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/linux/arch/riscv/kernel/probes/
H A DMakefilediff 829adda597fef2fe133d57aac681580b2e292268 Thu Dec 17 17:01:43 CET 2020 Guo Ren <guoren@linux.alibaba.com> riscv: Add KPROBES_ON_FTRACE supported

This patch adds support for kprobes on ftrace call sites to avoids
much of the overhead with regular kprobes. Try it with simple
steps:

echo 'p:myprobe sys_clone a0=%a0 a1=%a1 stack_val=+4($stack)' > /sys/kernel/de
bug/tracing/kprobe_events
echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable
cat /sys/kernel/debug/tracing/trace
tracer: nop

entries-in-buffer/entries-written: 1/1 #P:1

_-----=> irqs-off
/ _----=> need-resched
| / _---=> hardirq/softirq
|| / _--=> preempt-depth
||| / delay
TASK-PID CPU# |||| TIMESTAMP FUNCTION
| | | |||| | |
sh-92 [000] .... 369.899962: myprobe: (sys_clone+0x0/0x28) a0=0x1200011 a1=0x0 stack_val=0x201c20ffffffe0
cat /sys/kernel/debug/kprobes/list
ffffffe00020b584 k sys_clone+0x0 [FTRACE]
^^^^^^

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
/linux/arch/riscv/
H A DKconfigdiff 829adda597fef2fe133d57aac681580b2e292268 Thu Dec 17 17:01:43 CET 2020 Guo Ren <guoren@linux.alibaba.com> riscv: Add KPROBES_ON_FTRACE supported

This patch adds support for kprobes on ftrace call sites to avoids
much of the overhead with regular kprobes. Try it with simple
steps:

echo 'p:myprobe sys_clone a0=%a0 a1=%a1 stack_val=+4($stack)' > /sys/kernel/de
bug/tracing/kprobe_events
echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable
cat /sys/kernel/debug/tracing/trace
tracer: nop

entries-in-buffer/entries-written: 1/1 #P:1

_-----=> irqs-off
/ _----=> need-resched
| / _---=> hardirq/softirq
|| / _--=> preempt-depth
||| / delay
TASK-PID CPU# |||| TIMESTAMP FUNCTION
| | | |||| | |
sh-92 [000] .... 369.899962: myprobe: (sys_clone+0x0/0x28) a0=0x1200011 a1=0x0 stack_val=0x201c20ffffffe0
cat /sys/kernel/debug/kprobes/list
ffffffe00020b584 k sys_clone+0x0 [FTRACE]
^^^^^^

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>