c6x: add ret_from_kernel_thread(), simplify kernel_thread() (46f15067) · Commits · e / devices / android_kernel_xiaomi_nabu

arch/c6x/kernel/entry.S

+20 −0

Original line number	Diff line number	Diff line
		@@ -400,6 +400,26 @@ ret_from_fork_2:
		STW .D2T2 B0,*+SP(REGS_A4+8)
		ENDPROC(ret_from_fork)

		ENTRY(ret_from_kernel_thread)
		#ifdef CONFIG_C6X_BIG_KERNEL
		MVKL .S1 schedule_tail,A0
		MVKH .S1 schedule_tail,A0
		B .S2X A0
		#else
		B .S2 schedule_tail
		#endif
		LDW .D2T2 +SP(REGS_A0+8),B10 / get fn */
		ADDKPC .S2 0f,B3,3
		0:
		B .S2 B10 /* call fn */
		LDW .D2T1 +SP(REGS_A1+8),A4 / get arg */
		MVKL .S2 sys_exit,B11
		MVKH .S2 sys_exit,B11
		ADDKPC .S2 0f,B3,1
		0:
		BNOP .S2 B11,5 /* jump to sys_exit */
		ENDPROC(ret_from_kernel_thread)

		;;
		;; These are the interrupt handlers, responsible for calling __do_IRQ()
		;; int6 is used for syscalls (see _system_call entry)

arch/c6x/kernel/process.c

+12 −26

Original line number	Diff line number	Diff line
		@@ -25,6 +25,7 @@ void (*c6x_restart)(void);
		void (*c6x_halt)(void);

		extern asmlinkage void ret_from_fork(void);
		extern asmlinkage void ret_from_kernel_thread(void);

		/*
		* power off function, if any
		@@ -103,36 +104,21 @@ void machine_power_off(void)
		halt_loop();
		}

		static void kernel_thread_helper(int dummy, void arg, int (fn)(void *))
		{
		do_exit(fn(arg));
		}

		/*
		* Create a kernel thread
		*/
		int kernel_thread(int (fn)(void ), void * arg, unsigned long flags)
		{
		struct pt_regs regs;

		/*
		* copy_thread sets a4 to zero (child return from fork)
		* so we can't just set things up to directly return to
		* fn.
		*/
		memset(&regs, 0, sizeof(regs));
		regs.b4 = (unsigned long) arg;
		regs.a6 = (unsigned long) fn;
		regs.pc = (unsigned long) kernel_thread_helper;
		local_save_flags(regs.csr);
		regs.csr \|= 1;
		regs.tsr = 5; /* Set GEE and GIE in TSR */
		struct pt_regs regs = {
		.a0 = (unsigned long)fn,
		.a1 = (unsigned long)arg,
		.tsr = 0, /* kernel mode */
		};

		/* Ok, create the new process.. */
		return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED, -1, &regs,
		0, NULL, NULL);
		}
		EXPORT_SYMBOL(kernel_thread);

		void flush_thread(void)
		{
		@@ -192,21 +178,21 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
		childregs = task_pt_regs(p);

		childregs = regs;
		childregs->a4 = 0;

		if (usp == -1)
		if (usp == -1) {
		/* case of __kernel_thread: we return to supervisor space */
		childregs->sp = (unsigned long)(childregs + 1);
		else
		p->thread.pc = (unsigned long) ret_from_kernel_thread;
		} else {
		/* Otherwise use the given stack */
		childregs->sp = usp;
		p->thread.pc = (unsigned long) ret_from_fork;
		}

		/* Set usp/ksp */
		p->thread.usp = childregs->sp;
		/* switch_to uses stack to save/restore 14 callee-saved regs */
		thread_saved_ksp(p) = (unsigned long)childregs - 8;
		p->thread.pc = (unsigned int) ret_from_fork;
		p->thread.wchan = (unsigned long) ret_from_fork;
		p->thread.wchan = p->thread.pc;
		#ifdef __DSBT__
		{
		unsigned long dp;