xref: /linux/arch/riscv/kernel/process.c (revision c79c3c34f75d72a066e292b10aa50fc758c97c89)
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 
25 register unsigned long gp_in_global __asm__("gp");
26 
27 #ifdef CONFIG_STACKPROTECTOR
28 #include <linux/stackprotector.h>
29 unsigned long __stack_chk_guard __read_mostly;
30 EXPORT_SYMBOL(__stack_chk_guard);
31 #endif
32 
33 extern asmlinkage void ret_from_fork(void);
34 extern asmlinkage void ret_from_kernel_thread(void);
35 
36 void arch_cpu_idle(void)
37 {
38 	wait_for_interrupt();
39 	raw_local_irq_enable();
40 }
41 
42 void show_regs(struct pt_regs *regs)
43 {
44 	show_regs_print_info(KERN_DEFAULT);
45 
46 	pr_cont("epc: " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
47 		regs->epc, regs->ra, regs->sp);
48 	pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
49 		regs->gp, regs->tp, regs->t0);
50 	pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
51 		regs->t1, regs->t2, regs->s0);
52 	pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
53 		regs->s1, regs->a0, regs->a1);
54 	pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
55 		regs->a2, regs->a3, regs->a4);
56 	pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
57 		regs->a5, regs->a6, regs->a7);
58 	pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
59 		regs->s2, regs->s3, regs->s4);
60 	pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
61 		regs->s5, regs->s6, regs->s7);
62 	pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
63 		regs->s8, regs->s9, regs->s10);
64 	pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
65 		regs->s11, regs->t3, regs->t4);
66 	pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
67 		regs->t5, regs->t6);
68 
69 	pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
70 		regs->status, regs->badaddr, regs->cause);
71 }
72 
73 void start_thread(struct pt_regs *regs, unsigned long pc,
74 	unsigned long sp)
75 {
76 	regs->status = SR_PIE;
77 	if (has_fpu) {
78 		regs->status |= SR_FS_INITIAL;
79 		/*
80 		 * Restore the initial value to the FP register
81 		 * before starting the user program.
82 		 */
83 		fstate_restore(current, regs);
84 	}
85 	regs->epc = pc;
86 	regs->sp = sp;
87 }
88 
89 void flush_thread(void)
90 {
91 #ifdef CONFIG_FPU
92 	/*
93 	 * Reset FPU state and context
94 	 *	frm: round to nearest, ties to even (IEEE default)
95 	 *	fflags: accrued exceptions cleared
96 	 */
97 	fstate_off(current, task_pt_regs(current));
98 	memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
99 #endif
100 }
101 
102 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
103 {
104 	fstate_save(src, task_pt_regs(src));
105 	*dst = *src;
106 	return 0;
107 }
108 
109 int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
110 		struct task_struct *p, unsigned long tls)
111 {
112 	struct pt_regs *childregs = task_pt_regs(p);
113 
114 	/* p->thread holds context to be restored by __switch_to() */
115 	if (unlikely(p->flags & PF_KTHREAD)) {
116 		/* Kernel thread */
117 		memset(childregs, 0, sizeof(struct pt_regs));
118 		childregs->gp = gp_in_global;
119 		/* Supervisor/Machine, irqs on: */
120 		childregs->status = SR_PP | SR_PIE;
121 
122 		p->thread.ra = (unsigned long)ret_from_kernel_thread;
123 		p->thread.s[0] = usp; /* fn */
124 		p->thread.s[1] = arg;
125 	} else {
126 		*childregs = *(current_pt_regs());
127 		if (usp) /* User fork */
128 			childregs->sp = usp;
129 		if (clone_flags & CLONE_SETTLS)
130 			childregs->tp = tls;
131 		childregs->a0 = 0; /* Return value of fork() */
132 		p->thread.ra = (unsigned long)ret_from_fork;
133 	}
134 	p->thread.sp = (unsigned long)childregs; /* kernel sp */
135 	return 0;
136 }
137