From: Jinjie Ruan <ruanjinjie@huawei.com>
To: <catalin.marinas@arm.com>, <will@kernel.org>,
<mark.rutland@arm.com>, <oleg@redhat.com>, <kees@kernel.org>,
<luto@amacapital.net>, <wad@chromium.org>, <peterz@infradead.org>,
<ada.coupriediaz@arm.com>, <linusw@kernel.org>,
<kevin.brodsky@arm.com>, <yeoreum.yun@arm.com>,
<thuth@redhat.com>, <james.morse@arm.com>,
<vladimir.murzin@arm.com>, <broonie@kernel.org>,
<pengcan@kylinos.cn>, <liqiang01@kylinos.cn>,
<ryan.roberts@arm.com>, <linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Cc: <ruanjinjie@huawei.com>
Subject: [PATCH v18 10/14] arm64: syscall: Use exit-specific flags check in el0_svc_common()
Date: Wed, 2 Sep 2026 17:55:33 +0800 [thread overview]
Message-ID: <20260902095537.602517-11-ruanjinjie@huawei.com> (raw)
In-Reply-To: <20260902095537.602517-1-ruanjinjie@huawei.com>
The syscall exit path in el0_svc_common() re-evaluates all
_TIF_SYSCALL_WORK flags, but this mask contains flags that only
matter on entry:
- _TIF_SECCOMP: seccomp filtering is entry-only
- _TIF_SYSCALL_EMU: PTRACE_SYSEMU skips the syscall on entry
Re-checking them on exit is unnecessary and may trigger redundant work.
Switch to _TIF_SYSCALL_EXIT_WORK for the exit-path re-check to evaluate
only exit-relevant flags (_TIF_SYSCALL_TRACE, _TIF_SYSCALL_AUDIT, and
_TIF_SYSCALL_TRACEPOINT).
No functional change intended.
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Reviewed-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
arch/arm64/kernel/syscall.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index 0061fc63e7ba..a8e0bf8d362e 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -54,11 +54,6 @@ static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
syscall_set_return_value(current, regs, 0, ret);
}
-static inline bool has_syscall_work(unsigned long flags)
-{
- return unlikely(flags & _TIF_SYSCALL_WORK);
-}
-
static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
const syscall_fn_t syscall_table[])
{
@@ -95,7 +90,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
return;
}
- if (has_syscall_work(flags)) {
+ if (unlikely(flags & _TIF_SYSCALL_WORK)) {
/*
* The de-facto standard way to skip a system call using ptrace
* is to set the system call to -1 (NO_SYSCALL) and set x0 to a
@@ -125,9 +120,9 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
* check again. However, if we were tracing entry, then we always trace
* exit regardless, as the old entry assembly did.
*/
- if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
+ if (!(unlikely(flags & _TIF_SYSCALL_WORK)) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
flags = read_thread_flags();
- if (has_syscall_work(flags) || flags & _TIF_SINGLESTEP)
+ if (unlikely(flags & _TIF_SYSCALL_EXIT_WORK) || flags & _TIF_SINGLESTEP)
arm64_syscall_exit_to_user_mode_work(regs);
return;
}
--
2.34.1
next prev parent reply other threads:[~2026-09-02 9:55 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-02 9:55 [PATCH v18 00/14] arm64: entry: Convert to Generic Entry Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 01/14] arm64: ptrace: Fix redundant syscall exit stop for PTRACE_SYSEMU_SINGLESTEP Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 02/14] arm64: ptrace: Rework audit_syscall_entry() Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 03/14] arm64: ptrace: Open-code seccomp check in syscall_trace_enter() Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 04/14] arm64: ptrace: Rename and clean up syscall_trace_enter() Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 05/14] arm64: ptrace: Protect rseq_syscall() from tracer PC modifications Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 06/14] arm64: syscall: Rework the syscall exit path in el0_svc_common() Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 07/14] arm64: ptrace: Pass thread flags to trace enter/exit Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 08/14] arm64: ptrace: Extract arm64_syscall_exit_to_user_mode_work() helper Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 09/14] arm64: ptrace: Align syscall exit work semantics with generic entry Jinjie Ruan
2026-09-02 9:55 ` Jinjie Ruan [this message]
2026-09-02 9:55 ` [PATCH v18 11/14] arm64: syscall: Simplify el0_svc_common() syscall exit path Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 12/14] arm64: ptrace: Make return type of arm64_syscall_trace_enter() bool Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 13/14] arm64: entry: Convert to generic entry Jinjie Ruan
2026-09-02 9:55 ` [PATCH v18 14/14] arm64: Inline el0_svc_common() Jinjie Ruan
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