X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=snapshot.cc;h=1cc3255bbbe057ebc2a68037ad58877eb2052f22;hb=3b08bb3248c8f63fc1c54da23da471cab0fe7239;hp=e6b38b58ff2fbd148f30695aff830a27a5810112;hpb=421c3af5d7265b26a4c946a710f2acd986c5d78a;p=model-checker.git diff --git a/snapshot.cc b/snapshot.cc index e6b38b5..1cc3255 100644 --- a/snapshot.cc +++ b/snapshot.cc @@ -10,21 +10,11 @@ #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 model_print -#else -#define SSDEBUG(...) do { } while (0) -#endif - -/* extern declaration definition */ -struct SnapShot *snapshotrecord = NULL; - /** PageAlignedAdressUpdate return a page aligned address for the * address being added as a side effect the numBytes are also changed. */ @@ -33,23 +23,47 @@ static void * PageAlignAddressUpward(void *addr) return (void *)((((uintptr_t)addr) + PAGESIZE - 1) & ~(PAGESIZE - 1)); } -#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; +#if USE_MPROTECT_SNAPSHOT -#else /* USE_MPROTECT_SNAPSHOT */ +/* Each snapshotrecord lists the firstbackingpage that must be written to + * revert to that snapshot */ +struct SnapShotRecord { + unsigned int firstBackingPage; +}; + +/** @brief Backing store page */ +typedef unsigned char snapshot_page_t[PAGESIZE]; + +/* List the base address of the corresponding page in the backing store so we + * know where to copy it to */ +struct BackingPageRecord { + void *basePtrOfPage; +}; + +/* Struct for each memory region */ +struct MemoryRegion { + void *basePtr; // base of memory region + int sizeInPages; // size of memory region in pages +}; + +/* Primary struct for snapshotting system */ +struct SnapShot { + struct MemoryRegion *regionsToSnapShot; //This pointer references an array of memory regions to snapshot + snapshot_page_t *backingStore; //This pointer references an array of snapshotpage's that form the backing store + void *backingStoreBasePtr; //This pointer references an array of snapshotpage's that form the backing store + struct BackingPageRecord *backingRecords; //This pointer references an array of backingpagerecord's (same number of elements as backingstore + struct SnapShotRecord *snapShots; //This pointer references the snapshot array + + unsigned int lastSnapShot; //Stores the next snapshot record we should use + unsigned int lastBackingPage; //Stores the next backingpage we should use + unsigned int lastRegion; //Stores the next memory region to be used + + unsigned int maxRegions; //Stores the max number of memory regions we support + unsigned int maxBackingPages; //Stores the total number of backing pages + unsigned int maxSnapShots; //Stores the total number of snapshots we allow +}; + +static struct SnapShot *snapshotrecord = NULL; /** ReturnPageAlignedAddress returns a page aligned address for the * address being added as a side effect the numBytes are also changed. @@ -109,46 +123,8 @@ static void HandlePF(int sig, siginfo_t *si, void *unused) // Handle error by quitting? } } -#endif /* USE_MPROTECT_SNAPSHOT */ - -#if !USE_MPROTECT_SNAPSHOT -static void createSharedMemory() -{ - //step 1. create shared memory. - 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; -} -/** - * Create a new mspace pointer for the non-snapshotting (i.e., inter-process - * shared) memory region. Only for fork-based snapshotting. - * - * @return The shared memory mspace - */ -mspace create_shared_mspace() -{ - if (!snapshotrecord) - createSharedMemory(); - return create_mspace_with_base((void *)(snapshotrecord->mSharedMemoryBase), SHARED_MEMORY_DEFAULT - sizeof(struct SnapShot), 1); -} -#endif - - -/** The initSnapshotLibrary function initializes the snapshot library. - * @param entryPoint the function that should run the program. - */ -#if USE_MPROTECT_SNAPSHOT - -void initSnapshotLibrary(unsigned int numbackingpages, +static void mprot_snapshot_init(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions, unsigned int numheappages, VoidFuncPtr entryPoint) { @@ -198,8 +174,131 @@ void initSnapshotLibrary(unsigned int numbackingpages, entryPoint(); } -#else -void initSnapshotLibrary(unsigned int numbackingpages, + +static void mprot_add_to_snapshot(void *addr, unsigned int numPages) +{ + 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; +} + +static snapshot_id mprot_take_snapshot() +{ + 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"); + model_print("Failed to mprotect inside of takeSnapShot\n"); + exit(EXIT_FAILURE); + } + } + unsigned int snapshot = snapshotrecord->lastSnapShot++; + if (snapshot == snapshotrecord->maxSnapShots) { + model_print("Out of snapshots\n"); + exit(EXIT_FAILURE); + } + snapshotrecord->snapShots[snapshot].firstBackingPage = snapshotrecord->lastBackingPage; + + return snapshot; +} + +static void mprot_roll_back(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 + + 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"); + model_print("Failed to mprotect inside of takeSnapShot\n"); + exit(EXIT_FAILURE); + } + } + 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; + mprot_take_snapshot(); //Make sure current snapshot is still good...All later ones are cleared +} + +#else /* !USE_MPROTECT_SNAPSHOT */ + +#include + +#define SHARED_MEMORY_DEFAULT (100 * ((size_t)1 << 20)) // 100mb for the shared memory +#define STACK_SIZE_DEFAULT (((size_t)1 << 20) * 20) // 20 mb out of the above 100 mb for my stack + +struct SnapShot { + void *mSharedMemoryBase; + void *mStackBase; + size_t mStackSize; + volatile snapshot_id mIDToRollback; + ucontext_t mContextToRollback; + snapshot_id currSnapShotID; +}; + +static struct SnapShot *snapshotrecord = NULL; + +/** @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; + +static void createSharedMemory() +{ + //step 1. create shared memory. + 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; +} + +/** + * Create a new mspace pointer for the non-snapshotting (i.e., inter-process + * shared) memory region. Only for fork-based snapshotting. + * + * @return The shared memory mspace + */ +mspace create_shared_mspace() +{ + if (!snapshotrecord) + createSharedMemory(); + return create_mspace_with_base((void *)(snapshotrecord->mSharedMemoryBase), SHARED_MEMORY_DEFAULT - sizeof(struct SnapShot), 1); +} + +static void fork_snapshot_init(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions, unsigned int numheappages, VoidFuncPtr entryPoint) { @@ -244,7 +343,7 @@ void initSnapshotLibrary(unsigned int numbackingpages, 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\n", + DEBUG("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 { @@ -258,85 +357,16 @@ void initSnapshotLibrary(unsigned int numbackingpages, } } } -#endif - -/** The addMemoryRegionToSnapShot function assumes that addr is page aligned. - */ -void addMemoryRegionToSnapShot(void *addr, unsigned int numPages) -{ -#if USE_MPROTECT_SNAPSHOT - 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; -#endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS. -} -/** The takeSnapshot function takes a snapshot. - * @return The snapshot identifier. - */ -snapshot_id takeSnapshot() +static snapshot_id fork_take_snapshot() { -#if USE_MPROTECT_SNAPSHOT - 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"); - model_print("Failed to mprotect inside of takeSnapShot\n"); - exit(EXIT_FAILURE); - } - } - unsigned int snapshot = snapshotrecord->lastSnapShot++; - if (snapshot == snapshotrecord->maxSnapShots) { - model_print("Out of snapshots\n"); - exit(EXIT_FAILURE); - } - snapshotrecord->snapShots[snapshot].firstBackingPage = snapshotrecord->lastBackingPage; - - return snapshot; -#else swapcontext(&savedUserSnapshotContext, &savedSnapshotContext); - SSDEBUG("TAKESNAPSHOT RETURN\n"); + DEBUG("TAKESNAPSHOT RETURN\n"); return snapshotid; -#endif } -/** The rollBack function rollback to the given snapshot identifier. - * @param theID is the snapshot identifier to rollback to. - */ -void rollBack(snapshot_id theID) +static void fork_roll_back(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 - 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"); - model_print("Failed to mprotect inside of takeSnapShot\n"); - exit(EXIT_FAILURE); - } - } - 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; - takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared -#else snapshotrecord->mIDToRollback = theID; volatile int sTemp = 0; getcontext(&snapshotrecord->mContextToRollback); @@ -348,12 +378,61 @@ void rollBack(snapshot_id theID) */ if (!sTemp) { sTemp = 1; - SSDEBUG("Invoked rollback\n"); + DEBUG("Invoked rollback\n"); exit(EXIT_SUCCESS); } /* * This fix obviates the need for a finalize call. hence less dependences for model-checker.... */ snapshotrecord->mIDToRollback = -1; +} + +#endif /* !USE_MPROTECT_SNAPSHOT */ + +/** 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 + mprot_snapshot_init(numbackingpages, numsnapshots, nummemoryregions, numheappages, entryPoint); +#else + fork_snapshot_init(numbackingpages, numsnapshots, nummemoryregions, numheappages, entryPoint); +#endif +} + +/** The addMemoryRegionToSnapShot function assumes that addr is page aligned. */ +void addMemoryRegionToSnapShot(void *addr, unsigned int numPages) +{ +#if USE_MPROTECT_SNAPSHOT + mprot_add_to_snapshot(addr, numPages); +#else + /* not needed for fork-based snapshotting */ +#endif +} + +/** The takeSnapshot function takes a snapshot. + * @return The snapshot identifier. + */ +snapshot_id takeSnapshot() +{ +#if USE_MPROTECT_SNAPSHOT + return mprot_take_snapshot(); +#else + return fork_take_snapshot(); +#endif +} + +/** The rollBack function rollback to the given snapshot identifier. + * @param theID is the snapshot identifier to rollback to. + */ +void rollBack(snapshot_id theID) +{ +#if USE_MPROTECT_SNAPSHOT + mprot_roll_back(theID); +#else + fork_roll_back(theID); #endif }