+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#ifndef _SYS_DTRACE_IMPL_H
+#define _SYS_DTRACE_IMPL_H
+
+/* #pragma ident "@(#)dtrace_impl.h 1.21 06/05/19 SMI" */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * DTrace Dynamic Tracing Software: Kernel Implementation Interfaces
+ *
+ * Note: The contents of this file are private to the implementation of the
+ * Solaris system and DTrace subsystem and are subject to change at any time
+ * without notice. Applications and drivers using these interfaces will fail
+ * to run on future releases. These interfaces should not be used for any
+ * purpose except those expressly outlined in dtrace(7D) and libdtrace(3LIB).
+ * Please refer to the "Solaris Dynamic Tracing Guide" for more information.
+ */
+
+#include <sys/dtrace.h>
+
+/*
+ * DTrace Implementation Constants and Typedefs
+ */
+#define DTRACE_MAXPROPLEN 128
+#define DTRACE_DYNVAR_CHUNKSIZE 256
+
+struct dtrace_probe;
+struct dtrace_ecb;
+struct dtrace_predicate;
+struct dtrace_action;
+struct dtrace_provider;
+struct dtrace_state;
+
+typedef struct dtrace_probe dtrace_probe_t;
+typedef struct dtrace_ecb dtrace_ecb_t;
+typedef struct dtrace_predicate dtrace_predicate_t;
+typedef struct dtrace_action dtrace_action_t;
+typedef struct dtrace_provider dtrace_provider_t;
+typedef struct dtrace_meta dtrace_meta_t;
+typedef struct dtrace_state dtrace_state_t;
+typedef uint32_t dtrace_optid_t;
+typedef uint32_t dtrace_specid_t;
+typedef uint64_t dtrace_genid_t;
+
+/*
+ * DTrace Probes
+ *
+ * The probe is the fundamental unit of the DTrace architecture. Probes are
+ * created by DTrace providers, and managed by the DTrace framework. A probe
+ * is identified by a unique <provider, module, function, name> tuple, and has
+ * a unique probe identifier assigned to it. (Some probes are not associated
+ * with a specific point in text; these are called _unanchored probes_ and have
+ * no module or function associated with them.) Probes are represented as a
+ * dtrace_probe structure. To allow quick lookups based on each element of the
+ * probe tuple, probes are hashed by each of provider, module, function and
+ * name. (If a lookup is performed based on a regular expression, a
+ * dtrace_probekey is prepared, and a linear search is performed.) Each probe
+ * is additionally pointed to by a linear array indexed by its identifier. The
+ * identifier is the provider's mechanism for indicating to the DTrace
+ * framework that a probe has fired: the identifier is passed as the first
+ * argument to dtrace_probe(), where it is then mapped into the corresponding
+ * dtrace_probe structure. From the dtrace_probe structure, dtrace_probe() can
+ * iterate over the probe's list of enabling control blocks; see "DTrace
+ * Enabling Control Blocks", below.)
+ */
+struct dtrace_probe {
+ dtrace_id_t dtpr_id; /* probe identifier */
+ dtrace_ecb_t *dtpr_ecb; /* ECB list; see below */
+ dtrace_ecb_t *dtpr_ecb_last; /* last ECB in list */
+ void *dtpr_arg; /* provider argument */
+ dtrace_cacheid_t dtpr_predcache; /* predicate cache ID */
+ int dtpr_aframes; /* artificial frames */
+ dtrace_provider_t *dtpr_provider; /* pointer to provider */
+ char *dtpr_mod; /* probe's module name */
+ char *dtpr_func; /* probe's function name */
+ char *dtpr_name; /* probe's name */
+ dtrace_probe_t *dtpr_nextmod; /* next in module hash */
+ dtrace_probe_t *dtpr_prevmod; /* previous in module hash */
+ dtrace_probe_t *dtpr_nextfunc; /* next in function hash */
+ dtrace_probe_t *dtpr_prevfunc; /* previous in function hash */
+ dtrace_probe_t *dtpr_nextname; /* next in name hash */
+ dtrace_probe_t *dtpr_prevname; /* previous in name hash */
+ dtrace_genid_t dtpr_gen; /* probe generation ID */
+};
+
+typedef int dtrace_probekey_f(const char *, const char *, int);
+
+typedef struct dtrace_probekey {
+ const char *dtpk_prov; /* provider name to match */
+ dtrace_probekey_f *dtpk_pmatch; /* provider matching function */
+ const char *dtpk_mod; /* module name to match */
+ dtrace_probekey_f *dtpk_mmatch; /* module matching function */
+ const char *dtpk_func; /* func name to match */
+ dtrace_probekey_f *dtpk_fmatch; /* func matching function */
+ const char *dtpk_name; /* name to match */
+ dtrace_probekey_f *dtpk_nmatch; /* name matching function */
+ dtrace_id_t dtpk_id; /* identifier to match */
+} dtrace_probekey_t;
+
+typedef struct dtrace_hashbucket {
+ struct dtrace_hashbucket *dthb_next; /* next on hash chain */
+ dtrace_probe_t *dthb_chain; /* chain of probes */
+ int dthb_len; /* number of probes here */
+} dtrace_hashbucket_t;
+
+typedef struct dtrace_hash {
+ dtrace_hashbucket_t **dth_tab; /* hash table */
+ int dth_size; /* size of hash table */
+ int dth_mask; /* mask to index into table */
+ int dth_nbuckets; /* total number of buckets */
+ uintptr_t dth_nextoffs; /* offset of next in probe */
+ uintptr_t dth_prevoffs; /* offset of prev in probe */
+ uintptr_t dth_stroffs; /* offset of str in probe */
+} dtrace_hash_t;
+
+/*
+ * DTrace Enabling Control Blocks
+ *
+ * When a provider wishes to fire a probe, it calls into dtrace_probe(),
+ * passing the probe identifier as the first argument. As described above,
+ * dtrace_probe() maps the identifier into a pointer to a dtrace_probe_t
+ * structure. This structure contains information about the probe, and a
+ * pointer to the list of Enabling Control Blocks (ECBs). Each ECB points to
+ * DTrace consumer state, and contains an optional predicate, and a list of
+ * actions. (Shown schematically below.) The ECB abstraction allows a single
+ * probe to be multiplexed across disjoint consumers, or across disjoint
+ * enablings of a single probe within one consumer.
+ *
+ * Enabling Control Block
+ * dtrace_ecb_t
+ * +------------------------+
+ * | dtrace_epid_t ---------+--------------> Enabled Probe ID (EPID)
+ * | dtrace_state_t * ------+--------------> State associated with this ECB
+ * | dtrace_predicate_t * --+---------+
+ * | dtrace_action_t * -----+----+ |
+ * | dtrace_ecb_t * ---+ | | | Predicate (if any)
+ * +-------------------+----+ | | dtrace_predicate_t
+ * | | +---> +--------------------+
+ * | | | dtrace_difo_t * ---+----> DIFO
+ * | | +--------------------+
+ * | |
+ * Next ECB | | Action
+ * (if any) | | dtrace_action_t
+ * : +--> +-------------------+
+ * : | dtrace_actkind_t -+------> kind
+ * v | dtrace_difo_t * --+------> DIFO (if any)
+ * | dtrace_recdesc_t -+------> record descr.
+ * | dtrace_action_t * +------+
+ * +-------------------+ |
+ * | Next action
+ * +-------------------------------+ (if any)
+ * |
+ * | Action
+ * | dtrace_action_t
+ * +--> +-------------------+
+ * | dtrace_actkind_t -+------> kind
+ * | dtrace_difo_t * --+------> DIFO (if any)
+ * | dtrace_action_t * +------+
+ * +-------------------+ |
+ * | Next action
+ * +-------------------------------+ (if any)
+ * |
+ * :
+ * v
+ *
+ *
+ * dtrace_probe() iterates over the ECB list. If the ECB needs less space
+ * than is available in the principal buffer, the ECB is processed: if the
+ * predicate is non-NULL, the DIF object is executed. If the result is
+ * non-zero, the action list is processed, with each action being executed
+ * accordingly. When the action list has been completely executed, processing
+ * advances to the next ECB. processing advances to the next ECB. If the
+ * result is non-zero; For each ECB, it first determines the The ECB
+ * abstraction allows disjoint consumers to multiplex on single probes.
+ */
+struct dtrace_ecb {
+ dtrace_epid_t dte_epid; /* enabled probe ID */
+ uint32_t dte_alignment; /* required alignment */
+ size_t dte_needed; /* bytes needed */
+ size_t dte_size; /* total size of payload */
+ dtrace_predicate_t *dte_predicate; /* predicate, if any */
+ dtrace_action_t *dte_action; /* actions, if any */
+ dtrace_ecb_t *dte_next; /* next ECB on probe */
+ dtrace_state_t *dte_state; /* pointer to state */
+ uint32_t dte_cond; /* security condition */
+ dtrace_probe_t *dte_probe; /* pointer to probe */
+ dtrace_action_t *dte_action_last; /* last action on ECB */
+ uint64_t dte_uarg; /* library argument */
+};
+
+struct dtrace_predicate {
+ dtrace_difo_t *dtp_difo; /* DIF object */
+ dtrace_cacheid_t dtp_cacheid; /* cache identifier */
+ int dtp_refcnt; /* reference count */
+};
+
+struct dtrace_action {
+ dtrace_actkind_t dta_kind; /* kind of action */
+ uint16_t dta_intuple; /* boolean: in aggregation */
+ uint32_t dta_refcnt; /* reference count */
+ dtrace_difo_t *dta_difo; /* pointer to DIFO */
+ dtrace_recdesc_t dta_rec; /* record description */
+ dtrace_action_t *dta_prev; /* previous action */
+ dtrace_action_t *dta_next; /* next action */
+};
+
+typedef struct dtrace_aggregation {
+ dtrace_action_t dtag_action; /* action; must be first */
+ dtrace_aggid_t dtag_id; /* identifier */
+ dtrace_ecb_t *dtag_ecb; /* corresponding ECB */
+ dtrace_action_t *dtag_first; /* first action in tuple */
+ uint32_t dtag_base; /* base of aggregation */
+ uint8_t dtag_hasarg; /* boolean: has argument */
+ uint64_t dtag_initial; /* initial value */
+ void (*dtag_aggregate)(uint64_t *, uint64_t, uint64_t);
+} dtrace_aggregation_t;
+
+/*
+ * DTrace Buffers
+ *
+ * Principal buffers, aggregation buffers, and speculative buffers are all
+ * managed with the dtrace_buffer structure. By default, this structure
+ * includes twin data buffers -- dtb_tomax and dtb_xamot -- that serve as the
+ * active and passive buffers, respectively. For speculative buffers,
+ * dtb_xamot will be NULL; for "ring" and "fill" buffers, dtb_xamot will point
+ * to a scratch buffer. For all buffer types, the dtrace_buffer structure is
+ * always allocated on a per-CPU basis; a single dtrace_buffer structure is
+ * never shared among CPUs. (That is, there is never true sharing of the
+ * dtrace_buffer structure; to prevent false sharing of the structure, it must
+ * always be aligned to the coherence granularity -- generally 64 bytes.)
+ *
+ * One of the critical design decisions of DTrace is that a given ECB always
+ * stores the same quantity and type of data. This is done to assure that the
+ * only metadata required for an ECB's traced data is the EPID. That is, from
+ * the EPID, the consumer can determine the data layout. (The data buffer
+ * layout is shown schematically below.) By assuring that one can determine
+ * data layout from the EPID, the metadata stream can be separated from the
+ * data stream -- simplifying the data stream enormously.
+ *
+ * base of data buffer ---> +------+--------------------+------+
+ * | EPID | data | EPID |
+ * +------+--------+------+----+------+
+ * | data | EPID | data |
+ * +---------------+------+-----------+
+ * | data, cont. |
+ * +------+--------------------+------+
+ * | EPID | data | |
+ * +------+--------------------+ |
+ * | || |
+ * | || |
+ * | \/ |
+ * : :
+ * . .
+ * . .
+ * . .
+ * : :
+ * | |
+ * limit of data buffer ---> +----------------------------------+
+ *
+ * When evaluating an ECB, dtrace_probe() determines if the ECB's needs of the
+ * principal buffer (both scratch and payload) exceed the available space. If
+ * the ECB's needs exceed available space (and if the principal buffer policy
+ * is the default "switch" policy), the ECB is dropped, the buffer's drop count
+ * is incremented, and processing advances to the next ECB. If the ECB's needs
+ * can be met with the available space, the ECB is processed, but the offset in
+ * the principal buffer is only advanced if the ECB completes processing
+ * without error.
+ *
+ * When a buffer is to be switched (either because the buffer is the principal
+ * buffer with a "switch" policy or because it is an aggregation buffer), a
+ * cross call is issued to the CPU associated with the buffer. In the cross
+ * call context, interrupts are disabled, and the active and the inactive
+ * buffers are atomically switched. This involves switching the data pointers,
+ * copying the various state fields (offset, drops, errors, etc.) into their
+ * inactive equivalents, and clearing the state fields. Because interrupts are
+ * disabled during this procedure, the switch is guaranteed to appear atomic to
+ * dtrace_probe().
+ *
+ * DTrace Ring Buffering
+ *
+ * To process a ring buffer correctly, one must know the oldest valid record.
+ * Processing starts at the oldest record in the buffer and continues until
+ * the end of the buffer is reached. Processing then resumes starting with
+ * the record stored at offset 0 in the buffer, and continues until the
+ * youngest record is processed. If trace records are of a fixed-length,
+ * determining the oldest record is trivial:
+ *
+ * - If the ring buffer has not wrapped, the oldest record is the record
+ * stored at offset 0.
+ *
+ * - If the ring buffer has wrapped, the oldest record is the record stored
+ * at the current offset.
+ *
+ * With variable length records, however, just knowing the current offset
+ * doesn't suffice for determining the oldest valid record: assuming that one
+ * allows for arbitrary data, one has no way of searching forward from the
+ * current offset to find the oldest valid record. (That is, one has no way
+ * of separating data from metadata.) It would be possible to simply refuse to
+ * process any data in the ring buffer between the current offset and the
+ * limit, but this leaves (potentially) an enormous amount of otherwise valid
+ * data unprocessed.
+ *
+ * To effect ring buffering, we track two offsets in the buffer: the current
+ * offset and the _wrapped_ offset. If a request is made to reserve some
+ * amount of data, and the buffer has wrapped, the wrapped offset is
+ * incremented until the wrapped offset minus the current offset is greater
+ * than or equal to the reserve request. This is done by repeatedly looking
+ * up the ECB corresponding to the EPID at the current wrapped offset, and
+ * incrementing the wrapped offset by the size of the data payload
+ * corresponding to that ECB. If this offset is greater than or equal to the
+ * limit of the data buffer, the wrapped offset is set to 0. Thus, the
+ * current offset effectively "chases" the wrapped offset around the buffer.
+ * Schematically:
+ *
+ * base of data buffer ---> +------+--------------------+------+
+ * | EPID | data | EPID |
+ * +------+--------+------+----+------+
+ * | data | EPID | data |
+ * +---------------+------+-----------+
+ * | data, cont. |
+ * +------+---------------------------+
+ * | EPID | data |
+ * current offset ---> +------+---------------------------+
+ * | invalid data |
+ * wrapped offset ---> +------+--------------------+------+
+ * | EPID | data | EPID |
+ * +------+--------+------+----+------+
+ * | data | EPID | data |
+ * +---------------+------+-----------+
+ * : :
+ * . .
+ * . ... valid data ... .
+ * . .
+ * : :
+ * +------+-------------+------+------+
+ * | EPID | data | EPID | data |
+ * +------+------------++------+------+
+ * | data, cont. | leftover |
+ * limit of data buffer ---> +-------------------+--------------+
+ *
+ * If the amount of requested buffer space exceeds the amount of space
+ * available between the current offset and the end of the buffer:
+ *
+ * (1) all words in the data buffer between the current offset and the limit
+ * of the data buffer (marked "leftover", above) are set to
+ * DTRACE_EPIDNONE
+ *
+ * (2) the wrapped offset is set to zero
+ *
+ * (3) the iteration process described above occurs until the wrapped offset
+ * is greater than the amount of desired space.
+ *
+ * The wrapped offset is implemented by (re-)using the inactive offset.
+ * In a "switch" buffer policy, the inactive offset stores the offset in
+ * the inactive buffer; in a "ring" buffer policy, it stores the wrapped
+ * offset.
+ *
+ * DTrace Scratch Buffering
+ *
+ * Some ECBs may wish to allocate dynamically-sized temporary scratch memory.
+ * To accommodate such requests easily, scratch memory may be allocated in
+ * the buffer beyond the current offset plus the needed memory of the current
+ * ECB. If there isn't sufficient room in the buffer for the requested amount
+ * of scratch space, the allocation fails and an error is generated. Scratch
+ * memory is tracked in the dtrace_mstate_t and is automatically freed when
+ * the ECB ceases processing. Note that ring buffers cannot allocate their
+ * scratch from the principal buffer -- lest they needlessly overwrite older,
+ * valid data. Ring buffers therefore have their own dedicated scratch buffer
+ * from which scratch is allocated.
+ */
+#define DTRACEBUF_RING 0x0001 /* bufpolicy set to "ring" */
+#define DTRACEBUF_FILL 0x0002 /* bufpolicy set to "fill" */
+#define DTRACEBUF_NOSWITCH 0x0004 /* do not switch buffer */
+#define DTRACEBUF_WRAPPED 0x0008 /* ring buffer has wrapped */
+#define DTRACEBUF_DROPPED 0x0010 /* drops occurred */
+#define DTRACEBUF_ERROR 0x0020 /* errors occurred */
+#define DTRACEBUF_FULL 0x0040 /* "fill" buffer is full */
+#define DTRACEBUF_CONSUMED 0x0080 /* buffer has been consumed */
+#define DTRACEBUF_INACTIVE 0x0100 /* buffer is not yet active */
+
+typedef struct dtrace_buffer {
+ uint64_t dtb_offset; /* current offset in buffer */
+ uint64_t dtb_size; /* size of buffer */
+ uint32_t dtb_flags; /* flags */
+ uint32_t dtb_drops; /* number of drops */
+ caddr_t dtb_tomax; /* active buffer */
+ caddr_t dtb_xamot; /* inactive buffer */
+ uint32_t dtb_xamot_flags; /* inactive flags */
+ uint32_t dtb_xamot_drops; /* drops in inactive buffer */
+ uint64_t dtb_xamot_offset; /* offset in inactive buffer */
+ uint32_t dtb_errors; /* number of errors */
+ uint32_t dtb_xamot_errors; /* errors in inactive buffer */
+#ifndef _LP64
+ uint64_t dtb_pad1;
+#endif
+} dtrace_buffer_t;
+
+/*
+ * DTrace Aggregation Buffers
+ *
+ * Aggregation buffers use much of the same mechanism as described above
+ * ("DTrace Buffers"). However, because an aggregation is fundamentally a
+ * hash, there exists dynamic metadata associated with an aggregation buffer
+ * that is not associated with other kinds of buffers. This aggregation
+ * metadata is _only_ relevant for the in-kernel implementation of
+ * aggregations; it is not actually relevant to user-level consumers. To do
+ * this, we allocate dynamic aggregation data (hash keys and hash buckets)
+ * starting below the _limit_ of the buffer, and we allocate data from the
+ * _base_ of the buffer. When the aggregation buffer is copied out, _only_ the
+ * data is copied out; the metadata is simply discarded. Schematically,
+ * aggregation buffers look like:
+ *
+ * base of data buffer ---> +-------+------+-----------+-------+
+ * | aggid | key | value | aggid |
+ * +-------+------+-----------+-------+
+ * | key |
+ * +-------+-------+-----+------------+
+ * | value | aggid | key | value |
+ * +-------+------++-----+------+-----+
+ * | aggid | key | value | |
+ * +-------+------+-------------+ |
+ * | || |
+ * | || |
+ * | \/ |
+ * : :
+ * . .
+ * . .
+ * . .
+ * : :
+ * | /\ |
+ * | || +------------+
+ * | || | |
+ * +---------------------+ |
+ * | hash keys |
+ * | (dtrace_aggkey structures) |
+ * | |
+ * +----------------------------------+
+ * | hash buckets |
+ * | (dtrace_aggbuffer structure) |
+ * | |
+ * limit of data buffer ---> +----------------------------------+
+ *
+ *
+ * As implied above, just as we assure that ECBs always store a constant
+ * amount of data, we assure that a given aggregation -- identified by its
+ * aggregation ID -- always stores data of a constant quantity and type.
+ * As with EPIDs, this allows the aggregation ID to serve as the metadata for a
+ * given record.
+ *
+ * Note that the size of the dtrace_aggkey structure must be sizeof (uintptr_t)
+ * aligned. (If this the structure changes such that this becomes false, an
+ * assertion will fail in dtrace_aggregate().)
+ */
+typedef struct dtrace_aggkey {
+ uint32_t dtak_hashval; /* hash value */
+ uint32_t dtak_action:4; /* action -- 4 bits */
+ uint32_t dtak_size:28; /* size -- 28 bits */
+ caddr_t dtak_data; /* data pointer */
+ struct dtrace_aggkey *dtak_next; /* next in hash chain */
+} dtrace_aggkey_t;
+
+typedef struct dtrace_aggbuffer {
+ uintptr_t dtagb_hashsize; /* number of buckets */
+ uintptr_t dtagb_free; /* free list of keys */
+ dtrace_aggkey_t **dtagb_hash; /* hash table */
+} dtrace_aggbuffer_t;
+
+/*
+ * DTrace Speculations
+ *
+ * Speculations have a per-CPU buffer and a global state. Once a speculation
+ * buffer has been comitted or discarded, it cannot be reused until all CPUs
+ * have taken the same action (commit or discard) on their respective
+ * speculative buffer. However, because DTrace probes may execute in arbitrary
+ * context, other CPUs cannot simply be cross-called at probe firing time to
+ * perform the necessary commit or discard. The speculation states thus
+ * optimize for the case that a speculative buffer is only active on one CPU at
+ * the time of a commit() or discard() -- for if this is the case, other CPUs
+ * need not take action, and the speculation is immediately available for
+ * reuse. If the speculation is active on multiple CPUs, it must be
+ * asynchronously cleaned -- potentially leading to a higher rate of dirty
+ * speculative drops. The speculation states are as follows:
+ *
+ * DTRACESPEC_INACTIVE <= Initial state; inactive speculation
+ * DTRACESPEC_ACTIVE <= Allocated, but not yet speculatively traced to
+ * DTRACESPEC_ACTIVEONE <= Speculatively traced to on one CPU
+ * DTRACESPEC_ACTIVEMANY <= Speculatively traced to on more than one CPU
+ * DTRACESPEC_COMMITTING <= Currently being commited on one CPU
+ * DTRACESPEC_COMMITTINGMANY <= Currently being commited on many CPUs
+ * DTRACESPEC_DISCARDING <= Currently being discarded on many CPUs
+ *
+ * The state transition diagram is as follows:
+ *
+ * +----------------------------------------------------------+
+ * | |
+ * | +------------+ |
+ * | +-------------------| COMMITTING |<-----------------+ |
+ * | | +------------+ | |
+ * | | copied spec. ^ commit() on | | discard() on
+ * | | into principal | active CPU | | active CPU
+ * | | | commit() | |
+ * V V | | |
+ * +----------+ +--------+ +-----------+
+ * | INACTIVE |---------------->| ACTIVE |--------------->| ACTIVEONE |
+ * +----------+ speculation() +--------+ speculate() +-----------+
+ * ^ ^ | | |
+ * | | | discard() | |
+ * | | asynchronously | discard() on | | speculate()
+ * | | cleaned V inactive CPU | | on inactive
+ * | | +------------+ | | CPU
+ * | +-------------------| DISCARDING |<-----------------+ |
+ * | +------------+ |
+ * | asynchronously ^ |
+ * | copied spec. | discard() |
+ * | into principal +------------------------+ |
+ * | | V
+ * +----------------+ commit() +------------+
+ * | COMMITTINGMANY |<----------------------------------| ACTIVEMANY |
+ * +----------------+ +------------+
+ */
+typedef enum dtrace_speculation_state {
+ DTRACESPEC_INACTIVE = 0,
+ DTRACESPEC_ACTIVE,
+ DTRACESPEC_ACTIVEONE,
+ DTRACESPEC_ACTIVEMANY,
+ DTRACESPEC_COMMITTING,
+ DTRACESPEC_COMMITTINGMANY,
+ DTRACESPEC_DISCARDING
+} dtrace_speculation_state_t;
+
+typedef struct dtrace_speculation {
+ dtrace_speculation_state_t dtsp_state; /* current speculation state */
+ int dtsp_cleaning; /* non-zero if being cleaned */
+ dtrace_buffer_t *dtsp_buffer; /* speculative buffer */
+} dtrace_speculation_t;
+
+/*
+ * DTrace Dynamic Variables
+ *
+ * The dynamic variable problem is obviously decomposed into two subproblems:
+ * allocating new dynamic storage, and freeing old dynamic storage. The
+ * presence of the second problem makes the first much more complicated -- or
+ * rather, the absence of the second renders the first trivial. This is the
+ * case with aggregations, for which there is effectively no deallocation of
+ * dynamic storage. (Or more accurately, all dynamic storage is deallocated
+ * when a snapshot is taken of the aggregation.) As DTrace dynamic variables
+ * allow for both dynamic allocation and dynamic deallocation, the
+ * implementation of dynamic variables is quite a bit more complicated than
+ * that of their aggregation kin.
+ *
+ * We observe that allocating new dynamic storage is tricky only because the
+ * size can vary -- the allocation problem is much easier if allocation sizes
+ * are uniform. We further observe that in D, the size of dynamic variables is
+ * actually _not_ dynamic -- dynamic variable sizes may be determined by static
+ * analysis of DIF text. (This is true even of putatively dynamically-sized
+ * objects like strings and stacks, the sizes of which are dictated by the
+ * "stringsize" and "stackframes" variables, respectively.) We exploit this by
+ * performing this analysis on all DIF before enabling any probes. For each
+ * dynamic load or store, we calculate the dynamically-allocated size plus the
+ * size of the dtrace_dynvar structure plus the storage required to key the
+ * data. For all DIF, we take the largest value and dub it the _chunksize_.
+ * We then divide dynamic memory into two parts: a hash table that is wide
+ * enough to have every chunk in its own bucket, and a larger region of equal
+ * chunksize units. Whenever we wish to dynamically allocate a variable, we
+ * always allocate a single chunk of memory. Depending on the uniformity of
+ * allocation, this will waste some amount of memory -- but it eliminates the
+ * non-determinism inherent in traditional heap fragmentation.
+ *
+ * Dynamic objects are allocated by storing a non-zero value to them; they are
+ * deallocated by storing a zero value to them. Dynamic variables are
+ * complicated enormously by being shared between CPUs. In particular,
+ * consider the following scenario:
+ *
+ * CPU A CPU B
+ * +---------------------------------+ +---------------------------------+
+ * | | | |
+ * | allocates dynamic object a[123] | | |
+ * | by storing the value 345 to it | | |
+ * | ---------> |
+ * | | | wishing to load from object |
+ * | | | a[123], performs lookup in |
+ * | | | dynamic variable space |
+ * | <--------- |
+ * | deallocates object a[123] by | | |
+ * | storing 0 to it | | |
+ * | | | |
+ * | allocates dynamic object b[567] | | performs load from a[123] |
+ * | by storing the value 789 to it | | |
+ * : : : :
+ * . . . .
+ *
+ * This is obviously a race in the D program, but there are nonetheless only
+ * two valid values for CPU B's load from a[123]: 345 or 0. Most importantly,
+ * CPU B may _not_ see the value 789 for a[123].
+ *
+ * There are essentially two ways to deal with this:
+ *
+ * (1) Explicitly spin-lock variables. That is, if CPU B wishes to load
+ * from a[123], it needs to lock a[123] and hold the lock for the
+ * duration that it wishes to manipulate it.
+ *
+ * (2) Avoid reusing freed chunks until it is known that no CPU is referring
+ * to them.
+ *
+ * The implementation of (1) is rife with complexity, because it requires the
+ * user of a dynamic variable to explicitly decree when they are done using it.
+ * Were all variables by value, this perhaps wouldn't be debilitating -- but
+ * dynamic variables of non-scalar types are tracked by reference. That is, if
+ * a dynamic variable is, say, a string, and that variable is to be traced to,
+ * say, the principal buffer, the DIF emulation code returns to the main
+ * dtrace_probe() loop a pointer to the underlying storage, not the contents of
+ * the storage. Further, code calling on DIF emulation would have to be aware
+ * that the DIF emulation has returned a reference to a dynamic variable that
+ * has been potentially locked. The variable would have to be unlocked after
+ * the main dtrace_probe() loop is finished with the variable, and the main
+ * dtrace_probe() loop would have to be careful to not call any further DIF
+ * emulation while the variable is locked to avoid deadlock. More generally,
+ * if one were to implement (1), DIF emulation code dealing with dynamic
+ * variables could only deal with one dynamic variable at a time (lest deadlock
+ * result). To sum, (1) exports too much subtlety to the users of dynamic
+ * variables -- increasing maintenance burden and imposing serious constraints
+ * on future DTrace development.
+ *
+ * The implementation of (2) is also complex, but the complexity is more
+ * manageable. We need to be sure that when a variable is deallocated, it is
+ * not placed on a traditional free list, but rather on a _dirty_ list. Once a
+ * variable is on a dirty list, it cannot be found by CPUs performing a
+ * subsequent lookup of the variable -- but it may still be in use by other
+ * CPUs. To assure that all CPUs that may be seeing the old variable have
+ * cleared out of probe context, a dtrace_sync() can be issued. Once the
+ * dtrace_sync() has completed, it can be known that all CPUs are done
+ * manipulating the dynamic variable -- the dirty list can be atomically
+ * appended to the free list. Unfortunately, there's a slight hiccup in this
+ * mechanism: dtrace_sync() may not be issued from probe context. The
+ * dtrace_sync() must be therefore issued asynchronously from non-probe
+ * context. For this we rely on the DTrace cleaner, a cyclic that runs at the
+ * "cleanrate" frequency. To ease this implementation, we define several chunk
+ * lists:
+ *
+ * - Dirty. Deallocated chunks, not yet cleaned. Not available.
+ *
+ * - Rinsing. Formerly dirty chunks that are currently being asynchronously
+ * cleaned. Not available, but will be shortly. Dynamic variable
+ * allocation may not spin or block for availability, however.
+ *
+ * - Clean. Clean chunks, ready for allocation -- but not on the free list.
+ *
+ * - Free. Available for allocation.
+ *
+ * Moreover, to avoid absurd contention, _each_ of these lists is implemented
+ * on a per-CPU basis. This is only for performance, not correctness; chunks
+ * may be allocated from another CPU's free list. The algorithm for allocation
+ * then is this:
+ *
+ * (1) Attempt to atomically allocate from current CPU's free list. If list
+ * is non-empty and allocation is successful, allocation is complete.
+ *
+ * (2) If the clean list is non-empty, atomically move it to the free list,
+ * and reattempt (1).
+ *
+ * (3) If the dynamic variable space is in the CLEAN state, look for free
+ * and clean lists on other CPUs by setting the current CPU to the next
+ * CPU, and reattempting (1). If the next CPU is the current CPU (that
+ * is, if all CPUs have been checked), atomically switch the state of
+ * the dynamic variable space based on the following:
+ *
+ * - If no free chunks were found and no dirty chunks were found,
+ * atomically set the state to EMPTY.
+ *
+ * - If dirty chunks were found, atomically set the state to DIRTY.
+ *
+ * - If rinsing chunks were found, atomically set the state to RINSING.
+ *
+ * (4) Based on state of dynamic variable space state, increment appropriate
+ * counter to indicate dynamic drops (if in EMPTY state) vs. dynamic
+ * dirty drops (if in DIRTY state) vs. dynamic rinsing drops (if in
+ * RINSING state). Fail the allocation.
+ *
+ * The cleaning cyclic operates with the following algorithm: for all CPUs
+ * with a non-empty dirty list, atomically move the dirty list to the rinsing
+ * list. Perform a dtrace_sync(). For all CPUs with a non-empty rinsing list,
+ * atomically move the rinsing list to the clean list. Perform another
+ * dtrace_sync(). By this point, all CPUs have seen the new clean list; the
+ * state of the dynamic variable space can be restored to CLEAN.
+ *
+ * There exist two final races that merit explanation. The first is a simple
+ * allocation race:
+ *
+ * CPU A CPU B
+ * +---------------------------------+ +---------------------------------+
+ * | | | |
+ * | allocates dynamic object a[123] | | allocates dynamic object a[123] |
+ * | by storing the value 345 to it | | by storing the value 567 to it |
+ * | | | |
+ * : : : :
+ * . . . .
+ *
+ * Again, this is a race in the D program. It can be resolved by having a[123]
+ * hold the value 345 or a[123] hold the value 567 -- but it must be true that
+ * a[123] have only _one_ of these values. (That is, the racing CPUs may not
+ * put the same element twice on the same hash chain.) This is resolved
+ * simply: before the allocation is undertaken, the start of the new chunk's
+ * hash chain is noted. Later, after the allocation is complete, the hash
+ * chain is atomically switched to point to the new element. If this fails
+ * (because of either concurrent allocations or an allocation concurrent with a
+ * deletion), the newly allocated chunk is deallocated to the dirty list, and
+ * the whole process of looking up (and potentially allocating) the dynamic
+ * variable is reattempted.
+ *
+ * The final race is a simple deallocation race:
+ *
+ * CPU A CPU B
+ * +---------------------------------+ +---------------------------------+
+ * | | | |
+ * | deallocates dynamic object | | deallocates dynamic object |
+ * | a[123] by storing the value 0 | | a[123] by storing the value 0 |
+ * | to it | | to it |
+ * | | | |
+ * : : : :
+ * . . . .
+ *
+ * Once again, this is a race in the D program, but it is one that we must
+ * handle without corrupting the underlying data structures. Because
+ * deallocations require the deletion of a chunk from the middle of a hash
+ * chain, we cannot use a single-word atomic operation to remove it. For this,
+ * we add a spin lock to the hash buckets that is _only_ used for deallocations
+ * (allocation races are handled as above). Further, this spin lock is _only_
+ * held for the duration of the delete; before control is returned to the DIF
+ * emulation code, the hash bucket is unlocked.
+ */
+typedef struct dtrace_key {
+ uint64_t dttk_value; /* data value or data pointer */
+ uint64_t dttk_size; /* 0 if by-val, >0 if by-ref */
+} dtrace_key_t;
+
+typedef struct dtrace_tuple {
+ uint32_t dtt_nkeys; /* number of keys in tuple */
+ uint32_t dtt_pad; /* padding */
+ dtrace_key_t dtt_key[1]; /* array of tuple keys */
+} dtrace_tuple_t;
+
+typedef struct dtrace_dynvar {
+ uint64_t dtdv_hashval; /* hash value -- 0 if free */
+ struct dtrace_dynvar *dtdv_next; /* next on list or hash chain */
+ void *dtdv_data; /* pointer to data */
+ dtrace_tuple_t dtdv_tuple; /* tuple key */
+} dtrace_dynvar_t;
+
+typedef enum dtrace_dynvar_op {
+ DTRACE_DYNVAR_ALLOC,
+ DTRACE_DYNVAR_NOALLOC,
+ DTRACE_DYNVAR_DEALLOC
+} dtrace_dynvar_op_t;
+
+typedef struct dtrace_dynhash {
+ dtrace_dynvar_t *dtdh_chain; /* hash chain for this bucket */
+ uintptr_t dtdh_lock; /* deallocation lock */
+#ifdef _LP64
+ uintptr_t dtdh_pad[6]; /* pad to avoid false sharing */
+#else
+ uintptr_t dtdh_pad[14]; /* pad to avoid false sharing */
+#endif
+} dtrace_dynhash_t;
+
+typedef struct dtrace_dstate_percpu {
+ dtrace_dynvar_t *dtdsc_free; /* free list for this CPU */
+ dtrace_dynvar_t *dtdsc_dirty; /* dirty list for this CPU */
+ dtrace_dynvar_t *dtdsc_rinsing; /* rinsing list for this CPU */
+ dtrace_dynvar_t *dtdsc_clean; /* clean list for this CPU */
+ uint64_t dtdsc_drops; /* number of capacity drops */
+ uint64_t dtdsc_dirty_drops; /* number of dirty drops */
+ uint64_t dtdsc_rinsing_drops; /* number of rinsing drops */
+#ifdef _LP64
+ uint64_t dtdsc_pad; /* pad to avoid false sharing */
+#else
+ uint64_t dtdsc_pad[2]; /* pad to avoid false sharing */
+#endif
+} dtrace_dstate_percpu_t;
+
+typedef enum dtrace_dstate_state {
+ DTRACE_DSTATE_CLEAN = 0,
+ DTRACE_DSTATE_EMPTY,
+ DTRACE_DSTATE_DIRTY,
+ DTRACE_DSTATE_RINSING
+} dtrace_dstate_state_t;
+
+typedef struct dtrace_dstate {
+ void *dtds_base; /* base of dynamic var. space */
+ size_t dtds_size; /* size of dynamic var. space */
+ size_t dtds_hashsize; /* number of buckets in hash */
+ size_t dtds_chunksize; /* size of each chunk */
+ dtrace_dynhash_t *dtds_hash; /* pointer to hash table */
+ dtrace_dstate_state_t dtds_state; /* current dynamic var. state */
+ dtrace_dstate_percpu_t *dtds_percpu; /* per-CPU dyn. var. state */
+} dtrace_dstate_t;
+
+/*
+ * DTrace Variable State
+ *
+ * The DTrace variable state tracks user-defined variables in its dtrace_vstate
+ * structure. Each DTrace consumer has exactly one dtrace_vstate structure,
+ * but some dtrace_vstate structures may exist without a corresponding DTrace
+ * consumer (see "DTrace Helpers", below). As described in <sys/dtrace.h>,
+ * user-defined variables can have one of three scopes:
+ *
+ * DIFV_SCOPE_GLOBAL => global scope
+ * DIFV_SCOPE_THREAD => thread-local scope (i.e. "self->" variables)
+ * DIFV_SCOPE_LOCAL => clause-local scope (i.e. "this->" variables)
+ *
+ * The variable state tracks variables by both their scope and their allocation
+ * type:
+ *
+ * - The dtvs_globals and dtvs_locals members each point to an array of
+ * dtrace_statvar structures. These structures contain both the variable
+ * metadata (dtrace_difv structures) and the underlying storage for all
+ * statically allocated variables, including statically allocated
+ * DIFV_SCOPE_GLOBAL variables and all DIFV_SCOPE_LOCAL variables.
+ *
+ * - The dtvs_tlocals member points to an array of dtrace_difv structures for
+ * DIFV_SCOPE_THREAD variables. As such, this array tracks _only_ the
+ * variable metadata for DIFV_SCOPE_THREAD variables; the underlying storage
+ * is allocated out of the dynamic variable space.
+ *
+ * - The dtvs_dynvars member is the dynamic variable state associated with the
+ * variable state. The dynamic variable state (described in "DTrace Dynamic
+ * Variables", above) tracks all DIFV_SCOPE_THREAD variables and all
+ * dynamically-allocated DIFV_SCOPE_GLOBAL variables.
+ */
+typedef struct dtrace_statvar {
+ uint64_t dtsv_data; /* data or pointer to it */
+ size_t dtsv_size; /* size of pointed-to data */
+ int dtsv_refcnt; /* reference count */
+ dtrace_difv_t dtsv_var; /* variable metadata */
+} dtrace_statvar_t;
+
+typedef struct dtrace_vstate {
+ dtrace_state_t *dtvs_state; /* back pointer to state */
+ dtrace_statvar_t **dtvs_globals; /* statically-allocated glbls */
+ int dtvs_nglobals; /* number of globals */
+ dtrace_difv_t *dtvs_tlocals; /* thread-local metadata */
+ int dtvs_ntlocals; /* number of thread-locals */
+ dtrace_statvar_t **dtvs_locals; /* clause-local data */
+ int dtvs_nlocals; /* number of clause-locals */
+ dtrace_dstate_t dtvs_dynvars; /* dynamic variable state */
+} dtrace_vstate_t;
+
+/*
+ * DTrace Machine State
+ *
+ * In the process of processing a fired probe, DTrace needs to track and/or
+ * cache some per-CPU state associated with that particular firing. This is
+ * state that is always discarded after the probe firing has completed, and
+ * much of it is not specific to any DTrace consumer, remaining valid across
+ * all ECBs. This state is tracked in the dtrace_mstate structure.
+ */
+#define DTRACE_MSTATE_ARGS 0x00000001
+#define DTRACE_MSTATE_PROBE 0x00000002
+#define DTRACE_MSTATE_EPID 0x00000004
+#define DTRACE_MSTATE_TIMESTAMP 0x00000008
+#define DTRACE_MSTATE_STACKDEPTH 0x00000010
+#define DTRACE_MSTATE_CALLER 0x00000020
+#define DTRACE_MSTATE_IPL 0x00000040
+#define DTRACE_MSTATE_FLTOFFS 0x00000080
+#define DTRACE_MSTATE_WALLTIMESTAMP 0x00000100
+#define DTRACE_MSTATE_USTACKDEPTH 0x00000200
+#define DTRACE_MSTATE_UCALLER 0x00000400
+
+typedef struct dtrace_mstate {
+ uintptr_t dtms_scratch_base; /* base of scratch space */
+ uintptr_t dtms_scratch_ptr; /* current scratch pointer */
+ size_t dtms_scratch_size; /* scratch size */
+ uint32_t dtms_present; /* variables that are present */
+ uint64_t dtms_arg[5]; /* cached arguments */
+ dtrace_epid_t dtms_epid; /* current EPID */
+ uint64_t dtms_timestamp; /* cached timestamp */
+ hrtime_t dtms_walltimestamp; /* cached wall timestamp */
+ int dtms_stackdepth; /* cached stackdepth */
+ int dtms_ustackdepth; /* cached ustackdepth */
+ struct dtrace_probe *dtms_probe; /* current probe */
+ uintptr_t dtms_caller; /* cached caller */
+ uint64_t dtms_ucaller; /* cached user-level caller */
+ int dtms_ipl; /* cached interrupt pri lev */
+ int dtms_fltoffs; /* faulting DIFO offset */
+ uintptr_t dtms_strtok; /* saved strtok() pointer */
+} dtrace_mstate_t;
+
+#define DTRACE_COND_OWNER 0x1
+#define DTRACE_COND_USERMODE 0x2
+#define DTRACE_COND_ZONEOWNER 0x4
+
+#define DTRACE_PROBEKEY_MAXDEPTH 8 /* max glob recursion depth */
+
+/*
+ * DTrace Activity
+ *
+ * Each DTrace consumer is in one of several states, which (for purposes of
+ * avoiding yet-another overloading of the noun "state") we call the current
+ * _activity_. The activity transitions on dtrace_go() (from DTRACIOCGO), on
+ * dtrace_stop() (from DTRACIOCSTOP) and on the exit() action. Activities may
+ * only transition in one direction; the activity transition diagram is a
+ * directed acyclic graph. The activity transition diagram is as follows:
+ *
+ *
+ * +----------+ +--------+ +--------+
+ * | INACTIVE |------------------>| WARMUP |------------------>| ACTIVE |
+ * +----------+ dtrace_go(), +--------+ dtrace_go(), +--------+
+ * before BEGIN | after BEGIN | | |
+ * | | | |
+ * exit() action | | | |
+ * from BEGIN ECB | | | |
+ * | | | |
+ * v | | |
+ * +----------+ exit() action | | |
+ * +-----------------------------| DRAINING |<-------------------+ | |
+ * | +----------+ | |
+ * | | | |
+ * | dtrace_stop(), | | |
+ * | before END | | |
+ * | | | |
+ * | v | |
+ * | +---------+ +----------+ | |
+ * | | STOPPED |<----------------| COOLDOWN |<----------------------+ |
+ * | +---------+ dtrace_stop(), +----------+ dtrace_stop(), |
+ * | after END before END |
+ * | |
+ * | +--------+ |
+ * +----------------------------->| KILLED |<--------------------------+
+ * deadman timeout or +--------+ deadman timeout or
+ * killed consumer killed consumer
+ *
+ * Note that once a DTrace consumer has stopped tracing, there is no way to
+ * restart it; if a DTrace consumer wishes to restart tracing, it must reopen
+ * the DTrace pseudodevice.
+ */
+typedef enum dtrace_activity {
+ DTRACE_ACTIVITY_INACTIVE = 0, /* not yet running */
+ DTRACE_ACTIVITY_WARMUP, /* while starting */
+ DTRACE_ACTIVITY_ACTIVE, /* running */
+ DTRACE_ACTIVITY_DRAINING, /* before stopping */
+ DTRACE_ACTIVITY_COOLDOWN, /* while stopping */
+ DTRACE_ACTIVITY_STOPPED, /* after stopping */
+ DTRACE_ACTIVITY_KILLED /* killed */
+} dtrace_activity_t;
+
+/*
+ * DTrace dof modes
+ *
+ * DTrace has four "dof modes". They are:
+ *
+ * DTRACE_DOF_MODE_NEVER Never load any dof, period.
+ * DTRACE_DOF_MODE_LAZY_ON Defer loading dof until later
+ * DTRACE_DOF_MODE_LAZY_OFF Load all deferred dof now, and any new dof
+ * DTRACE_DOF_MODE_NON_LAZY Load all dof immediately.
+ *
+ * It is legal to transition between the two lazy modes. The NEVER and
+ * NON_LAZY modes are permanent, and must not change once set.
+ *
+ * The current dof mode is kept in dtrace_dof_mode, which is protected by the
+ * dtrace_dof_mode_lock. This is a RW lock, reads require shared access, writes
+ * require exclusive access. Because NEVER and NON_LAZY are permanent states,
+ * it is legal to test for those modes without holding the dof mode lock.
+ *
+ * Lock ordering is dof mode lock before any dtrace lock, and before the
+ * process p_dtrace_sprlock. In general, other locks should not be held when
+ * taking the dof mode lock. Acquiring the dof mode lock in exclusive mode
+ * will block process fork, exec, and exit, so it should be held exclusive
+ * for as short a time as possible.
+ */
+
+#define DTRACE_DOF_MODE_NEVER 0
+#define DTRACE_DOF_MODE_LAZY_ON 1
+#define DTRACE_DOF_MODE_LAZY_OFF 2
+#define DTRACE_DOF_MODE_NON_LAZY 3
+
+/*
+ * DTrace Helper Implementation
+ *
+ * A description of the helper architecture may be found in <sys/dtrace.h>.
+ * Each process contains a pointer to its helpers in its p_dtrace_helpers
+ * member. This is a pointer to a dtrace_helpers structure, which contains an
+ * array of pointers to dtrace_helper structures, helper variable state (shared
+ * among a process's helpers) and a generation count. (The generation count is
+ * used to provide an identifier when a helper is added so that it may be
+ * subsequently removed.) The dtrace_helper structure is self-explanatory,
+ * containing pointers to the objects needed to execute the helper. Note that
+ * helpers are _duplicated_ across fork(2), and destroyed on exec(2). No more
+ * than dtrace_helpers_max are allowed per-process.
+ */
+#define DTRACE_HELPER_ACTION_USTACK 0
+#define DTRACE_NHELPER_ACTIONS 1
+
+typedef struct dtrace_helper_action {
+ int dtha_generation; /* helper action generation */
+ int dtha_nactions; /* number of actions */
+ dtrace_difo_t *dtha_predicate; /* helper action predicate */
+ dtrace_difo_t **dtha_actions; /* array of actions */
+ struct dtrace_helper_action *dtha_next; /* next helper action */
+} dtrace_helper_action_t;
+
+typedef struct dtrace_helper_provider {
+ int dthp_generation; /* helper provider generation */
+ uint32_t dthp_ref; /* reference count */
+ dof_helper_t dthp_prov; /* DOF w/ provider and probes */
+} dtrace_helper_provider_t;
+
+typedef struct dtrace_helpers {
+ dtrace_helper_action_t **dthps_actions; /* array of helper actions */
+ dtrace_vstate_t dthps_vstate; /* helper action var. state */
+ dtrace_helper_provider_t **dthps_provs; /* array of providers */
+ uint_t dthps_nprovs; /* count of providers */
+ uint_t dthps_maxprovs; /* provider array size */
+ int dthps_generation; /* current generation */
+ pid_t dthps_pid; /* pid of associated proc */
+ int dthps_deferred; /* helper in deferred list */
+ struct dtrace_helpers *dthps_next; /* next pointer */
+ struct dtrace_helpers *dthps_prev; /* prev pointer */
+} dtrace_helpers_t;
+
+/*
+ * DTrace Helper Action Tracing
+ *
+ * Debugging helper actions can be arduous. To ease the development and
+ * debugging of helpers, DTrace contains a tracing-framework-within-a-tracing-
+ * framework: helper tracing. If dtrace_helptrace_enabled is non-zero (which
+ * it is by default on DEBUG kernels), all helper activity will be traced to a
+ * global, in-kernel ring buffer. Each entry includes a pointer to the specific
+ * helper, the location within the helper, and a trace of all local variables.
+ * The ring buffer may be displayed in a human-readable format with the
+ * ::dtrace_helptrace mdb(1) dcmd.
+ */
+#define DTRACE_HELPTRACE_NEXT (-1)
+#define DTRACE_HELPTRACE_DONE (-2)
+#define DTRACE_HELPTRACE_ERR (-3)
+
+typedef struct dtrace_helptrace {
+ dtrace_helper_action_t *dtht_helper; /* helper action */
+ int dtht_where; /* where in helper action */
+ int dtht_nlocals; /* number of locals */
+ int dtht_fault; /* type of fault (if any) */
+ int dtht_fltoffs; /* DIF offset */
+ uint64_t dtht_illval; /* faulting value */
+ uint64_t dtht_locals[1]; /* local variables */
+} dtrace_helptrace_t;
+
+/*
+ * DTrace Credentials
+ *
+ * In probe context, we have limited flexibility to examine the credentials
+ * of the DTrace consumer that created a particular enabling. We use
+ * the Least Privilege interfaces to cache the consumer's cred pointer and
+ * some facts about that credential in a dtrace_cred_t structure. These
+ * can limit the consumer's breadth of visibility and what actions the
+ * consumer may take.
+ */
+#define DTRACE_CRV_ALLPROC 0x01
+#define DTRACE_CRV_KERNEL 0x02
+#define DTRACE_CRV_ALLZONE 0x04
+
+#define DTRACE_CRV_ALL (DTRACE_CRV_ALLPROC | DTRACE_CRV_KERNEL | \
+ DTRACE_CRV_ALLZONE)
+
+#define DTRACE_CRA_PROC 0x0001
+#define DTRACE_CRA_PROC_CONTROL 0x0002
+#define DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER 0x0004
+#define DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE 0x0008
+#define DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG 0x0010
+#define DTRACE_CRA_KERNEL 0x0020
+#define DTRACE_CRA_KERNEL_DESTRUCTIVE 0x0040
+
+#define DTRACE_CRA_ALL (DTRACE_CRA_PROC | \
+ DTRACE_CRA_PROC_CONTROL | \
+ DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER | \
+ DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE | \
+ DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG | \
+ DTRACE_CRA_KERNEL | \
+ DTRACE_CRA_KERNEL_DESTRUCTIVE)
+
+typedef struct dtrace_cred {
+ cred_t *dcr_cred;
+ uint8_t dcr_destructive;
+ uint8_t dcr_visible;
+ uint16_t dcr_action;
+} dtrace_cred_t;
+
+/*
+ * DTrace Consumer State
+ *
+ * Each DTrace consumer has an associated dtrace_state structure that contains
+ * its in-kernel DTrace state -- including options, credentials, statistics and
+ * pointers to ECBs, buffers, speculations and formats. A dtrace_state
+ * structure is also allocated for anonymous enablings. When anonymous state
+ * is grabbed, the grabbing consumers dts_anon pointer is set to the grabbed
+ * dtrace_state structure.
+ */
+struct dtrace_state {
+ dev_t dts_dev; /* device */
+ int dts_necbs; /* total number of ECBs */
+ dtrace_ecb_t **dts_ecbs; /* array of ECBs */
+ dtrace_epid_t dts_epid; /* next EPID to allocate */
+ size_t dts_needed; /* greatest needed space */
+ struct dtrace_state *dts_anon; /* anon. state, if grabbed */
+ dtrace_activity_t dts_activity; /* current activity */
+ dtrace_vstate_t dts_vstate; /* variable state */
+ dtrace_buffer_t *dts_buffer; /* principal buffer */
+ dtrace_buffer_t *dts_aggbuffer; /* aggregation buffer */
+ dtrace_speculation_t *dts_speculations; /* speculation array */
+ int dts_nspeculations; /* number of speculations */
+ int dts_naggregations; /* number of aggregations */
+ dtrace_aggregation_t **dts_aggregations; /* aggregation array */
+ vmem_t *dts_aggid_arena; /* arena for aggregation IDs */
+ uint64_t dts_errors; /* total number of errors */
+ uint32_t dts_speculations_busy; /* number of spec. busy */
+ uint32_t dts_speculations_unavail; /* number of spec unavail */
+ uint32_t dts_stkstroverflows; /* stack string tab overflows */
+ uint32_t dts_dblerrors; /* errors in ERROR probes */
+ uint32_t dts_reserve; /* space reserved for END */
+ hrtime_t dts_laststatus; /* time of last status */
+ cyclic_id_t dts_cleaner; /* cleaning cyclic */
+ cyclic_id_t dts_deadman; /* deadman cyclic */
+ hrtime_t dts_alive; /* time last alive */
+ char dts_speculates; /* boolean: has speculations */
+ char dts_destructive; /* boolean: has dest. actions */
+ int dts_nformats; /* number of formats */
+ char **dts_formats; /* format string array */
+ dtrace_optval_t dts_options[DTRACEOPT_MAX]; /* options */
+ dtrace_cred_t dts_cred; /* credentials */
+ size_t dts_nretained; /* number of retained enabs */
+#if defined(__APPLE__)
+ uint64_t dts_arg_error_illval;
+#endif /* __APPLE__ */
+};
+
+struct dtrace_provider {
+ dtrace_pattr_t dtpv_attr; /* provider attributes */
+ dtrace_ppriv_t dtpv_priv; /* provider privileges */
+ dtrace_pops_t dtpv_pops; /* provider operations */
+ char *dtpv_name; /* provider name */
+ void *dtpv_arg; /* provider argument */
+ uint_t dtpv_defunct; /* boolean: defunct provider */
+ struct dtrace_provider *dtpv_next; /* next provider */
+};
+
+struct dtrace_meta {
+ dtrace_mops_t dtm_mops; /* meta provider operations */
+ char *dtm_name; /* meta provider name */
+ void *dtm_arg; /* meta provider user arg */
+ uint64_t dtm_count; /* no. of associated provs. */
+};
+
+/*
+ * DTrace Enablings
+ *
+ * A dtrace_enabling structure is used to track a collection of ECB
+ * descriptions -- before they have been turned into actual ECBs. This is
+ * created as a result of DOF processing, and is generally used to generate
+ * ECBs immediately thereafter. However, enablings are also generally
+ * retained should the probes they describe be created at a later time; as
+ * each new module or provider registers with the framework, the retained
+ * enablings are reevaluated, with any new match resulting in new ECBs. To
+ * prevent probes from being matched more than once, the enabling tracks the
+ * last probe generation matched, and only matches probes from subsequent
+ * generations.
+ */
+typedef struct dtrace_enabling {
+ dtrace_ecbdesc_t **dten_desc; /* all ECB descriptions */
+ int dten_ndesc; /* number of ECB descriptions */
+ int dten_maxdesc; /* size of ECB array */
+ dtrace_vstate_t *dten_vstate; /* associated variable state */
+ dtrace_genid_t dten_probegen; /* matched probe generation */
+ dtrace_ecbdesc_t *dten_current; /* current ECB description */
+ int dten_error; /* current error value */
+ int dten_primed; /* boolean: set if primed */
+ struct dtrace_enabling *dten_prev; /* previous enabling */
+ struct dtrace_enabling *dten_next; /* next enabling */
+} dtrace_enabling_t;
+
+/*
+ * DTrace Anonymous Enablings
+ *
+ * Anonymous enablings are DTrace enablings that are not associated with a
+ * controlling process, but rather derive their enabling from DOF stored as
+ * properties in the dtrace.conf file. If there is an anonymous enabling, a
+ * DTrace consumer state and enabling are created on attach. The state may be
+ * subsequently grabbed by the first consumer specifying the "grabanon"
+ * option. As long as an anonymous DTrace enabling exists, dtrace(7D) will
+ * refuse to unload.
+ */
+typedef struct dtrace_anon {
+ dtrace_state_t *dta_state; /* DTrace consumer state */
+ dtrace_enabling_t *dta_enabling; /* pointer to enabling */
+ processorid_t dta_beganon; /* which CPU BEGIN ran on */
+} dtrace_anon_t;
+
+/*
+ * DTrace Error Debugging
+ */
+#ifdef DEBUG
+#define DTRACE_ERRDEBUG
+#endif
+
+#ifdef DTRACE_ERRDEBUG
+
+typedef struct dtrace_errhash {
+ const char *dter_msg; /* error message */
+ int dter_count; /* number of times seen */
+} dtrace_errhash_t;
+
+#define DTRACE_ERRHASHSZ 256 /* must be > number of err msgs */
+
+#endif /* DTRACE_ERRDEBUG */
+
+/*
+ * DTrace Toxic Ranges
+ *
+ * DTrace supports safe loads from probe context; if the address turns out to
+ * be invalid, a bit will be set by the kernel indicating that DTrace
+ * encountered a memory error, and DTrace will propagate the error to the user
+ * accordingly. However, there may exist some regions of memory in which an
+ * arbitrary load can change system state, and from which it is impossible to
+ * recover from such a load after it has been attempted. Examples of this may
+ * include memory in which programmable I/O registers are mapped (for which a
+ * read may have some implications for the device) or (in the specific case of
+ * UltraSPARC-I and -II) the virtual address hole. The platform is required
+ * to make DTrace aware of these toxic ranges; DTrace will then check that
+ * target addresses are not in a toxic range before attempting to issue a
+ * safe load.
+ */
+typedef struct dtrace_toxrange {
+ uintptr_t dtt_base; /* base of toxic range */
+ uintptr_t dtt_limit; /* limit of toxic range */
+} dtrace_toxrange_t;
+
+extern uint64_t dtrace_getarg(int, int);
+extern greg_t dtrace_getfp(void);
+extern int dtrace_getipl(void);
+extern uintptr_t dtrace_caller(int);
+extern uint32_t dtrace_cas32(uint32_t *, uint32_t, uint32_t);
+extern void *dtrace_casptr(void *, void *, void *);
+#if !defined(__APPLE__)
+extern void dtrace_copyin(uintptr_t, uintptr_t, size_t);
+extern void dtrace_copyinstr(uintptr_t, uintptr_t, size_t);
+extern void dtrace_copyout(uintptr_t, uintptr_t, size_t);
+extern void dtrace_copyoutstr(uintptr_t, uintptr_t, size_t);
+#else
+extern void dtrace_copyin(user_addr_t, uintptr_t, size_t);
+extern void dtrace_copyinstr(user_addr_t, uintptr_t, size_t);
+extern void dtrace_copyout(uintptr_t, user_addr_t, size_t);
+extern void dtrace_copyoutstr(uintptr_t, user_addr_t, size_t);
+#endif /* __APPLE__ */
+extern void dtrace_getpcstack(pc_t *, int, int, uint32_t *);
+#if !defined(__APPLE__)
+extern ulong_t dtrace_getreg(struct regs *, uint_t);
+#else
+extern uint64_t dtrace_getreg(struct regs *, uint_t);
+#endif /* __APPLE__ */
+extern int dtrace_getstackdepth(int);
+extern void dtrace_getupcstack(uint64_t *, int);
+extern void dtrace_getufpstack(uint64_t *, uint64_t *, int);
+extern int dtrace_getustackdepth(void);
+extern uintptr_t dtrace_fulword(void *);
+#if !defined(__APPLE__)
+extern uint8_t dtrace_fuword8(void *);
+extern uint16_t dtrace_fuword16(void *);
+extern uint32_t dtrace_fuword32(void *);
+extern uint64_t dtrace_fuword64(void *);
+extern void dtrace_probe_error(dtrace_state_t *, dtrace_epid_t, int, int,
+ int, uintptr_t);
+#else
+extern uint8_t dtrace_fuword8(user_addr_t);
+extern uint16_t dtrace_fuword16(user_addr_t);
+extern uint32_t dtrace_fuword32(user_addr_t);
+extern uint64_t dtrace_fuword64(user_addr_t);
+extern void dtrace_probe_error(dtrace_state_t *, dtrace_epid_t, int, int,
+ int, uint64_t);
+#endif /* __APPLE__ */
+extern int dtrace_assfail(const char *, const char *, int);
+extern int dtrace_attached(void);
+extern hrtime_t dtrace_gethrestime(void);
+
+#ifdef __sparc
+extern void dtrace_flush_windows(void);
+extern void dtrace_flush_user_windows(void);
+extern uint_t dtrace_getotherwin(void);
+extern uint_t dtrace_getfprs(void);
+#else
+extern void dtrace_copy(uintptr_t, uintptr_t, size_t);
+extern void dtrace_copystr(uintptr_t, uintptr_t, size_t);
+#endif
+
+/*
+ * DTrace Assertions
+ *
+ * DTrace calls ASSERT from probe context. To assure that a failed ASSERT
+ * does not induce a markedly more catastrophic failure (e.g., one from which
+ * a dump cannot be gleaned), DTrace must define its own ASSERT to be one that
+ * may safely be called from probe context. This header file must thus be
+ * included by any DTrace component that calls ASSERT from probe context, and
+ * _only_ by those components. (The only exception to this is kernel
+ * debugging infrastructure at user-level that doesn't depend on calling
+ * ASSERT.)
+ */
+#undef ASSERT
+#ifdef DEBUG
+#define ASSERT(EX) ((void)((EX) || \
+ dtrace_assfail(#EX, __FILE__, __LINE__)))
+#else
+#define ASSERT(X) ((void)0)
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _SYS_DTRACE_IMPL_H */
+
projects / apple / xnu.git / blobdiff