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-/*
- * 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 2007 Sun Microsystems, Inc. All rights reserved.
- * Use is subject to license terms.
- *
- * Portions Copyright (c) 2012 by Delphix. All rights reserved.
- * Portions Copyright (c) 2016 by Joyent, Inc.
- */
-
-#ifndef _SYS_DTRACE_IMPL_H
-#define _SYS_DTRACE_IMPL_H
-
-#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>
-#include <kern/kalloc.h>
-
-/*
- * DTrace Implementation Locks
- */
-extern lck_attr_t dtrace_lck_attr;
-extern lck_grp_t dtrace_lck_grp;
-extern lck_mtx_t dtrace_procwaitfor_lock;
-
-/*
- * 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_nextprov; /* next in provider hash */
- dtrace_probe_t *dtpr_prevprov; /* previous in provider hash */
- 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 */
- void *dthb_chain; /* chain of elements */
- int dthb_len; /* number of probes here */
-} dtrace_hashbucket_t;
-
-typedef const char* dtrace_strkey_f(void*, uintptr_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 element */
- uintptr_t dth_prevoffs; /* offset of prev in element */
- dtrace_strkey_f *dth_getstr; /* func to retrieve str in element */
- uintptr_t dth_stroffs; /* offset of str in element */
-} 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. The ECB abstraction allows disjoint consumers
- * to multiplex on single probes.
- *
- * Execution of the ECB results in consuming dte_size bytes in the buffer
- * to record data. During execution, dte_needed bytes must be available in
- * the buffer. This space is used for both recorded data and tuple data.
- */
-struct dtrace_ecb {
- dtrace_epid_t dte_epid; /* enabled probe ID */
- uint32_t dte_alignment; /* required alignment */
- size_t dte_needed; /* space needed for execution */
- size_t dte_size; /* size of recorded 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. The ECB always
- * proceeds the recorded data as part of the dtrace_rechdr_t structure that
- * includes the EPID and a high-resolution timestamp used for output ordering
- * consistency.
- *
- * base of data buffer ---> +--------+--------------------+--------+
- * | rechdr | data | rechdr |
- * +--------+------+--------+----+--------+
- * | data | rechdr | data |
- * +---------------+--------+-------------+
- * | data, cont. |
- * +--------+--------------------+--------+
- * | rechdr | 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_cur_limit; /* current limit before signaling/dropping */
- uint64_t dtb_limit; /* limit before signaling */
- 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
- uint64_t dtb_switched; /* time of last switch */
- uint64_t dtb_interval; /* observed switch interval */
- uint64_t dtb_pad2[4]; /* pad to avoid false sharing */
-} 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 */
-} 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 *__zpercpu 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
-#define DTRACE_MSTATE_MACHTIMESTAMP 0x00000800
-#define DTRACE_MSTATE_MACHCTIMESTAMP 0x00001000
-
-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 */
- uint64_t dtms_machtimestamp; /* cached mach absolute timestamp */
- uint64_t dtms_machctimestamp; /* cached mach continuous 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 */
- uintptr_t dtms_strtok_limit; /* upper bound of strtok ptr */
- uint32_t dtms_access; /* memory access rights */
- dtrace_difo_t *dtms_difo; /* current dif object */
-} 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 */
-
-/*
- * Access flag used by dtrace_mstate.dtms_access.
- */
-#define DTRACE_ACCESS_KERNEL 0x1 /* the priv to read kmem */
-
-
-/*
- * 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;
-
-
-/*
- * APPLE NOTE: DTrace dof modes implementation
- *
- * 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 kernel symbol modes are used to control when the kernel may dispose of
- * symbol information used by the fbt/sdt provider. The kernel itself, as well as
- * every kext, has symbol table/nlist info that has historically been preserved
- * for dtrace's use. This allowed dtrace to be lazy about allocating fbt/sdt probes,
- * at the expense of keeping the symbol info in the kernel permanently.
- *
- * Starting in 10.7+, fbt probes may be created from userspace, in the same
- * fashion as pid probes. The kernel allows dtrace "first right of refusal"
- * whenever symbol data becomes available (such as a kext load). If dtrace is
- * active, it will immediately read/copy the needed data, and then the kernel
- * may free it. If dtrace is not active, it returns immediately, having done
- * no work or allocations, and the symbol data is freed. Should dtrace need
- * this data later, it is expected that the userspace client will push the
- * data into the kernel via ioctl calls.
- *
- * The kernel symbol modes are used to control what dtrace does with symbol data:
- *
- * DTRACE_KERNEL_SYMBOLS_NEVER Effectively disables fbt/sdt
- * DTRACE_KERNEL_SYMBOLS_FROM_KERNEL Immediately read/copy symbol data
- * DTRACE_KERNEL_SYMBOLS_FROM_USERSPACE Wait for symbols from userspace
- * DTRACE_KERNEL_SYMBOLS_ALWAYS_FROM_KERNEL Immediately read/copy symbol data
- *
- * It is legal to transition between DTRACE_KERNEL_SYMBOLS_FROM_KERNEL and
- * DTRACE_KERNEL_SYMBOLS_FROM_USERSPACE. The DTRACE_KERNEL_SYMBOLS_NEVER and
- * DTRACE_KERNEL_SYMBOLS_ALWAYS_FROM_KERNEL are permanent modes, intended to
- * disable fbt probes entirely, or prevent any symbols being loaded from
- * userspace.
-*
- * The kernel symbol mode is kept in dtrace_kernel_symbol_mode, which is protected
- * by the dtrace_lock.
- */
-
-#define DTRACE_KERNEL_SYMBOLS_NEVER 0
-#define DTRACE_KERNEL_SYMBOLS_FROM_KERNEL 1
-#define DTRACE_KERNEL_SYMBOLS_FROM_USERSPACE 2
-#define DTRACE_KERNEL_SYMBOLS_ALWAYS_FROM_KERNEL 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;
-
-typedef struct dtrace_format {
- uint64_t dtf_refcount;
- char dtf_str[];
-} dtrace_format_t;
-
-#define DTRACE_FORMAT_SIZE(fmt) (strlen(fmt->dtf_str) + 1 + sizeof(dtrace_format_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 */
- dtrace_format_t **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 */
- uint64_t dts_arg_error_illval;
- uint32_t dts_buf_over_limit; /* number of bufs over dtb_limit */
- uint64_t **dts_rstate; /* per-CPU random state */
-};
-
-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 */
- uint64_t dtpv_probe_count; /* number of associated probes */
- uint64_t dtpv_ecb_count; /* number of associated enabled ECBs */
-};
-
-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; /* number of associated providers */
-};
-
-/*
- * 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
- */
-#if 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 */
-
-typedef struct dtrace_string dtrace_string_t;
-
-typedef struct dtrace_string {
- dtrace_string_t *dtst_next;
- dtrace_string_t *dtst_prev;
- uint32_t dtst_refcount;
- char dtst_str[];
-} dtrace_string_t;
-
-/**
- * DTrace Matching pre-conditions
- *
- * Used when matching new probes to discard matching of enablings that
- * doesn't match the condition tested by dmc_func
- */
-typedef struct dtrace_match_cond {
- int (*dmc_func)(dtrace_probedesc_t*, void*);
- void *dmc_data;
-} dtrace_match_cond_t;
-
-
-/*
- * 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, dtrace_mstate_t*, dtrace_vstate_t*);
-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 *);
-extern void dtrace_copyin(user_addr_t, uintptr_t, size_t, volatile uint16_t *);
-extern void dtrace_copyinstr(user_addr_t, uintptr_t, size_t, volatile uint16_t *);
-extern void dtrace_copyout(uintptr_t, user_addr_t, size_t, volatile uint16_t *);
-extern void dtrace_copyoutstr(uintptr_t, user_addr_t, size_t, volatile uint16_t *);
-extern void dtrace_getpcstack(pc_t *, int, int, uint32_t *);
-extern uint64_t dtrace_load64(uintptr_t);
-extern int dtrace_canload(uint64_t, size_t, dtrace_mstate_t*, dtrace_vstate_t*);
-
-extern uint64_t dtrace_getreg(struct regs *, uint_t);
-extern uint64_t dtrace_getvmreg(uint_t);
-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 *);
-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 int dtrace_proc_waitfor(dtrace_procdesc_t*);
-extern void dtrace_probe_error(dtrace_state_t *, dtrace_epid_t, int, int,
- int, uint64_t);
-extern int dtrace_assfail(const char *, const char *, int);
-extern int dtrace_attached(void);
-extern hrtime_t dtrace_gethrestime(void);
-
-extern void dtrace_flush_caches(void);
-
-extern void dtrace_copy(uintptr_t, uintptr_t, size_t);
-extern void dtrace_copystr(uintptr_t, uintptr_t, size_t, volatile uint16_t *);
-
-extern void* dtrace_ptrauth_strip(void*, uint64_t);
-extern int dtrace_is_valid_ptrauth_key(uint64_t);
-
-extern uint64_t dtrace_physmem_read(uint64_t, size_t);
-extern void dtrace_physmem_write(uint64_t, uint64_t, size_t);
-
-extern void dtrace_livedump(char *, size_t);
-
-/*
- * DTrace state handling
- */
-extern minor_t dtrace_state_reserve(void);
-extern dtrace_state_t* dtrace_state_allocate(minor_t minor);
-extern dtrace_state_t* dtrace_state_get(minor_t minor);
-extern void dtrace_state_free(minor_t minor);
-
-/*
- * DTrace restriction checks
- */
-extern boolean_t dtrace_is_restricted(void);
-extern boolean_t dtrace_are_restrictions_relaxed(void);
-extern boolean_t dtrace_fbt_probes_restricted(void);
-extern boolean_t dtrace_sdt_probes_restricted(void);
-extern boolean_t dtrace_can_attach_to_proc(proc_t);
-
-/*
- * DTrace Assertions
- *
- * DTrace calls ASSERT and VERIFY from probe context. To assure that a failed
- * ASSERT or VERIFYdoes not induce a markedly more catastrophic failure (e.g.,
- * one from which a dump cannot be gleaned), DTrace must define its own ASSERT
- * and VERIFY macros to be ones that may safely be called from probe context.
- * This header file must thus be included by any DTrace component that calls
- * ASSERT and/or VERIFY 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
-#undef VERIFY
-
-#define VERIFY(EX) ((void)((EX) || \
- dtrace_assfail(#EX, __FILE__, __LINE__)))
-
-#if 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 */
-