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Message-ID: <20210330021440.44280b7f@xhacker>
Date: Tue, 30 Mar 2021 02:14:40 +0800
From: Jisheng Zhang <jszhang3@...l.ustc.edu.cn>
To: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Masami Hiramatsu <mhiramat@...nel.org>,
"Steven Rostedt (VMware)" <rostedt@...dmis.org>,
Guo Ren <guoren@...ux.alibaba.com>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] riscv: kprobes/ftrace: Add recursion protection to the
ftrace callback
From: Jisheng Zhang <jszhang@...nel.org>
Currently, the riscv's kprobes(powerred by ftrace) handler is
preemptible. Futher check indicates we miss something similar as the
commit c536aa1c5b17 ("kprobes/ftrace: Add recursion protection to the
ftrace callback"), so do similar modifications as the commit does.
Fixes: 829adda597fe ("riscv: Add KPROBES_ON_FTRACE supported")
Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
---
arch/riscv/kernel/probes/ftrace.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/kernel/probes/ftrace.c b/arch/riscv/kernel/probes/ftrace.c
index 17ca5e923bb0..aab85a82f419 100644
--- a/arch/riscv/kernel/probes/ftrace.c
+++ b/arch/riscv/kernel/probes/ftrace.c
@@ -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);
--
2.31.0
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