4f0bfe0fb8
between being commited to a machno and having acquired the lock, the scheduler could come in an schedule us on a different processor. the solution is to have dtmachlock() take a special -1 argument to mean "current mach" and return the actual mach number after the lock has been acquired and interrupts being disabled.
311 lines
7.4 KiB
C
311 lines
7.4 KiB
C
#pragma lib "libdtracy.a"
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#pragma src "/sys/src/libdtracy"
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/*
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triggered probes run in "probe context", which involves grabbing a per-CPU lock using dtmachlock/dtmachunlock.
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everything else in the library assumes that the calling code has grabbed a global lock (which is done in 9/port/devtracy.c).
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*/
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enum {
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DTSTRMAX = 256,
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DTRECMAX = 1024,
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DTMAXAGGBUF = 16,
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DTBUFSZ = 65536,
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DTANUMBUCKETS = 1024,
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DTABUCKETS = DTBUFSZ - 4 * DTANUMBUCKETS,
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};
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#define DTANIL ((u32int)-1)
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typedef struct DTProbe DTProbe;
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typedef struct DTExprState DTExprState;
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typedef struct DTAct DTAct;
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typedef struct DTActGr DTActGr;
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typedef struct DTClause DTClause;
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typedef struct DTEnab DTEnab;
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typedef struct DTChan DTChan;
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typedef struct DTExpr DTExpr;
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typedef struct DTProvider DTProvider;
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typedef struct DTAgg DTAgg;
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typedef struct DTBuf DTBuf;
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typedef struct DTTrigInfo DTTrigInfo;
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/*
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we assign all pairs (probe,action-group) (called an enabling or DTEnab) a unique ID called EPID.
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we could also use probe IDs and action group IDs but using a single 32-bit ID for both is more flexible/efficient.
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epid == -1 indicates a fault record (see below)
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*/
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struct DTEnab {
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u32int epid;
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DTActGr *gr;
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DTEnab *probnext, *probprev;
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DTEnab *channext;
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DTProbe *prob;
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};
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/* probes are never freed */
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struct DTProbe {
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int nenable;
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char *name;
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DTEnab enablist;
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DTProvider *prov;
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void *aux; /* for the provider */
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DTProbe *provnext;
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};
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struct DTProvider {
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char *name;
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/*
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provide() is called when the user first uses a provider.
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provide() should call dtpnew() to create probes.
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*/
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void (*provide)(DTProvider *);
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int (*enable)(DTProbe *); /* enable the probe. return >= 0 for success and < 0 for failure */
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void (*disable)(DTProbe *); /* disable the probe */
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/* for the library, not the provider */
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DTProbe *probes;
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int provided;
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};
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/*
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the dtracy vm is a simple RISC machine with (currently) 16 64-bit registers.
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all operations are 64-bit.
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instruction encoding:
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31:24 opcode
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23:16 a
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15:8 b
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7:0 c
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*/
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enum {
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/* Rc = Ra (op) Rb */
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DTE_ADD = 0x00,
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DTE_SUB = 0x01,
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DTE_MUL = 0x02,
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DTE_SDIV = 0x03,
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DTE_SMOD = 0x04,
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DTE_UDIV = 0x05,
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DTE_UMOD = 0x06,
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DTE_AND = 0x07,
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DTE_OR = 0x08,
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DTE_XOR = 0x09,
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DTE_XNOR = 0x0A,
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DTE_LSL = 0x0B, /* logical shift left */
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DTE_LSR = 0x0C, /* logical shift right */
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DTE_ASR = 0x0D, /* arithmetic shift right */
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DTE_SEQ = 0x10, /* set if equal */
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DTE_SNE = 0x11, /* set if not equal */
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DTE_SLT = 0x12, /* set if less than */
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DTE_SLE = 0x13, /* set if less or equal */
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/* immediate operations, const = 10 top bits of ab, sign extended and shifted left by 6 bottom bits */
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DTE_LDI = 0x20, /* Rc = const */
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DTE_XORI = 0x21, /* Rc = Rc ^ const */
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/* if(Ra (op) Rb) PC += c; */
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DTE_BEQ = 0x30,
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DTE_BNE = 0x31,
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DTE_BLT = 0x32,
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DTE_BLE = 0x33,
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DTE_LDV = 0x40, /* R[b] = Var[a] */
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DTE_ZXT = 0x50, /* R[c] = lower b bits of R[a], zero extended, 0 < b <= 64 */
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DTE_SXT = 0x51, /* R[c] = lower b bits of R[a], sign extended, 0 < b <= 64 */
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DTE_RET = 0xF0, /* RET Ra */
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};
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#define DTE(op,a,b,c) ((op)<<24|(a)<<16|(b)<<8|(c))
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struct DTExpr {
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int n;
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u32int *b;
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};
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/*
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aggregation buffers are hashtables and use a different record format.
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there are DTANUMBUCKETS 4-byte buckets at the end of the buffer.
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each entry is (link,id,key,val) with a 4-byte link field for the hash chains and a 4-byte aggregation id.
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the aggregation id actually contains all the data in the DTAgg struct:
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4-bit type
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12-bit keysize in qwords
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16-bit unique id
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the struct is just for kernel convenience
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*/
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enum {
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AGGCNT,
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AGGSUM,
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AGGAVG,
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AGGSTD,
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AGGMIN,
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AGGMAX,
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};
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struct DTAgg {
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int id;
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u16int keysize; /* in bytes */
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u16int recsize;
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uchar type;
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};
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/* an action is an expression, plus info about what to do with the result */
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struct DTAct {
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enum {
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ACTTRACE, /* record the result. size is the number of bytes used. 0 <= size <= 8 */
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ACTTRACESTR, /* take the result to be a pointer to a null-terminated string. store it as zero-padded char[size]. */
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/*
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ACTAGGKEY and ACTAGGVAL together record a value in an aggregation.
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they must occur as a pair and targ must point to an already allocated aggregation buffer.
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currently 0 <= size <= 8.
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*/
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ACTAGGKEY,
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ACTAGGVAL,
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ACTCANCEL, /* (must be last action) don't write anything into the main buffer. used to avoid pointless records when using aggregations. */
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} type;
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DTExpr *p;
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int size;
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DTAgg agg;
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};
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/* an action group is an optional predicate and a set of actions. */
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struct DTActGr {
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u32int id;
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int ref;
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DTExpr *pred; /* if non-nil and evaluates to 0, skip the actions. */
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int nact;
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DTAct *acts;
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DTChan *chan;
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int reclen; /* record size, including 12-byte header */
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};
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/* a clause lists probe wildcard expressions and an action group. only used during set-up. */
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struct DTClause {
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int nprob;
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char **probs;
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DTActGr *gr;
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};
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struct DTBuf {
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int wr;
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uchar data[DTBUFSZ];
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};
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/* a chan is the kernel representation of a client. */
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struct DTChan {
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enum {
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DTCSTOP,
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DTCGO,
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DTCFAULT,
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} state;
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char errstr[64];
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u32int epidalloc; /* lowest unused EPID */
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/* we have 2 buffers per cpu, one for writing and one for reading. dtcread() swaps them if empty. */
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DTBuf **wrbufs;
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DTBuf **rdbufs;
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/* aggregations use separate buffers */
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DTBuf **aggwrbufs;
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DTBuf **aggrdbufs;
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/* list of enablings. */
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DTEnab *enab;
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};
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/* this struct collects the state during the execution of a probe */
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struct DTTrigInfo {
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/* filled in by caller of dtptrigger */
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u64int arg[10];
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/* filled in by dtptrigger */
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int machno;
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int epid;
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u64int ts;
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DTChan *ch;
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};
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/* fault records are used to note when a probe had to be aborted (e.g. because of a page fault) */
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enum {
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DTFILL = 1, /* illegal address */
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};
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void dtinit(int);
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void dtsync(void);
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/* probe functions */
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DTProbe *dtpnew(char *, DTProvider *, void *aux);
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int dtpmatch(char *, DTProbe ***);
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int dtplist(DTProbe ***);
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void dtptrigger(DTProbe *, DTTrigInfo *);
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/* expression functions */
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int dteverify(DTExpr *);
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int dtefmt(Fmt *);
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#pragma varargck type "I" u32int
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/* action group functions */
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void dtgpack(Fmt *, DTActGr *);
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char *dtgunpack(char *, DTActGr **);
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int dtgverify(DTChan *, DTActGr *);
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void dtgfree(DTActGr *);
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/* clause functions */
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void dtclpack(Fmt *, DTClause *);
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char *dtclunpack(char *, DTClause **);
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void dtclfree(DTClause *);
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/* chan functions */
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DTChan *dtcnew(void);
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void dtcfree(DTChan *);
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int dtcaddgr(DTChan *, char *, DTActGr *);
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int dtcaddcl(DTChan *, DTClause *);
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int dtcread(DTChan *, void *, int);
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int dtcaggread(DTChan *, void *, int);
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void dtcreset(DTChan *);
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void dtcrun(DTChan *, int);
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int dtcfault(DTTrigInfo *, int, char *, ...);
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/* aggbuf functions */
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int dtaunpackid(DTAgg *);
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void dtarecord(DTChan *, int, DTAgg *, uchar *, int, s64int);
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extern DTProvider *dtproviders[];
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extern int dtnmach;
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/* helper */
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char *dtstrdup(char *);
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/* these functions are provided by the kernel interface */
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uvlong dttime(void); /* return current timestamp */
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void *dtrealloc(void *, ulong);
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void dtfree(void *);
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void *dtmalloc(ulong);
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int dtmachlock(int); /* lock the per-cpu lock */
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void dtmachunlock(int); /* unlock the per-cpu lock */
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void dtcoherence(void); /* memory barrier */
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uvlong dtgetvar(int); /* return the value of a variable */
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int dtpeek(uvlong, void*, int); /* safe memmemove(). returns -1 on error. */
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enum {
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DTV_ARG0,
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DTV_ARG1,
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DTV_ARG2,
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DTV_ARG3,
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DTV_ARG4,
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DTV_ARG5,
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DTV_ARG6,
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DTV_ARG7,
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DTV_ARG8,
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DTV_ARG9,
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DTV_PID,
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DTV_MACHNO,
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DTV_TIME,
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DTV_PROBE,
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DTNVARS,
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};
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extern char *dtvarnames[DTNVARS];
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