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
 36extern asmlinkage void ret_from_fork(void);
 37extern asmlinkage void ret_from_kernel_thread(void);
 38
 39void arch_cpu_idle(void)
 40{
 41	wait_for_interrupt();
 42	local_irq_enable();
 43}
 44
 45void 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
 76void start_thread(struct pt_regs *regs, unsigned long pc,
 77	unsigned long sp)
 78{
 79	regs->sstatus = SR_SPIE /* User mode, irqs on */ | SR_FS_INITIAL;
 80	regs->sepc = pc;
 81	regs->sp = sp;
 82	set_fs(USER_DS);
 83}
 84
 85void flush_thread(void)
 86{
 87	/*
 88	 * Reset FPU context
 89	 *	frm: round to nearest, ties to even (IEEE default)
 90	 *	fflags: accrued exceptions cleared
 91	 */
 92	memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
 93}
 94
 95int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 96{
 97	fstate_save(src, task_pt_regs(src));
 98	*dst = *src;
 99	return 0;
100}
101
102int copy_thread(unsigned long clone_flags, unsigned long usp,
103	unsigned long arg, struct task_struct *p)
104{
105	struct pt_regs *childregs = task_pt_regs(p);
106
107	/* p->thread holds context to be restored by __switch_to() */
108	if (unlikely(p->flags & PF_KTHREAD)) {
109		/* Kernel thread */
110		const register unsigned long gp __asm__ ("gp");
111		memset(childregs, 0, sizeof(struct pt_regs));
112		childregs->gp = gp;
113		childregs->sstatus = SR_SPP | SR_SPIE; /* Supervisor, irqs on */
114
115		p->thread.ra = (unsigned long)ret_from_kernel_thread;
116		p->thread.s[0] = usp; /* fn */
117		p->thread.s[1] = arg;
118	} else {
119		*childregs = *(current_pt_regs());
120		if (usp) /* User fork */
121			childregs->sp = usp;
122		if (clone_flags & CLONE_SETTLS)
123			childregs->tp = childregs->a5;
124		childregs->a0 = 0; /* Return value of fork() */
125		p->thread.ra = (unsigned long)ret_from_fork;
126	}
127	p->thread.sp = (unsigned long)childregs; /* kernel sp */
128	return 0;
129}