X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=snapshot.cc;h=5cb920b1d156427c077b5c68ab942163fe926dc9;hb=5f71c5e271a6fd27f2300b87b6bb45e122348320;hp=af4284361d61f076c16c12675945ec5d364b968c;hpb=06d9618fd028c3d5a60c65ad6508cfae24741688;p=model-checker.git diff --git a/snapshot.cc b/snapshot.cc index af42843..5cb920b 100644 --- a/snapshot.cc +++ b/snapshot.cc @@ -3,149 +3,161 @@ #include #include #include -#include -#include -#include -#include "snapshot.h" -#include "snapshotimp.h" -#include "mymemory.h" -#include -#include -#include -#include +#include #include #include #include -#define FAILURE(mesg) { printf("failed in the API: %s with errno relative message: %s\n", mesg, strerror( errno ) ); exit(EXIT_FAILURE); } +#include "hashtable.h" +#include "snapshot.h" +#include "snapshotimp.h" +#include "mymemory.h" +#include "common.h" + +#define FAILURE(mesg) { model_print("failed in the API: %s with errno relative message: %s\n", mesg, strerror(errno)); exit(EXIT_FAILURE); } #ifdef CONFIG_SSDEBUG -#define SSDEBUG printf +#define SSDEBUG model_print #else #define SSDEBUG(...) do { } while (0) #endif /* extern declaration definition */ -#if USE_MPROTECT_SNAPSHOT -struct SnapShot * snapshotrecord = NULL; -#else -struct Snapshot * sTheRecord = NULL; -#endif - -#if !USE_MPROTECT_SNAPSHOT -static ucontext_t savedSnapshotContext; -static ucontext_t savedUserSnapshotContext; -static snapshot_id snapshotid = 0; -#endif +struct SnapShot *snapshotrecord = NULL; /** PageAlignedAdressUpdate return a page aligned address for the * address being added as a side effect the numBytes are also changed. */ -static void * PageAlignAddressUpward(void * addr) { - return (void *)((((uintptr_t)addr)+PAGESIZE-1)&~(PAGESIZE-1)); +static void * PageAlignAddressUpward(void *addr) +{ + return (void *)((((uintptr_t)addr) + PAGESIZE - 1) & ~(PAGESIZE - 1)); } -#if USE_MPROTECT_SNAPSHOT +#if !USE_MPROTECT_SNAPSHOT +/** @statics +* These variables are necessary because the stack is shared region and +* there exists a race between all processes executing the same function. +* To avoid the problem above, we require variables allocated in 'safe' regions. +* The bug was actually observed with the forkID, these variables below are +* used to indicate the various contexts to which to switch to. +* +* @savedSnapshotContext: contains the point to which takesnapshot() call should switch to. +* @savedUserSnapshotContext: contains the point to which the process whose snapshotid is equal to the rollbackid should switch to +* @snapshotid: it is a running counter for the various forked processes snapshotid. it is incremented and set in a persistently shared record +*/ +static ucontext_t savedSnapshotContext; +static ucontext_t savedUserSnapshotContext; +static snapshot_id snapshotid = 0; + +#else /* USE_MPROTECT_SNAPSHOT */ /** ReturnPageAlignedAddress returns a page aligned address for the * address being added as a side effect the numBytes are also changed. */ -static void * ReturnPageAlignedAddress(void * addr) { - return (void *)(((uintptr_t)addr)&~(PAGESIZE-1)); +static void * ReturnPageAlignedAddress(void *addr) +{ + return (void *)(((uintptr_t)addr) & ~(PAGESIZE - 1)); } /** The initSnapShotRecord method initialized the snapshotting data - * structures for the mprotect based snapshot. + * structures for the mprotect based snapshot. */ -static void initSnapShotRecord(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions) { - snapshotrecord=( struct SnapShot * )MYMALLOC(sizeof(struct SnapShot)); - snapshotrecord->regionsToSnapShot=( struct MemoryRegion * )MYMALLOC(sizeof(struct MemoryRegion)*nummemoryregions); - snapshotrecord->backingStoreBasePtr= ( struct SnapShotPage * )MYMALLOC( sizeof( struct SnapShotPage ) * (numbackingpages + 1) ); +static void initSnapShotRecord(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions) +{ + snapshotrecord = (struct SnapShot *)model_malloc(sizeof(struct SnapShot)); + snapshotrecord->regionsToSnapShot = (struct MemoryRegion *)model_malloc(sizeof(struct MemoryRegion) * nummemoryregions); + snapshotrecord->backingStoreBasePtr = (void *)model_malloc(sizeof(snapshot_page_t) * (numbackingpages + 1)); //Page align the backingstorepages - snapshotrecord->backingStore=( struct SnapShotPage * )PageAlignAddressUpward(snapshotrecord->backingStoreBasePtr); - snapshotrecord->backingRecords=( struct BackingPageRecord * )MYMALLOC(sizeof(struct BackingPageRecord)*numbackingpages); - snapshotrecord->snapShots= ( struct SnapShotRecord * )MYMALLOC(sizeof(struct SnapShotRecord)*numsnapshots); - snapshotrecord->lastSnapShot=0; - snapshotrecord->lastBackingPage=0; - snapshotrecord->lastRegion=0; - snapshotrecord->maxRegions=nummemoryregions; - snapshotrecord->maxBackingPages=numbackingpages; - snapshotrecord->maxSnapShots=numsnapshots; + snapshotrecord->backingStore = (snapshot_page_t *)PageAlignAddressUpward(snapshotrecord->backingStoreBasePtr); + snapshotrecord->backingRecords = (struct BackingPageRecord *)model_malloc(sizeof(struct BackingPageRecord) * numbackingpages); + snapshotrecord->snapShots = (struct SnapShotRecord *)model_malloc(sizeof(struct SnapShotRecord) * numsnapshots); + snapshotrecord->lastSnapShot = 0; + snapshotrecord->lastBackingPage = 0; + snapshotrecord->lastRegion = 0; + snapshotrecord->maxRegions = nummemoryregions; + snapshotrecord->maxBackingPages = numbackingpages; + snapshotrecord->maxSnapShots = numsnapshots; } /** HandlePF is the page fault handler for mprotect based snapshotting * algorithm. */ -static void HandlePF( int sig, siginfo_t *si, void * unused){ - if( si->si_code == SEGV_MAPERR ){ - printf("Real Fault at %p\n", si->si_addr); - exit( EXIT_FAILURE ); +static void HandlePF(int sig, siginfo_t *si, void *unused) +{ + if (si->si_code == SEGV_MAPERR) { + model_print("Real Fault at %p\n", si->si_addr); + print_trace(); + model_print("For debugging, place breakpoint at: %s:%d\n", + __FILE__, __LINE__); + exit(EXIT_FAILURE); } void* addr = ReturnPageAlignedAddress(si->si_addr); - unsigned int backingpage=snapshotrecord->lastBackingPage++; //Could run out of pages... - if (backingpage==snapshotrecord->maxBackingPages) { - printf("Out of backing pages at %p\n", si->si_addr); - exit( EXIT_FAILURE ); + unsigned int backingpage = snapshotrecord->lastBackingPage++; //Could run out of pages... + if (backingpage == snapshotrecord->maxBackingPages) { + model_print("Out of backing pages at %p\n", si->si_addr); + exit(EXIT_FAILURE); } //copy page - memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(struct SnapShotPage)); + memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(snapshot_page_t)); //remember where to copy page back to - snapshotrecord->backingRecords[backingpage].basePtrOfPage=addr; + snapshotrecord->backingRecords[backingpage].basePtrOfPage = addr; //set protection to read/write - if (mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE )) { + if (mprotect(addr, sizeof(snapshot_page_t), PROT_READ | PROT_WRITE)) { perror("mprotect"); // Handle error by quitting? } } -#endif //nothing to handle for non snapshotting case. +#endif /* USE_MPROTECT_SNAPSHOT */ -void createSharedLibrary(){ #if !USE_MPROTECT_SNAPSHOT +void createSharedMemory() +{ //step 1. create shared memory. - if( sTheRecord ) return; - int fd = shm_open( "/ModelChecker-Snapshotter", O_RDWR | O_CREAT, 0777 ); //universal permissions. - if( -1 == fd ) FAILURE("shm_open"); - if( -1 == ftruncate( fd, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT ) ) FAILURE( "ftruncate" ); - void * memMapBase = mmap( 0, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 ); - if( MAP_FAILED == memMapBase ) FAILURE("mmap"); - sTheRecord = ( struct Snapshot * )memMapBase; - sTheRecord->mSharedMemoryBase = (void *)((uintptr_t)memMapBase + sizeof(struct Snapshot)); - sTheRecord->mStackBase = (void *)((uintptr_t)memMapBase + (size_t)SHARED_MEMORY_DEFAULT); - sTheRecord->mStackSize = STACK_SIZE_DEFAULT; - sTheRecord->mIDToRollback = -1; - sTheRecord->currSnapShotID = 0; - sTheRecord->mbFinalize = false; -#endif + void *memMapBase = mmap(0, SHARED_MEMORY_DEFAULT + STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0); + if (MAP_FAILED == memMapBase) + FAILURE("mmap"); + + //Setup snapshot record at top of free region + snapshotrecord = (struct SnapShot *)memMapBase; + snapshotrecord->mSharedMemoryBase = (void *)((uintptr_t)memMapBase + sizeof(struct SnapShot)); + snapshotrecord->mStackBase = (void *)((uintptr_t)memMapBase + SHARED_MEMORY_DEFAULT); + snapshotrecord->mStackSize = STACK_SIZE_DEFAULT; + snapshotrecord->mIDToRollback = -1; + snapshotrecord->currSnapShotID = 0; } +#endif + -/** The initSnapShotLibrary function initializes the Snapshot library. +/** The initSnapshotLibrary function initializes the snapshot library. * @param entryPoint the function that should run the program. */ -void initSnapShotLibrary(unsigned int numbackingpages, - unsigned int numsnapshots, unsigned int nummemoryregions, - unsigned int numheappages, VoidFuncPtr entryPoint) { #if USE_MPROTECT_SNAPSHOT + +void initSnapshotLibrary(unsigned int numbackingpages, + unsigned int numsnapshots, unsigned int nummemoryregions, + unsigned int numheappages, VoidFuncPtr entryPoint) +{ /* Setup a stack for our signal handler.... */ stack_t ss; - ss.ss_sp = MYMALLOC(SIGSTACKSIZE); + ss.ss_sp = PageAlignAddressUpward(model_malloc(SIGSTACKSIZE + PAGESIZE - 1)); ss.ss_size = SIGSTACKSIZE; ss.ss_flags = 0; sigaltstack(&ss, NULL); struct sigaction sa; sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART | SA_ONSTACK; - sigemptyset( &sa.sa_mask ); + sigemptyset(&sa.sa_mask); sa.sa_sigaction = HandlePF; #ifdef MAC - if( sigaction( SIGBUS, &sa, NULL ) == -1 ){ - printf("SIGACTION CANNOT BE INSTALLED\n"); + if (sigaction(SIGBUS, &sa, NULL) == -1) { + model_print("SIGACTION CANNOT BE INSTALLED\n"); exit(EXIT_FAILURE); } #endif - if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){ - printf("SIGACTION CANNOT BE INSTALLED\n"); + if (sigaction(SIGSEGV, &sa, NULL) == -1) { + model_print("SIGACTION CANNOT BE INSTALLED\n"); exit(EXIT_FAILURE); } @@ -157,115 +169,124 @@ void initSnapShotLibrary(unsigned int numbackingpages, siginfo_t si; memset(&si, 0, sizeof(si)); - si.si_addr=ss.ss_sp; + si.si_addr = ss.ss_sp; HandlePF(SIGSEGV, &si, NULL); snapshotrecord->lastBackingPage--; //remove the fake page we copied - basemySpace=MYMALLOC((numheappages+1)*PAGESIZE); - void * pagealignedbase=PageAlignAddressUpward(basemySpace); - mySpace = create_mspace_with_base(pagealignedbase, numheappages*PAGESIZE, 1 ); + void *basemySpace = model_malloc((numheappages + 1) * PAGESIZE); + void *pagealignedbase = PageAlignAddressUpward(basemySpace); + user_snapshot_space = create_mspace_with_base(pagealignedbase, numheappages * PAGESIZE, 1); addMemoryRegionToSnapShot(pagealignedbase, numheappages); + + void *base_model_snapshot_space = model_malloc((numheappages + 1) * PAGESIZE); + pagealignedbase = PageAlignAddressUpward(base_model_snapshot_space); + model_snapshot_space = create_mspace_with_base(pagealignedbase, numheappages * PAGESIZE, 1); + addMemoryRegionToSnapShot(pagealignedbase, numheappages); + entryPoint(); +} #else +void initSnapshotLibrary(unsigned int numbackingpages, + unsigned int numsnapshots, unsigned int nummemoryregions, + unsigned int numheappages, VoidFuncPtr entryPoint) +{ + if (!snapshotrecord) + createSharedMemory(); - basemySpace=system_malloc((numheappages+1)*PAGESIZE); - void * pagealignedbase=PageAlignAddressUpward(basemySpace); - mySpace = create_mspace_with_base(pagealignedbase, numheappages*PAGESIZE, 1 ); - createSharedLibrary(); + void *base_model_snapshot_space = malloc((numheappages + 1) * PAGESIZE); + void *pagealignedbase = PageAlignAddressUpward(base_model_snapshot_space); + model_snapshot_space = create_mspace_with_base(pagealignedbase, numheappages * PAGESIZE, 1); //step 2 setup the stack context. - - int alreadySwapped = 0; - getcontext( &savedSnapshotContext ); - if( !alreadySwapped ){ - alreadySwapped = 1; - ucontext_t currentContext, swappedContext, newContext; - getcontext( &newContext ); - newContext.uc_stack.ss_sp = sTheRecord->mStackBase; - newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT; - newContext.uc_link = ¤tContext; - makecontext( &newContext, entryPoint, 0 ); - swapcontext( &swappedContext, &newContext ); - } - - //add the code to take a snapshot here... - //to return to user process, do a second swapcontext... + ucontext_t newContext; + getcontext(&newContext); + newContext.uc_stack.ss_sp = snapshotrecord->mStackBase; + newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT; + makecontext(&newContext, entryPoint, 0); + /* switch to a new entryPoint context, on a new stack */ + swapcontext(&savedSnapshotContext, &newContext); + + /* switch back here when takesnapshot is called */ pid_t forkedID = 0; - snapshotid = sTheRecord->currSnapShotID; - bool swapContext = false; - while( !sTheRecord->mbFinalize ){ - sTheRecord->currSnapShotID=snapshotid+1; + snapshotid = snapshotrecord->currSnapShotID; + /* This bool indicates that the current process's snapshotid is same + as the id to which the rollback needs to occur */ + + bool rollback = false; + while (true) { + snapshotrecord->currSnapShotID = snapshotid + 1; forkedID = fork(); - if( 0 == forkedID ){ - ucontext_t currentContext; -#if 0 - int dbg = 0; - while( !dbg ); -#endif - if( swapContext ) - swapcontext( ¤tContext, &( sTheRecord->mContextToRollback ) ); - else{ - swapcontext( ¤tContext, &savedUserSnapshotContext ); + + if (0 == forkedID) { + /* If the rollback bool is set, switch to the context we need to + return to during a rollback. */ + if (rollback) { + setcontext(&(snapshotrecord->mContextToRollback)); + } else { + /*Child process which is forked as a result of takesnapshot + call should switch back to the takesnapshot context*/ + setcontext(&savedUserSnapshotContext); } } else { int status; int retVal; - SSDEBUG("The process id of child is %d and the process id of this process is %d and snapshot id is %d", - forkedID, getpid(), snapshotid ); + SSDEBUG("The process id of child is %d and the process id of this process is %d and snapshot id is %d\n", + forkedID, getpid(), snapshotid); do { - retVal=waitpid( forkedID, &status, 0 ); - } while( -1 == retVal && errno == EINTR ); + retVal = waitpid(forkedID, &status, 0); + } while (-1 == retVal && errno == EINTR); - if( sTheRecord->mIDToRollback != snapshotid ) + if (snapshotrecord->mIDToRollback != snapshotid) { exit(EXIT_SUCCESS); - else{ - swapContext = true; } + rollback = true; } } - -#endif } +#endif -/** The addMemoryRegionToSnapShot function assumes that addr is page aligned. +/** The addMemoryRegionToSnapShot function assumes that addr is page aligned. */ -void addMemoryRegionToSnapShot( void * addr, unsigned int numPages) { +void addMemoryRegionToSnapShot(void *addr, unsigned int numPages) +{ #if USE_MPROTECT_SNAPSHOT - unsigned int memoryregion=snapshotrecord->lastRegion++; - if (memoryregion==snapshotrecord->maxRegions) { - printf("Exceeded supported number of memory regions!\n"); + unsigned int memoryregion = snapshotrecord->lastRegion++; + if (memoryregion == snapshotrecord->maxRegions) { + model_print("Exceeded supported number of memory regions!\n"); exit(EXIT_FAILURE); } - snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr; - snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages; + snapshotrecord->regionsToSnapShot[memoryregion].basePtr = addr; + snapshotrecord->regionsToSnapShot[memoryregion].sizeInPages = numPages; #endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS. } /** The takeSnapshot function takes a snapshot. * @return The snapshot identifier. */ -snapshot_id takeSnapshot( ){ +snapshot_id takeSnapshot() +{ #if USE_MPROTECT_SNAPSHOT - for(unsigned int region=0; regionlastRegion;region++) { - if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ ) == -1 ){ + for (unsigned int region = 0; region < snapshotrecord->lastRegion; region++) { + if (mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages * sizeof(snapshot_page_t), PROT_READ) == -1) { perror("mprotect"); - printf("Failed to mprotect inside of takeSnapShot\n"); + model_print("Failed to mprotect inside of takeSnapShot\n"); exit(EXIT_FAILURE); } } - unsigned int snapshot=snapshotrecord->lastSnapShot++; - if (snapshot==snapshotrecord->maxSnapShots) { - printf("Out of snapshots\n"); + unsigned int snapshot = snapshotrecord->lastSnapShot++; + if (snapshot == snapshotrecord->maxSnapShots) { + model_print("Out of snapshots\n"); exit(EXIT_FAILURE); } - snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage; + snapshotrecord->snapShots[snapshot].firstBackingPage = snapshotrecord->lastBackingPage; return snapshot; #else - swapcontext( &savedUserSnapshotContext, &savedSnapshotContext ); + swapcontext(&savedUserSnapshotContext, &savedSnapshotContext); + SSDEBUG("TAKESNAPSHOT RETURN\n"); return snapshotid; #endif } @@ -273,48 +294,53 @@ snapshot_id takeSnapshot( ){ /** The rollBack function rollback to the given snapshot identifier. * @param theID is the snapshot identifier to rollback to. */ -void rollBack( snapshot_id theID ){ +void rollBack(snapshot_id theID) +{ +#if USE_MPROTECT_SNAPSHOT == 2 + if (snapshotrecord->lastSnapShot == (theID + 1)) { + for (unsigned int page = snapshotrecord->snapShots[theID].firstBackingPage; page < snapshotrecord->lastBackingPage; page++) { + memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(snapshot_page_t)); + } + return; + } +#endif + #if USE_MPROTECT_SNAPSHOT - std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap; - for(unsigned int region=0; regionlastRegion;region++) { - if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE ) == -1 ){ + HashTable< void *, bool, uintptr_t, 4, model_malloc, model_calloc, model_free> duplicateMap; + for (unsigned int region = 0; region < snapshotrecord->lastRegion; region++) { + if (mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages * sizeof(snapshot_page_t), PROT_READ | PROT_WRITE) == -1) { perror("mprotect"); - printf("Failed to mprotect inside of takeSnapShot\n"); + model_print("Failed to mprotect inside of takeSnapShot\n"); exit(EXIT_FAILURE); } } - for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; pagelastBackingPage; page++) { - bool oldVal = false; - if( duplicateMap.find( snapshotrecord->backingRecords[page].basePtrOfPage ) != duplicateMap.end() ){ - oldVal = true; - } - else{ - duplicateMap[ snapshotrecord->backingRecords[page].basePtrOfPage ] = true; - } - if( !oldVal ){ - memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage)); + for (unsigned int page = snapshotrecord->snapShots[theID].firstBackingPage; page < snapshotrecord->lastBackingPage; page++) { + if (!duplicateMap.contains(snapshotrecord->backingRecords[page].basePtrOfPage)) { + duplicateMap.put(snapshotrecord->backingRecords[page].basePtrOfPage, true); + memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(snapshot_page_t)); } } - snapshotrecord->lastSnapShot=theID; - snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage; + snapshotrecord->lastSnapShot = theID; + snapshotrecord->lastBackingPage = snapshotrecord->snapShots[theID].firstBackingPage; takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared #else - sTheRecord->mIDToRollback = theID; - int sTemp = 0; - getcontext( &sTheRecord->mContextToRollback ); - if( !sTemp ){ + snapshotrecord->mIDToRollback = theID; + volatile int sTemp = 0; + getcontext(&snapshotrecord->mContextToRollback); + /* + * This is used to quit the process on rollback, so that the process + * which needs to rollback can quit allowing the process whose + * snapshotid matches the rollbackid to switch to this context and + * continue.... + */ + if (!sTemp) { sTemp = 1; - SSDEBUG("Invoked rollback"); + SSDEBUG("Invoked rollback\n"); exit(EXIT_SUCCESS); } -#endif -} - -/** The finalize method shuts down the snapshotting system. */ -//Subramanian -- remove this function from the external interface and -//have us call it internally -void finalize(){ -#if !USE_MPROTECT_SNAPSHOT - sTheRecord->mbFinalize = true; + /* + * This fix obviates the need for a finalize call. hence less dependences for model-checker.... + */ + snapshotrecord->mIDToRollback = -1; #endif }