+boolean_t panic_include_zprint = FALSE;
+boolean_t zone_gc_allowed_by_time_throttle = TRUE;
+
+/*
+ * Zone leak debugging code
+ *
+ * When enabled, this code keeps a log to track allocations to a particular zone that have not
+ * yet been freed. Examining this log will reveal the source of a zone leak. The log is allocated
+ * only when logging is enabled, so there is no effect on the system when it's turned off. Logging is
+ * off by default.
+ *
+ * Enable the logging via the boot-args. Add the parameter "zlog=<zone>" to boot-args where <zone>
+ * is the name of the zone you wish to log.
+ *
+ * This code only tracks one zone, so you need to identify which one is leaking first.
+ * Generally, you'll know you have a leak when you get a "zalloc retry failed 3" panic from the zone
+ * garbage collector. Note that the zone name printed in the panic message is not necessarily the one
+ * containing the leak. So do a zprint from gdb and locate the zone with the bloated size. This
+ * is most likely the problem zone, so set zlog in boot-args to this zone name, reboot and re-run the test. The
+ * next time it panics with this message, examine the log using the kgmacros zstack, findoldest and countpcs.
+ * See the help in the kgmacros for usage info.
+ *
+ *
+ * Zone corruption logging
+ *
+ * Logging can also be used to help identify the source of a zone corruption. First, identify the zone
+ * that is being corrupted, then add "-zc zlog=<zone name>" to the boot-args. When -zc is used in conjunction
+ * with zlog, it changes the logging style to track both allocations and frees to the zone. So when the
+ * corruption is detected, examining the log will show you the stack traces of the callers who last allocated
+ * and freed any particular element in the zone. Use the findelem kgmacro with the address of the element that's been
+ * corrupted to examine its history. This should lead to the source of the corruption.
+ */
+
+static int log_records; /* size of the log, expressed in number of records */
+
+#define MAX_ZONE_NAME 32 /* max length of a zone name we can take from the boot-args */
+
+static char zone_name_to_log[MAX_ZONE_NAME] = ""; /* the zone name we're logging, if any */
+
+/*
+ * The number of records in the log is configurable via the zrecs parameter in boot-args. Set this to
+ * the number of records you want in the log. For example, "zrecs=1000" sets it to 1000 records. Note
+ * that the larger the size of the log, the slower the system will run due to linear searching in the log,
+ * but one doesn't generally care about performance when tracking down a leak. The log is capped at 8000
+ * records since going much larger than this tends to make the system unresponsive and unbootable on small
+ * memory configurations. The default value is 4000 records.
+ */
+#if defined(__LP64__)
+#define ZRECORDS_MAX 16000 /* Max records allowed in the log */
+#else
+#define ZRECORDS_MAX 8000 /* Max records allowed in the log */
+#endif
+#define ZRECORDS_DEFAULT 4000 /* default records in log if zrecs is not specificed in boot-args */
+
+/*
+ * Each record in the log contains a pointer to the zone element it refers to, a "time" number that allows
+ * the records to be ordered chronologically, and a small array to hold the pc's from the stack trace. A
+ * record is added to the log each time a zalloc() is done in the zone_of_interest. For leak debugging,
+ * the record is cleared when a zfree() is done. For corruption debugging, the log tracks both allocs and frees.
+ * If the log fills, old records are replaced as if it were a circular buffer.
+ */
+
+struct zrecord {
+ void *z_element; /* the element that was zalloc'ed of zfree'ed */
+ uint32_t z_opcode:1, /* whether it was a zalloc or zfree */
+ z_time:31; /* time index when operation was done */
+ void *z_pc[MAX_ZTRACE_DEPTH]; /* stack trace of caller */
+};
+
+/*
+ * Opcodes for the z_opcode field:
+ */
+
+#define ZOP_ALLOC 1
+#define ZOP_FREE 0
+
+/*
+ * The allocation log and all the related variables are protected by the zone lock for the zone_of_interest
+ */
+
+static struct zrecord *zrecords; /* the log itself, dynamically allocated when logging is enabled */
+static int zcurrent = 0; /* index of the next slot in the log to use */
+static int zrecorded = 0; /* number of allocations recorded in the log */
+static unsigned int ztime = 0; /* a timestamp of sorts */
+static zone_t zone_of_interest = NULL; /* the zone being watched; corresponds to zone_name_to_log */
+
+/*
+ * Decide if we want to log this zone by doing a string compare between a zone name and the name
+ * of the zone to log. Return true if the strings are equal, false otherwise. Because it's not
+ * possible to include spaces in strings passed in via the boot-args, a period in the logname will
+ * match a space in the zone name.
+ */
+
+static int
+log_this_zone(const char *zonename, const char *logname)
+{
+ int len;
+ const char *zc = zonename;
+ const char *lc = logname;
+
+ /*
+ * Compare the strings. We bound the compare by MAX_ZONE_NAME.
+ */
+
+ for (len = 1; len <= MAX_ZONE_NAME; zc++, lc++, len++) {
+
+ /*
+ * If the current characters don't match, check for a space in
+ * in the zone name and a corresponding period in the log name.
+ * If that's not there, then the strings don't match.
+ */
+
+ if (*zc != *lc && !(*zc == ' ' && *lc == '.'))
+ break;
+
+ /*
+ * The strings are equal so far. If we're at the end, then it's a match.
+ */
+
+ if (*zc == '\0')
+ return TRUE;
+ }
+
+ return FALSE;
+}
+
+
+/*
+ * 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) (zrecords && (z) == zone_of_interest)
+
+extern boolean_t zlog_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 z_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 z_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 */
+#define ZLEAK_ALLOCATION_MAP_NUM 16384
+#define ZLEAK_TRACE_MAP_NUM 8192
+
+uint32_t zleak_alloc_buckets = ZLEAK_ALLOCATION_MAP_NUM;
+uint32_t zleak_trace_buckets = 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_mtx_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;
+
+ /* -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");
+ }
+
+ /* zfactor=XXXX (override how often to sample the zone allocator) */
+ if (PE_parse_boot_argn("zfactor", &z_sample_factor, sizeof(z_sample_factor))) {
+ printf("Zone leak factor override:%u\n", z_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!");
+ }
+ }
+
+ /* 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!");
+ }
+ }
+
+ /* 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_mtx_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
+ * 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
+
projects / apple / xnu.git / blobdiff