From 2ada1a461101f16a0be8ba75200c8ae4f9ff9d84 Mon Sep 17 00:00:00 2001 From: Brian Norris Date: Wed, 2 Jan 2013 18:45:25 -0800 Subject: [PATCH] snapshot: separate struct SnapShot naming The "struct SnapShot snapshotrecord;" structure is very uninformative in naming and is distinctly different for mprotect-based and fork-based snapshotting. This renames the struct in order to more clearly separate its usage in the different implementations. --- snapshot.cc | 116 ++++++++++++++++++++++++++-------------------------- 1 file changed, 58 insertions(+), 58 deletions(-) diff --git a/snapshot.cc b/snapshot.cc index 1931268..fe5110a 100644 --- a/snapshot.cc +++ b/snapshot.cc @@ -47,7 +47,7 @@ struct MemoryRegion { }; /* Primary struct for snapshotting system */ -struct SnapShot { +struct 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 @@ -63,7 +63,7 @@ struct SnapShot { unsigned int maxSnapShots; //Stores the total number of snapshots we allow }; -static struct SnapShot *snapshotrecord = NULL; +static struct mprot_snapshotter *mprot_snap = NULL; /** ReturnPageAlignedAddress returns a page aligned address for the * address being added as a side effect the numBytes are also changed. @@ -78,19 +78,19 @@ static void * ReturnPageAlignedAddress(void *addr) */ 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)); + mprot_snap = (struct mprot_snapshotter *)model_malloc(sizeof(struct mprot_snapshotter)); + mprot_snap->regionsToSnapShot = (struct MemoryRegion *)model_malloc(sizeof(struct MemoryRegion) * nummemoryregions); + mprot_snap->backingStoreBasePtr = (void *)model_malloc(sizeof(snapshot_page_t) * (numbackingpages + 1)); //Page align the backingstorepages - 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; + mprot_snap->backingStore = (snapshot_page_t *)PageAlignAddressUpward(mprot_snap->backingStoreBasePtr); + mprot_snap->backingRecords = (struct BackingPageRecord *)model_malloc(sizeof(struct BackingPageRecord) * numbackingpages); + mprot_snap->snapShots = (struct SnapShotRecord *)model_malloc(sizeof(struct SnapShotRecord) * numsnapshots); + mprot_snap->lastSnapShot = 0; + mprot_snap->lastBackingPage = 0; + mprot_snap->lastRegion = 0; + mprot_snap->maxRegions = nummemoryregions; + mprot_snap->maxBackingPages = numbackingpages; + mprot_snap->maxSnapShots = numsnapshots; } /** HandlePF is the page fault handler for mprotect based snapshotting @@ -107,16 +107,16 @@ static void HandlePF(int sig, siginfo_t *si, void *unused) } void* addr = ReturnPageAlignedAddress(si->si_addr); - unsigned int backingpage = snapshotrecord->lastBackingPage++; //Could run out of pages... - if (backingpage == snapshotrecord->maxBackingPages) { + 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(snapshot_page_t)); + 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(snapshot_page_t), PROT_READ | PROT_WRITE)) { perror("mprotect"); @@ -160,7 +160,7 @@ static void mprot_snapshot_init(unsigned int numbackingpages, memset(&si, 0, sizeof(si)); si.si_addr = ss.ss_sp; HandlePF(SIGSEGV, &si, NULL); - snapshotrecord->lastBackingPage--; //remove the fake page we copied + mprot_snap->lastBackingPage--; //remove the fake page we copied void *basemySpace = model_malloc((numheappages + 1) * PAGESIZE); void *pagealignedbase = PageAlignAddressUpward(basemySpace); @@ -177,31 +177,31 @@ static void mprot_snapshot_init(unsigned int numbackingpages, static void mprot_add_to_snapshot(void *addr, unsigned int numPages) { - unsigned int memoryregion = snapshotrecord->lastRegion++; - if (memoryregion == snapshotrecord->maxRegions) { + unsigned int memoryregion = mprot_snap->lastRegion++; + if (memoryregion == mprot_snap->maxRegions) { model_print("Exceeded supported number of memory regions!\n"); exit(EXIT_FAILURE); } - snapshotrecord->regionsToSnapShot[memoryregion].basePtr = addr; - snapshotrecord->regionsToSnapShot[memoryregion].sizeInPages = numPages; + mprot_snap->regionsToSnapShot[memoryregion].basePtr = addr; + mprot_snap->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) { + 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 = snapshotrecord->lastSnapShot++; - if (snapshot == snapshotrecord->maxSnapShots) { + unsigned int snapshot = mprot_snap->lastSnapShot++; + if (snapshot == mprot_snap->maxSnapShots) { model_print("Out of snapshots\n"); exit(EXIT_FAILURE); } - snapshotrecord->snapShots[snapshot].firstBackingPage = snapshotrecord->lastBackingPage; + mprot_snap->snapShots[snapshot].firstBackingPage = mprot_snap->lastBackingPage; return snapshot; } @@ -209,30 +209,30 @@ static snapshot_id mprot_take_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)); + 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 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) { + 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 = 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)); + 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)); } } - snapshotrecord->lastSnapShot = theID; - snapshotrecord->lastBackingPage = snapshotrecord->snapShots[theID].firstBackingPage; + 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 } @@ -243,7 +243,7 @@ static void mprot_roll_back(snapshot_id theID) #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 { +struct fork_snapshotter { void *mSharedMemoryBase; void *mStackBase; size_t mStackSize; @@ -252,7 +252,7 @@ struct SnapShot { snapshot_id currSnapShotID; }; -static struct SnapShot *snapshotrecord = NULL; +static struct fork_snapshotter *fork_snap = NULL; /** @statics * These variables are necessary because the stack is shared region and @@ -277,12 +277,12 @@ static void createSharedMemory() 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; + 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; } /** @@ -293,16 +293,16 @@ static void createSharedMemory() */ mspace create_shared_mspace() { - if (!snapshotrecord) + if (!fork_snap) createSharedMemory(); - return create_mspace_with_base((void *)(snapshotrecord->mSharedMemoryBase), SHARED_MEMORY_DEFAULT - sizeof(struct SnapShot), 1); + 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 (!snapshotrecord) + if (!fork_snap) createSharedMemory(); void *base_model_snapshot_space = malloc((numheappages + 1) * PAGESIZE); @@ -312,7 +312,7 @@ static void fork_snapshot_init(unsigned int numbackingpages, //step 2 setup the stack context. ucontext_t newContext; getcontext(&newContext); - newContext.uc_stack.ss_sp = snapshotrecord->mStackBase; + 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 */ @@ -320,20 +320,20 @@ static void fork_snapshot_init(unsigned int numbackingpages, /* switch back here when takesnapshot is called */ pid_t forkedID = 0; - snapshotid = snapshotrecord->currSnapShotID; + 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) { - snapshotrecord->currSnapShotID = snapshotid + 1; + fork_snap->currSnapShotID = snapshotid + 1; forkedID = fork(); 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)); + setcontext(&(fork_snap->mContextToRollback)); } else { /*Child process which is forked as a result of takesnapshot call should switch back to the takesnapshot context*/ @@ -350,7 +350,7 @@ static void fork_snapshot_init(unsigned int numbackingpages, retVal = waitpid(forkedID, &status, 0); } while (-1 == retVal && errno == EINTR); - if (snapshotrecord->mIDToRollback != snapshotid) { + if (fork_snap->mIDToRollback != snapshotid) { exit(EXIT_SUCCESS); } rollback = true; @@ -367,9 +367,9 @@ static snapshot_id fork_take_snapshot() static void fork_roll_back(snapshot_id theID) { - snapshotrecord->mIDToRollback = theID; + fork_snap->mIDToRollback = theID; volatile int sTemp = 0; - getcontext(&snapshotrecord->mContextToRollback); + 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 @@ -384,7 +384,7 @@ static void fork_roll_back(snapshot_id theID) /* * This fix obviates the need for a finalize call. hence less dependences for model-checker.... */ - snapshotrecord->mIDToRollback = -1; + fork_snap->mIDToRollback = -1; } #endif /* !USE_MPROTECT_SNAPSHOT */ -- 2.34.1