openrisc: use generic kernel_thread/kernel_execve (cbf23cf1) · Commits · e / devices / android_kernel_teracube_emerald

arch/openrisc/Kconfig

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -22,6 +22,8 @@ config OPENRISC
	select GENERIC_STRNCPY_FROM_USER		select GENERIC_STRNCPY_FROM_USER
	select GENERIC_STRNLEN_USER		select GENERIC_STRNLEN_USER
	select MODULES_USE_ELF_RELA		select MODULES_USE_ELF_RELA
			select GENERIC_KERNEL_THREAD
			select GENERIC_KERNEL_EXECVE

	config MMU		config MMU
	def_bool y		def_bool y

arch/openrisc/kernel/entry.S

+10 −20

Original line number	Original line	Diff line number	Diff line
	@@ -894,6 +894,16 @@ ENTRY(ret_from_fork)
	l.jal schedule_tail		l.jal schedule_tail
	l.nop		l.nop

			/* Check if we are a kernel thread */
			l.sfeqi r20,0
			l.bf 1f
			l.nop

			/* ...we are a kernel thread so invoke the requested callback */
			l.jalr r20
			l.or r3,r22,r0

			1:
	/* _syscall_returns expect r11 to contain return value */		/* _syscall_returns expect r11 to contain return value */
	l.lwz r11,PT_GPR11(r1)		l.lwz r11,PT_GPR11(r1)

	@@ -915,26 +925,6 @@ ENTRY(ret_from_fork)
	l.j _syscall_return		l.j _syscall_return
	l.nop		l.nop

	/* Since syscalls don't save call-clobbered registers, the args to
	* kernel_thread_helper will need to be passed through callee-saved
	* registers and copied to the parameter registers when the thread
	* begins running.
	*
	* See arch/openrisc/kernel/process.c:
	* The args are passed as follows:
	* arg1 (r3) : passed in r20
	* arg2 (r4) : passed in r22
	*/

	ENTRY(_kernel_thread_helper)
	l.or r3,r20,r0
	l.or r4,r22,r0
	l.movhi r31,hi(kernel_thread_helper)
	l.ori r31,r31,lo(kernel_thread_helper)
	l.jr r31
	l.nop


	/* ========================================================[ switch ] === */		/* ========================================================[ switch ] === */

	/*		/*

arch/openrisc/kernel/process.c

+56 −82

Original line number	Original line	Diff line number	Diff line
	@@ -109,65 +109,82 @@ void release_thread(struct task_struct *dead_task)
	*/		*/
	extern asmlinkage void ret_from_fork(void);		extern asmlinkage void ret_from_fork(void);

			/*
			* copy_thread
			* @clone_flags: flags
			* @usp: user stack pointer or fn for kernel thread
			* @arg: arg to fn for kernel thread; always NULL for userspace thread
			* @p: the newly created task
			* @regs: CPU context to copy for userspace thread; always NULL for kthread
			*
			* At the top of a newly initialized kernel stack are two stacked pt_reg
			* structures. The first (topmost) is the userspace context of the thread.
			* The second is the kernelspace context of the thread.
			*
			* A kernel thread will not be returning to userspace, so the topmost pt_regs
			* struct can be uninitialized; it _does_ need to exist, though, because
			* a kernel thread can become a userspace thread by doing a kernel_execve, in
			* which case the topmost context will be initialized and used for 'returning'
			* to userspace.
			*
			* The second pt_reg struct needs to be initialized to 'return' to
			* ret_from_fork. A kernel thread will need to set r20 to the address of
			* a function to call into (with arg in r22); userspace threads need to set
			* r20 to NULL in which case ret_from_fork will just continue a return to
			* userspace.
			*
			* A kernel thread 'fn' may return; this is effectively what happens when
			* kernel_execve is called. In that case, the userspace pt_regs must have
			* been initialized (which kernel_execve takes care of, see start_thread
			* below); ret_from_fork will then continue its execution causing the
			* 'kernel thread' to return to userspace as a userspace thread.
			*/

	int		int
	copy_thread(unsigned long clone_flags, unsigned long usp,		copy_thread(unsigned long clone_flags, unsigned long usp,
	unsigned long unused, struct task_struct p, struct pt_regs regs)		unsigned long arg, struct task_struct p, struct pt_regs regs)
	{		{
	struct pt_regs *childregs;		struct pt_regs *userregs;
	struct pt_regs *kregs;		struct pt_regs *kregs;
	unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;		unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
	struct thread_info *ti;
	unsigned long top_of_kernel_stack;		unsigned long top_of_kernel_stack;

	top_of_kernel_stack = sp;		top_of_kernel_stack = sp;

	p->set_child_tid = p->clear_child_tid = NULL;		p->set_child_tid = p->clear_child_tid = NULL;

	/* Copy registers */		/* Locate userspace context on stack... */
	/* redzone */		sp -= STACK_FRAME_OVERHEAD; /* redzone */
	sp -= STACK_FRAME_OVERHEAD;
	sp -= sizeof(struct pt_regs);		sp -= sizeof(struct pt_regs);
	childregs = (struct pt_regs *)sp;		userregs = (struct pt_regs *) sp;

	/* Copy parent registers */		/* ...and kernel context */
	childregs = regs;		sp -= STACK_FRAME_OVERHEAD; /* redzone */
			sp -= sizeof(struct pt_regs);
			kregs = (struct pt_regs *)sp;

	if ((childregs->sr & SPR_SR_SM) == 1) {		if (unlikely(p->flags & PF_KTHREAD)) {
	/* for kernel thread, set `current_thread_info'		memset(kregs, 0, sizeof(struct pt_regs));
	* and stackptr in new task		kregs->gpr[20] = usp; /* fn, kernel thread */
	*/		kregs->gpr[22] = arg;
	childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
	childregs->gpr[10] = (unsigned long)task_thread_info(p);
	} else {		} else {
	childregs->sp = usp;		userregs = regs;
	}

	childregs->gpr[11] = 0; /* Result from fork() */		userregs->sp = usp;
			userregs->gpr[11] = 0; /* Result from fork() */

	/*		kregs->gpr[20] = 0; /* Userspace thread */
	* The way this works is that at some point in the future		}
	* some task will call _switch to switch to the new task.
	* That will pop off the stack frame created below and start
	* the new task running at ret_from_fork. The new task will
	* do some house keeping and then return from the fork or clone
	* system call, using the stack frame created above.
	*/
	/* redzone */
	sp -= STACK_FRAME_OVERHEAD;
	sp -= sizeof(struct pt_regs);
	kregs = (struct pt_regs *)sp;

	ti = task_thread_info(p);
	ti->ksp = sp;

	/* kregs->sp must store the location of the 'pre-switch' kernel stack		/*
	* pointer... for a newly forked process, this is simply the top of		* _switch wants the kernel stack page in pt_regs->sp so that it
	* the kernel stack.		* can restore it to thread_info->ksp... see _switch for details.
	*/		*/
	kregs->sp = top_of_kernel_stack;		kregs->sp = top_of_kernel_stack;
	kregs->gpr[10] = (unsigned long)task_thread_info(p);
	kregs->gpr[9] = (unsigned long)ret_from_fork;		kregs->gpr[9] = (unsigned long)ret_from_fork;

			task_thread_info(p)->ksp = (unsigned long)kregs;

	return 0;		return 0;
	}		}

	@@ -176,16 +193,14 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
	*/		*/
	void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)		void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
	{		{
	unsigned long sr = regs->sr & ~SPR_SR_SM;		unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;

	set_fs(USER_DS);		set_fs(USER_DS);
	memset(regs->gpr, 0, sizeof(regs->gpr));		memset(regs, 0, sizeof(struct pt_regs));

	regs->pc = pc;		regs->pc = pc;
	regs->sr = sr;		regs->sr = sr;
	regs->sp = sp;		regs->sp = sp;

	/* printk("start thread, ksp = %lx\n", current_thread_info()->ksp);*/
	}		}

	/* Fill in the fpu structure for a core dump. */		/* Fill in the fpu structure for a core dump. */
	@@ -236,31 +251,6 @@ void dump_elf_thread(elf_greg_t dest, struct pt_regs regs)
	dest[35] = 0;		dest[35] = 0;
	}		}

	extern void _kernel_thread_helper(void);

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

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

	memset(&regs, 0, sizeof(regs));

	regs.gpr[20] = (unsigned long)fn;
	regs.gpr[22] = (unsigned long)arg;
	regs.sr = mfspr(SPR_SR);
	regs.pc = (unsigned long)_kernel_thread_helper;

	return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED,
	0, &regs, 0, NULL, NULL);
	}

	/*		/*
	* sys_execve() executes a new program.		* sys_execve() executes a new program.
	*/		*/
	@@ -291,19 +281,3 @@ unsigned long get_wchan(struct task_struct *p)

	return 0;		return 0;
	}		}

	int kernel_execve(const char filename, char const argv[], char *const envp[])
	{
	register long __res asm("r11") = __NR_execve;
	register long __a asm("r3") = (long)(filename);
	register long __b asm("r4") = (long)(argv);
	register long __c asm("r5") = (long)(envp);
	__asm__ volatile ("l.sys 1"
	: "=r" (__res), "=r"(__a), "=r"(__b), "=r"(__c)
	: "0"(__res), "1"(__a), "2"(__b), "3"(__c)
	: "r6", "r7", "r8", "r12", "r13", "r15",
	"r17", "r19", "r21", "r23", "r25", "r27",
	"r29", "r31");
	__asm__ volatile ("l.nop");
	return __res;
	}