linux-kernel - [PATCH v8 02/12] arm64/ptrace: Split report

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Message-ID: <20251126071446.3234218-3-ruanjinjie@huawei.com>
Date: Wed, 26 Nov 2025 15:14:36 +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>,
	<charlie@...osinc.com>, <akpm@...ux-foundation.org>, <ldv@...ace.io>,
	<macro@...am.me.uk>, <deller@....de>, <mark.rutland@....com>,
	<efault@....de>, <song@...nel.org>, <mbenes@...e.cz>, <ryan.roberts@....com>,
	<ada.coupriediaz@....com>, <anshuman.khandual@....com>, <broonie@...nel.org>,
	<kevin.brodsky@....com>, <pengcan@...inos.cn>, <dvyukov@...gle.com>,
	<kmal@...k.li>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-kselftest@...r.kernel.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH v8 02/12] arm64/ptrace: Split report_syscall()

The generic syscall entry code has the form:

| syscall_trace_enter()
| {
|	ptrace_report_syscall_entry()
| }
|
| syscall_exit_work()
| {
|	ptrace_report_syscall_exit()
| }

In preparation for moving arm64 over to the generic entry code, split
report_syscall() to two separate enter and exit functions to align
the structure of the arm64 code with syscall_trace_enter() and
syscall_exit_work() from the generic entry code.

No functional changes.

Suggested-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
---
v8:
- report_syscall_enter() -> report_syscall_entry().
- Add ptrace_save_reg() helper.
---
 arch/arm64/kernel/ptrace.c | 41 +++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 4b001121c72d..abc5baa29cc9 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2317,9 +2317,10 @@ enum ptrace_syscall_dir {
 	PTRACE_SYSCALL_EXIT,
 };
 
-static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
+static inline unsigned long ptrace_save_reg(struct pt_regs *regs,
+					    enum ptrace_syscall_dir dir,
+					    int *regno)
 {
-	int regno;
 	unsigned long saved_reg;
 
 	/*
@@ -2338,15 +2339,31 @@ static void report_syscall(struct pt_regs *regs, enum ptrace_syscall_dir dir)
 	 * - Syscall stops behave differently to seccomp and pseudo-step traps
 	 *   (the latter do not nobble any registers).
 	 */
-	regno = (is_compat_task() ? 12 : 7);
-	saved_reg = regs->regs[regno];
-	regs->regs[regno] = dir;
+	*regno = (is_compat_task() ? 12 : 7);
+	saved_reg = regs->regs[*regno];
+	regs->regs[*regno] = dir;
 
-	if (dir == PTRACE_SYSCALL_ENTER) {
-		if (ptrace_report_syscall_entry(regs))
-			forget_syscall(regs);
-		regs->regs[regno] = saved_reg;
-	} else if (!test_thread_flag(TIF_SINGLESTEP)) {
+	return saved_reg;
+}
+
+static void report_syscall_entry(struct pt_regs *regs)
+{
+	unsigned long saved_reg;
+	int regno;
+
+	saved_reg = ptrace_save_reg(regs, PTRACE_SYSCALL_ENTER, &regno);
+	if (ptrace_report_syscall_entry(regs))
+		forget_syscall(regs);
+	regs->regs[regno] = saved_reg;
+}
+
+static void report_syscall_exit(struct pt_regs *regs)
+{
+	unsigned long saved_reg;
+	int regno;
+
+	saved_reg = ptrace_save_reg(regs, PTRACE_SYSCALL_EXIT, &regno);
+	if (!test_thread_flag(TIF_SINGLESTEP)) {
 		ptrace_report_syscall_exit(regs, 0);
 		regs->regs[regno] = saved_reg;
 	} else {
@@ -2366,7 +2383,7 @@ int syscall_trace_enter(struct pt_regs *regs)
 	unsigned long flags = read_thread_flags();
 
 	if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
-		report_syscall(regs, PTRACE_SYSCALL_ENTER);
+		report_syscall_entry(regs);
 		if (flags & _TIF_SYSCALL_EMU)
 			return NO_SYSCALL;
 	}
@@ -2394,7 +2411,7 @@ void syscall_trace_exit(struct pt_regs *regs)
 		trace_sys_exit(regs, syscall_get_return_value(current, regs));
 
 	if (flags & (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP))
-		report_syscall(regs, PTRACE_SYSCALL_EXIT);
+		report_syscall_exit(regs);
 
 	rseq_syscall(regs);
 }
-- 
2.34.1