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 #include <asm/cpuidle.h>
27 #include <asm/vector.h>
28
29 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
30 #include <linux/stackprotector.h>
31 unsigned long __stack_chk_guard __read_mostly;
32 EXPORT_SYMBOL(__stack_chk_guard);
33 #endif
34
35 extern asmlinkage void ret_from_fork(void);
36
arch_cpu_idle(void)37 void arch_cpu_idle(void)
38 {
39 cpu_do_idle();
40 }
41
__show_regs(struct pt_regs * regs)42 void __show_regs(struct pt_regs *regs)
43 {
44 show_regs_print_info(KERN_DEFAULT);
45
46 if (!user_mode(regs)) {
47 pr_cont("epc : %pS\n", (void *)regs->epc);
48 pr_cont(" ra : %pS\n", (void *)regs->ra);
49 }
50
51 pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
52 regs->epc, regs->ra, regs->sp);
53 pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
54 regs->gp, regs->tp, regs->t0);
55 pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
56 regs->t1, regs->t2, regs->s0);
57 pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
58 regs->s1, regs->a0, regs->a1);
59 pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
60 regs->a2, regs->a3, regs->a4);
61 pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
62 regs->a5, regs->a6, regs->a7);
63 pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
64 regs->s2, regs->s3, regs->s4);
65 pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
66 regs->s5, regs->s6, regs->s7);
67 pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
68 regs->s8, regs->s9, regs->s10);
69 pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
70 regs->s11, regs->t3, regs->t4);
71 pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
72 regs->t5, regs->t6);
73
74 pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
75 regs->status, regs->badaddr, regs->cause);
76 }
show_regs(struct pt_regs * regs)77 void show_regs(struct pt_regs *regs)
78 {
79 __show_regs(regs);
80 if (!user_mode(regs))
81 dump_backtrace(regs, NULL, KERN_DEFAULT);
82 }
83
84 #ifdef CONFIG_COMPAT
85 static bool compat_mode_supported __read_mostly;
86
compat_elf_check_arch(Elf32_Ehdr * hdr)87 bool compat_elf_check_arch(Elf32_Ehdr *hdr)
88 {
89 return compat_mode_supported &&
90 hdr->e_machine == EM_RISCV &&
91 hdr->e_ident[EI_CLASS] == ELFCLASS32;
92 }
93
compat_mode_detect(void)94 static int __init compat_mode_detect(void)
95 {
96 unsigned long tmp = csr_read(CSR_STATUS);
97
98 csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
99 compat_mode_supported =
100 (csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;
101
102 csr_write(CSR_STATUS, tmp);
103
104 pr_info("riscv: ELF compat mode %s",
105 compat_mode_supported ? "supported" : "unsupported");
106
107 return 0;
108 }
109 early_initcall(compat_mode_detect);
110 #endif
111
start_thread(struct pt_regs * regs,unsigned long pc,unsigned long sp)112 void start_thread(struct pt_regs *regs, unsigned long pc,
113 unsigned long sp)
114 {
115 regs->status = SR_PIE;
116 if (has_fpu()) {
117 regs->status |= SR_FS_INITIAL;
118 /*
119 * Restore the initial value to the FP register
120 * before starting the user program.
121 */
122 fstate_restore(current, regs);
123 }
124 regs->epc = pc;
125 regs->sp = sp;
126
127 #ifdef CONFIG_64BIT
128 regs->status &= ~SR_UXL;
129
130 if (is_compat_task())
131 regs->status |= SR_UXL_32;
132 else
133 regs->status |= SR_UXL_64;
134 #endif
135 }
136
flush_thread(void)137 void flush_thread(void)
138 {
139 #ifdef CONFIG_FPU
140 /*
141 * Reset FPU state and context
142 * frm: round to nearest, ties to even (IEEE default)
143 * fflags: accrued exceptions cleared
144 */
145 fstate_off(current, task_pt_regs(current));
146 memset(¤t->thread.fstate, 0, sizeof(current->thread.fstate));
147 #endif
148 #ifdef CONFIG_RISCV_ISA_V
149 /* Reset vector state */
150 riscv_v_vstate_ctrl_init(current);
151 riscv_v_vstate_off(task_pt_regs(current));
152 kfree(current->thread.vstate.datap);
153 memset(¤t->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
154 #endif
155 }
156
arch_release_task_struct(struct task_struct * tsk)157 void arch_release_task_struct(struct task_struct *tsk)
158 {
159 /* Free the vector context of datap. */
160 if (has_vector())
161 kfree(tsk->thread.vstate.datap);
162 }
163
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)164 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
165 {
166 fstate_save(src, task_pt_regs(src));
167 *dst = *src;
168 /* clear entire V context, including datap for a new task */
169 memset(&dst->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
170
171 return 0;
172 }
173
copy_thread(struct task_struct * p,const struct kernel_clone_args * args)174 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
175 {
176 unsigned long clone_flags = args->flags;
177 unsigned long usp = args->stack;
178 unsigned long tls = args->tls;
179 struct pt_regs *childregs = task_pt_regs(p);
180
181 memset(&p->thread.s, 0, sizeof(p->thread.s));
182
183 /* p->thread holds context to be restored by __switch_to() */
184 if (unlikely(args->fn)) {
185 /* Kernel thread */
186 memset(childregs, 0, sizeof(struct pt_regs));
187 /* Supervisor/Machine, irqs on: */
188 childregs->status = SR_PP | SR_PIE;
189
190 p->thread.s[0] = (unsigned long)args->fn;
191 p->thread.s[1] = (unsigned long)args->fn_arg;
192 } else {
193 *childregs = *(current_pt_regs());
194 /* Turn off status.VS */
195 riscv_v_vstate_off(childregs);
196 if (usp) /* User fork */
197 childregs->sp = usp;
198 if (clone_flags & CLONE_SETTLS)
199 childregs->tp = tls;
200 childregs->a0 = 0; /* Return value of fork() */
201 p->thread.s[0] = 0;
202 }
203 p->thread.ra = (unsigned long)ret_from_fork;
204 p->thread.sp = (unsigned long)childregs; /* kernel sp */
205 return 0;
206 }
207