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darling-xnu/bsd/sys/dtrace_impl.h
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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>
/*
* 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 */
#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
#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);
/*
* 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 void dtrace_restriction_policy_load(void);
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 */
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