diff options
Diffstat (limited to 'Documentation/trace/kprobetrace.txt')
| -rw-r--r-- | Documentation/trace/kprobetrace.txt | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt index 4208253..1541524 100644 --- a/Documentation/trace/kprobetrace.txt +++ b/Documentation/trace/kprobetrace.txt @@ -35,13 +35,13 @@ Synopsis of kprobe_events MEMADDR : Address where the probe is inserted. FETCHARGS : Arguments. Each probe can have up to 128 args. - %REG : Fetch register REG - @ADDR : Fetch memory at ADDR (ADDR should be in kernel) + %REG : Fetch register REG + @ADDR : Fetch memory at ADDR (ADDR should be in kernel) @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol) - $sN : Fetch Nth entry of stack (N >= 0) - $sa : Fetch stack address. - $aN : Fetch function argument. (N >= 0)(*) - $rv : Fetch return value.(**) + $stackN : Fetch Nth entry of stack (N >= 0) + $stack : Fetch stack address. + $argN : Fetch function argument. (N >= 0)(*) + $retval : Fetch return value.(**) +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(***) NAME=FETCHARG: Set NAME as the argument name of FETCHARG. @@ -84,13 +84,13 @@ Usage examples To add a probe as a new event, write a new definition to kprobe_events as below. - echo p:myprobe do_sys_open dfd=$a0 filename=$a1 flags=$a2 mode=$a3 > /sys/kernel/debug/tracing/kprobe_events + echo p:myprobe do_sys_open dfd=$arg0 filename=$arg1 flags=$arg2 mode=$arg3 > /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. As this example shows, users can choose more familiar names for each arguments. - echo r:myretprobe do_sys_open $rv >> /sys/kernel/debug/tracing/kprobe_events + echo r:myretprobe do_sys_open $retval >> /sys/kernel/debug/tracing/kprobe_events This sets a kretprobe on the return point of do_sys_open() function with recording return value as "myretprobe" event. @@ -137,11 +137,11 @@ events, you need to enable it. # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | <...>-1447 [001] 1038282.286875: myprobe: (do_sys_open+0x0/0xd6) dfd=3 filename=7fffd1ec4440 flags=8000 mode=0 - <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $rv=fffffffffffffffe + <...>-1447 [001] 1038282.286878: myretprobe: (sys_openat+0xc/0xe <- do_sys_open) $retval=fffffffffffffffe <...>-1447 [001] 1038282.286885: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=40413c flags=8000 mode=1b6 - <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 + <...>-1447 [001] 1038282.286915: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3 <...>-1447 [001] 1038282.286969: myprobe: (do_sys_open+0x0/0xd6) dfd=ffffff9c filename=4041c6 flags=98800 mode=10 - <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $rv=3 + <...>-1447 [001] 1038282.286976: myretprobe: (sys_open+0x1b/0x1d <- do_sys_open) $retval=3 Each line shows when the kernel hits an event, and <- SYMBOL means kernel |