arch/score/kernel/process.c

   1 /*
   2  * arch/score/kernel/process.c
   3  *
   4  * Score Processor version.
   5  *
   6  * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   7  *  Chen Liqin <liqin.chen@sunplusct.com>
   8  *  Lennox Wu <lennox.wu@sunplusct.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, see the file COPYING, or write
  22  * to the Free Software Foundation, Inc.,
  23  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/reboot.h>
  28 #include <linux/elfcore.h>
  29 #include <linux/pm.h>
  30 #include <linux/rcupdate.h>
  31 #include <linux/sched/task.h>
  32 #include <linux/sched/task_stack.h>
  33
  34 void (*pm_power_off)(void);
  35 EXPORT_SYMBOL(pm_power_off);
  36
  37 /* If or when software machine-restart is implemented, add code here. */
  38 void machine_restart(char *command) {}
  39
  40 /* If or when software machine-halt is implemented, add code here. */
  41 void machine_halt(void) {}
  42
  43 /* If or when software machine-power-off is implemented, add code here. */
  44 void machine_power_off(void) {}
  45
  46 void ret_from_fork(void);
  47 void ret_from_kernel_thread(void);
  48
  49 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
  50 {
  51         unsigned long status;
  52
  53         /* New thread loses kernel privileges. */
  54         status = regs->cp0_psr & ~(KU_MASK);
  55         status |= KU_USER;
  56         regs->cp0_psr = status;
  57         regs->cp0_epc = pc;
  58         regs->regs[0] = sp;
  59 }
  60
  61 /*
  62  * When a process does an "exec", machine state like FPU and debug
  63  * registers need to be reset.  This is a hook function for that.
  64  * Currently we don't have any such state to reset, so this is empty.
  65  */
  66 void flush_thread(void) {}
  67
  68 /*
  69  * set up the kernel stack and exception frames for a new process
  70  */
  71 int copy_thread(unsigned long clone_flags, unsigned long usp,
  72                 unsigned long arg, struct task_struct *p)
  73 {
  74         struct thread_info *ti = task_thread_info(p);
  75         struct pt_regs *childregs = task_pt_regs(p);
  76         struct pt_regs *regs = current_pt_regs();
  77
  78         p->thread.reg0 = (unsigned long) childregs;
  79         if (unlikely(p->flags & PF_KTHREAD)) {
  80                 memset(childregs, 0, sizeof(struct pt_regs));
  81                 p->thread.reg12 = usp;
  82                 p->thread.reg13 = arg;
  83                 p->thread.reg3 = (unsigned long) ret_from_kernel_thread;
  84         } else {
  85                 *childregs = *current_pt_regs();
  86                 childregs->regs[7] = 0;         /* Clear error flag */
  87                 childregs->regs[4] = 0;         /* Child gets zero as return value */
  88                 if (usp)
  89                         childregs->regs[0] = usp;       /* user fork */
  90                 p->thread.reg3 = (unsigned long) ret_from_fork;
  91         }
  92
  93         p->thread.cp0_psr = 0;
  94
  95         return 0;
  96 }
  97
  98 /* Fill in the fpu structure for a core dump. */
  99 int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
 100 {
 101         return 1;
 102 }
 103
 104 unsigned long thread_saved_pc(struct task_struct *tsk)
 105 {
 106         return task_pt_regs(tsk)->cp0_epc;
 107 }
 108
 109 unsigned long get_wchan(struct task_struct *task)
 110 {
 111         if (!task || task == current || task->state == TASK_RUNNING)
 112                 return 0;
 113
 114         if (!task_stack_page(task))
 115                 return 0;
 116
 117         return task_pt_regs(task)->cp0_epc;
 118 }
 119
 120 unsigned long arch_align_stack(unsigned long sp)
 121 {
 122         return sp;
 123 }