+
+/*
+ * Test if we want to log this zalloc/zfree event. We log if this is the zone we're interested in and
+ * the buffer for the records has been allocated.
+ */
+
+#define DO_LOGGING(z) (z->zone_logging == TRUE && z->zlog_btlog)
+
+extern boolean_t kmem_alloc_ready;
+
+#if CONFIG_ZLEAKS
+#pragma mark -
+#pragma mark Zone Leak Detection
+
+/*
+ * The zone leak detector, abbreviated 'zleak', keeps track of a subset of the currently outstanding
+ * allocations made by the zone allocator. Every zleak_sample_factor allocations in each zone, we capture a
+ * backtrace. Every free, we examine the table and determine if the allocation was being tracked,
+ * and stop tracking it if it was being tracked.
+ *
+ * We track the allocations in the zallocations hash table, which stores the address that was returned from
+ * the zone allocator. Each stored entry in the zallocations table points to an entry in the ztraces table, which
+ * stores the backtrace associated with that allocation. This provides uniquing for the relatively large
+ * backtraces - we don't store them more than once.
+ *
+ * Data collection begins when the zone map is 50% full, and only occurs for zones that are taking up
+ * a large amount of virtual space.
+ */
+#define ZLEAK_STATE_ENABLED 0x01 /* Zone leak monitoring should be turned on if zone_map fills up. */
+#define ZLEAK_STATE_ACTIVE 0x02 /* We are actively collecting traces. */
+#define ZLEAK_STATE_ACTIVATING 0x04 /* Some thread is doing setup; others should move along. */
+#define ZLEAK_STATE_FAILED 0x08 /* Attempt to allocate tables failed. We will not try again. */
+uint32_t zleak_state = 0; /* State of collection, as above */
+
+boolean_t panic_include_ztrace = FALSE; /* Enable zleak logging on panic */
+vm_size_t zleak_global_tracking_threshold; /* Size of zone map at which to start collecting data */
+vm_size_t zleak_per_zone_tracking_threshold; /* Size a zone will have before we will collect data on it */
+unsigned int zleak_sample_factor = 1000; /* Allocations per sample attempt */
+
+/*
+ * Counters for allocation statistics.
+ */
+
+/* Times two active records want to occupy the same spot */
+unsigned int z_alloc_collisions = 0;
+unsigned int z_trace_collisions = 0;
+
+/* Times a new record lands on a spot previously occupied by a freed allocation */
+unsigned int z_alloc_overwrites = 0;
+unsigned int z_trace_overwrites = 0;
+
+/* Times a new alloc or trace is put into the hash table */
+unsigned int z_alloc_recorded = 0;
+unsigned int z_trace_recorded = 0;
+
+/* Times zleak_log returned false due to not being able to acquire the lock */
+unsigned int z_total_conflicts = 0;
+
+
+#pragma mark struct zallocation
+/*
+ * Structure for keeping track of an allocation
+ * An allocation bucket is in use if its element is not NULL
+ */
+struct zallocation {
+ uintptr_t za_element; /* the element that was zalloc'ed or zfree'ed, NULL if bucket unused */
+ vm_size_t za_size; /* how much memory did this allocation take up? */
+ uint32_t za_trace_index; /* index into ztraces for backtrace associated with allocation */
+ /* TODO: #if this out */
+ uint32_t za_hit_count; /* for determining effectiveness of hash function */
+};
+
+/* Size must be a power of two for the zhash to be able to just mask off bits instead of mod */
+uint32_t zleak_alloc_buckets = CONFIG_ZLEAK_ALLOCATION_MAP_NUM;
+uint32_t zleak_trace_buckets = CONFIG_ZLEAK_TRACE_MAP_NUM;
+
+vm_size_t zleak_max_zonemap_size;
+
+/* Hashmaps of allocations and their corresponding traces */
+static struct zallocation* zallocations;
+static struct ztrace* ztraces;
+
+/* not static so that panic can see this, see kern/debug.c */
+struct ztrace* top_ztrace;
+
+/* Lock to protect zallocations, ztraces, and top_ztrace from concurrent modification. */
+static lck_spin_t zleak_lock;
+static lck_attr_t zleak_lock_attr;
+static lck_grp_t zleak_lock_grp;
+static lck_grp_attr_t zleak_lock_grp_attr;
+
+/*
+ * Initializes the zone leak monitor. Called from zone_init()
+ */
+static void
+zleak_init(vm_size_t max_zonemap_size)
+{
+ char scratch_buf[16];
+ boolean_t zleak_enable_flag = FALSE;
+
+ zleak_max_zonemap_size = max_zonemap_size;
+ zleak_global_tracking_threshold = max_zonemap_size / 2;
+ zleak_per_zone_tracking_threshold = zleak_global_tracking_threshold / 8;
+
+#if CONFIG_EMBEDDED
+ if (PE_parse_boot_argn("-zleakon", scratch_buf, sizeof(scratch_buf))) {
+ zleak_enable_flag = TRUE;
+ printf("zone leak detection enabled\n");
+ } else {
+ zleak_enable_flag = FALSE;
+ printf("zone leak detection disabled\n");
+ }
+#else /* CONFIG_EMBEDDED */
+ /* -zleakoff (flag to disable zone leak monitor) */
+ if (PE_parse_boot_argn("-zleakoff", scratch_buf, sizeof(scratch_buf))) {
+ zleak_enable_flag = FALSE;
+ printf("zone leak detection disabled\n");
+ } else {
+ zleak_enable_flag = TRUE;
+ printf("zone leak detection enabled\n");
+ }
+#endif /* CONFIG_EMBEDDED */
+
+ /* zfactor=XXXX (override how often to sample the zone allocator) */
+ if (PE_parse_boot_argn("zfactor", &zleak_sample_factor, sizeof(zleak_sample_factor))) {
+ printf("Zone leak factor override: %u\n", zleak_sample_factor);
+ }
+
+ /* zleak-allocs=XXXX (override number of buckets in zallocations) */
+ if (PE_parse_boot_argn("zleak-allocs", &zleak_alloc_buckets, sizeof(zleak_alloc_buckets))) {
+ printf("Zone leak alloc buckets override: %u\n", zleak_alloc_buckets);
+ /* uses 'is power of 2' trick: (0x01000 & 0x00FFF == 0) */
+ if (zleak_alloc_buckets == 0 || (zleak_alloc_buckets & (zleak_alloc_buckets - 1))) {
+ printf("Override isn't a power of two, bad things might happen!\n");
+ }
+ }
+
+ /* zleak-traces=XXXX (override number of buckets in ztraces) */
+ if (PE_parse_boot_argn("zleak-traces", &zleak_trace_buckets, sizeof(zleak_trace_buckets))) {
+ printf("Zone leak trace buckets override: %u\n", zleak_trace_buckets);
+ /* uses 'is power of 2' trick: (0x01000 & 0x00FFF == 0) */
+ if (zleak_trace_buckets == 0 || (zleak_trace_buckets & (zleak_trace_buckets - 1))) {
+ printf("Override isn't a power of two, bad things might happen!\n");
+ }
+ }
+
+ /* allocate the zleak_lock */
+ lck_grp_attr_setdefault(&zleak_lock_grp_attr);
+ lck_grp_init(&zleak_lock_grp, "zleak_lock", &zleak_lock_grp_attr);
+ lck_attr_setdefault(&zleak_lock_attr);
+ lck_spin_init(&zleak_lock, &zleak_lock_grp, &zleak_lock_attr);
+
+ if (zleak_enable_flag) {
+ zleak_state = ZLEAK_STATE_ENABLED;
+ }
+}
+
+#if CONFIG_ZLEAKS
+
+/*
+ * Support for kern.zleak.active sysctl - a simplified
+ * version of the zleak_state variable.
+ */
+int
+get_zleak_state(void)
+{
+ if (zleak_state & ZLEAK_STATE_FAILED) {
+ return -1;
+ }
+ if (zleak_state & ZLEAK_STATE_ACTIVE) {
+ return 1;
+ }
+ return 0;
+}
+
+#endif
+
+
+kern_return_t
+zleak_activate(void)
+{
+ kern_return_t retval;
+ vm_size_t z_alloc_size = zleak_alloc_buckets * sizeof(struct zallocation);
+ vm_size_t z_trace_size = zleak_trace_buckets * sizeof(struct ztrace);
+ void *allocations_ptr = NULL;
+ void *traces_ptr = NULL;
+
+ /* Only one thread attempts to activate at a time */
+ if (zleak_state & (ZLEAK_STATE_ACTIVE | ZLEAK_STATE_ACTIVATING | ZLEAK_STATE_FAILED)) {
+ return KERN_SUCCESS;
+ }
+
+ /* Indicate that we're doing the setup */
+ lck_spin_lock(&zleak_lock);
+ if (zleak_state & (ZLEAK_STATE_ACTIVE | ZLEAK_STATE_ACTIVATING | ZLEAK_STATE_FAILED)) {
+ lck_spin_unlock(&zleak_lock);
+ return KERN_SUCCESS;
+ }
+
+ zleak_state |= ZLEAK_STATE_ACTIVATING;
+ lck_spin_unlock(&zleak_lock);
+
+ /* Allocate and zero tables */
+ retval = kmem_alloc_kobject(kernel_map, (vm_offset_t*)&allocations_ptr, z_alloc_size, VM_KERN_MEMORY_OSFMK);
+ if (retval != KERN_SUCCESS) {
+ goto fail;
+ }
+
+ retval = kmem_alloc_kobject(kernel_map, (vm_offset_t*)&traces_ptr, z_trace_size, VM_KERN_MEMORY_OSFMK);
+ if (retval != KERN_SUCCESS) {
+ goto fail;
+ }
+
+ bzero(allocations_ptr, z_alloc_size);
+ bzero(traces_ptr, z_trace_size);
+
+ /* Everything's set. Install tables, mark active. */
+ zallocations = allocations_ptr;
+ ztraces = traces_ptr;
+
+ /*
+ * Initialize the top_ztrace to the first entry in ztraces,
+ * so we don't have to check for null in zleak_log
+ */
+ top_ztrace = &ztraces[0];
+
+ /*
+ * Note that we do need a barrier between installing
+ * the tables and setting the active flag, because the zfree()
+ * path accesses the table without a lock if we're active.
+ */
+ lck_spin_lock(&zleak_lock);
+ zleak_state |= ZLEAK_STATE_ACTIVE;
+ zleak_state &= ~ZLEAK_STATE_ACTIVATING;
+ lck_spin_unlock(&zleak_lock);
+
+ return 0;
+
+fail:
+ /*
+ * If we fail to allocate memory, don't further tax
+ * the system by trying again.
+ */
+ lck_spin_lock(&zleak_lock);
+ zleak_state |= ZLEAK_STATE_FAILED;
+ zleak_state &= ~ZLEAK_STATE_ACTIVATING;
+ lck_spin_unlock(&zleak_lock);
+
+ if (allocations_ptr != NULL) {
+ kmem_free(kernel_map, (vm_offset_t)allocations_ptr, z_alloc_size);
+ }
+
+ if (traces_ptr != NULL) {
+ kmem_free(kernel_map, (vm_offset_t)traces_ptr, z_trace_size);
+ }
+
+ return retval;
+}
+
+/*
+ * TODO: What about allocations that never get deallocated,
+ * especially ones with unique backtraces? Should we wait to record
+ * until after boot has completed?
+ * (How many persistent zallocs are there?)
+ */
+
+/*
+ * This function records the allocation in the allocations table,
+ * and stores the associated backtrace in the traces table
+ * (or just increments the refcount if the trace is already recorded)
+ * If the allocation slot is in use, the old allocation is replaced with the new allocation, and
+ * the associated trace's refcount is decremented.
+ * If the trace slot is in use, it returns.
+ * The refcount is incremented by the amount of memory the allocation consumes.
+ * The return value indicates whether to try again next time.
+ */
+static boolean_t
+zleak_log(uintptr_t* bt,
+ uintptr_t addr,
+ uint32_t depth,
+ vm_size_t allocation_size)
+{
+ /* Quit if there's someone else modifying the hash tables */
+ if (!lck_spin_try_lock(&zleak_lock)) {
+ z_total_conflicts++;
+ return FALSE;
+ }
+
+ struct zallocation* allocation = &zallocations[hashaddr(addr, zleak_alloc_buckets)];
+
+ uint32_t trace_index = hashbacktrace(bt, depth, zleak_trace_buckets);
+ struct ztrace* trace = &ztraces[trace_index];
+
+ allocation->za_hit_count++;
+ trace->zt_hit_count++;
projects / apple / xnu.git / blobdiff