/* * Process creation support for Hexagon * * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 and * only version 2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301, USA. */ #include <linux/sched.h>#include <linux/types.h>#include <linux/module.h>#include <linux/tick.h>#include <linux/uaccess.h>#include <linux/slab.h> /* * Program thread launch.  Often defined as a macro in processor.h, * but we're shooting for a small footprint and it's not an inner-loop * performance-critical operation. * * The Hexagon ABI specifies that R28 is zero'ed before program launch, * so that gets automatically done here.  If we ever stop doing that here, * we'll probably want to define the ELF_PLAT_INIT macro. */void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp){	/* Set to run with user-mode data segmentation */	set_fs(USER_DS);	/* We want to zero all data-containing registers. Is this overkill? */	memset(regs, 0, sizeof(*regs));	/* We might want to also zero all Processor registers here */	pt_set_usermode(regs);	pt_set_elr(regs, pc);	pt_set_rte_sp(regs, sp);} /* *  Spin, or better still, do a hardware or VM wait instruction *  If hardware or VM offer wait termination even though interrupts *  are disabled. */static void default_idle(void){	__vmwait();} void (*idle_sleep)(void) = default_idle; void cpu_idle(void){	while (1) {		tick_nohz_idle_enter();		local_irq_disable();		while (!need_resched()) {			idle_sleep();			/*  interrupts wake us up, but aren't serviced  */			local_irq_enable();	/* service interrupt   */			local_irq_disable();		}		local_irq_enable();		tick_nohz_idle_exit();		schedule();	}} /* *  Return saved PC of a blocked thread */unsigned long thread_saved_pc(struct task_struct *tsk){	return 0;} /* * Copy architecture-specific thread state */int copy_thread(unsigned long clone_flags, unsigned long usp,		unsigned long arg, struct task_struct *p){	struct thread_info *ti = task_thread_info(p);	struct hexagon_switch_stack *ss;	struct pt_regs *childregs;	asmlinkage void ret_from_fork(void); 	childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) -					sizeof(*childregs)); 	ti->regs = childregs; 	/*	 * Establish kernel stack pointer and initial PC for new thread	 * Note that unlike the usual situation, we do not copy the	 * parent's callee-saved here; those are in pt_regs and whatever	 * we leave here will be overridden on return to userland.	 */	ss = (struct hexagon_switch_stack *) ((unsigned long) childregs -						    sizeof(*ss));	ss->lr = (unsigned long)ret_from_fork;	p->thread.switch_sp = ss;	if (unlikely(p->flags & PF_KTHREAD)) {		memset(childregs, 0, sizeof(struct pt_regs));		/* r24 <- fn, r25 <- arg */		ss->r2524 = usp | ((u64)arg << 32);		pt_set_kmode(childregs);		return 0;	}	memcpy(childregs, current_pt_regs(), sizeof(*childregs));	ss->r2524 = 0; 	if (usp)		pt_set_rte_sp(childregs, usp); 	/* Child sees zero return value */	childregs->r00 = 0; 	/*	 * The clone syscall has the C signature:	 * int [r0] clone(int flags [r0],	 *           void *child_frame [r1],	 *           void *parent_tid [r2],	 *           void *child_tid [r3],	 *           void *thread_control_block [r4]);	 * ugp is used to provide TLS support.	 */	if (clone_flags & CLONE_SETTLS)		childregs->ugp = childregs->r04; 	/*	 * Parent sees new pid -- not necessary, not even possible at	 * this point in the fork process	 * Might also want to set things like ti->addr_limit	 */ 	return 0;} /* * Release any architecture-specific resources locked by thread */void release_thread(struct task_struct *dead_task){} /* * Free any architecture-specific thread data structures, etc. */void exit_thread(void){} /* * Some archs flush debug and FPU info here */void flush_thread(void){} /* * The "wait channel" terminology is archaic, but what we want * is an identification of the point at which the scheduler * was invoked by a blocked thread. */unsigned long get_wchan(struct task_struct *p){	unsigned long fp, pc;	unsigned long stack_page;	int count = 0;	if (!p || p == current || p->state == TASK_RUNNING)		return 0; 	stack_page = (unsigned long)task_stack_page(p);	fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp;	do {		if (fp < (stack_page + sizeof(struct thread_info)) ||			fp >= (THREAD_SIZE - 8 + stack_page))			return 0;		pc = ((unsigned long *)fp)[1];		if (!in_sched_functions(pc))			return pc;		fp = *(unsigned long *) fp;	} while (count++ < 16); 	return 0;} /* * Required placeholder. */int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu){	return 0;}