1PT_INSN_SYNC_FORWARD(3) PT_INSN_SYNC_FORWARD(3)
2
6 pt_insn_sync_forward, pt_insn_sync_backward, pt_insn_sync_set - syn‐
7 chronize an Intel(R) Processor Trace instruction flow decoder
8
10 #include <intel-pt.h>
11 int pt_insn_sync_forward(struct pt_insn_decoder *decoder);
12 int pt_insn_sync_backward(struct pt_insn_decoder *decoder);
13 int pt_insn_sync_set(struct pt_insn_decoder *decoder,
14 uint64_t offset);
15 Link with -lipt.
17
19 These functions synchronize an Intel Processor Trace (Intel PT) in‐
20 struction flow decoder pointed to by decoder onto the trace stream in
21 decoder’s trace buffer.
22 They search for a Packet Stream Boundary (PSB) packet in the trace
24 stream and, if successful, set decoder’s current position and synchro‐
25 nization position to that packet and start processing packets. For
26 synchronization to be successfull, there must be a full PSB+ header in
27 the trace stream.
28 pt_insn_sync_forward() searches in forward direction from decoder’s
30 current position towards the end of the trace buffer. If decoder has
31 been newly allocated and has not been synchronized yet, the search
32 starts from the beginning of the trace.
33 pt_insn_sync_backward() searches in backward direction from decoder’s
35 current position towards the beginning of the trace buffer. If decoder
36 has been newly allocated and has not been synchronized yet, the search
37 starts from the end of the trace.
38 pt_insn_sync_set() searches at offset bytes from the beginning of its
40 trace buffer.
41
43 All synchronization functions return zero or a positive value on suc‐
44 cess or a negative pt_error_code enumeration constant in case of an er‐
45 ror.
46 On success, a bit-vector of pt_status_flag enumeration constants is re‐
48 turned. The pt_status_flag enumeration is declared as:
49 /** Decoder status flags. */
51 enum pt_status_flag {
52 /** There is an event pending. */
53 pts_event_pending = 1 << 0,
54 /** The address has been suppressed. */
56 pts_ip_suppressed = 1 << 1,
57 /** There is no more trace data available. */
59 pts_eos = 1 << 2
60 };
61 The pts_event_pending flag indicates that one or more events are pend‐
63 ing. Use pt_insn_event(3) to process pending events before calling
64 pt_insn_next(3).
65 The pt_eos flag indicates that the information contained in the Intel
67 PT stream has been consumed. Calls to pt_insn_next() will provide in‐
68 structions as long as the instruction’s address can be determined with‐
69 out trace.
70
72 pte_invalid
73 The decoder argument is NULL.
74 pte_eos
76 There is no (further) PSB+ header in the trace stream (pt_in‐
77 sn_sync_forward() and pt_insn_sync_backward()) or at offset
78 bytes into the trace buffer (pt_insn_sync_set()).
79 pte_nosync
81 There is no PSB packet at offset bytes from the beginning of the
82 trace (pt_insn_sync_set() only).
83 pte_bad_opc
85 The decoder encountered an unsupported Intel PT packet opcode.
86 pte_bad_packet
88 The decoder encountered an unsupported Intel PT packet payload.
89
91 The following example re-synchronizes an Intel PT instruction flow de‐
92 coder after decode errors:
93 int foo(struct pt_insn_decoder *decoder) {
95 for (;;) {
96 int status;
97 status = pt_insn_sync_forward(decoder);
99 if (status < 0)
100 return status;
101 do {
103 status = decode(decoder, status);
104 } while (status >= 0);
105 }
106 }
107
109 pt_insn_alloc_decoder(3), pt_insn_free_decoder(3), pt_insn_get_off‐
110 set(3), pt_insn_get_sync_offset(3), pt_insn_get_config(3), pt_in‐
111 sn_time(3), pt_insn_core_bus_ratio(3), pt_insn_next(3), pt_in‐
112 sn_event(3)
113 PT_INSN_SYNC_FORWARD(3)