From f8bffbf1222a64336a81974fc25fe846656ac53e Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 6 May 2015 21:46:53 +0900 Subject: perf probe: Support $params special probe argument $params is similar to $vars but matches only function parameters not local variables. Thus, this is useful for tracing function parameter changing or tracing function call with parameters. Testing it: # perf probe tcp_sendmsg '$params' Added new event: probe:tcp_sendmsg (on tcp_sendmsg with $params) You can now use it in all perf tools, such as: perf record -e probe:tcp_sendmsg -aR sleep 1 # perf probe -l probe:tcp_sendmsg (on tcp_sendmsg@acme/git/linux/net/ipv4/tcp.c with iocb sk msg size) # perf record -a -e probe:* press some random letters to generate TCP (sshd) traffic... ^C[ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.223 MB perf.data (6 samples) ] # perf script sshd 6385 [2] 3.907529: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24 sshd 6385 [2] 4.138973: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24 sshd 6385 [2] 4.378966: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24 sshd 6385 [2] 4.603681: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24 sshd 6385 [2] 4.818455: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24 sshd 6385 [2] 5.043603: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24 # cat /sys/kernel/debug/tracing/events/probe/tcp_sendmsg/format name: tcp_sendmsg ID: 1927 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1; signed:0; field:int common_pid; offset:4; size:4; signed:1; field:unsigned long __probe_ip; offset:8; size:8; signed:0; field:u64 iocb; offset:16; size:8; signed:0; field:u64 sk; offset:24; size:8; signed:0; field:u64 msg; offset:32; size:8; signed:0; field:u64 size; offset:40; size:8; signed:0; print fmt: "(%lx) iocb=0x%Lx sk=0x%Lx msg=0x%Lx size=0x%Lx", REC->__probe_ip, REC->iocb, REC->sk, REC->msg, REC->size # Do some system wide tracing of this probe + write syscalls: # perf trace -e write --ev probe:* --filter-pids 6385 462.612 (0.010 ms): bash/19153 write(fd: 1, buf: 0x7f7556c78000, count: 29 ) = 29 462.701 (0.027 ms): sshd/19152 write(fd: 3, buf: 0x7f78dd12e160, count: 68 ) ... 462.701 ( ): probe:tcp_sendmsg:(ffffffff8163db30) iocb=0xffff8803ebec7e70 sk=0xffff88042196ab80 msg=0xffff8803ebec7da8 size=0x44) 462.710 (0.035 ms): sshd/19152 ... [continued]: write()) = 68 462.787 (0.009 ms): bash/19153 write(fd: 2, buf: 0x7f7556c77000, count: 22 ) = 22 462.865 (0.002 ms): sshd/19152 write(fd: 3, buf: 0x7f78dd12e160, count: 68 ) ... 462.865 ( ): probe:tcp_sendmsg:(ffffffff8163db30) iocb=0xffff8803ebec7e70 sk=0xffff88042196ab80 msg=0xffff8803ebec7da8 size=0x44) 462.873 (0.010 ms): sshd/19152 ... [continued]: write()) = 68 Signed-off-by: Masami Hiramatsu Tested-by: Arnaldo Carvalho de Melo Cc: Ananth N Mavinakayanahalli Cc: David Ahern Cc: Hemant Kumar Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20150506124653.4961.59806.stgit@localhost.localdomain [ Add some examples to the changelog message showing how to use it ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/probe-finder.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) (limited to 'tools/perf/util/probe-finder.c') diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index b5bf9d5..63d3389 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -1087,6 +1087,7 @@ found: struct local_vars_finder { struct probe_finder *pf; struct perf_probe_arg *args; + bool vars; int max_args; int nargs; int ret; @@ -1101,7 +1102,7 @@ static int copy_variables_cb(Dwarf_Die *die_mem, void *data) tag = dwarf_tag(die_mem); if (tag == DW_TAG_formal_parameter || - tag == DW_TAG_variable) { + (tag == DW_TAG_variable && vf->vars)) { if (convert_variable_location(die_mem, vf->pf->addr, vf->pf->fb_ops, &pf->sp_die, NULL) == 0) { @@ -1127,26 +1128,28 @@ static int expand_probe_args(Dwarf_Die *sc_die, struct probe_finder *pf, Dwarf_Die die_mem; int i; int n = 0; - struct local_vars_finder vf = {.pf = pf, .args = args, + struct local_vars_finder vf = {.pf = pf, .args = args, .vars = false, .max_args = MAX_PROBE_ARGS, .ret = 0}; for (i = 0; i < pf->pev->nargs; i++) { /* var never be NULL */ - if (strcmp(pf->pev->args[i].var, "$vars") == 0) { - pr_debug("Expanding $vars into:"); - vf.nargs = n; - /* Special local variables */ - die_find_child(sc_die, copy_variables_cb, (void *)&vf, - &die_mem); - pr_debug(" (%d)\n", vf.nargs - n); - if (vf.ret < 0) - return vf.ret; - n = vf.nargs; - } else { + if (strcmp(pf->pev->args[i].var, PROBE_ARG_VARS) == 0) + vf.vars = true; + else if (strcmp(pf->pev->args[i].var, PROBE_ARG_PARAMS) != 0) { /* Copy normal argument */ args[n] = pf->pev->args[i]; n++; + continue; } + pr_debug("Expanding %s into:", pf->pev->args[i].var); + vf.nargs = n; + /* Special local variables */ + die_find_child(sc_die, copy_variables_cb, (void *)&vf, + &die_mem); + pr_debug(" (%d)\n", vf.nargs - n); + if (vf.ret < 0) + return vf.ret; + n = vf.nargs; } return n; } -- cgit v1.1