summaryrefslogtreecommitdiff
path: root/arch/riscv/kernel/process.c
blob: e4bc61c4e58af9c6c3914692c240021d053d72d8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
 *  Chen Liqin <liqin.chen@sunplusct.com>
 *  Lennox Wu <lennox.wu@sunplusct.com>
 * Copyright (C) 2012 Regents of the University of California
 * Copyright (C) 2017 SiFive
 */

#include <linux/cpu.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/tick.h>
#include <linux/ptrace.h>
#include <linux/uaccess.h>

#include <asm/unistd.h>
#include <asm/processor.h>
#include <asm/csr.h>
#include <asm/stacktrace.h>
#include <asm/string.h>
#include <asm/switch_to.h>
#include <asm/thread_info.h>
#include <asm/cpuidle.h>
#include <asm/vector.h>
#include <asm/cpufeature.h>

#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
#include <linux/stackprotector.h>
unsigned long __stack_chk_guard __read_mostly;
EXPORT_SYMBOL(__stack_chk_guard);
#endif

extern asmlinkage void ret_from_fork(void);

void noinstr arch_cpu_idle(void)
{
	cpu_do_idle();
}

int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
{
	if (!unaligned_ctl_available())
		return -EINVAL;

	tsk->thread.align_ctl = val;
	return 0;
}

int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
{
	if (!unaligned_ctl_available())
		return -EINVAL;

	return put_user(tsk->thread.align_ctl, (unsigned long __user *)adr);
}

void __show_regs(struct pt_regs *regs)
{
	show_regs_print_info(KERN_DEFAULT);

	if (!user_mode(regs)) {
		pr_cont("epc : %pS\n", (void *)regs->epc);
		pr_cont(" ra : %pS\n", (void *)regs->ra);
	}

	pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
		regs->epc, regs->ra, regs->sp);
	pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
		regs->gp, regs->tp, regs->t0);
	pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
		regs->t1, regs->t2, regs->s0);
	pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
		regs->s1, regs->a0, regs->a1);
	pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
		regs->a2, regs->a3, regs->a4);
	pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
		regs->a5, regs->a6, regs->a7);
	pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
		regs->s2, regs->s3, regs->s4);
	pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
		regs->s5, regs->s6, regs->s7);
	pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
		regs->s8, regs->s9, regs->s10);
	pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
		regs->s11, regs->t3, regs->t4);
	pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
		regs->t5, regs->t6);

	pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
		regs->status, regs->badaddr, regs->cause);
}
void show_regs(struct pt_regs *regs)
{
	__show_regs(regs);
	if (!user_mode(regs))
		dump_backtrace(regs, NULL, KERN_DEFAULT);
}

#ifdef CONFIG_COMPAT
static bool compat_mode_supported __read_mostly;

bool compat_elf_check_arch(Elf32_Ehdr *hdr)
{
	return compat_mode_supported &&
	       hdr->e_machine == EM_RISCV &&
	       hdr->e_ident[EI_CLASS] == ELFCLASS32;
}

static int __init compat_mode_detect(void)
{
	unsigned long tmp = csr_read(CSR_STATUS);

	csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
	compat_mode_supported =
			(csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;

	csr_write(CSR_STATUS, tmp);

	pr_info("riscv: ELF compat mode %s",
			compat_mode_supported ? "supported" : "unsupported");

	return 0;
}
early_initcall(compat_mode_detect);
#endif

void start_thread(struct pt_regs *regs, unsigned long pc,
	unsigned long sp)
{
	regs->status = SR_PIE;
	if (has_fpu()) {
		regs->status |= SR_FS_INITIAL;
		/*
		 * Restore the initial value to the FP register
		 * before starting the user program.
		 */
		fstate_restore(current, regs);
	}
	regs->epc = pc;
	regs->sp = sp;

#ifdef CONFIG_64BIT
	regs->status &= ~SR_UXL;

	if (is_compat_task())
		regs->status |= SR_UXL_32;
	else
		regs->status |= SR_UXL_64;
#endif
}

void flush_thread(void)
{
#ifdef CONFIG_FPU
	/*
	 * Reset FPU state and context
	 *	frm: round to nearest, ties to even (IEEE default)
	 *	fflags: accrued exceptions cleared
	 */
	fstate_off(current, task_pt_regs(current));
	memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
#endif
#ifdef CONFIG_RISCV_ISA_V
	/* Reset vector state */
	riscv_v_vstate_ctrl_init(current);
	riscv_v_vstate_off(task_pt_regs(current));
	kfree(current->thread.vstate.datap);
	memset(&current->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
	clear_tsk_thread_flag(current, TIF_RISCV_V_DEFER_RESTORE);
#endif
}

void arch_release_task_struct(struct task_struct *tsk)
{
	/* Free the vector context of datap. */
	if (has_vector())
		riscv_v_thread_free(tsk);
}

int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
	fstate_save(src, task_pt_regs(src));
	*dst = *src;
	/* clear entire V context, including datap for a new task */
	memset(&dst->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
	memset(&dst->thread.kernel_vstate, 0, sizeof(struct __riscv_v_ext_state));
	clear_tsk_thread_flag(dst, TIF_RISCV_V_DEFER_RESTORE);

	return 0;
}

int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
	unsigned long clone_flags = args->flags;
	unsigned long usp = args->stack;
	unsigned long tls = args->tls;
	struct pt_regs *childregs = task_pt_regs(p);

	memset(&p->thread.s, 0, sizeof(p->thread.s));

	/* p->thread holds context to be restored by __switch_to() */
	if (unlikely(args->fn)) {
		/* Kernel thread */
		memset(childregs, 0, sizeof(struct pt_regs));
		/* Supervisor/Machine, irqs on: */
		childregs->status = SR_PP | SR_PIE;

		p->thread.s[0] = (unsigned long)args->fn;
		p->thread.s[1] = (unsigned long)args->fn_arg;
	} else {
		*childregs = *(current_pt_regs());
		/* Turn off status.VS */
		riscv_v_vstate_off(childregs);
		if (usp) /* User fork */
			childregs->sp = usp;
		if (clone_flags & CLONE_SETTLS)
			childregs->tp = tls;
		childregs->a0 = 0; /* Return value of fork() */
		p->thread.s[0] = 0;
	}
	p->thread.riscv_v_flags = 0;
	if (has_vector())
		riscv_v_thread_alloc(p);
	p->thread.ra = (unsigned long)ret_from_fork;
	p->thread.sp = (unsigned long)childregs; /* kernel sp */
	return 0;
}

void __init arch_task_cache_init(void)
{
	riscv_v_setup_ctx_cache();
}