(2015/01/05 21:31), Wang Nan wrote: > In original code, the probed instruction doesn't get optimized after > > echo 0 > /sys/kernel/debug/kprobes/enabled > echo 1 > /sys/kernel/debug/kprobes/enabled > > This is because original code checks kprobes_all_disarmed in > optimize_kprobe(), but this flag is turned off after calling that > function. Therefore, optimize_kprobe() will see > kprobes_all_disarmed == true and doesn't do the optimization.
OK, a workaround is to disable/enable optimizing via sysctl. > > This patch simply turns off kprobes_all_disarmed earlier to enable > optimization. > Anyway, thank you for finding that! :) Acked-by: Masami Hiramatsu <[email protected]> > Signed-off-by: Wang Nan <[email protected]> > --- > kernel/kprobes.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index bad4e95..b185464 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -2320,6 +2320,12 @@ static void arm_all_kprobes(void) > if (!kprobes_all_disarmed) > goto already_enabled; > > + /* > + * optimize_kprobe() called by arm_kprobe() checks > + * kprobes_all_disarmed, so set kprobes_all_disarmed before > + * arm_kprobe. > + */ > + kprobes_all_disarmed = false; > /* Arming kprobes doesn't optimize kprobe itself */ > for (i = 0; i < KPROBE_TABLE_SIZE; i++) { > head = &kprobe_table[i]; > @@ -2328,7 +2334,6 @@ static void arm_all_kprobes(void) > arm_kprobe(p); > } > > - kprobes_all_disarmed = false; > printk(KERN_INFO "Kprobes globally enabled\n"); > > already_enabled: > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
