#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
-#include <map>
-#include <cstring>
-#include <cstdio>
-#include "snapshot.h"
-#include "snapshotimp.h"
-#include "mymemory.h"
-#include <fcntl.h>
-#include <assert.h>
-#include <pthread.h>
-#include <semaphore.h>
+#include <string.h>
#include <errno.h>
#include <sys/wait.h>
#include <ucontext.h>
-#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 "mymemory.h"
+#include "common.h"
-#ifdef CONFIG_SSDEBUG
-#define SSDEBUG printf
-#else
-#define SSDEBUG(...) do { } while (0)
-#endif
+#define FAILURE(mesg) { model_print("failed in the API: %s with errno relative message: %s\n", mesg, strerror(errno)); exit(EXIT_FAILURE); }
+
+/** 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));
+}
-/* extern declaration definition */
#if USE_MPROTECT_SNAPSHOT
-struct SnapShot * snapshotrecord = NULL;
-struct Snapshot_t * sTheRecord = NULL;
-#else
-struct Snapshot_t * sTheRecord = NULL;
-#endif
-#if !USE_MPROTECT_SNAPSHOT
-static ucontext_t savedSnapshotContext;
-static ucontext_t savedUserSnapshotContext;
-static snapshot_id snapshotid = 0;
-#endif
+/* Each SnapShotRecord lists the firstbackingpage that must be written to
+ * revert to that snapshot */
+struct SnapShotRecord {
+ unsigned int firstBackingPage;
+};
-#if USE_MPROTECT_SNAPSHOT
+/** @brief Backing store page */
+typedef unsigned char snapshot_page_t[PAGESIZE];
-/** The initSnapShotRecord method initialized the snapshotting data
- * structures for the mprotect based snapshot.
+/* 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
+};
+
+/** ReturnPageAlignedAddress returns a page aligned address for the
+ * address being added as a side effect the numBytes are also changed.
*/
-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 * ReturnPageAlignedAddress(void *addr)
+{
+ return (void *)(((uintptr_t)addr) & ~(PAGESIZE - 1));
+}
+
+/* Primary struct for snapshotting system */
+struct mprot_snapshotter {
+ mprot_snapshotter(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions);
+ ~mprot_snapshotter();
+
+ 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
+
+ MEMALLOC
+};
+
+static struct mprot_snapshotter *mprot_snap = NULL;
+
+mprot_snapshotter::mprot_snapshotter(unsigned int backing_pages, unsigned int snapshots, unsigned int regions) :
+ lastSnapShot(0),
+ lastBackingPage(0),
+ lastRegion(0),
+ maxRegions(regions),
+ maxBackingPages(backing_pages),
+ maxSnapShots(snapshots)
+{
+ regionsToSnapShot = (struct MemoryRegion *)model_malloc(sizeof(struct MemoryRegion) * regions);
+ backingStoreBasePtr = (void *)model_malloc(sizeof(snapshot_page_t) * (backing_pages + 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;
+ backingStore = (snapshot_page_t *)PageAlignAddressUpward(backingStoreBasePtr);
+ backingRecords = (struct BackingPageRecord *)model_malloc(sizeof(struct BackingPageRecord) * backing_pages);
+ snapShots = (struct SnapShotRecord *)model_malloc(sizeof(struct SnapShotRecord) * snapshots);
+}
+
+mprot_snapshotter::~mprot_snapshotter()
+{
+ model_free(regionsToSnapShot);
+ model_free(backingStoreBasePtr);
+ model_free(backingRecords);
+ model_free(snapShots);
}
-#endif //nothing to initialize for the fork based snapshotting.
-/** HandlePF is the page fault handler for mprotect based snapshotting
+/** mprot_handle_pf is the page fault handler for mprotect based snapshotting
* algorithm.
*/
-
-void HandlePF( int sig, siginfo_t *si, void * unused){
-#if USE_MPROTECT_SNAPSHOT
- if( si->si_code == SEGV_MAPERR ){
- printf("Real Fault at %p\n", si->si_addr);
- exit( EXIT_FAILURE );
+static void mprot_handle_pf(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 = mprot_snap->lastBackingPage++; //Could run out of pages...
+ if (backingpage == mprot_snap->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(&(mprot_snap->backingStore[backingpage]), addr, sizeof(snapshot_page_t));
//remember where to copy page back to
- snapshotrecord->backingRecords[backingpage].basePtrOfPage=addr;
+ mprot_snap->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.
-}
-
-/** ReturnPageAlignedAddress returns a page aligned address for the
- * address being added as a side effect the numBytes are also changed.
- */
-
-void * ReturnPageAlignedAddress(void * addr) {
- return (void *)(((uintptr_t)addr)&~(PAGESIZE-1));
}
-/** PageAlignedAdressUpdate return a page aligned address for the
- * address being added as a side effect the numBytes are also changed.
- */
-
-void * PageAlignAddressUpward(void * addr) {
- return (void *)((((uintptr_t)addr)+PAGESIZE-1)&~(PAGESIZE-1));
-}
-#ifdef __cplusplus
-extern "C" {
-#endif
- void createSharedLibrary(){
-#if !USE_MPROTECT_SNAPSHOT
- //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" );
- char * memMapBase = ( char * ) 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_t * )memMapBase;
- sTheRecord->mSharedMemoryBase = memMapBase + sizeof( struct Snapshot_t );
- sTheRecord->mStackBase = ( char * )memMapBase + ( size_t )SHARED_MEMORY_DEFAULT;
- sTheRecord->mStackSize = STACK_SIZE_DEFAULT;
- sTheRecord->mIDToRollback = -1;
- sTheRecord->currSnapShotID = 0;
- sTheRecord->mbFinalize = false;
-#endif
- }
-#ifdef __cplusplus
-}
-#endif
-
-/** The initSnapShotLibrary function initializes the Snapshot library.
- * @param entryPoint the function that should run the program.
- */
-void initSnapShotLibrary(unsigned int numbackingpages,
+static void mprot_snapshot_init(unsigned int numbackingpages,
unsigned int numsnapshots, unsigned int nummemoryregions,
- unsigned int numheappages, VoidFuncPtr entryPoint) {
-#if USE_MPROTECT_SNAPSHOT
+ 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 );
- sa.sa_sigaction = HandlePF;
+ sigemptyset(&sa.sa_mask);
+ sa.sa_sigaction = mprot_handle_pf;
#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);
}
- initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
+ mprot_snap = new mprot_snapshotter(numbackingpages, numsnapshots, nummemoryregions);
- // EVIL HACK: We need to make sure that calls into the HandlePF method don't cause dynamic links
+ // EVIL HACK: We need to make sure that calls into the mprot_handle_pf method don't cause dynamic links
// The problem is that we end up protecting state in the dynamic linker...
// Solution is to call our signal handler before we start protecting stuff...
siginfo_t si;
memset(&si, 0, sizeof(si));
- 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 );
- addMemoryRegionToSnapShot(pagealignedbase, numheappages);
+ si.si_addr = ss.ss_sp;
+ mprot_handle_pf(SIGSEGV, &si, NULL);
+ mprot_snap->lastBackingPage--; //remove the fake page we copied
+
+ void *basemySpace = model_malloc((numheappages + 1) * PAGESIZE);
+ void *pagealignedbase = PageAlignAddressUpward(basemySpace);
+ user_snapshot_space = create_mspace_with_base(pagealignedbase, numheappages * PAGESIZE, 1);
+ snapshot_add_memory_region(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);
+ snapshot_add_memory_region(pagealignedbase, numheappages);
+
entryPoint();
-#else
+}
- basemySpace=system_malloc((numheappages+1)*PAGESIZE);
- void * pagealignedbase=PageAlignAddressUpward(basemySpace);
- mySpace = create_mspace_with_base(pagealignedbase, numheappages*PAGESIZE, 1 );
- createSharedLibrary();
+static void mprot_add_to_snapshot(void *addr, unsigned int numPages)
+{
+ unsigned int memoryregion = mprot_snap->lastRegion++;
+ if (memoryregion == mprot_snap->maxRegions) {
+ model_print("Exceeded supported number of memory regions!\n");
+ exit(EXIT_FAILURE);
+ }
- //step 2 setup the stack context.
+ mprot_snap->regionsToSnapShot[memoryregion].basePtr = addr;
+ mprot_snap->regionsToSnapShot[memoryregion].sizeInPages = numPages;
+}
+
+static snapshot_id mprot_take_snapshot()
+{
+ for (unsigned int region = 0; region < mprot_snap->lastRegion; region++) {
+ if (mprotect(mprot_snap->regionsToSnapShot[region].basePtr, mprot_snap->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 = mprot_snap->lastSnapShot++;
+ if (snapshot == mprot_snap->maxSnapShots) {
+ model_print("Out of snapshots\n");
+ exit(EXIT_FAILURE);
+ }
+ mprot_snap->snapShots[snapshot].firstBackingPage = mprot_snap->lastBackingPage;
+
+ return snapshot;
+}
+
+static void mprot_roll_back(snapshot_id theID)
+{
+#if USE_MPROTECT_SNAPSHOT == 2
+ if (mprot_snap->lastSnapShot == (theID + 1)) {
+ for (unsigned int page = mprot_snap->snapShots[theID].firstBackingPage; page < mprot_snap->lastBackingPage; page++) {
+ memcpy(mprot_snap->backingRecords[page].basePtrOfPage, &mprot_snap->backingStore[page], sizeof(snapshot_page_t));
+ }
+ return;
+ }
+#endif
- 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 );
+ HashTable< void *, bool, uintptr_t, 4, model_malloc, model_calloc, model_free> duplicateMap;
+ for (unsigned int region = 0; region < mprot_snap->lastRegion; region++) {
+ if (mprotect(mprot_snap->regionsToSnapShot[region].basePtr, mprot_snap->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 = mprot_snap->snapShots[theID].firstBackingPage; page < mprot_snap->lastBackingPage; page++) {
+ if (!duplicateMap.contains(mprot_snap->backingRecords[page].basePtrOfPage)) {
+ duplicateMap.put(mprot_snap->backingRecords[page].basePtrOfPage, true);
+ memcpy(mprot_snap->backingRecords[page].basePtrOfPage, &mprot_snap->backingStore[page], sizeof(snapshot_page_t));
+ }
+ }
+ mprot_snap->lastSnapShot = theID;
+ mprot_snap->lastBackingPage = mprot_snap->snapShots[theID].firstBackingPage;
+ mprot_take_snapshot(); //Make sure current snapshot is still good...All later ones are cleared
+}
+
+#else /* !USE_MPROTECT_SNAPSHOT */
+
+#include <ucontext.h>
+
+#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 fork_snapshotter {
+ void *mSharedMemoryBase;
+ void *mStackBase;
+ size_t mStackSize;
+ volatile snapshot_id mIDToRollback;
+ ucontext_t mContextToRollback;
+ snapshot_id currSnapShotID;
+};
+
+static struct fork_snapshotter *fork_snap = 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
+ fork_snap = (struct fork_snapshotter *)memMapBase;
+ fork_snap->mSharedMemoryBase = (void *)((uintptr_t)memMapBase + sizeof(struct fork_snapshotter));
+ fork_snap->mStackBase = (void *)((uintptr_t)memMapBase + SHARED_MEMORY_DEFAULT);
+ fork_snap->mStackSize = STACK_SIZE_DEFAULT;
+ fork_snap->mIDToRollback = -1;
+ fork_snap->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 (!fork_snap)
+ createSharedMemory();
+ return create_mspace_with_base((void *)(fork_snap->mSharedMemoryBase), SHARED_MEMORY_DEFAULT - sizeof(struct fork_snapshotter), 1);
+}
+
+static void fork_snapshot_init(unsigned int numbackingpages,
+ unsigned int numsnapshots, unsigned int nummemoryregions,
+ unsigned int numheappages, VoidFuncPtr entryPoint)
+{
+ if (!fork_snap)
+ createSharedMemory();
- //add the code to take a snapshot here...
- //to return to user process, do a second swapcontext...
+ 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.
+ ucontext_t newContext;
+ getcontext(&newContext);
+ newContext.uc_stack.ss_sp = fork_snap->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 = fork_snap->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) {
+ fork_snap->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(&(fork_snap->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 );
+ 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 {
- 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 (fork_snap->mIDToRollback != snapshotid) {
exit(EXIT_SUCCESS);
- else{
- swapContext = true;
}
+ rollback = true;
}
}
+}
-#endif
+static snapshot_id fork_take_snapshot()
+{
+ swapcontext(&savedUserSnapshotContext, &savedSnapshotContext);
+ DEBUG("TAKESNAPSHOT RETURN\n");
+ return snapshotid;
}
-/** 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) {
- printf("Exceeded supported number of memory regions!\n");
- exit(EXIT_FAILURE);
+static void fork_roll_back(snapshot_id theID)
+{
+ fork_snap->mIDToRollback = theID;
+ volatile int sTemp = 0;
+ getcontext(&fork_snap->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;
+ DEBUG("Invoked rollback\n");
+ exit(EXIT_SUCCESS);
}
-
- snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr;
- snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
-#endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS.
+ /*
+ * This fix obviates the need for a finalize call. hence less dependences for model-checker....
+ */
+ fork_snap->mIDToRollback = -1;
}
-/** The takeSnapshot function takes a snapshot.
- * @return The snapshot identifier.
- */
+#endif /* !USE_MPROTECT_SNAPSHOT */
-snapshot_id takeSnapshot( ){
+/**
+ * @brief Initializes the snapshot system
+ * @param entryPoint the function that should run the program.
+ */
+void snapshot_system_init(unsigned int numbackingpages,
+ unsigned int numsnapshots, unsigned int nummemoryregions,
+ unsigned int numheappages, VoidFuncPtr entryPoint)
+{
#if USE_MPROTECT_SNAPSHOT
- for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
- if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ ) == -1 ){
- perror("mprotect");
- printf("Failed to mprotect inside of takeSnapShot\n");
- exit(EXIT_FAILURE);
- }
- }
- unsigned int snapshot=snapshotrecord->lastSnapShot++;
- if (snapshot==snapshotrecord->maxSnapShots) {
- printf("Out of snapshots\n");
- exit(EXIT_FAILURE);
- }
- snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage;
+ mprot_snapshot_init(numbackingpages, numsnapshots, nummemoryregions, numheappages, entryPoint);
+#else
+ fork_snapshot_init(numbackingpages, numsnapshots, nummemoryregions, numheappages, entryPoint);
+#endif
+}
- return snapshot;
+/** Assumes that addr is page aligned. */
+void snapshot_add_memory_region(void *addr, unsigned int numPages)
+{
+#if USE_MPROTECT_SNAPSHOT
+ mprot_add_to_snapshot(addr, numPages);
#else
- swapcontext( &savedUserSnapshotContext, &savedSnapshotContext );
- return snapshotid;
+ /* not needed for fork-based snapshotting */
#endif
}
-/** The rollBack function rollback to the given snapshot identifier.
- * @param theID is the snapshot identifier to rollback to.
+/** Takes a snapshot of memory.
+ * @return The snapshot identifier.
*/
-
-void rollBack( snapshot_id theID ){
+snapshot_id take_snapshot()
+{
#if USE_MPROTECT_SNAPSHOT
- std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap;
- for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
- if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE ) == -1 ){
- perror("mprotect");
- printf("Failed to mprotect inside of takeSnapShot\n");
- exit(EXIT_FAILURE);
- }
- }
- for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; page<snapshotrecord->lastBackingPage; 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));
- }
- }
- snapshotrecord->lastSnapShot=theID;
- snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage;
- takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared
+ return mprot_take_snapshot();
#else
- sTheRecord->mIDToRollback = theID;
- int sTemp = 0;
- getcontext( &sTheRecord->mContextToRollback );
- if( !sTemp ){
- sTemp = 1;
- SSDEBUG("Invoked rollback");
- exit(EXIT_SUCCESS);
- }
+ return fork_take_snapshot();
#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;
+/** Rolls the memory state back to the given snapshot identifier.
+ * @param theID is the snapshot identifier to rollback to.
+ */
+void snapshot_roll_back(snapshot_id theID)
+{
+#if USE_MPROTECT_SNAPSHOT
+ mprot_roll_back(theID);
+#else
+ fork_roll_back(theID);
#endif
}
-
projects / c11tester.git / blobdiff