NAME | SYNOPSIS | DESCRIPTION | API | EXAMPLE | SEE ALSO | COLOPHON |
|
|
PERF-DLFILTER(1) perf Manual PERF-DLFILTER(1)
perf-dlfilter - Filter sample events using a dynamically loaded shared object file
perf script [--dlfilter file.so ] [ --dlarg arg ]...
This option is used to process data through a custom filter provided by a dynamically loaded shared object file. Arguments can be passed using --dlarg and retrieved using perf_dlfilter_fns.args(). If file.so does not contain "/", then it will be found either in the current directory, or perf tools exec path which is ~/libexec/perf-core/dlfilters for a local build and install (refer perf --exec-path), or the dynamic linker paths.
The API for filtering consists of the following: #include <perf/perf_dlfilter.h> const struct perf_dlfilter_fns perf_dlfilter_fns; int start(void **data, void *ctx); int stop(void *data, void *ctx); int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx); int filter_event_early(void *data, const struct perf_dlfilter_sample *sample, void *ctx); const char *filter_description(const char **long_description); If implemented, start will be called at the beginning, before any calls to filter_event or filter_event_early. Return 0 to indicate success, or return a negative error code. *data can be assigned for use by other functions. ctx is needed for calls to perf_dlfilter_fns, but most perf_dlfilter_fns are not valid when called from start. If implemented, stop will be called at the end, after any calls to filter_event or filter_event_early. Return 0 to indicate success, or return a negative error code. data is set by start. ctx is needed for calls to perf_dlfilter_fns, but most perf_dlfilter_fns are not valid when called from stop. If implemented, filter_event will be called for each sample event. Return 0 to keep the sample event, 1 to filter it out, or return a negative error code. data is set by start. ctx is needed for calls to perf_dlfilter_fns. filter_event_early is the same as filter_event except it is called before internal filtering. If implemented, filter_description should return a one-line description of the filter, and optionally a longer description. The perf_dlfilter_sample structure filter_event and filter_event_early are passed a perf_dlfilter_sample structure, which contains the following fields: /* * perf sample event information (as per perf script and <linux/perf_event.h>) */ struct perf_dlfilter_sample { __u32 size; /* Size of this structure (for compatibility checking) */ __u16 ins_lat; /* Refer PERF_SAMPLE_WEIGHT_TYPE in <linux/perf_event.h> */ __u16 p_stage_cyc; /* Refer PERF_SAMPLE_WEIGHT_TYPE in <linux/perf_event.h> */ __u64 ip; __s32 pid; __s32 tid; __u64 time; __u64 addr; __u64 id; __u64 stream_id; __u64 period; __u64 weight; /* Refer PERF_SAMPLE_WEIGHT_TYPE in <linux/perf_event.h> */ __u64 transaction; /* Refer PERF_SAMPLE_TRANSACTION in <linux/perf_event.h> */ __u64 insn_cnt; /* For instructions-per-cycle (IPC) */ __u64 cyc_cnt; /* For instructions-per-cycle (IPC) */ __s32 cpu; __u32 flags; /* Refer PERF_DLFILTER_FLAG_* above */ __u64 data_src; /* Refer PERF_SAMPLE_DATA_SRC in <linux/perf_event.h> */ __u64 phys_addr; /* Refer PERF_SAMPLE_PHYS_ADDR in <linux/perf_event.h> */ __u64 data_page_size; /* Refer PERF_SAMPLE_DATA_PAGE_SIZE in <linux/perf_event.h> */ __u64 code_page_size; /* Refer PERF_SAMPLE_CODE_PAGE_SIZE in <linux/perf_event.h> */ __u64 cgroup; /* Refer PERF_SAMPLE_CGROUP in <linux/perf_event.h> */ __u8 cpumode; /* Refer CPUMODE_MASK etc in <linux/perf_event.h> */ __u8 addr_correlates_sym; /* True => resolve_addr() can be called */ __u16 misc; /* Refer perf_event_header in <linux/perf_event.h> */ __u32 raw_size; /* Refer PERF_SAMPLE_RAW in <linux/perf_event.h> */ const void *raw_data; /* Refer PERF_SAMPLE_RAW in <linux/perf_event.h> */ __u64 brstack_nr; /* Number of brstack entries */ const struct perf_branch_entry *brstack; /* Refer <linux/perf_event.h> */ __u64 raw_callchain_nr; /* Number of raw_callchain entries */ const __u64 *raw_callchain; /* Refer <linux/perf_event.h> */ const char *event; }; The perf_dlfilter_fns structure The perf_dlfilter_fns structure is populated with function pointers when the file is loaded. The functions can be called by filter_event or filter_event_early. struct perf_dlfilter_fns { const struct perf_dlfilter_al *(*resolve_ip)(void *ctx); const struct perf_dlfilter_al *(*resolve_addr)(void *ctx); char **(*args)(void *ctx, int *dlargc); __s32 (*resolve_address)(void *ctx, __u64 address, struct perf_dlfilter_al *al); const __u8 *(*insn)(void *ctx, __u32 *length); const char *(*srcline)(void *ctx, __u32 *line_number); struct perf_event_attr *(*attr)(void *ctx); __s32 (*object_code)(void *ctx, __u64 ip, void *buf, __u32 len); void *(*reserved[120])(void *); }; resolve_ip returns information about ip. resolve_addr returns information about addr (if addr_correlates_sym). args returns arguments from --dlarg options. resolve_address provides information about address. al→size must be set before calling. Returns 0 on success, -1 otherwise. insn returns instruction bytes and length. srcline return source file name and line number. attr returns perf_event_attr, refer <linux/perf_event.h>. object_code reads object code and returns the number of bytes read. The perf_dlfilter_al structure The perf_dlfilter_al structure contains information about an address. /* * Address location (as per perf script) */ struct perf_dlfilter_al { __u32 size; /* Size of this structure (for compatibility checking) */ __u32 symoff; const char *sym; __u64 addr; /* Mapped address (from dso) */ __u64 sym_start; __u64 sym_end; const char *dso; __u8 sym_binding; /* STB_LOCAL, STB_GLOBAL or STB_WEAK, refer <elf.h> */ __u8 is_64_bit; /* Only valid if dso is not NULL */ __u8 is_kernel_ip; /* True if in kernel space */ __u32 buildid_size; __u8 *buildid; /* Below members are only populated by resolve_ip() */ __u8 filtered; /* true if this sample event will be filtered out */ const char *comm; }; perf_dlfilter_sample flags The flags member of perf_dlfilter_sample corresponds with the flags field of perf script. The bits of the flags are as follows: /* Definitions for perf_dlfilter_sample flags */ enum { PERF_DLFILTER_FLAG_BRANCH = 1ULL << 0, PERF_DLFILTER_FLAG_CALL = 1ULL << 1, PERF_DLFILTER_FLAG_RETURN = 1ULL << 2, PERF_DLFILTER_FLAG_CONDITIONAL = 1ULL << 3, PERF_DLFILTER_FLAG_SYSCALLRET = 1ULL << 4, PERF_DLFILTER_FLAG_ASYNC = 1ULL << 5, PERF_DLFILTER_FLAG_INTERRUPT = 1ULL << 6, PERF_DLFILTER_FLAG_TX_ABORT = 1ULL << 7, PERF_DLFILTER_FLAG_TRACE_BEGIN = 1ULL << 8, PERF_DLFILTER_FLAG_TRACE_END = 1ULL << 9, PERF_DLFILTER_FLAG_IN_TX = 1ULL << 10, PERF_DLFILTER_FLAG_VMENTRY = 1ULL << 11, PERF_DLFILTER_FLAG_VMEXIT = 1ULL << 12, };
Filter out everything except branches from "foo" to "bar": #include <perf/perf_dlfilter.h> #include <string.h> const struct perf_dlfilter_fns perf_dlfilter_fns; int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx) { const struct perf_dlfilter_al *al; const struct perf_dlfilter_al *addr_al; if (!sample->ip || !sample->addr_correlates_sym) return 1; al = perf_dlfilter_fns.resolve_ip(ctx); if (!al || !al->sym || strcmp(al->sym, "foo")) return 1; addr_al = perf_dlfilter_fns.resolve_addr(ctx); if (!addr_al || !addr_al->sym || strcmp(addr_al->sym, "bar")) return 1; return 0; } To build the shared object, assuming perf has been installed for the local user i.e. perf_dlfilter.h is in ~/include/perf : gcc -c -I ~/include -fpic dlfilter-example.c gcc -shared -o dlfilter-example.so dlfilter-example.o To use the filter with perf script: perf script --dlfilter dlfilter-example.so
perf-script(1)
This page is part of the perf (Performance analysis tools for
Linux (in Linux source tree)) project. Information about the
project can be found at
⟨https://perf.wiki.kernel.org/index.php/Main_Page⟩. If you have a
bug report for this manual page, send it to
linux-kernel@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git⟩
on 2021-08-27. (At that time, the date of the most recent commit
that was found in the repository was 2021-08-26.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
perf 2021-07-01 PERF-DLFILTER(1)
Pages that refer to this page: perf-script(1)