path: root/src/VBox/VMM/PDMLdr.cpp

/* $Id: PDMLdr.cpp 28800 2010-04-27 08:22:32Z vboxsync $ */
/** @file
 * PDM - Pluggable Device Manager, module loader.
 */

/*
 * Copyright (C) 2006-2007 Oracle Corporation
 *
 * 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 (GPL) 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.
 */

//#define PDMLDR_FAKE_MODE

/*******************************************************************************
*   Header Files                                                               *
*******************************************************************************/
#define LOG_GROUP LOG_GROUP_PDM_LDR
#include "PDMInternal.h"
#include <VBox/pdm.h>
#include <VBox/mm.h>
#include <VBox/vmm.h>
#include <VBox/vm.h>
#include <VBox/uvm.h>
#include <VBox/sup.h>
#include <VBox/param.h>
#include <VBox/err.h>
#include <VBox/hwaccm.h>

#include <VBox/log.h>
#include <iprt/assert.h>
#include <iprt/alloc.h>
#include <iprt/ldr.h>
#include <iprt/path.h>
#include <iprt/string.h>

#include <limits.h>


/*******************************************************************************
*   Structures and Typedefs                                                    *
*******************************************************************************/
/**
 * Structure which the user argument of the RTLdrGetBits() callback points to.
 * @internal
 */
typedef struct PDMGETIMPORTARGS
{
    PVM         pVM;
    PPDMMOD     pModule;
} PDMGETIMPORTARGS, *PPDMGETIMPORTARGS;


/*******************************************************************************
*   Internal Functions                                                         *
*******************************************************************************/
static DECLCALLBACK(int) pdmR3GetImportRC(RTLDRMOD hLdrMod, const char *pszModule, const char *pszSymbol, unsigned uSymbol, RTUINTPTR *pValue, void *pvUser);
static int      pdmR3LoadR0U(PUVM pUVM, const char *pszFilename, const char *pszName);
static char *   pdmR3FileRC(const char *pszFile);
static char *   pdmR3FileR0(const char *pszFile);
static char *   pdmR3File(const char *pszFile, const char *pszDefaultExt, bool fShared);
static DECLCALLBACK(int) pdmR3QueryModFromEIPEnumSymbols(RTLDRMOD hLdrMod, const char *pszSymbol, unsigned uSymbol, RTUINTPTR Value, void *pvUser);



/**
 * Loads the VMMR0.r0 module early in the init process.
 *
 * @returns VBox status code.
 * @param   pUVM            Pointer to the user mode VM structure.
 */
VMMR3DECL(int) PDMR3LdrLoadVMMR0U(PUVM pUVM)
{
    return pdmR3LoadR0U(pUVM, NULL, VMMR0_MAIN_MODULE_NAME);
}


/**
 * Init the module loader part of PDM.
 *
 * This routine will load the Host Context Ring-0 and Guest
 * Context VMM modules.
 *
 * @returns VBox stutus code.
 * @param   pUVM        Pointer to the user mode VM structure.
 * @param   pvVMMR0Mod  The opqaue returned by PDMR3LdrLoadVMMR0.
 */
int pdmR3LdrInitU(PUVM pUVM)
{
#if defined(PDMLDR_FAKE_MODE) || !defined(VBOX_WITH_RAW_MODE)
    return VINF_SUCCESS;

#else

    /*
     * Load the mandatory GC module, the VMMR0.r0 is loaded before VM creation.
     */
    return PDMR3LdrLoadRC(pUVM->pVM, NULL, VMMGC_MAIN_MODULE_NAME);
#endif
}


/**
 * Terminate the module loader part of PDM.
 *
 * This will unload and free all modules.
 *
 * @param   pVM         The VM handle.
 *
 * @remarks This is normally called twice during termination.
 */
void pdmR3LdrTermU(PUVM pUVM)
{
    /*
     * Free the modules.
     */
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    PPDMMOD pModule = pUVM->pdm.s.pModules;
    pUVM->pdm.s.pModules = NULL;
    while (pModule)
    {
        /* free loader item. */
        if (pModule->hLdrMod != NIL_RTLDRMOD)
        {
            int rc2 = RTLdrClose(pModule->hLdrMod);
            AssertRC(rc2);
            pModule->hLdrMod = NIL_RTLDRMOD;
        }

        /* free bits. */
        switch (pModule->eType)
        {
            case PDMMOD_TYPE_R0:
            {
                Assert(pModule->ImageBase);
                int rc2 = SUPR3FreeModule((void *)(uintptr_t)pModule->ImageBase);
                AssertRC(rc2);
                pModule->ImageBase = 0;
                break;
            }

#ifdef VBOX_WITH_RAW_MODE
            case PDMMOD_TYPE_RC:
#endif
            case PDMMOD_TYPE_R3:
                /* MM will free this memory for us - it's alloc only memory. :-) */
                break;

            default:
                AssertMsgFailed(("eType=%d\n", pModule->eType));
                break;
        }
        pModule->pvBits = NULL;

        void    *pvFree = pModule;
        pModule = pModule->pNext;
        RTMemFree(pvFree);
    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
}


/**
 * Applies relocations to GC modules.
 *
 * This must be done very early in the relocation
 * process so that components can resolve GC symbols during relocation.
 *
 * @param   pUVM        Pointer to the user mode VM structure.
 * @param   offDelta    Relocation delta relative to old location.
 */
VMMR3DECL(void) PDMR3LdrRelocateU(PUVM pUVM, RTGCINTPTR offDelta)
{
#ifdef VBOX_WITH_RAW_MODE
    LogFlow(("PDMR3LdrRelocate: offDelta=%RGv\n", offDelta));

    /*
     * GC Modules.
     */
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    if (pUVM->pdm.s.pModules)
    {
        /*
         * The relocation have to be done in two passes so imports
         * can be correctely resolved. The first pass will update
         * the ImageBase saving the current value in OldImageBase.
         * The second pass will do the actual relocation.
         */
        /* pass 1 */
        PPDMMOD pCur;
        for (pCur = pUVM->pdm.s.pModules; pCur; pCur = pCur->pNext)
        {
            if (pCur->eType == PDMMOD_TYPE_RC)
            {
                pCur->OldImageBase = pCur->ImageBase;
                pCur->ImageBase = MMHyperR3ToRC(pUVM->pVM, pCur->pvBits);
            }
        }

        /* pass 2 */
        for (pCur = pUVM->pdm.s.pModules; pCur; pCur = pCur->pNext)
        {
            if (pCur->eType == PDMMOD_TYPE_RC)
            {
                PDMGETIMPORTARGS Args;
                Args.pVM = pUVM->pVM;
                Args.pModule = pCur;
                int rc = RTLdrRelocate(pCur->hLdrMod, pCur->pvBits, pCur->ImageBase, pCur->OldImageBase,
                                       pdmR3GetImportRC, &Args);
                AssertFatalMsgRC(rc, ("RTLdrRelocate failed, rc=%d\n", rc));
                DBGFR3ModuleRelocate(pUVM->pVM, pCur->OldImageBase, pCur->ImageBase, RTLdrSize(pCur->hLdrMod),
                                     pCur->szFilename, pCur->szName);
            }
        }
    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
#endif
}


/**
 * Loads a module into the host context ring-3.
 *
 * This is used by the driver and device init functions to load modules
 * containing the drivers and devices. The function can be extended to
 * load modules which are not native to the environment we're running in,
 * but at the moment this is not required.
 *
 * No reference counting is kept, since we don't implement any facilities
 * for unloading the module. But the module will naturally be released
 * when the VM terminates.
 *
 * @returns VBox status code.
 * @param   pUVM            Pointer to the user mode VM structure.
 * @param   pszFilename     Filename of the module binary.
 * @param   pszName         Module name. Case sensitive and the length is limited!
 */
int pdmR3LoadR3U(PUVM pUVM, const char *pszFilename, const char *pszName)
{
    /*
     * Validate input.
     */
    AssertMsg(pUVM->pVM->pdm.s.offVM, ("bad init order!\n"));
    Assert(pszFilename);
    size_t cchFilename = strlen(pszFilename);
    Assert(pszName);
    size_t cchName = strlen(pszName);
    PPDMMOD  pCur;
    if (cchName >= sizeof(pCur->szName))
    {
        AssertMsgFailed(("Name is too long, cchName=%d pszName='%s'\n", cchName, pszName));
        return VERR_INVALID_PARAMETER;
    }

    /*
     * Try lookup the name and see if the module exists.
     */
    int rc;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    for (pCur = pUVM->pdm.s.pModules; pCur; pCur = pCur->pNext)
    {
        if (!strcmp(pCur->szName, pszName))
        {
            if (pCur->eType == PDMMOD_TYPE_R3)
                rc = VINF_PDM_ALREADY_LOADED;
            else
                rc = VERR_PDM_MODULE_NAME_CLASH;
            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);

            AssertMsgRC(rc, ("We've already got a module '%s' loaded!\n", pszName));
            return rc;
        }
    }

    /*
     * Allocate the module list node and initialize it.
     */
    const char *pszSuff = RTLdrGetSuff();
    size_t      cchSuff = RTPathHaveExt(pszFilename) ? 0 : strlen(pszSuff);
    PPDMMOD     pModule = (PPDMMOD)RTMemAllocZ(RT_OFFSETOF(PDMMOD, szFilename[cchFilename + cchSuff + 1]));
    if (pModule)
    {
        pModule->eType = PDMMOD_TYPE_R3;
        memcpy(pModule->szName, pszName, cchName); /* memory is zero'ed, no need to copy terminator :-) */
        memcpy(pModule->szFilename, pszFilename, cchFilename);
        memcpy(&pModule->szFilename[cchFilename], pszSuff, cchSuff);

        /*
         * Load the loader item.
         */
        rc = SUPR3HardenedVerifyFile(pModule->szFilename, "pdmR3LoadR3U", NULL);
        if (RT_SUCCESS(rc))
            rc = RTLdrLoad(pModule->szFilename, &pModule->hLdrMod);
        if (RT_SUCCESS(rc))
        {
            pModule->pNext = pUVM->pdm.s.pModules;
            pUVM->pdm.s.pModules = pModule;
        }
        else
        {
            /* Something went wrong, most likely module not found. Don't consider other unlikely errors */
            rc = VMSetError(pUVM->pVM, rc, RT_SRC_POS, N_("Unable to load R3 module %s (%s)"), pModule->szFilename, pszName);
            RTMemFree(pModule);
        }
    }
    else
        rc = VERR_NO_MEMORY;

    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    return rc;
}


#ifdef VBOX_WITH_RAW_MODE
/**
 * Resolve an external symbol during RTLdrGetBits() of a RC module.
 *
 * @returns VBox status code.
 * @param   hLdrMod         The loader module handle.
 * @param   pszModule       Module name.
 * @param   pszSymbol       Symbol name, NULL if uSymbol should be used.
 * @param   uSymbol         Symbol ordinal, ~0 if pszSymbol should be used.
 * @param   pValue          Where to store the symbol value (address).
 * @param   pvUser          User argument.
 */
static DECLCALLBACK(int) pdmR3GetImportRC(RTLDRMOD hLdrMod, const char *pszModule, const char *pszSymbol, unsigned uSymbol, RTUINTPTR *pValue, void *pvUser)
{
    PVM         pVM     = ((PPDMGETIMPORTARGS)pvUser)->pVM;
    PPDMMOD     pModule = ((PPDMGETIMPORTARGS)pvUser)->pModule;

    /*
     * Adjust input.
     */
    if (pszModule && !*pszModule)
        pszModule = NULL;

    /*
     * Builtin module.
     */
    if (!pszModule || !strcmp(pszModule, "VMMGCBuiltin.gc"))
    {
        int rc = VINF_SUCCESS;
        if (!strcmp(pszSymbol, "g_VM"))
            *pValue = pVM->pVMRC;
        else if (!strcmp(pszSymbol, "g_CPUM"))
            *pValue = VM_RC_ADDR(pVM, &pVM->cpum);
        else if (!strcmp(pszSymbol, "g_TRPM"))
            *pValue = VM_RC_ADDR(pVM, &pVM->trpm);
        else if (!strcmp(pszSymbol, "g_TRPMCPU"))
            *pValue = VM_RC_ADDR(pVM, &pVM->aCpus[0].trpm);
        else if (   !strncmp(pszSymbol, "VMM", 3)
                 || !strcmp(pszSymbol, "g_Logger")
                 || !strcmp(pszSymbol, "g_RelLogger"))
        {
            RTRCPTR RCPtr = 0;
            rc = VMMR3GetImportRC(pVM, pszSymbol, &RCPtr);
            if (RT_SUCCESS(rc))
                *pValue = RCPtr;
        }
        else if (   !strncmp(pszSymbol, "TM", 2)
                 || !strcmp(pszSymbol, "g_pSUPGlobalInfoPage"))
        {
            RTRCPTR RCPtr = 0;
            rc = TMR3GetImportRC(pVM, pszSymbol, &RCPtr);
            if (RT_SUCCESS(rc))
                *pValue = RCPtr;
        }
        else
        {
            AssertMsg(!pszModule, ("Unknown builtin symbol '%s' for module '%s'!\n", pszSymbol, pModule->szName)); NOREF(pModule);
            rc = VERR_SYMBOL_NOT_FOUND;
        }
        if (RT_SUCCESS(rc) || pszModule)
            return rc;
    }

    /*
     * Search for module.
     */
    PUVM     pUVM = pVM->pUVM;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    PPDMMOD  pCur = pUVM->pdm.s.pModules;
    while (pCur)
    {
        if (    pCur->eType == PDMMOD_TYPE_RC
            &&  (   !pszModule
                 || !strcmp(pCur->szName, pszModule))
           )
        {
            /* Search for the symbol. */
            int rc = RTLdrGetSymbolEx(pCur->hLdrMod, pCur->pvBits, pCur->ImageBase, pszSymbol, pValue);
            if (RT_SUCCESS(rc))
            {
                AssertMsg(*pValue - pCur->ImageBase < RTLdrSize(pCur->hLdrMod),
                          ("%RRv-%RRv %s %RRv\n", (RTRCPTR)pCur->ImageBase,
                           (RTRCPTR)(pCur->ImageBase + RTLdrSize(pCur->hLdrMod) - 1),
                           pszSymbol, (RTRCPTR)*pValue));
                RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
                return rc;
            }
            if (pszModule)
            {
                RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
                AssertMsgFailed(("Couldn't find symbol '%s' in module '%s'!\n", pszSymbol, pszModule));
                LogRel(("PDMLdr: Couldn't find symbol '%s' in module '%s'!\n", pszSymbol, pszModule));
                return VERR_SYMBOL_NOT_FOUND;
            }
        }

        /* next */
        pCur = pCur->pNext;
    }

    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    AssertMsgFailed(("Couldn't find module '%s' for resolving symbol '%s'!\n", pszModule, pszSymbol));
    return VERR_SYMBOL_NOT_FOUND;
}


/**
 * Loads a module into the guest context (i.e. into the Hypervisor memory region).
 *
 * @returns VBox status code.
 * @param   pVM             The VM to load it into.
 * @param   pszFilename     Filename of the module binary.
 * @param   pszName         Module name. Case sensitive and the length is limited!
 */
VMMR3DECL(int) PDMR3LdrLoadRC(PVM pVM, const char *pszFilename, const char *pszName)
{
    /*
     * Validate input.
     */
    AssertMsg(pVM->pdm.s.offVM, ("bad init order!\n"));
    PUVM     pUVM = pVM->pUVM;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    PPDMMOD  pCur = pUVM->pdm.s.pModules;
    while (pCur)
    {
        if (!strcmp(pCur->szName, pszName))
        {
            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
            AssertMsgFailed(("We've already got a module '%s' loaded!\n", pszName));
            return VERR_PDM_MODULE_NAME_CLASH;
        }
        /* next */
        pCur = pCur->pNext;
    }

    /*
     * Find the file if not specified.
     */
    char *pszFile = NULL;
    if (!pszFilename)
        pszFilename = pszFile = pdmR3FileRC(pszName);

    /*
     * Allocate the module list node.
     */
    PPDMMOD     pModule = (PPDMMOD)RTMemAllocZ(sizeof(*pModule) + strlen(pszFilename));
    if (!pModule)
    {
        RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
        RTMemTmpFree(pszFile);
        return VERR_NO_MEMORY;
    }
    AssertMsg(strlen(pszName) + 1 < sizeof(pModule->szName),
              ("pazName is too long (%d chars) max is %d chars.\n", strlen(pszName), sizeof(pModule->szName) - 1));
    strcpy(pModule->szName, pszName);
    pModule->eType = PDMMOD_TYPE_RC;
    strcpy(pModule->szFilename, pszFilename);


    /*
     * Open the loader item.
     */
    int rc = SUPR3HardenedVerifyFile(pszFilename, "PDMR3LdrLoadRC", NULL);
    if (RT_SUCCESS(rc))
        rc = RTLdrOpen(pszFilename, 0, RTLDRARCH_X86_32, &pModule->hLdrMod);
    if (RT_SUCCESS(rc))
    {
        /*
         * Allocate space in the hypervisor.
         */
        size_t          cb = RTLdrSize(pModule->hLdrMod);
        cb = RT_ALIGN_Z(cb, PAGE_SIZE);
        uint32_t        cPages = (uint32_t)(cb >> PAGE_SHIFT);
        if (((size_t)cPages << PAGE_SHIFT) == cb)
        {
            PSUPPAGE    paPages = (PSUPPAGE)RTMemTmpAlloc(cPages * sizeof(paPages[0]));
            if (paPages)
            {
                rc = SUPR3PageAllocEx(cPages, 0 /*fFlags*/, &pModule->pvBits, NULL /*pR0Ptr*/, paPages);
                if (RT_SUCCESS(rc))
                {
                    RTGCPTR GCPtr;
                    rc = MMR3HyperMapPages(pVM, pModule->pvBits, NIL_RTR0PTR,
                                           cPages, paPages, pModule->szName, &GCPtr);
                    if (RT_SUCCESS(rc))
                    {
                        MMR3HyperReserve(pVM, PAGE_SIZE, "fence", NULL);

                        /*
                         * Get relocated image bits.
                         */
                        Assert(MMHyperR3ToRC(pVM, pModule->pvBits) == GCPtr);
                        pModule->ImageBase = GCPtr;
                        PDMGETIMPORTARGS Args;
                        Args.pVM = pVM;
                        Args.pModule = pModule;
                        rc = RTLdrGetBits(pModule->hLdrMod, pModule->pvBits, pModule->ImageBase, pdmR3GetImportRC, &Args);
                        if (RT_SUCCESS(rc))
                        {
                            /*
                             * Insert the module.
                             */
                            if (pUVM->pdm.s.pModules)
                            {
                                /* we don't expect this list to be very long, so rather save the tail pointer. */
                                pCur = pUVM->pdm.s.pModules;
                                while (pCur->pNext)
                                    pCur = pCur->pNext;
                                pCur->pNext = pModule;
                            }
                            else
                                pUVM->pdm.s.pModules = pModule; /* (pNext is zeroed by alloc) */
                            Log(("PDM: RC Module at %RRv %s (%s)\n", (RTRCPTR)pModule->ImageBase, pszName, pszFilename));
                            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
                            RTMemTmpFree(pszFile);
                            RTMemTmpFree(paPages);
                            return VINF_SUCCESS;
                        }
                    }
                    else
                    {
                        AssertRC(rc);
                        SUPR3PageFreeEx(pModule->pvBits, cPages);
                    }
                }
                else
                    AssertMsgFailed(("SUPR3PageAlloc(%d,) -> %Rrc\n", cPages, rc));
                RTMemTmpFree(paPages);
            }
            else
                rc = VERR_NO_TMP_MEMORY;
        }
        else
            rc = VERR_OUT_OF_RANGE;
        int rc2 = RTLdrClose(pModule->hLdrMod);
        AssertRC(rc2);
    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);

    /* Don't consider VERR_PDM_MODULE_NAME_CLASH and VERR_NO_MEMORY above as these are very unlikely. */
    if (RT_FAILURE(rc))
        rc = VMSetError(pVM, rc, RT_SRC_POS, N_("Cannot load GC module %s"), pszFilename);

    RTMemFree(pModule);
    RTMemTmpFree(pszFile);
    return rc;
}
#endif /* VBOX_WITH_RAW_MODE */


/**
 * Loads a module into the ring-0 context.
 *
 * @returns VBox status code.
 * @param   pUVM            Pointer to the user mode VM structure.
 * @param   pszFilename     Filename of the module binary.
 * @param   pszName         Module name. Case sensitive and the length is limited!
 */
static int pdmR3LoadR0U(PUVM pUVM, const char *pszFilename, const char *pszName)
{
    /*
     * Validate input.
     */
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    PPDMMOD pCur = pUVM->pdm.s.pModules;
    while (pCur)
    {
        if (!strcmp(pCur->szName, pszName))
        {
            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
            AssertMsgFailed(("We've already got a module '%s' loaded!\n", pszName));
            return VERR_PDM_MODULE_NAME_CLASH;
        }
        /* next */
        pCur = pCur->pNext;
    }

    /*
     * Find the file if not specified.
     */
    char *pszFile = NULL;
    if (!pszFilename)
        pszFilename = pszFile = pdmR3FileR0(pszName);

    /*
     * Allocate the module list node.
     */
    PPDMMOD     pModule = (PPDMMOD)RTMemAllocZ(sizeof(*pModule) + strlen(pszFilename));
    if (!pModule)
    {
        RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
        RTMemTmpFree(pszFile);
        return VERR_NO_MEMORY;
    }
    AssertMsg(strlen(pszName) + 1 < sizeof(pModule->szName),
              ("pazName is too long (%d chars) max is %d chars.\n", strlen(pszName), sizeof(pModule->szName) - 1));
    strcpy(pModule->szName, pszName);
    pModule->eType = PDMMOD_TYPE_R0;
    strcpy(pModule->szFilename, pszFilename);

    /*
     * Ask the support library to load it.
     */
    void *pvImageBase;
    int rc = SUPR3LoadModule(pszFilename, pszName, &pvImageBase);
    if (RT_SUCCESS(rc))
    {
        pModule->hLdrMod = NIL_RTLDRMOD;
        pModule->ImageBase = (uintptr_t)pvImageBase;

        /*
         * Insert the module.
         */
        if (pUVM->pdm.s.pModules)
        {
            /* we don't expect this list to be very long, so rather save the tail pointer. */
            pCur = pUVM->pdm.s.pModules;
            while (pCur->pNext)
                pCur = pCur->pNext;
            pCur->pNext = pModule;
        }
        else
            pUVM->pdm.s.pModules = pModule; /* (pNext is zeroed by alloc) */
        Log(("PDM: R0 Module at %RHv %s (%s)\n", (RTR0PTR)pModule->ImageBase, pszName, pszFilename));
        RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
        RTMemTmpFree(pszFile);
        return VINF_SUCCESS;
    }

    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    RTMemFree(pModule);
    LogRel(("pdmR3LoadR0U: pszName=\"%s\" rc=%Rrc\n", pszName, rc));

    /* Don't consider VERR_PDM_MODULE_NAME_CLASH and VERR_NO_MEMORY above as these are very unlikely. */
    if (RT_FAILURE(rc) && pUVM->pVM) /** @todo VMR3SetErrorU. */
        rc = VMSetError(pUVM->pVM, rc, RT_SRC_POS, N_("Cannot load R0 module %s"), pszFilename);

    RTMemTmpFree(pszFile); /* might be reference thru pszFilename in the above VMSetError call. */
    return rc;
}



/**
 * Get the address of a symbol in a given HC ring 3 module.
 *
 * @returns VBox status code.
 * @param   pVM             VM handle.
 * @param   pszModule       Module name.
 * @param   pszSymbol       Symbol name. If it's value is less than 64k it's treated like a
 *                          ordinal value rather than a string pointer.
 * @param   ppvValue        Where to store the symbol value.
 */
VMMR3DECL(int) PDMR3LdrGetSymbolR3(PVM pVM, const char *pszModule, const char *pszSymbol, void **ppvValue)
{
    /*
     * Validate input.
     */
    AssertMsg(pVM->pdm.s.offVM, ("bad init order!\n"));

    /*
     * Find the module.
     */
    PUVM pUVM = pVM->pUVM;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    for (PPDMMOD pModule = pUVM->pdm.s.pModules; pModule; pModule = pModule->pNext)
    {
        if (    pModule->eType == PDMMOD_TYPE_R3
            &&  !strcmp(pModule->szName, pszModule))
        {
            RTUINTPTR Value = 0;
            int rc = RTLdrGetSymbolEx(pModule->hLdrMod, pModule->pvBits, pModule->ImageBase, pszSymbol, &Value);
            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
            if (RT_SUCCESS(rc))
            {
                *ppvValue = (void *)(uintptr_t)Value;
                Assert((uintptr_t)*ppvValue == Value);
            }
            else
            {
                if ((uintptr_t)pszSymbol < 0x10000)
                    AssertMsg(rc, ("Couldn't symbol '%u' in module '%s'\n", (unsigned)(uintptr_t)pszSymbol, pszModule));
                else
                    AssertMsg(rc, ("Couldn't symbol '%s' in module '%s'\n", pszSymbol, pszModule));
            }
            return rc;
        }
    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    AssertMsgFailed(("Couldn't locate module '%s'\n", pszModule));
    return VERR_SYMBOL_NOT_FOUND;
}


/**
 * Get the address of a symbol in a given HC ring 0 module.
 *
 * @returns VBox status code.
 * @param   pVM             VM handle.
 * @param   pszModule       Module name. If NULL the main R0 module (VMMR0.r0) is assumes.
 * @param   pszSymbol       Symbol name. If it's value is less than 64k it's treated like a
 *                          ordinal value rather than a string pointer.
 * @param   ppvValue        Where to store the symbol value.
 */
VMMR3DECL(int) PDMR3LdrGetSymbolR0(PVM pVM, const char *pszModule, const char *pszSymbol, PRTR0PTR ppvValue)
{
#ifdef PDMLDR_FAKE_MODE
    *ppvValue = 0xdeadbeef;
    return VINF_SUCCESS;

#else
    /*
     * Validate input.
     */
    AssertMsg(pVM->pdm.s.offVM, ("bad init order!\n"));
    if (!pszModule)
        pszModule = "VMMR0.r0";

    /*
     * Find the module.
     */
    PUVM pUVM = pVM->pUVM;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    for (PPDMMOD pModule = pUVM->pdm.s.pModules; pModule; pModule = pModule->pNext)
    {
        if (    pModule->eType == PDMMOD_TYPE_R0
            &&  !strcmp(pModule->szName, pszModule))
        {
            int rc = SUPR3GetSymbolR0((void *)(uintptr_t)pModule->ImageBase, pszSymbol, (void **)ppvValue);
            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
            if (RT_FAILURE(rc))
            {
                AssertMsgRC(rc, ("Couldn't find symbol '%s' in module '%s'\n", pszSymbol, pszModule));
                LogRel(("PDMGetSymbol: Couldn't find symbol '%s' in module '%s'\n", pszSymbol, pszModule));
            }
            return rc;
        }
    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    AssertMsgFailed(("Couldn't locate module '%s'\n", pszModule));
    return VERR_SYMBOL_NOT_FOUND;
#endif
}


/**
 * Same as PDMR3LdrGetSymbolR0 except that the module will be attempted loaded if not found.
 *
 * @returns VBox status code.
 * @param   pVM             VM handle.
 * @param   pszModule       Module name. If NULL the main R0 module (VMMR0.r0) is assumed.
 * @param   pszSymbol       Symbol name. If it's value is less than 64k it's treated like a
 *                          ordinal value rather than a string pointer.
 * @param   ppvValue        Where to store the symbol value.
 */
VMMR3DECL(int) PDMR3LdrGetSymbolR0Lazy(PVM pVM, const char *pszModule, const char *pszSymbol, PRTR0PTR ppvValue)
{
#ifdef PDMLDR_FAKE_MODE
    *ppvValue = 0xdeadbeef;
    return VINF_SUCCESS;

#else
    /*
     * Since we're lazy, we'll only check if the module is present
     * and hand it over to PDMR3LdrGetSymbolR0 when that's done.
     */
    AssertMsg(pVM->pdm.s.offVM, ("bad init order!\n"));
    if (pszModule)
    {
        AssertMsgReturn(!strpbrk(pszModule, "/\\:\n\r\t"), ("pszModule=%s\n", pszModule), VERR_INVALID_PARAMETER);
        PUVM    pUVM = pVM->pUVM;
        PPDMMOD pModule;
        RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
        for (pModule = pUVM->pdm.s.pModules; pModule; pModule = pModule->pNext)
            if (    pModule->eType == PDMMOD_TYPE_R0
                &&  !strcmp(pModule->szName, pszModule))
                break;
        RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
        if (!pModule)
        {
            int rc = pdmR3LoadR0U(pUVM, NULL, pszModule);
            AssertMsgRCReturn(rc, ("pszModule=%s rc=%Rrc\n", pszModule, rc), VERR_MODULE_NOT_FOUND);
        }
    }
    return PDMR3LdrGetSymbolR0(pVM, pszModule, pszSymbol, ppvValue);
#endif
}


/**
 * Get the address of a symbol in a given RC module.
 *
 * @returns VBox status code.
 * @param   pVM             VM handle.
 * @param   pszModule       Module name. If NULL the main R0 module (VMMGC.gc) is assumes.
 * @param   pszSymbol       Symbol name. If it's value is less than 64k it's treated like a
 *                          ordinal value rather than a string pointer.
 * @param   pRCPtrValue     Where to store the symbol value.
 */
VMMR3DECL(int) PDMR3LdrGetSymbolRC(PVM pVM, const char *pszModule, const char *pszSymbol, PRTRCPTR pRCPtrValue)
{
#if defined(PDMLDR_FAKE_MODE) || !defined(VBOX_WITH_RAW_MODE)
    *pRCPtrValue = 0xfeedf00d;
    return VINF_SUCCESS;

#else
    /*
     * Validate input.
     */
    AssertMsg(pVM->pdm.s.offVM, ("bad init order!\n"));
    if (!pszModule)
        pszModule = "VMMGC.gc";

    /*
     * Find the module.
     */
    PUVM pUVM = pVM->pUVM;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    for (PPDMMOD pModule = pUVM->pdm.s.pModules; pModule; pModule = pModule->pNext)
    {
        if (    pModule->eType == PDMMOD_TYPE_RC
            &&  !strcmp(pModule->szName, pszModule))
        {
            RTUINTPTR Value;
            int rc = RTLdrGetSymbolEx(pModule->hLdrMod, pModule->pvBits, pModule->ImageBase, pszSymbol, &Value);
            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
            if (RT_SUCCESS(rc))
            {
                *pRCPtrValue = (RTGCPTR)Value;
                Assert(*pRCPtrValue == Value);
            }
            else
            {
                if ((uintptr_t)pszSymbol < 0x10000)
                    AssertMsg(rc, ("Couldn't symbol '%u' in module '%s'\n", (unsigned)(uintptr_t)pszSymbol, pszModule));
                else
                    AssertMsg(rc, ("Couldn't symbol '%s' in module '%s'\n", pszSymbol, pszModule));
            }
            return rc;
        }
    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    AssertMsgFailed(("Couldn't locate module '%s'\n", pszModule));
    return VERR_SYMBOL_NOT_FOUND;
#endif
}


/**
 * Same as PDMR3LdrGetSymbolRC except that the module will be attempted loaded if not found.
 *
 * @returns VBox status code.
 * @param   pVM             VM handle.
 * @param   pszModule       Module name. If NULL the main R0 module (VMMGC.gc) is assumes.
 * @param   pszSymbol       Symbol name. If it's value is less than 64k it's treated like a
 *                          ordinal value rather than a string pointer.
 * @param   pRCPtrValue     Where to store the symbol value.
 */
VMMR3DECL(int) PDMR3LdrGetSymbolRCLazy(PVM pVM, const char *pszModule, const char *pszSymbol, PRTRCPTR pRCPtrValue)
{
#if defined(PDMLDR_FAKE_MODE) || !defined(VBOX_WITH_RAW_MODE)
    *pRCPtrValue = 0xfeedf00d;
    return VINF_SUCCESS;

#else
    /*
     * Since we're lazy, we'll only check if the module is present
     * and hand it over to PDMR3LdrGetSymbolRC when that's done.
     */
    AssertMsg(pVM->pdm.s.offVM, ("bad init order!\n"));
    if (pszModule)
    {
        AssertMsgReturn(!strpbrk(pszModule, "/\\:\n\r\t"), ("pszModule=%s\n", pszModule), VERR_INVALID_PARAMETER);
        PUVM    pUVM = pVM->pUVM;
        PPDMMOD pModule;
        RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
        for (pModule = pUVM->pdm.s.pModules; pModule; pModule = pModule->pNext)
            if (    pModule->eType == PDMMOD_TYPE_RC
                &&  !strcmp(pModule->szName, pszModule))
                break;
        RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
        if (!pModule)
        {
            char *pszFilename = pdmR3FileRC(pszModule);
            AssertMsgReturn(pszFilename, ("pszModule=%s\n", pszModule), VERR_MODULE_NOT_FOUND);
            int rc = PDMR3LdrLoadRC(pVM, pszFilename, pszModule);
            RTMemTmpFree(pszFilename);
            AssertMsgRCReturn(rc, ("pszModule=%s rc=%Rrc\n", pszModule, rc), VERR_MODULE_NOT_FOUND);
        }
    }
    return PDMR3LdrGetSymbolRC(pVM, pszModule, pszSymbol, pRCPtrValue);
#endif
}


/**
 * Constructs the full filename for a R3 image file.
 *
 * @returns Pointer to temporary memory containing the filename.
 *          Caller must free this using RTMemTmpFree().
 * @returns NULL on failure.
 *
 * @param   pszFile     File name (no path).
 */
char *pdmR3FileR3(const char *pszFile, bool fShared)
{
    return pdmR3File(pszFile, NULL, fShared);
}


/**
 * Constructs the full filename for a R0 image file.
 *
 * @returns Pointer to temporary memory containing the filename.
 *          Caller must free this using RTMemTmpFree().
 * @returns NULL on failure.
 *
 * @param   pszFile     File name (no path).
 */
char *pdmR3FileR0(const char *pszFile)
{
    return pdmR3File(pszFile, NULL, /*fShared=*/false);
}


/**
 * Constructs the full filename for a RC image file.
 *
 * @returns Pointer to temporary memory containing the filename.
 *          Caller must free this using RTMemTmpFree().
 * @returns NULL on failure.
 *
 * @param   pszFile     File name (no path).
 */
char *pdmR3FileRC(const char *pszFile)
{
    return pdmR3File(pszFile, NULL, /*fShared=*/false);
}


/**
 * Worker for pdmR3File().
 *
 * @returns Pointer to temporary memory containing the filename.
 *          Caller must free this using RTMemTmpFree().
 * @returns NULL on failure.
 *
 * @param   pszDir        Directory part
 * @param   pszFile       File name part
 * @param   pszDefaultExt Extension part
 */
static char *pdmR3FileConstruct(const char *pszDir, const char *pszFile, const char *pszDefaultExt)
{
    /*
     * Allocate temp memory for return buffer.
     */
    size_t cchDir  = strlen(pszDir);
    size_t cchFile = strlen(pszFile);
    size_t cchDefaultExt;

    /*
     * Default extention?
     */
    if (!pszDefaultExt || strchr(pszFile, '.'))
        cchDefaultExt = 0;
    else
        cchDefaultExt = strlen(pszDefaultExt);

    size_t cchPath = cchDir + 1 + cchFile + cchDefaultExt + 1;
    AssertMsgReturn(cchPath <= RTPATH_MAX, ("Path too long!\n"), NULL);

    char *pszRet = (char *)RTMemTmpAlloc(cchDir + 1 + cchFile + cchDefaultExt + 1);
    AssertMsgReturn(pszRet, ("Out of temporary memory!\n"), NULL);

    /*
     * Construct the filename.
     */
    memcpy(pszRet, pszDir, cchDir);
    pszRet[cchDir++] = '/';            /* this works everywhere */
    memcpy(pszRet + cchDir, pszFile, cchFile + 1);
    if (cchDefaultExt)
        memcpy(pszRet + cchDir + cchFile, pszDefaultExt, cchDefaultExt + 1);

    return pszRet;
}


/**
 * Worker for pdmR3FileRC(), pdmR3FileR0() and pdmR3FileR3().
 *
 * @returns Pointer to temporary memory containing the filename.
 *          Caller must free this using RTMemTmpFree().
 * @returns NULL on failure.
 * @param   pszFile         File name (no path).
 * @param   pszDefaultExt   The default extention, NULL if none.
 * @param   fShared         If true, search in the shared directory (/usr/lib on Unix), else
 *                          search in the private directory (/usr/lib/virtualbox on Unix).
 *                          Ignored if VBOX_PATH_SHARED_LIBS is not defined.
 * @todo    We'll have this elsewhere than in the root later!
 * @todo    Remove the fShared hack again once we don't need to link against VBoxDD anymore!
 */
static char *pdmR3File(const char *pszFile, const char *pszDefaultExt, bool fShared)
{
    char szPath[RTPATH_MAX];
    int  rc;

    rc = fShared ? RTPathSharedLibs(szPath, sizeof(szPath))
                 : RTPathAppPrivateArch(szPath, sizeof(szPath));
    if (!RT_SUCCESS(rc))
    {
        AssertMsgFailed(("RTPath[SharedLibs|AppPrivateArch](,%d) failed rc=%d!\n", sizeof(szPath), rc));
        return NULL;
    }

    return pdmR3FileConstruct(szPath, pszFile, pszDefaultExt);
}


/** @internal */
typedef struct QMFEIPARG
{
    RTRCUINTPTR uPC;

    char       *pszNearSym1;
    size_t     cchNearSym1;
    RTRCINTPTR  offNearSym1;

    char       *pszNearSym2;
    size_t      cchNearSym2;
    RTRCINTPTR  offNearSym2;
} QMFEIPARG, *PQMFEIPARG;

/**
 * Queries module information from an PC (eip/rip).
 *
 * This is typically used to locate a crash address.
 *
 * @returns VBox status code.
 *
 * @param   pVM         VM handle
 * @param   uPC         The program counter (eip/rip) to locate the module for.
 * @param   pszModName  Where to store the module name.
 * @param   cchModName  Size of the module name buffer.
 * @param   pMod        Base address of the module.
 * @param   pszNearSym1 Name of the closes symbol from below.
 * @param   cchNearSym1 Size of the buffer pointed to by pszNearSym1.
 * @param   pNearSym1   The address of pszNearSym1.
 * @param   pszNearSym2 Name of the closes symbol from below.
 * @param   cchNearSym2 Size of the buffer pointed to by pszNearSym2.
 * @param   pNearSym2   The address of pszNearSym2.
 */
VMMR3DECL(int) PDMR3LdrQueryRCModFromPC(PVM pVM, RTRCPTR uPC,
                                        char *pszModName,  size_t cchModName,  PRTRCPTR pMod,
                                        char *pszNearSym1, size_t cchNearSym1, PRTRCPTR pNearSym1,
                                        char *pszNearSym2, size_t cchNearSym2, PRTRCPTR pNearSym2)
{
    PUVM    pUVM = pVM->pUVM;
    int     rc   = VERR_MODULE_NOT_FOUND;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    for (PPDMMOD pCur= pUVM->pdm.s.pModules; pCur; pCur = pCur->pNext)
    {
        /* Skip anything which isn't in GC. */
        if (pCur->eType != PDMMOD_TYPE_RC)
            continue;
        if (uPC - pCur->ImageBase < RTLdrSize(pCur->hLdrMod))
        {
            if (pMod)
                *pMod = pCur->ImageBase;
            if (pszModName && cchModName)
            {
                *pszModName = '\0';
                strncat(pszModName, pCur->szName, cchModName);
            }
            if (pNearSym1)   *pNearSym1   = 0;
            if (pNearSym2)   *pNearSym2   = 0;
            if (pszNearSym1) *pszNearSym1 = '\0';
            if (pszNearSym2) *pszNearSym2 = '\0';

            /*
             * Locate the nearest symbols.
             */
            QMFEIPARG   Args;
            Args.uPC         = uPC;
            Args.pszNearSym1 = pszNearSym1;
            Args.cchNearSym1 = cchNearSym1;
            Args.offNearSym1 = RTRCINTPTR_MIN;
            Args.pszNearSym2 = pszNearSym2;
            Args.cchNearSym2 = cchNearSym2;
            Args.offNearSym2 = RTRCINTPTR_MAX;

            rc = RTLdrEnumSymbols(pCur->hLdrMod, RTLDR_ENUM_SYMBOL_FLAGS_ALL, pCur->pvBits, pCur->ImageBase,
                                  pdmR3QueryModFromEIPEnumSymbols, &Args);
            if (pNearSym1 && Args.offNearSym1 != INT_MIN)
                *pNearSym1 = Args.offNearSym1 + uPC;
            if (pNearSym2 && Args.offNearSym2 != INT_MAX)
                *pNearSym2 = Args.offNearSym2 + uPC;

            rc = VINF_SUCCESS;
            if (pCur->eType == PDMMOD_TYPE_RC)
                break;
        }

    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    return rc;
}


/**
 * Enumeration callback function used by RTLdrEnumSymbols().
 *
 * @returns VBox status code. Failure will stop the enumeration.
 * @param   hLdrMod         The loader module handle.
 * @param   pszSymbol       Symbol name. NULL if ordinal only.
 * @param   uSymbol         Symbol ordinal, ~0 if not used.
 * @param   Value           Symbol value.
 * @param   pvUser          The user argument specified to RTLdrEnumSymbols().
 */
static DECLCALLBACK(int) pdmR3QueryModFromEIPEnumSymbols(RTLDRMOD hLdrMod, const char *pszSymbol, unsigned uSymbol, RTUINTPTR Value, void *pvUser)
{
    PQMFEIPARG pArgs = (PQMFEIPARG)pvUser;

    RTINTPTR off = Value - pArgs->uPC;
    if (off <= 0)   /* near1 is before or at same location. */
    {
        if (off > pArgs->offNearSym1)
        {
            pArgs->offNearSym1 = off;
            if (pArgs->pszNearSym1 && pArgs->cchNearSym1)
            {
                *pArgs->pszNearSym1 = '\0';
                if (pszSymbol)
                    strncat(pArgs->pszNearSym1, pszSymbol, pArgs->cchNearSym1);
                else
                {
                    char szOrd[32];
                    RTStrPrintf(szOrd, sizeof(szOrd), "#%#x", uSymbol);
                    strncat(pArgs->pszNearSym1, szOrd, pArgs->cchNearSym1);
                }
            }
        }
    }
    else            /* near2 is after */
    {
        if (off < pArgs->offNearSym2)
        {
            pArgs->offNearSym2 = off;
            if (pArgs->pszNearSym2 && pArgs->cchNearSym2)
            {
                *pArgs->pszNearSym2 = '\0';
                if (pszSymbol)
                    strncat(pArgs->pszNearSym2, pszSymbol, pArgs->cchNearSym2);
                else
                {
                    char szOrd[32];
                    RTStrPrintf(szOrd, sizeof(szOrd), "#%#x", uSymbol);
                    strncat(pArgs->pszNearSym2, szOrd, pArgs->cchNearSym2);
                }
            }
        }
    }

    return VINF_SUCCESS;
}


/**
 * Enumerate all PDM modules.
 *
 * @returns VBox status.
 * @param   pVM             VM Handle.
 * @param   pfnCallback     Function to call back for each of the modules.
 * @param   pvArg           User argument.
 */
VMMR3DECL(int)  PDMR3LdrEnumModules(PVM pVM, PFNPDMR3ENUM pfnCallback, void *pvArg)
{
    PUVM pUVM = pVM->pUVM;
    int  rc   = VINF_SUCCESS;
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    for (PPDMMOD pCur = pUVM->pdm.s.pModules; pCur; pCur = pCur->pNext)
    {
        rc = pfnCallback(pVM,
                         pCur->szFilename,
                         pCur->szName,
                         pCur->ImageBase,
                         pCur->eType == PDMMOD_TYPE_RC ? RTLdrSize(pCur->hLdrMod) : 0,
                         pCur->eType == PDMMOD_TYPE_RC,
                         pvArg);
        if (RT_FAILURE(rc))
            break;
    }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    return rc;
}


/**
 * Locates a module.
 *
 * @returns Pointer to the module if found.
 * @param   pUVM            Pointer to the user mode VM structure.
 * @param   pszModule       The module name.
 * @param   enmType         The module type.
 * @param   fLazy           Lazy loading the module if set.
 */
static PPDMMOD pdmR3LdrFindModule(PUVM pUVM, const char *pszModule, PDMMODTYPE enmType, bool fLazy)
{
    RTCritSectEnter(&pUVM->pdm.s.ListCritSect);
    for (PPDMMOD pModule = pUVM->pdm.s.pModules; pModule; pModule = pModule->pNext)
        if (    pModule->eType == enmType
            &&  !strcmp(pModule->szName, pszModule))
        {
            RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
            return pModule;
        }
    RTCritSectLeave(&pUVM->pdm.s.ListCritSect);
    if (fLazy)
    {
        switch (enmType)
        {
#ifdef VBOX_WITH_RAW_MODE
            case PDMMOD_TYPE_RC:
            {
                char *pszFilename = pdmR3FileRC(pszModule);
                if (pszFilename)
                {
                    int rc = PDMR3LdrLoadRC(pUVM->pVM, pszFilename, pszModule);
                    RTMemTmpFree(pszFilename);
                    if (RT_SUCCESS(rc))
                        return pdmR3LdrFindModule(pUVM, pszModule, enmType, false);
                }
                break;
            }
#endif

            case PDMMOD_TYPE_R0:
            {
                int rc = pdmR3LoadR0U(pUVM, NULL, pszModule);
                if (RT_SUCCESS(rc))
                    return pdmR3LdrFindModule(pUVM, pszModule, enmType, false);
                break;
            }

            default:
                AssertFailed();
        }
    }
    return NULL;
}


/**
 * Resolves a ring-0 or raw-mode context interface.
 *
 * @returns VBox status code.
 * @param   pVM             The VM handle.
 * @param   pvInterface     Pointer to the interface structure.  The symbol list
 *                          describes the layout.
 * @param   cbInterface     The size of the structure pvInterface is pointing
 *                          to.  For bounds checking.
 * @param   pszModule       The module name.  If NULL we assume it's the default
 *                          R0 or RC module (@a fRing0OrRC).  We'll attempt to
 *                          load the module if it isn't found in the module
 *                          list.
 * @param   pszSymPrefix    What to prefix the symbols in the list with.  The
 *                          idea is that you define a list that goes with an
 *                          interface (INTERFACE_SYM_LIST) and reuse it with
 *                          each implementation.
 * @param   pszSymList      The symbol list for the interface.  This is a
 *                          semi-colon separated list of symbol base names.  As
 *                          mentioned above, each is prefixed with @a
 *                          pszSymPrefix before resolving.  There are a couple
 *                          of special symbol names that will cause us to skip
 *                          ahead a little bit:
 *                              - U8:whatever,
 *                              - U16:whatever,
 *                              - U32:whatever,
 *                              - U64:whatever,
 *                              - RCPTR:whatever,
 *                              - R3PTR:whatever,
 *                              - R0PTR:whatever,
 *                              - GCPHYS:whatever,
 *                              - HCPHYS:whatever.
 * @param   fRing0          Set if it's a ring-0 context interface, clear if
 *                          it's raw-mode context interface.
 */
VMMR3DECL(int) PDMR3LdrGetInterfaceSymbols(PVM pVM, void *pvInterface, size_t cbInterface,
                                           const char *pszModule, const char *pszSymPrefix,
                                           const char *pszSymList, bool fRing0)
{
    /*
     * Find the module.
     */
    int     rc      = VINF_SUCCESS;
    PPDMMOD pModule = pdmR3LdrFindModule(pVM->pUVM,
                                         pszModule ? pszModule : fRing0 ? "VMMR0.r0" : "VMMGC.gc",
                                         fRing0 ? PDMMOD_TYPE_R0 : PDMMOD_TYPE_RC,
                                         true /*fLazy*/);
    if (pModule)
    {
        /* Prep the symbol name. */
        char            szSymbol[256];
        size_t const    cchSymPrefix = strlen(pszSymPrefix);
        AssertReturn(cchSymPrefix + 5 < sizeof(szSymbol), VERR_SYMBOL_NOT_FOUND);
        memcpy(szSymbol, pszSymPrefix, cchSymPrefix);

        /*
         * Iterate the symbol list.
         */
        uint32_t        offInterface = 0;
        const char     *pszCur       = pszSymList;
        while (pszCur)
        {
            /*
             * Find the end of the current symbol name.
             */
            size_t      cchSym;
            const char *pszNext = strchr(pszCur, ';');
            if (pszNext)
            {
                cchSym = pszNext - pszCur;
                pszNext++;
            }
            else
                cchSym = strlen(pszCur);
            AssertBreakStmt(cchSym > 0, rc = VERR_INVALID_PARAMETER);

            /* Is it a skip instruction? */
            const char *pszColon = (const char *)memchr(pszCur, ':', cchSym);
            if (pszColon)
            {
                /*
                 * String switch on the instruction and execute it, checking
                 * that we didn't overshoot the interface structure.
                 */
#define IS_SKIP_INSTR(szInstr) \
                (   cchSkip == sizeof(szInstr) - 1 \
                 && !memcmp(pszCur, szInstr, sizeof(szInstr) - 1) )

                size_t const cchSkip = pszColon - pszCur;
                if (IS_SKIP_INSTR("U8"))
                    offInterface += sizeof(uint8_t);
                else if (IS_SKIP_INSTR("U16"))
                    offInterface += sizeof(uint16_t);
                else if (IS_SKIP_INSTR("U32"))
                    offInterface += sizeof(uint32_t);
                else if (IS_SKIP_INSTR("U64"))
                    offInterface += sizeof(uint64_t);
                else if (IS_SKIP_INSTR("RCPTR"))
                    offInterface += sizeof(RTRCPTR);
                else if (IS_SKIP_INSTR("R3PTR"))
                    offInterface += sizeof(RTR3PTR);
                else if (IS_SKIP_INSTR("R0PTR"))
                    offInterface += sizeof(RTR0PTR);
                else if (IS_SKIP_INSTR("HCPHYS"))
                    offInterface += sizeof(RTHCPHYS);
                else if (IS_SKIP_INSTR("GCPHYS"))
                    offInterface += sizeof(RTGCPHYS);
                else
                    AssertMsgFailedBreakStmt(("Invalid skip instruction %.*s (prefix=%s)\n", cchSym, pszCur, pszSymPrefix),
                                             rc = VERR_INVALID_PARAMETER);
                AssertMsgBreakStmt(offInterface <= cbInterface,
                                   ("off=%#x cb=%#x (sym=%.*s prefix=%s)\n", offInterface, cbInterface, cchSym, pszCur, pszSymPrefix),
                                   rc = VERR_BUFFER_OVERFLOW);
#undef IS_SKIP_INSTR
            }
            else
            {
                /*
                 * Construct the symbol name, get its value, store it and
                 * advance the interface cursor.
                 */
                AssertReturn(cchSymPrefix + cchSym < sizeof(szSymbol), VERR_SYMBOL_NOT_FOUND);
                memcpy(&szSymbol[cchSymPrefix], pszCur, cchSym);
                szSymbol[cchSymPrefix + cchSym] = '\0';

                if (fRing0)
                {
                    void *pvValue;
                    rc = SUPR3GetSymbolR0((void *)(RTR0PTR)pModule->ImageBase, szSymbol, &pvValue);
                    AssertMsgRCBreak(rc, ("Couldn't find symbol '%s' in module '%s'\n", szSymbol, pModule->szName));

                    PRTR0PTR pValue = (PRTR0PTR)((uintptr_t)pvInterface + offInterface);
                    AssertMsgBreakStmt(offInterface + sizeof(*pValue) <= cbInterface,
                                       ("off=%#x cb=%#x sym=%s\n", offInterface, cbInterface, szSymbol),
                                       rc = VERR_BUFFER_OVERFLOW);
                    *pValue = (RTR0PTR)pvValue;
                    Assert((void *)*pValue == pvValue);
                    offInterface += sizeof(*pValue);
                }
                else
                {
                    RTUINTPTR Value;
                    rc = RTLdrGetSymbolEx(pModule->hLdrMod, pModule->pvBits, pModule->ImageBase, szSymbol, &Value);
                    AssertMsgRCBreak(rc, ("Couldn't find symbol '%s' in module '%s'\n", szSymbol, pModule->szName));

                    PRTRCPTR pValue = (PRTRCPTR)((uintptr_t)pvInterface + offInterface);
                    AssertMsgBreakStmt(offInterface + sizeof(*pValue) <= cbInterface,
                                       ("off=%#x cb=%#x sym=%s\n", offInterface, cbInterface, szSymbol),
                                       rc = VERR_BUFFER_OVERFLOW);
                    *pValue = (RTRCPTR)Value;
                    Assert(*pValue == Value);
                    offInterface += sizeof(*pValue);
                }
            }

            /* advance */
            pszCur = pszNext;
        }

    }
    else
        rc = VERR_MODULE_NOT_FOUND;
    return rc;
}