arch/riscv/kernel/process.c

   1 /*
   2  * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   3  *  Chen Liqin <liqin.chen@sunplusct.com>
   4  *  Lennox Wu <lennox.wu@sunplusct.com>
   5  * Copyright (C) 2012 Regents of the University of California
   6  * Copyright (C) 2017 SiFive
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, see the file COPYING, or write
  20  * to the Free Software Foundation, Inc.,
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/sched.h>
  25 #include <linux/sched/task_stack.h>
  26 #include <linux/tick.h>
  27 #include <linux/ptrace.h>
  28 #include <linux/uaccess.h>
  29
  30 #include <asm/unistd.h>
  31 #include <asm/processor.h>
  32 #include <asm/csr.h>
  33 #include <asm/string.h>
  34 #include <asm/switch_to.h>
  35
  36 extern asmlinkage void ret_from_fork(void);
  37 extern asmlinkage void ret_from_kernel_thread(void);
  38
  39 void arch_cpu_idle(void)
  40 {
  41         wait_for_interrupt();
  42         local_irq_enable();
  43 }
  44
  45 void show_regs(struct pt_regs *regs)
  46 {
  47         show_regs_print_info(KERN_DEFAULT);
  48
  49         pr_cont("sepc: " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
  50                 regs->sepc, regs->ra, regs->sp);
  51         pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
  52                 regs->gp, regs->tp, regs->t0);
  53         pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
  54                 regs->t1, regs->t2, regs->s0);
  55         pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
  56                 regs->s1, regs->a0, regs->a1);
  57         pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
  58                 regs->a2, regs->a3, regs->a4);
  59         pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
  60                 regs->a5, regs->a6, regs->a7);
  61         pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
  62                 regs->s2, regs->s3, regs->s4);
  63         pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
  64                 regs->s5, regs->s6, regs->s7);
  65         pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
  66                 regs->s8, regs->s9, regs->s10);
  67         pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
  68                 regs->s11, regs->t3, regs->t4);
  69         pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
  70                 regs->t5, regs->t6);
  71
  72         pr_cont("sstatus: " REG_FMT " sbadaddr: " REG_FMT " scause: " REG_FMT "\n",
  73                 regs->sstatus, regs->sbadaddr, regs->scause);
  74 }
  75
  76 void start_thread(struct pt_regs *regs, unsigned long pc,
  77         unsigned long sp)
  78 {
  79         regs->sstatus = SR_SPIE;
  80         if (has_fpu)
  81                 regs->sstatus |= SR_FS_INITIAL;
  82         regs->sepc = pc;
  83         regs->sp = sp;
  84         set_fs(USER_DS);
  85 }
  86
  87 void flush_thread(void)
  88 {
  89 #ifdef CONFIG_FPU
  90         /*
  91          * Reset FPU context
  92          *      frm: round to nearest, ties to even (IEEE default)
  93          *      fflags: accrued exceptions cleared
  94          */
  95         memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
  96 #endif
  97 }
  98
  99 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 100 {
 101         fstate_save(src, task_pt_regs(src));
 102         *dst = *src;
 103         return 0;
 104 }
 105
 106 int copy_thread(unsigned long clone_flags, unsigned long usp,
 107         unsigned long arg, struct task_struct *p)
 108 {
 109         struct pt_regs *childregs = task_pt_regs(p);
 110
 111         /* p->thread holds context to be restored by __switch_to() */
 112         if (unlikely(p->flags & PF_KTHREAD)) {
 113                 /* Kernel thread */
 114                 const register unsigned long gp __asm__ ("gp");
 115                 memset(childregs, 0, sizeof(struct pt_regs));
 116                 childregs->gp = gp;
 117                 childregs->sstatus = SR_SPP | SR_SPIE; /* Supervisor, irqs on */
 118
 119                 p->thread.ra = (unsigned long)ret_from_kernel_thread;
 120                 p->thread.s[0] = usp; /* fn */
 121                 p->thread.s[1] = arg;
 122         } else {
 123                 *childregs = *(current_pt_regs());
 124                 if (usp) /* User fork */
 125                         childregs->sp = usp;
 126                 if (clone_flags & CLONE_SETTLS)
 127                         childregs->tp = childregs->a5;
 128                 childregs->a0 = 0; /* Return value of fork() */
 129                 p->thread.ra = (unsigned long)ret_from_fork;
 130         }
 131         p->thread.sp = (unsigned long)childregs; /* kernel sp */
 132         return 0;
 133 }