6 perf-dlfilter - Filter sample events using a dynamically loaded shared
12 'perf script' [--dlfilter file.so ] [ --dlarg arg ]...
17 This option is used to process data through a custom filter provided by a
18 dynamically loaded shared object file. Arguments can be passed using --dlarg
19 and retrieved using perf_dlfilter_fns.args().
21 If 'file.so' does not contain "/", then it will be found either in the current
22 directory, or perf tools exec path which is ~/libexec/perf-core/dlfilters for
23 a local build and install (refer perf --exec-path), or the dynamic linker
29 The API for filtering consists of the following:
33 #include <perf/perf_dlfilter.h>
35 const struct perf_dlfilter_fns perf_dlfilter_fns;
37 int start(void **data, void *ctx);
38 int stop(void *data, void *ctx);
39 int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx);
40 int filter_event_early(void *data, const struct perf_dlfilter_sample *sample, void *ctx);
41 const char *filter_description(const char **long_description);
44 If implemented, 'start' will be called at the beginning, before any
45 calls to 'filter_event' or 'filter_event_early'. Return 0 to indicate success,
46 or return a negative error code. '*data' can be assigned for use by other
47 functions. 'ctx' is needed for calls to perf_dlfilter_fns, but most
48 perf_dlfilter_fns are not valid when called from 'start'.
50 If implemented, 'stop' will be called at the end, after any calls to
51 'filter_event' or 'filter_event_early'. Return 0 to indicate success, or
52 return a negative error code. 'data' is set by 'start'. 'ctx' is needed
53 for calls to perf_dlfilter_fns, but most perf_dlfilter_fns are not valid
54 when called from 'stop'.
56 If implemented, 'filter_event' will be called for each sample event.
57 Return 0 to keep the sample event, 1 to filter it out, or return a negative
58 error code. 'data' is set by 'start'. 'ctx' is needed for calls to
61 'filter_event_early' is the same as 'filter_event' except it is called before
64 If implemented, 'filter_description' should return a one-line description
65 of the filter, and optionally a longer description.
67 The perf_dlfilter_sample structure
68 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
70 'filter_event' and 'filter_event_early' are passed a perf_dlfilter_sample
71 structure, which contains the following fields:
75 * perf sample event information (as per perf script and <linux/perf_event.h>)
77 struct perf_dlfilter_sample {
78 __u32 size; /* Size of this structure (for compatibility checking) */
79 __u16 ins_lat; /* Refer PERF_SAMPLE_WEIGHT_TYPE in <linux/perf_event.h> */
80 __u16 p_stage_cyc; /* Refer PERF_SAMPLE_WEIGHT_TYPE in <linux/perf_event.h> */
89 __u64 weight; /* Refer PERF_SAMPLE_WEIGHT_TYPE in <linux/perf_event.h> */
90 __u64 transaction; /* Refer PERF_SAMPLE_TRANSACTION in <linux/perf_event.h> */
91 __u64 insn_cnt; /* For instructions-per-cycle (IPC) */
92 __u64 cyc_cnt; /* For instructions-per-cycle (IPC) */
94 __u32 flags; /* Refer PERF_DLFILTER_FLAG_* above */
95 __u64 data_src; /* Refer PERF_SAMPLE_DATA_SRC in <linux/perf_event.h> */
96 __u64 phys_addr; /* Refer PERF_SAMPLE_PHYS_ADDR in <linux/perf_event.h> */
97 __u64 data_page_size; /* Refer PERF_SAMPLE_DATA_PAGE_SIZE in <linux/perf_event.h> */
98 __u64 code_page_size; /* Refer PERF_SAMPLE_CODE_PAGE_SIZE in <linux/perf_event.h> */
99 __u64 cgroup; /* Refer PERF_SAMPLE_CGROUP in <linux/perf_event.h> */
100 __u8 cpumode; /* Refer CPUMODE_MASK etc in <linux/perf_event.h> */
101 __u8 addr_correlates_sym; /* True => resolve_addr() can be called */
102 __u16 misc; /* Refer perf_event_header in <linux/perf_event.h> */
103 __u32 raw_size; /* Refer PERF_SAMPLE_RAW in <linux/perf_event.h> */
104 const void *raw_data; /* Refer PERF_SAMPLE_RAW in <linux/perf_event.h> */
105 __u64 brstack_nr; /* Number of brstack entries */
106 const struct perf_branch_entry *brstack; /* Refer <linux/perf_event.h> */
107 __u64 raw_callchain_nr; /* Number of raw_callchain entries */
108 const __u64 *raw_callchain; /* Refer <linux/perf_event.h> */
113 The perf_dlfilter_fns structure
114 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
116 The 'perf_dlfilter_fns' structure is populated with function pointers when the
117 file is loaded. The functions can be called by 'filter_event' or
118 'filter_event_early'.
122 struct perf_dlfilter_fns {
123 const struct perf_dlfilter_al *(*resolve_ip)(void *ctx);
124 const struct perf_dlfilter_al *(*resolve_addr)(void *ctx);
125 char **(*args)(void *ctx, int *dlargc);
126 void *(*reserved[125])(void *);
130 'resolve_ip' returns information about ip.
132 'resolve_addr' returns information about addr (if addr_correlates_sym).
134 'args' returns arguments from --dlarg options.
136 The perf_dlfilter_al structure
137 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
139 The 'perf_dlfilter_al' structure contains information about an address.
144 * Address location (as per perf script)
146 struct perf_dlfilter_al {
147 __u32 size; /* Size of this structure (for compatibility checking) */
150 __u64 addr; /* Mapped address (from dso) */
154 __u8 sym_binding; /* STB_LOCAL, STB_GLOBAL or STB_WEAK, refer <elf.h> */
155 __u8 is_64_bit; /* Only valid if dso is not NULL */
156 __u8 is_kernel_ip; /* True if in kernel space */
159 /* Below members are only populated by resolve_ip() */
160 __u8 filtered; /* true if this sample event will be filtered out */
165 perf_dlfilter_sample flags
166 ~~~~~~~~~~~~~~~~~~~~~~~~~~
168 The 'flags' member of 'perf_dlfilter_sample' corresponds with the flags field
169 of perf script. The bits of the flags are as follows:
173 /* Definitions for perf_dlfilter_sample flags */
175 PERF_DLFILTER_FLAG_BRANCH = 1ULL << 0,
176 PERF_DLFILTER_FLAG_CALL = 1ULL << 1,
177 PERF_DLFILTER_FLAG_RETURN = 1ULL << 2,
178 PERF_DLFILTER_FLAG_CONDITIONAL = 1ULL << 3,
179 PERF_DLFILTER_FLAG_SYSCALLRET = 1ULL << 4,
180 PERF_DLFILTER_FLAG_ASYNC = 1ULL << 5,
181 PERF_DLFILTER_FLAG_INTERRUPT = 1ULL << 6,
182 PERF_DLFILTER_FLAG_TX_ABORT = 1ULL << 7,
183 PERF_DLFILTER_FLAG_TRACE_BEGIN = 1ULL << 8,
184 PERF_DLFILTER_FLAG_TRACE_END = 1ULL << 9,
185 PERF_DLFILTER_FLAG_IN_TX = 1ULL << 10,
186 PERF_DLFILTER_FLAG_VMENTRY = 1ULL << 11,
187 PERF_DLFILTER_FLAG_VMEXIT = 1ULL << 12,
194 Filter out everything except branches from "foo" to "bar":
198 #include <perf/perf_dlfilter.h>
201 const struct perf_dlfilter_fns perf_dlfilter_fns;
203 int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx)
205 const struct perf_dlfilter_al *al;
206 const struct perf_dlfilter_al *addr_al;
208 if (!sample->ip || !sample->addr_correlates_sym)
211 al = perf_dlfilter_fns.resolve_ip(ctx);
212 if (!al || !al->sym || strcmp(al->sym, "foo"))
215 addr_al = perf_dlfilter_fns.resolve_addr(ctx);
216 if (!addr_al || !addr_al->sym || strcmp(addr_al->sym, "bar"))
223 To build the shared object, assuming perf has been installed for the local user
224 i.e. perf_dlfilter.h is in ~/include/perf :
226 gcc -c -I ~/include -fpic dlfilter-example.c
227 gcc -shared -o dlfilter-example.so dlfilter-example.o
229 To use the filter with perf script:
231 perf script --dlfilter dlfilter-example.so
235 linkperf:perf-script[1]