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4 Commits

Author SHA1 Message Date
Jisheng Zhang
e31be8d343
riscv: kprobes/ftrace: Add recursion protection to the ftrace callback 
Currently, the riscv's kprobes(powerred by ftrace) handler is
preemptible. Futher check indicates we miss something similar as the
commit c536aa1c5b ("kprobes/ftrace: Add recursion protection to the
ftrace callback"), so do similar modifications as the commit does.

Fixes: 829adda597 ("riscv: Add KPROBES_ON_FTRACE supported")
Cc: stable@vger.kernel.org
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
 2021-04-15 21:32:34 -07:00
Colin Ian King
bab1770a2c
ftrace: Fix spelling mistake "disabed" -> "disabled" 
There is a spelling mistake in a comment, fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
 2021-03-16 21:19:40 -07:00
Nanyong Sun
288f6775a0
riscv: ftrace: Use ftrace_get_regs helper 
Use ftrace_get_regs() helper call to get pt_regs from ftrace_regs struct,
this makes the code simpler.

Signed-off-by: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
 2021-03-09 20:46:06 -08:00
Guo Ren
829adda597
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>
 2021-01-14 15:09:07 -08:00