linux/arch/riscv/kernel/process.c
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   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/cpu.h>
  11#include <linux/kernel.h>
  12#include <linux/sched.h>
  13#include <linux/sched/debug.h>
  14#include <linux/sched/task_stack.h>
  15#include <linux/tick.h>
  16#include <linux/ptrace.h>
  17#include <linux/uaccess.h>
  18
  19#include <asm/unistd.h>
  20#include <asm/processor.h>
  21#include <asm/csr.h>
  22#include <asm/stacktrace.h>
  23#include <asm/string.h>
  24#include <asm/switch_to.h>
  25#include <asm/thread_info.h>
  26
  27register unsigned long gp_in_global __asm__("gp");
  28
  29#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
  30#include <linux/stackprotector.h>
  31unsigned long __stack_chk_guard __read_mostly;
  32EXPORT_SYMBOL(__stack_chk_guard);
  33#endif
  34
  35extern asmlinkage void ret_from_fork(void);
  36extern asmlinkage void ret_from_kernel_thread(void);
  37
  38void arch_cpu_idle(void)
  39{
  40        wait_for_interrupt();
  41        raw_local_irq_enable();
  42}
  43
  44void __show_regs(struct pt_regs *regs)
  45{
  46        show_regs_print_info(KERN_DEFAULT);
  47
  48        if (!user_mode(regs)) {
  49                pr_cont("epc : %pS\n", (void *)regs->epc);
  50                pr_cont(" ra : %pS\n", (void *)regs->ra);
  51        }
  52
  53        pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
  54                regs->epc, regs->ra, regs->sp);
  55        pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
  56                regs->gp, regs->tp, regs->t0);
  57        pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
  58                regs->t1, regs->t2, regs->s0);
  59        pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
  60                regs->s1, regs->a0, regs->a1);
  61        pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
  62                regs->a2, regs->a3, regs->a4);
  63        pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
  64                regs->a5, regs->a6, regs->a7);
  65        pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
  66                regs->s2, regs->s3, regs->s4);
  67        pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
  68                regs->s5, regs->s6, regs->s7);
  69        pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
  70                regs->s8, regs->s9, regs->s10);
  71        pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
  72                regs->s11, regs->t3, regs->t4);
  73        pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
  74                regs->t5, regs->t6);
  75
  76        pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
  77                regs->status, regs->badaddr, regs->cause);
  78}
  79void show_regs(struct pt_regs *regs)
  80{
  81        __show_regs(regs);
  82        if (!user_mode(regs))
  83                dump_backtrace(regs, NULL, KERN_DEFAULT);
  84}
  85
  86void start_thread(struct pt_regs *regs, unsigned long pc,
  87        unsigned long sp)
  88{
  89        regs->status = SR_PIE;
  90        if (has_fpu()) {
  91                regs->status |= SR_FS_INITIAL;
  92                /*
  93                 * Restore the initial value to the FP register
  94                 * before starting the user program.
  95                 */
  96                fstate_restore(current, regs);
  97        }
  98        regs->epc = pc;
  99        regs->sp = sp;
 100}
 101
 102void flush_thread(void)
 103{
 104#ifdef CONFIG_FPU
 105        /*
 106         * Reset FPU state and context
 107         *      frm: round to nearest, ties to even (IEEE default)
 108         *      fflags: accrued exceptions cleared
 109         */
 110        fstate_off(current, task_pt_regs(current));
 111        memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
 112#endif
 113}
 114
 115int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 116{
 117        fstate_save(src, task_pt_regs(src));
 118        *dst = *src;
 119        return 0;
 120}
 121
 122int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
 123                struct task_struct *p, unsigned long tls)
 124{
 125        struct pt_regs *childregs = task_pt_regs(p);
 126
 127        /* p->thread holds context to be restored by __switch_to() */
 128        if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
 129                /* Kernel thread */
 130                memset(childregs, 0, sizeof(struct pt_regs));
 131                childregs->gp = gp_in_global;
 132                /* Supervisor/Machine, irqs on: */
 133                childregs->status = SR_PP | SR_PIE;
 134
 135                p->thread.ra = (unsigned long)ret_from_kernel_thread;
 136                p->thread.s[0] = usp; /* fn */
 137                p->thread.s[1] = arg;
 138        } else {
 139                *childregs = *(current_pt_regs());
 140                if (usp) /* User fork */
 141                        childregs->sp = usp;
 142                if (clone_flags & CLONE_SETTLS)
 143                        childregs->tp = tls;
 144                childregs->a0 = 0; /* Return value of fork() */
 145                p->thread.ra = (unsigned long)ret_from_fork;
 146        }
 147        p->thread.sp = (unsigned long)childregs; /* kernel sp */
 148        return 0;
 149}
 150