1perf-dlfilter(1) 2================ 3 4NAME 5---- 6perf-dlfilter - Filter sample events using a dynamically loaded shared 7object file 8 9SYNOPSIS 10-------- 11[verse] 12'perf script' [--dlfilter file.so ] [ --dlarg arg ]... 13 14DESCRIPTION 15----------- 16 17This option is used to process data through a custom filter provided by a 18dynamically loaded shared object file. Arguments can be passed using --dlarg 19and retrieved using perf_dlfilter_fns.args(). 20 21If 'file.so' does not contain "/", then it will be found either in the current 22directory, or perf tools exec path which is ~/libexec/perf-core/dlfilters for 23a local build and install (refer perf --exec-path), or the dynamic linker 24paths. 25 26API 27--- 28 29The API for filtering consists of the following: 30 31[source,c] 32---- 33#include <perf/perf_dlfilter.h> 34 35const struct perf_dlfilter_fns perf_dlfilter_fns; 36 37int start(void **data, void *ctx); 38int stop(void *data, void *ctx); 39int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx); 40int filter_event_early(void *data, const struct perf_dlfilter_sample *sample, void *ctx); 41const char *filter_description(const char **long_description); 42---- 43 44If implemented, 'start' will be called at the beginning, before any 45calls to 'filter_event' or 'filter_event_early'. Return 0 to indicate success, 46or return a negative error code. '*data' can be assigned for use by other 47functions. 'ctx' is needed for calls to perf_dlfilter_fns, but most 48perf_dlfilter_fns are not valid when called from 'start'. 49 50If 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 52return a negative error code. 'data' is set by 'start'. 'ctx' is needed 53for calls to perf_dlfilter_fns, but most perf_dlfilter_fns are not valid 54when called from 'stop'. 55 56If implemented, 'filter_event' will be called for each sample event. 57Return 0 to keep the sample event, 1 to filter it out, or return a negative 58error code. 'data' is set by 'start'. 'ctx' is needed for calls to 59'perf_dlfilter_fns'. 60 61'filter_event_early' is the same as 'filter_event' except it is called before 62internal filtering. 63 64If implemented, 'filter_description' should return a one-line description 65of the filter, and optionally a longer description. 66 67The perf_dlfilter_sample structure 68~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 69 70'filter_event' and 'filter_event_early' are passed a perf_dlfilter_sample 71structure, which contains the following fields: 72[source,c] 73---- 74/* 75 * perf sample event information (as per perf script and <linux/perf_event.h>) 76 */ 77struct 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> */ 81 __u64 ip; 82 __s32 pid; 83 __s32 tid; 84 __u64 time; 85 __u64 addr; 86 __u64 id; 87 __u64 stream_id; 88 __u64 period; 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) */ 93 __s32 cpu; 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> */ 109 const char *event; 110}; 111---- 112 113The perf_dlfilter_fns structure 114~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 115 116The 'perf_dlfilter_fns' structure is populated with function pointers when the 117file is loaded. The functions can be called by 'filter_event' or 118'filter_event_early'. 119 120[source,c] 121---- 122struct 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 __s32 (*resolve_address)(void *ctx, __u64 address, struct perf_dlfilter_al *al); 127 const __u8 *(*insn)(void *ctx, __u32 *length); 128 const char *(*srcline)(void *ctx, __u32 *line_number); 129 struct perf_event_attr *(*attr)(void *ctx); 130 __s32 (*object_code)(void *ctx, __u64 ip, void *buf, __u32 len); 131 void *(*reserved[120])(void *); 132}; 133---- 134 135'resolve_ip' returns information about ip. 136 137'resolve_addr' returns information about addr (if addr_correlates_sym). 138 139'args' returns arguments from --dlarg options. 140 141'resolve_address' provides information about 'address'. al->size must be set 142before calling. Returns 0 on success, -1 otherwise. 143 144'insn' returns instruction bytes and length. 145 146'srcline' return source file name and line number. 147 148'attr' returns perf_event_attr, refer <linux/perf_event.h>. 149 150'object_code' reads object code and returns the number of bytes read. 151 152The perf_dlfilter_al structure 153~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 154 155The 'perf_dlfilter_al' structure contains information about an address. 156 157[source,c] 158---- 159/* 160 * Address location (as per perf script) 161 */ 162struct perf_dlfilter_al { 163 __u32 size; /* Size of this structure (for compatibility checking) */ 164 __u32 symoff; 165 const char *sym; 166 __u64 addr; /* Mapped address (from dso) */ 167 __u64 sym_start; 168 __u64 sym_end; 169 const char *dso; 170 __u8 sym_binding; /* STB_LOCAL, STB_GLOBAL or STB_WEAK, refer <elf.h> */ 171 __u8 is_64_bit; /* Only valid if dso is not NULL */ 172 __u8 is_kernel_ip; /* True if in kernel space */ 173 __u32 buildid_size; 174 __u8 *buildid; 175 /* Below members are only populated by resolve_ip() */ 176 __u8 filtered; /* true if this sample event will be filtered out */ 177 const char *comm; 178}; 179---- 180 181perf_dlfilter_sample flags 182~~~~~~~~~~~~~~~~~~~~~~~~~~ 183 184The 'flags' member of 'perf_dlfilter_sample' corresponds with the flags field 185of perf script. The bits of the flags are as follows: 186 187[source,c] 188---- 189/* Definitions for perf_dlfilter_sample flags */ 190enum { 191 PERF_DLFILTER_FLAG_BRANCH = 1ULL << 0, 192 PERF_DLFILTER_FLAG_CALL = 1ULL << 1, 193 PERF_DLFILTER_FLAG_RETURN = 1ULL << 2, 194 PERF_DLFILTER_FLAG_CONDITIONAL = 1ULL << 3, 195 PERF_DLFILTER_FLAG_SYSCALLRET = 1ULL << 4, 196 PERF_DLFILTER_FLAG_ASYNC = 1ULL << 5, 197 PERF_DLFILTER_FLAG_INTERRUPT = 1ULL << 6, 198 PERF_DLFILTER_FLAG_TX_ABORT = 1ULL << 7, 199 PERF_DLFILTER_FLAG_TRACE_BEGIN = 1ULL << 8, 200 PERF_DLFILTER_FLAG_TRACE_END = 1ULL << 9, 201 PERF_DLFILTER_FLAG_IN_TX = 1ULL << 10, 202 PERF_DLFILTER_FLAG_VMENTRY = 1ULL << 11, 203 PERF_DLFILTER_FLAG_VMEXIT = 1ULL << 12, 204}; 205---- 206 207EXAMPLE 208------- 209 210Filter out everything except branches from "foo" to "bar": 211 212[source,c] 213---- 214#include <perf/perf_dlfilter.h> 215#include <string.h> 216 217const struct perf_dlfilter_fns perf_dlfilter_fns; 218 219int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx) 220{ 221 const struct perf_dlfilter_al *al; 222 const struct perf_dlfilter_al *addr_al; 223 224 if (!sample->ip || !sample->addr_correlates_sym) 225 return 1; 226 227 al = perf_dlfilter_fns.resolve_ip(ctx); 228 if (!al || !al->sym || strcmp(al->sym, "foo")) 229 return 1; 230 231 addr_al = perf_dlfilter_fns.resolve_addr(ctx); 232 if (!addr_al || !addr_al->sym || strcmp(addr_al->sym, "bar")) 233 return 1; 234 235 return 0; 236} 237---- 238 239To build the shared object, assuming perf has been installed for the local user 240i.e. perf_dlfilter.h is in ~/include/perf : 241 242 gcc -c -I ~/include -fpic dlfilter-example.c 243 gcc -shared -o dlfilter-example.so dlfilter-example.o 244 245To use the filter with perf script: 246 247 perf script --dlfilter dlfilter-example.so 248 249SEE ALSO 250-------- 251linkperf:perf-script[1] 252