diff options
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/kprobetrace.txt | 46 |
1 files changed, 20 insertions, 26 deletions
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt index 8f882ebd1368..aaa6c1067c78 100644 --- a/Documentation/trace/kprobetrace.txt +++ b/Documentation/trace/kprobetrace.txt @@ -42,7 +42,8 @@ Synopsis of kprobe_events aN : Fetch function argument. (N >= 0)(*) rv : Fetch return value.(**) ra : Fetch return address.(**) - +|-offs(FETCHARG) : fetch memory at FETCHARG +|- offs address.(***) + +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***) + NAME=FETCHARG: Set NAME as the argument name of FETCHARG. (*) aN may not correct on asmlinkaged functions and at the middle of function body. @@ -62,12 +63,10 @@ enabled: You can enable/disable the probe by writing 1 or 0 on it. format: - This shows the format of this probe event. It also shows aliases of arguments - which you specified to kprobe_events. + This shows the format of this probe event. filter: - You can write filtering rules of this event. And you can use both of aliase - names and field names for describing filters. + You can write filtering rules of this event. id: This shows the id of this probe event. @@ -85,10 +84,11 @@ Usage examples To add a probe as a new event, write a new definition to kprobe_events as below. - echo p:myprobe do_sys_open a0 a1 a2 a3 > /sys/kernel/debug/tracing/kprobe_events + echo p:myprobe do_sys_open dfd=a0 filename=a1 flags=a2 mode=a3 > /sys/kernel/debug/tracing/kprobe_events This sets a kprobe on the top of do_sys_open() function with recording -1st to 4th arguments as "myprobe" event. +1st to 4th arguments as "myprobe" event. As this example shows, users can +choose more familiar names for each arguments. echo r:myretprobe do_sys_open rv ra >> /sys/kernel/debug/tracing/kprobe_events @@ -99,7 +99,7 @@ recording return value and return address as "myretprobe" event. cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format name: myprobe -ID: 23 +ID: 75 format: field:unsigned short common_type; offset:0; size:2; field:unsigned char common_flags; offset:2; size:1; @@ -109,21 +109,15 @@ format: field: unsigned long ip; offset:16;tsize:8; field: int nargs; offset:24;tsize:4; - field: unsigned long arg0; offset:32;tsize:8; - field: unsigned long arg1; offset:40;tsize:8; - field: unsigned long arg2; offset:48;tsize:8; - field: unsigned long arg3; offset:56;tsize:8; + field: unsigned long dfd; offset:32;tsize:8; + field: unsigned long filename; offset:40;tsize:8; + field: unsigned long flags; offset:48;tsize:8; + field: unsigned long mode; offset:56;tsize:8; - alias: a0; original: arg0; - alias: a1; original: arg1; - alias: a2; original: arg2; - alias: a3; original: arg3; +print fmt: "%lx: dfd=%lx filename=%lx flags=%lx mode=%lx", ip, REC->dfd, REC->filename, REC->flags, REC->mode -print fmt: "%lx: 0x%lx 0x%lx 0x%lx 0x%lx", ip, arg0, arg1, arg2, arg3 - - You can see that the event has 4 arguments and alias expressions -corresponding to it. + You can see that the event has 4 arguments as in the expressions you specified. echo > /sys/kernel/debug/tracing/kprobe_events @@ -135,12 +129,12 @@ corresponding to it. # # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | - <...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: 0x3 0x7fffd1ec4440 0x8000 0x0 - <...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: 0xfffffffffffffffe 0xffffffff81367a3a - <...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: 0xffffff9c 0x40413c 0x8000 0x1b6 - <...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a - <...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: 0xffffff9c 0x4041c6 0x98800 0x10 - <...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: 0x3 0xffffffff81367a3a + <...>-1447 [001] 1038282.286875: do_sys_open+0x0/0xd6: dfd=3 filename=7fffd1ec4440 flags=8000 mode=0 + <...>-1447 [001] 1038282.286878: sys_openat+0xc/0xe <- do_sys_open: rv=fffffffffffffffe ra=ffffffff81367a3a + <...>-1447 [001] 1038282.286885: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=40413c flags=8000 mode=1b6 + <...>-1447 [001] 1038282.286915: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a + <...>-1447 [001] 1038282.286969: do_sys_open+0x0/0xd6: dfd=ffffff9c filename=4041c6 flags=98800 mode=10 + <...>-1447 [001] 1038282.286976: sys_open+0x1b/0x1d <- do_sys_open: rv=3 ra=ffffffff81367a3a Each line shows when the kernel hits a probe, and <- SYMBOL means kernel |