seccomp/mips: change syscall_trace_enter() to use secure_computing()

arch/mips/Kconfig selects HAVE_ARCH_SECCOMP_FILTER so syscall_trace_enter()
can just use __secure_computing(NULL) and rely on populate_seccomp_data(sd)
and "sd == NULL" checks in __secure_computing(sd) paths.

With the change above syscall_trace_enter() can just use secure_computing()
and avoid #ifdef + test_thread_flag(TIF_SECCOMP). CONFIG_GENERIC_ENTRY is
not defined, so test_syscall_work(SECCOMP) will check TIF_SECCOMP.

Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Thomas Bogendoerfer <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>

Author: oleg-nesterov

arch/mips/kernel/ptrace.c

@@ -1326,24 +1326,8 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs)
 			return -1;
 	}
 
-#ifdef CONFIG_SECCOMP
-	if (unlikely(test_thread_flag(TIF_SECCOMP))) {
-		int ret, i;
-		struct seccomp_data sd;
-		unsigned long args[6];
-
-		sd.nr = current_thread_info()->syscall;
-		sd.arch = syscall_get_arch(current);
-		syscall_get_arguments(current, regs, args);
-		for (i = 0; i < 6; i++)
-			sd.args[i] = args[i];
-		sd.instruction_pointer = KSTK_EIP(current);
-
-		ret = __secure_computing(&sd);
-		if (ret == -1)
-			return ret;
-	}
-#endif
+	if (secure_computing())
+		return -1;
 
 	if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
 		trace_sys_enter(regs, regs->regs[2]);