Unverified Commit e31be8d3 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Palmer Dabbelt
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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 c536aa1c ("kprobes/ftrace: Add recursion protection to the
ftrace callback"), so do similar modifications as the commit does.

Fixes: 829adda5 ("riscv: Add KPROBES_ON_FTRACE supported")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJisheng Zhang <jszhang@kernel.org>
Reviewed-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent 2349a3b2

arch/riscv/kernel/probes/ftrace.c

+10 −1
Original line number Diff line number Diff line
@@ -9,10 +9,16 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
	struct kprobe *p;

	struct pt_regs *regs;

	struct kprobe_ctlblk *kcb;

	int bit;



	bit = ftrace_test_recursion_trylock(ip, parent_ip);

	if (bit < 0)

		return;



	preempt_disable_notrace();

	p = get_kprobe((kprobe_opcode_t *)ip);

	if (unlikely(!p) || kprobe_disabled(p))

		return;

		goto out;



	regs = ftrace_get_regs(fregs);

	kcb = get_kprobe_ctlblk();
@@ -45,6 +51,9 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
		 */

		__this_cpu_write(current_kprobe, NULL);

	}

out:

	preempt_enable_notrace();

	ftrace_test_recursion_unlock(bit);

}

NOKPROBE_SYMBOL(kprobe_ftrace_handler);