linux-kernel - [PATCH v9 03/16] arm64/ptrace: Return early for ptrace_report_syscall

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Message-ID: <20251204082123.2792067-4-ruanjinjie@huawei.com>
Date: Thu, 4 Dec 2025 16:21:10 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <catalin.marinas@....com>, <will@...nel.org>, <oleg@...hat.com>,
	<tglx@...utronix.de>, <peterz@...radead.org>, <luto@...nel.org>,
	<shuah@...nel.org>, <kees@...nel.org>, <wad@...omium.org>, <deller@....de>,
	<macro@...am.me.uk>, <charlie@...osinc.com>, <kevin.brodsky@....com>,
	<ldv@...ace.io>, <mark.rutland@....com>, <song@...nel.org>,
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	<anshuman.khandual@....com>, <broonie@...nel.org>, <pengcan@...inos.cn>,
	<dvyukov@...gle.com>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH v9 03/16] arm64/ptrace: Return early for ptrace_report_syscall_entry() error

The generic entry abort the syscall_trace_enter() sequence if
ptrace_report_syscall_entry() errors out, but arm64 not.

As the ptrace_report_syscall_entry() comment said, the calling arch code
should abort the system call and must prevent normal entry so no system
call is made if ptrace_report_syscall_entry() return nonzero.

In preparation for moving arm64 over to the generic entry code,
return early if ptrace_report_syscall_entry() encounters an error.

Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
 arch/arm64/kernel/ptrace.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 4532e9831856..3926ce6aa268 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2346,15 +2346,18 @@ static __always_inline unsigned long ptrace_save_reg(struct pt_regs *regs,
 	return saved_reg;
 }
 
-static void report_syscall_entry(struct pt_regs *regs)
+static int report_syscall_entry(struct pt_regs *regs)
 {
 	unsigned long saved_reg;
-	int regno;
+	int regno, ret;
 
 	saved_reg = ptrace_save_reg(regs, PTRACE_SYSCALL_ENTER, &regno);
-	if (ptrace_report_syscall_entry(regs))
+	ret = ptrace_report_syscall_entry(regs);
+	if (ret)
 		forget_syscall(regs);
 	regs->regs[regno] = saved_reg;
+
+	return ret;
 }
 
 static void report_syscall_exit(struct pt_regs *regs)
@@ -2381,10 +2384,11 @@ static void report_syscall_exit(struct pt_regs *regs)
 int syscall_trace_enter(struct pt_regs *regs)
 {
 	unsigned long flags = read_thread_flags();
+	int ret;
 
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
-		report_syscall_entry(regs);
-		if (flags & _TIF_SYSCALL_EMU)
+		ret = report_syscall_entry(regs);
+		if (ret || (flags & _TIF_SYSCALL_EMU))
 			return NO_SYSCALL;
 	}
 
-- 
2.34.1