LTTng 0.88 adds dynamic instrumentation support (kprobes)

[Mathieu Desnoyers]

Hi,

LTTng 0.88 and LTTV 0.12.9 now support dynamic kernel instrumentation
with kprobes through a simple /mnt/debugfs/ltt/kprobes/ interface.

Usage example :

ltt-armall
echo do_fork > /mnt/debugfs/ltt/kprobes/enable
lttctl -C -w /tmp/trace trace
(so something)
lttctl -D trace
lttv -m textDump -e event.name=kernel.kprobe -t /tmp/trace

Trace set contains 1 traces

kernel.kprobe: 2486.393516120 (/tmp/trace/kernel_2), 0, 0, , , 0, 0x0,
    MODE_UNKNOWN { ip = FFFFFFFF8023CDC0 }
kernel.kprobe: 2489.826739495 (/tmp/trace/kernel_2), 25527, 25527, bash,
    , 25526, 0x0, SYSCALL { ip = FFFFFFFF8023CDC0 [do_fork+0x0/0x3e0] }
kernel.kprobe: 2491.618955019 (/tmp/trace/kernel_6), 25527, 25527, bash,
    , 25526, 0x0, SYSCALL { ip = FFFFFFFF8023CDC0 [do_fork+0x0/0x3e0] }
End trace set

Enable, disable and list operations are availables to manipulate the
active LTTng kprobes.

LTTV 0.12.9 adds support to print the symbol names along with the
kprobes addresses.

Mathieu

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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