linux-kernel - [PATCH] csky: Fixup perf probe -x hungup

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Message-Id: <20200414124129.9048-1-guoren@kernel.org>
Date:   Tue, 14 Apr 2020 20:41:29 +0800
From:   guoren@...nel.org
To:     linux-csky@...r.kernel.org
Cc:     arnd@...db.de, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, guoren@...nel.org,
        Guo Ren <guoren@...ux.alibaba.com>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH] csky: Fixup perf probe -x hungup

From: Guo Ren <guoren@...ux.alibaba.com>

case:
 # perf probe -x /lib/libc-2.28.9000.so memcpy
 # perf record -e probe_libc:memcpy -aR sleep 1

System hangup and cpu get in trap_c loop, because our hardware
singlestep state could still get interrupt signal. When we get in
uprobe_xol singlestep slot, we should disable irq in pt_regs->psr.

And is_swbp_insn() need a csky arch implementation with a low 16bit
mask.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Cc: Steven Rostedt (VMware) <rostedt@...dmis.org>
---
 arch/csky/kernel/probes/uprobes.c | 5 +++++
 arch/csky/kernel/ptrace.c         | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/arch/csky/kernel/probes/uprobes.c b/arch/csky/kernel/probes/uprobes.c
index b3a56c260e3e..1a9e0961b2b5 100644
--- a/arch/csky/kernel/probes/uprobes.c
+++ b/arch/csky/kernel/probes/uprobes.c
@@ -11,6 +11,11 @@
 
 #define UPROBE_TRAP_NR	UINT_MAX
 
+bool is_swbp_insn(uprobe_opcode_t *insn)
+{
+	return (*insn & 0xffff) == UPROBE_SWBP_INSN;
+}
+
 unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
 {
 	return instruction_pointer(regs);
diff --git a/arch/csky/kernel/ptrace.c b/arch/csky/kernel/ptrace.c
index 21ac2608f205..5a82230bddf9 100644
--- a/arch/csky/kernel/ptrace.c
+++ b/arch/csky/kernel/ptrace.c
@@ -41,6 +41,9 @@ static void singlestep_disable(struct task_struct *tsk)
 
 	regs = task_pt_regs(tsk);
 	regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_RUN;
+
+	/* Enable irq */
+	regs->sr |= BIT(6);
 }
 
 static void singlestep_enable(struct task_struct *tsk)
@@ -49,6 +52,9 @@ static void singlestep_enable(struct task_struct *tsk)
 
 	regs = task_pt_regs(tsk);
 	regs->sr = (regs->sr & TRACE_MODE_MASK) | TRACE_MODE_SI;
+
+	/* Disable irq */
+	regs->sr &= ~BIT(6);
 }
 
 /*
-- 
2.17.0