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SubjectRe: [v4,6/6] powerpc: kprobes: prefer ftrace when probing function entry
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On Wed, 2017-04-19 at 12:52:28 UTC, "Naveen N. Rao" wrote:
> KPROBES_ON_FTRACE avoids much of the overhead with regular kprobes as it
> eliminates the need for a trap, as well as the need to emulate or
> single-step instructions.
>
> Though OPTPROBES provides us with similar performance, we have limited
> optprobes trampoline slots. As such, when asked to probe at a function
> entry, default to using the ftrace infrastructure.
>
> With:
> # cd /sys/kernel/debug/tracing
> # echo 'p _do_fork' > kprobe_events
>
> before patch:
> # cat ../kprobes/list
> c0000000000daf08 k _do_fork+0x8 [DISABLED]
> c000000000044fc0 k kretprobe_trampoline+0x0 [OPTIMIZED]
>
> and after patch:
> # cat ../kprobes/list
> c0000000000d074c k _do_fork+0xc [DISABLED][FTRACE]
> c0000000000412b0 k kretprobe_trampoline+0x0 [OPTIMIZED]
>
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/24bd909e94776ecce95291bff910f1

cheers

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