[PATCH v15 04/11] arm64/ptrace: Expand secure_computing() in place

[Jinjie Ruan]

Refactor syscall_trace_enter() by open-coding the seccomp check
to align with the generic entry framework.

[Background]
The generic entry implementation expands the seccomp check in-place
instead of using the secure_computing() wrapper. It directly tests
SYSCALL_WORK_SECCOMP and calls the underlying __secure_computing()
function to handle syscall filtering.

[Changes]
1. Open-code seccomp check:
   - Instead of calling the secure_computing() wrapper, explicitly check
     the 'flags' parameter for _TIF_SECCOMP.
   - Call __secure_computing() directly if the flag is set.

[Why this matters]
- Aligns the arm64 syscall path with the generic entry implementation,
  simplifying future migration to the generic entry framework.
- No functional changes are intended; seccomp behavior remains identical.

Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Reviewed-by: Linus Walleij <linusw at kernel.org>
Reviewed-by: Yeoreum Yun <yeoreum.yun at arm.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky at arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie at huawei.com>
---
 arch/arm64/kernel/ptrace.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 8d296a07fbf7..ba8cb5ec967b 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -2420,8 +2420,11 @@ int syscall_trace_enter(struct pt_regs *regs, unsigned long flags)
 	}
 
 	/* Do the secure computing after ptrace; failures should be fast. */
-	if (secure_computing() == -1)
-		return NO_SYSCALL;
+	if (flags & _TIF_SECCOMP) {
+		ret = __secure_computing();
+		if (ret == -1)
+			return NO_SYSCALL;
+	}
 
 	/* Either of the above might have changed the syscall number */
 	syscall = syscall_get_nr(current, regs);
-- 
2.34.1