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