arch/riscv/kernel/process.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
   4  *  Chen Liqin <liqin.chen@sunplusct.com>
   5  *  Lennox Wu <lennox.wu@sunplusct.com>
   6  * Copyright (C) 2012 Regents of the University of California
   7  * Copyright (C) 2017 SiFive
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/sched.h>
  12 #include <linux/sched/task_stack.h>
  13 #include <linux/tick.h>
  14 #include <linux/ptrace.h>
  15 #include <linux/uaccess.h>
  16
  17 #include <asm/unistd.h>
  18 #include <asm/processor.h>
  19 #include <asm/csr.h>
  20 #include <asm/string.h>
  21 #include <asm/switch_to.h>
  22
  23 extern asmlinkage void ret_from_fork(void);
  24 extern asmlinkage void ret_from_kernel_thread(void);
  25
  26 void arch_cpu_idle(void)
  27 {
  28         wait_for_interrupt();
  29         local_irq_enable();
  30 }
  31
  32 void show_regs(struct pt_regs *regs)
  33 {
  34         show_regs_print_info(KERN_DEFAULT);
  35
  36         pr_cont("sepc: " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
  37                 regs->sepc, regs->ra, regs->sp);
  38         pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
  39                 regs->gp, regs->tp, regs->t0);
  40         pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
  41                 regs->t1, regs->t2, regs->s0);
  42         pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
  43                 regs->s1, regs->a0, regs->a1);
  44         pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
  45                 regs->a2, regs->a3, regs->a4);
  46         pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
  47                 regs->a5, regs->a6, regs->a7);
  48         pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
  49                 regs->s2, regs->s3, regs->s4);
  50         pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
  51                 regs->s5, regs->s6, regs->s7);
  52         pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
  53                 regs->s8, regs->s9, regs->s10);
  54         pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
  55                 regs->s11, regs->t3, regs->t4);
  56         pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
  57                 regs->t5, regs->t6);
  58
  59         pr_cont("sstatus: " REG_FMT " sbadaddr: " REG_FMT " scause: " REG_FMT "\n",
  60                 regs->sstatus, regs->sbadaddr, regs->scause);
  61 }
  62
  63 void start_thread(struct pt_regs *regs, unsigned long pc,
  64         unsigned long sp)
  65 {
  66         regs->sstatus = SR_SPIE;
  67         if (has_fpu)
  68                 regs->sstatus |= SR_FS_INITIAL;
  69         regs->sepc = pc;
  70         regs->sp = sp;
  71         set_fs(USER_DS);
  72 }
  73
  74 void flush_thread(void)
  75 {
  76 #ifdef CONFIG_FPU
  77         /*
  78          * Reset FPU context
  79          *      frm: round to nearest, ties to even (IEEE default)
  80          *      fflags: accrued exceptions cleared
  81          */
  82         memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
  83 #endif
  84 }
  85
  86 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
  87 {
  88         fstate_save(src, task_pt_regs(src));
  89         *dst = *src;
  90         return 0;
  91 }
  92
  93 int copy_thread(unsigned long clone_flags, unsigned long usp,
  94         unsigned long arg, struct task_struct *p)
  95 {
  96         struct pt_regs *childregs = task_pt_regs(p);
  97
  98         /* p->thread holds context to be restored by __switch_to() */
  99         if (unlikely(p->flags & PF_KTHREAD)) {
 100                 /* Kernel thread */
 101                 const register unsigned long gp __asm__ ("gp");
 102                 memset(childregs, 0, sizeof(struct pt_regs));
 103                 childregs->gp = gp;
 104                 childregs->sstatus = SR_SPP | SR_SPIE; /* Supervisor, irqs on */
 105
 106                 p->thread.ra = (unsigned long)ret_from_kernel_thread;
 107                 p->thread.s[0] = usp; /* fn */
 108                 p->thread.s[1] = arg;
 109         } else {
 110                 *childregs = *(current_pt_regs());
 111                 if (usp) /* User fork */
 112                         childregs->sp = usp;
 113                 if (clone_flags & CLONE_SETTLS)
 114                         childregs->tp = childregs->a5;
 115                 childregs->a0 = 0; /* Return value of fork() */
 116                 p->thread.ra = (unsigned long)ret_from_fork;
 117         }
 118         p->thread.sp = (unsigned long)childregs; /* kernel sp */
 119         return 0;
 120 }