handlers: (PhysHandlers=%d (%#x))\n" "From - To (incl) HandlerHC UserHC HandlerGC UserGC Type Description\n", pVM->pgm.s.pTreesHC->PhysHandlers, pVM->pgm.s.pTreesHC->PhysHandlers); RTAvlroGCPhysDoWithAll(&pVM->pgm.s.pTreesHC->PhysHandlers, true, pgmR3InfoHandlersPhysicalOne, &Args); } if (fVirtual) { pHlp->pfnPrintf(pHlp, "Virtual handlers:\n" "From - To (excl) HandlerHC HandlerGC Type Description\n"); RTAvlroGCPtrDoWithAll(&pVM->pgm.s.pTreesHC->VirtHandlers, true, pgmR3InfoHandlersVirtualOne, &Args); } } /** * Displays one physical handler range. * * @returns 0 * @param pNode Pointer to a PGMPHYSHANDLER. * @param pvUser Pointer to command helper functions. */ static DECLCALLBACK(int) pgmR3InfoHandlersPhysicalOne(PAVLROGCPHYSNODECORE pNode, void *pvUser) { PPGMPHYSHANDLER pCur = (PPGMPHYSHANDLER)pNode; PPGMHANDLERINFOARG pArgs= (PPGMHANDLERINFOARG)pvUser; PCDBGFINFOHLP pHlp = pArgs->pHlp; const char *pszType; switch (pCur->enmType) { case PGMPHYSHANDLERTYPE_MMIO: pszType = "MMIO "; break; case PGMPHYSHANDLERTYPE_PHYSICAL: pszType = "Natural"; break; case PGMPHYSHANDLERTYPE_PHYSICAL_WRITE: pszType = "Write "; break; case PGMPHYSHANDLERTYPE_PHYSICAL_ALL: pszType = "All "; break; default: pszType = "????"; break; } pHlp->pfnPrintf(pHlp, "%VGp - %VGp %VHv %VHv %VGv %VGv %s %s\n", pCur->Core.Key, pCur->Core.KeyLast, pCur->pfnHandlerR3, pCur->pvUserR3, pCur->pfnHandlerGC, pCur->pvUserGC, pszType, pCur->pszDesc); #ifdef VBOX_WITH_STATISTICS if (pArgs->fStats) pHlp->pfnPrintf(pHlp, " cPeriods: %9RU64 cTicks: %11RU64 Min: %11RU64 Avg: %11RU64 Max: %11RU64\n", pCur->Stat.cPeriods, pCur->Stat.cTicks, pCur->Stat.cTicksMin, pCur->Stat.cPeriods ? pCur->Stat.cTicks / pCur->Stat.cPeriods : 0, pCur->Stat.cTicksMax); #endif return 0; } /** * Displays one virtual handler range. * * @returns 0 * @param pNode Pointer to a PGMVIRTHANDLER. * @param pvUser Pointer to command helper functions. */ static DECLCALLBACK(int) pgmR3InfoHandlersVirtualOne(PAVLROGCPTRNODECORE pNode, void *pvUser) { PPGMVIRTHANDLER pCur = (PPGMVIRTHANDLER)pNode; PPGMHANDLERINFOARG pArgs= (PPGMHANDLERINFOARG)pvUser; PCDBGFINFOHLP pHlp = pArgs->pHlp; const char *pszType; switch (pCur->enmType) { case PGMVIRTHANDLERTYPE_NORMAL: pszType = "Natural"; break; case PGMVIRTHANDLERTYPE_WRITE: pszType = "Write "; break; case PGMVIRTHANDLERTYPE_ALL: pszType = "All "; break; case PGMVIRTHANDLERTYPE_EIP: pszType = "EIP "; break; case PGMVIRTHANDLERTYPE_HYPERVISOR: pszType = "WriteHyp "; break; default: pszType = "????"; break; } pHlp->pfnPrintf(pHlp, "%08x - %08x %08x %08x %s %s\n", pCur->GCPtr, pCur->GCPtrLast, pCur->pfnHandlerHC, pCur->pfnHandlerGC, pszType, pCur->pszDesc); #ifdef VBOX_WITH_STATISTICS if (pArgs->fStats) pHlp->pfnPrintf(pHlp, " cPeriods: %9RU64 cTicks: %11RU64 Min: %11RU64 Avg: %11RU64 Max: %11RU64\n", pCur->Stat.cPeriods, pCur->Stat.cTicks, pCur->Stat.cTicksMin, pCur->Stat.cPeriods ? pCur->Stat.cTicks / pCur->Stat.cPeriods : 0, pCur->Stat.cTicksMax); #endif return 0; }