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/task_stack.h>
 14#include <linux/tick.h>
 15#include <linux/ptrace.h>
 16#include <linux/uaccess.h>
 17
 18#include <asm/unistd.h>
 19#include <asm/processor.h>
 20#include <asm/csr.h>
 21#include <asm/string.h>
 22#include <asm/switch_to.h>
 23#include <asm/thread_info.h>
 24
 25extern asmlinkage void ret_from_fork(void);
 26extern asmlinkage void ret_from_kernel_thread(void);
 27
 28void arch_cpu_idle(void)
 29{
 30	wait_for_interrupt();
 31	local_irq_enable();
 32}
 33
 34void show_regs(struct pt_regs *regs)
 35{
 36	show_regs_print_info(KERN_DEFAULT);
 37
 38	pr_cont("sepc: " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
 39		regs->sepc, regs->ra, regs->sp);
 40	pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
 41		regs->gp, regs->tp, regs->t0);
 42	pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
 43		regs->t1, regs->t2, regs->s0);
 44	pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
 45		regs->s1, regs->a0, regs->a1);
 46	pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
 47		regs->a2, regs->a3, regs->a4);
 48	pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
 49		regs->a5, regs->a6, regs->a7);
 50	pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
 51		regs->s2, regs->s3, regs->s4);
 52	pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
 53		regs->s5, regs->s6, regs->s7);
 54	pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
 55		regs->s8, regs->s9, regs->s10);
 56	pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
 57		regs->s11, regs->t3, regs->t4);
 58	pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
 59		regs->t5, regs->t6);
 60
 61	pr_cont("sstatus: " REG_FMT " sbadaddr: " REG_FMT " scause: " REG_FMT "\n",
 62		regs->sstatus, regs->sbadaddr, regs->scause);
 63}
 64
 65void start_thread(struct pt_regs *regs, unsigned long pc,
 66	unsigned long sp)
 67{
 68	regs->sstatus = SR_SPIE;
 69	if (has_fpu) {
 70		regs->sstatus |= SR_FS_INITIAL;
 71		/*
 72		 * Restore the initial value to the FP register
 73		 * before starting the user program.
 74		 */
 75		fstate_restore(current, regs);
 76	}
 77	regs->sepc = pc;
 78	regs->sp = sp;
 79	set_fs(USER_DS);
 80}
 81
 82void flush_thread(void)
 83{
 84#ifdef CONFIG_FPU
 85	/*
 86	 * Reset FPU state and context
 87	 *	frm: round to nearest, ties to even (IEEE default)
 88	 *	fflags: accrued exceptions cleared
 89	 */
 90	fstate_off(current, task_pt_regs(current));
 91	memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
 92#endif
 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}