2011-11-01 07:41:49 +08:00
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/*
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* Process creation support for Hexagon
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*
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2012-09-20 05:22:02 +08:00
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* Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
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2011-11-01 07:41:49 +08:00
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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* only version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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#include <linux/sched.h>
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/tick.h>
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#include <linux/uaccess.h>
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#include <linux/slab.h>
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2012-05-30 06:23:14 +08:00
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#include <linux/tracehook.h>
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2011-11-01 07:41:49 +08:00
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/*
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* Program thread launch. Often defined as a macro in processor.h,
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* but we're shooting for a small footprint and it's not an inner-loop
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* performance-critical operation.
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*
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* The Hexagon ABI specifies that R28 is zero'ed before program launch,
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* so that gets automatically done here. If we ever stop doing that here,
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* we'll probably want to define the ELF_PLAT_INIT macro.
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*/
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void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
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{
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/* Set to run with user-mode data segmentation */
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set_fs(USER_DS);
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/* We want to zero all data-containing registers. Is this overkill? */
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memset(regs, 0, sizeof(*regs));
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/* We might want to also zero all Processor registers here */
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pt_set_usermode(regs);
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pt_set_elr(regs, pc);
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pt_set_rte_sp(regs, sp);
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}
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/*
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* Spin, or better still, do a hardware or VM wait instruction
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* If hardware or VM offer wait termination even though interrupts
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* are disabled.
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*/
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static void default_idle(void)
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{
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__vmwait();
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}
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void (*idle_sleep)(void) = default_idle;
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void cpu_idle(void)
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{
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while (1) {
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2012-03-08 05:27:23 +08:00
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tick_nohz_idle_enter();
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2011-11-01 07:41:49 +08:00
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local_irq_disable();
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while (!need_resched()) {
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idle_sleep();
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/* interrupts wake us up, but aren't serviced */
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local_irq_enable(); /* service interrupt */
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local_irq_disable();
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}
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local_irq_enable();
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2012-03-08 05:27:23 +08:00
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tick_nohz_idle_exit();
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2011-11-01 07:41:49 +08:00
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schedule();
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}
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}
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/*
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* Return saved PC of a blocked thread
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*/
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unsigned long thread_saved_pc(struct task_struct *tsk)
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{
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return 0;
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}
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/*
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* Copy architecture-specific thread state
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*/
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int copy_thread(unsigned long clone_flags, unsigned long usp,
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2012-10-23 10:51:14 +08:00
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unsigned long arg, struct task_struct *p)
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2011-11-01 07:41:49 +08:00
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{
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struct thread_info *ti = task_thread_info(p);
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struct hexagon_switch_stack *ss;
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struct pt_regs *childregs;
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asmlinkage void ret_from_fork(void);
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childregs = (struct pt_regs *) (((unsigned long) ti + THREAD_SIZE) -
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sizeof(*childregs));
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ti->regs = childregs;
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/*
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* Establish kernel stack pointer and initial PC for new thread
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2012-10-19 10:45:24 +08:00
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* Note that unlike the usual situation, we do not copy the
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* parent's callee-saved here; those are in pt_regs and whatever
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* we leave here will be overridden on return to userland.
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2011-11-01 07:41:49 +08:00
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*/
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ss = (struct hexagon_switch_stack *) ((unsigned long) childregs -
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sizeof(*ss));
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ss->lr = (unsigned long)ret_from_fork;
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p->thread.switch_sp = ss;
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2012-10-19 10:45:24 +08:00
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if (unlikely(p->flags & PF_KTHREAD)) {
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memset(childregs, 0, sizeof(struct pt_regs));
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/* r24 <- fn, r25 <- arg */
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2012-10-24 07:26:20 +08:00
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ss->r24 = usp;
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ss->r25 = arg;
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2012-10-19 10:45:24 +08:00
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pt_set_kmode(childregs);
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return 0;
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2011-11-01 07:41:49 +08:00
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}
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2012-10-27 07:25:46 +08:00
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memcpy(childregs, current_pt_regs(), sizeof(*childregs));
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2012-10-19 10:45:24 +08:00
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ss->r2524 = 0;
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2012-10-27 07:25:46 +08:00
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if (usp)
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pt_set_rte_sp(childregs, usp);
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2012-10-19 10:45:24 +08:00
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/* Child sees zero return value */
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childregs->r00 = 0;
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/*
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* The clone syscall has the C signature:
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* int [r0] clone(int flags [r0],
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* void *child_frame [r1],
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* void *parent_tid [r2],
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* void *child_tid [r3],
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* void *thread_control_block [r4]);
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* ugp is used to provide TLS support.
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*/
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if (clone_flags & CLONE_SETTLS)
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childregs->ugp = childregs->r04;
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2011-11-01 07:41:49 +08:00
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/*
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2012-10-19 10:45:24 +08:00
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* Parent sees new pid -- not necessary, not even possible at
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* this point in the fork process
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* Might also want to set things like ti->addr_limit
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2011-11-01 07:41:49 +08:00
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*/
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return 0;
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}
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/*
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* Release any architecture-specific resources locked by thread
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*/
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void release_thread(struct task_struct *dead_task)
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{
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}
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/*
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* Free any architecture-specific thread data structures, etc.
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*/
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void exit_thread(void)
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{
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}
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/*
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* Some archs flush debug and FPU info here
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*/
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void flush_thread(void)
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{
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}
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/*
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* The "wait channel" terminology is archaic, but what we want
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* is an identification of the point at which the scheduler
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* was invoked by a blocked thread.
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*/
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unsigned long get_wchan(struct task_struct *p)
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{
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unsigned long fp, pc;
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unsigned long stack_page;
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int count = 0;
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if (!p || p == current || p->state == TASK_RUNNING)
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return 0;
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stack_page = (unsigned long)task_stack_page(p);
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fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp;
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do {
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if (fp < (stack_page + sizeof(struct thread_info)) ||
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fp >= (THREAD_SIZE - 8 + stack_page))
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return 0;
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pc = ((unsigned long *)fp)[1];
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if (!in_sched_functions(pc))
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return pc;
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fp = *(unsigned long *) fp;
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} while (count++ < 16);
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return 0;
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}
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/*
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* Required placeholder.
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*/
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int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpu)
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{
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return 0;
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}
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2012-05-30 06:23:14 +08:00
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/*
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* Called on the exit path of event entry; see vm_entry.S
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*
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* Interrupts will already be disabled.
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*
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* Returns 0 if there's no need to re-check for more work.
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*/
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int do_work_pending(struct pt_regs *regs, u32 thread_info_flags)
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{
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2012-12-07 06:37:43 +08:00
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if (!(thread_info_flags & _TIF_WORK_MASK)) {
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2012-05-30 06:23:14 +08:00
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return 0;
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} /* shortcut -- no work to be done */
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local_irq_enable();
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if (thread_info_flags & _TIF_NEED_RESCHED) {
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schedule();
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return 1;
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}
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if (thread_info_flags & _TIF_SIGPENDING) {
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do_signal(regs);
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return 1;
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}
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if (thread_info_flags & _TIF_NOTIFY_RESUME) {
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clear_thread_flag(TIF_NOTIFY_RESUME);
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tracehook_notify_resume(regs);
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}
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/* Should not even reach here */
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panic("%s: bad thread_info flags 0x%08x\n", __func__,
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thread_info_flags);
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}
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