1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Author: Huacai Chen <chenhuacai@loongson.cn>
4 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
5 *
6 * Derived from MIPS:
7 * Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
8 * Copyright (C) 2005, 2006 by Ralf Baechle (ralf@linux-mips.org)
9 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
10 * Copyright (C) 2004 Thiemo Seufer
11 * Copyright (C) 2013 Imagination Technologies Ltd.
12 */
13 #include <linux/cpu.h>
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/errno.h>
17 #include <linux/sched.h>
18 #include <linux/sched/debug.h>
19 #include <linux/sched/task.h>
20 #include <linux/sched/task_stack.h>
21 #include <linux/mm.h>
22 #include <linux/stddef.h>
23 #include <linux/unistd.h>
24 #include <linux/export.h>
25 #include <linux/ptrace.h>
26 #include <linux/mman.h>
27 #include <linux/personality.h>
28 #include <linux/sys.h>
29 #include <linux/completion.h>
30 #include <linux/kallsyms.h>
31 #include <linux/random.h>
32 #include <linux/prctl.h>
33 #include <linux/nmi.h>
34
35 #include <asm/asm.h>
36 #include <asm/bootinfo.h>
37 #include <asm/cpu.h>
38 #include <asm/elf.h>
39 #include <asm/fpu.h>
40 #include <asm/io.h>
41 #include <asm/irq.h>
42 #include <asm/irq_regs.h>
43 #include <asm/loongarch.h>
44 #include <asm/pgtable.h>
45 #include <asm/processor.h>
46 #include <asm/reg.h>
47 #include <asm/vdso.h>
48
49 /*
50 * Idle related variables and functions
51 */
52
53 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
54 EXPORT_SYMBOL(boot_option_idle_override);
55
56 #ifdef CONFIG_HOTPLUG_CPU
arch_cpu_idle_dead(void)57 void arch_cpu_idle_dead(void)
58 {
59 play_dead();
60 }
61 #endif
62
63 asmlinkage void ret_from_fork(void);
64 asmlinkage void ret_from_kernel_thread(void);
65
start_thread(struct pt_regs * regs,unsigned long pc,unsigned long sp)66 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
67 {
68 unsigned long crmd;
69 unsigned long prmd;
70 unsigned long euen;
71
72 /* New thread loses kernel privileges. */
73 crmd = regs->csr_crmd & ~(PLV_MASK);
74 crmd |= PLV_USER;
75 regs->csr_crmd = crmd;
76
77 prmd = regs->csr_prmd & ~(PLV_MASK);
78 prmd |= PLV_USER;
79 regs->csr_prmd = prmd;
80
81 euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
82 regs->csr_euen = euen;
83 lose_fpu(0);
84
85 clear_thread_flag(TIF_LSX_CTX_LIVE);
86 clear_thread_flag(TIF_LASX_CTX_LIVE);
87 clear_used_math();
88 regs->csr_era = pc;
89 regs->regs[3] = sp;
90 }
91
exit_thread(struct task_struct * tsk)92 void exit_thread(struct task_struct *tsk)
93 {
94 }
95
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)96 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
97 {
98 /*
99 * Save any process state which is live in hardware registers to the
100 * parent context prior to duplication. This prevents the new child
101 * state becoming stale if the parent is preempted before copy_thread()
102 * gets a chance to save the parent's live hardware registers to the
103 * child context.
104 */
105 preempt_disable();
106
107 if (is_fpu_owner())
108 save_fp(current);
109
110 preempt_enable();
111
112 if (used_math())
113 memcpy(dst, src, sizeof(struct task_struct));
114 else
115 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));
116
117 return 0;
118 }
119
120 /*
121 * Copy architecture-specific thread state
122 */
copy_thread(struct task_struct * p,const struct kernel_clone_args * args)123 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
124 {
125 unsigned long childksp;
126 unsigned long tls = args->tls;
127 unsigned long usp = args->stack;
128 unsigned long clone_flags = args->flags;
129 struct pt_regs *childregs, *regs = current_pt_regs();
130
131 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE - 32;
132
133 /* set up new TSS. */
134 childregs = (struct pt_regs *) childksp - 1;
135 /* Put the stack after the struct pt_regs. */
136 childksp = (unsigned long) childregs;
137 p->thread.csr_euen = 0;
138 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
139 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
140 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
141 if (unlikely(args->fn)) {
142 /* kernel thread */
143 p->thread.reg03 = childksp;
144 p->thread.reg23 = (unsigned long)args->fn;
145 p->thread.reg24 = (unsigned long)args->fn_arg;
146 p->thread.reg01 = (unsigned long)ret_from_kernel_thread;
147 memset(childregs, 0, sizeof(struct pt_regs));
148 childregs->csr_euen = p->thread.csr_euen;
149 childregs->csr_crmd = p->thread.csr_crmd;
150 childregs->csr_prmd = p->thread.csr_prmd;
151 childregs->csr_ecfg = p->thread.csr_ecfg;
152 return 0;
153 }
154
155 /* user thread */
156 *childregs = *regs;
157 childregs->regs[4] = 0; /* Child gets zero as return value */
158 if (usp)
159 childregs->regs[3] = usp;
160
161 p->thread.reg03 = (unsigned long) childregs;
162 p->thread.reg01 = (unsigned long) ret_from_fork;
163
164 /*
165 * New tasks lose permission to use the fpu. This accelerates context
166 * switching for most programs since they don't use the fpu.
167 */
168 childregs->csr_euen = 0;
169
170 clear_tsk_thread_flag(p, TIF_USEDFPU);
171 clear_tsk_thread_flag(p, TIF_USEDSIMD);
172 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
173 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
174
175 if (clone_flags & CLONE_SETTLS)
176 childregs->regs[2] = tls;
177
178 return 0;
179 }
180
__get_wchan(struct task_struct * task)181 unsigned long __get_wchan(struct task_struct *task)
182 {
183 return 0;
184 }
185
stack_top(void)186 unsigned long stack_top(void)
187 {
188 unsigned long top = TASK_SIZE & PAGE_MASK;
189
190 /* Space for the VDSO & data page */
191 top -= PAGE_ALIGN(current->thread.vdso->size);
192 top -= PAGE_SIZE;
193
194 /* Space to randomize the VDSO base */
195 if (current->flags & PF_RANDOMIZE)
196 top -= VDSO_RANDOMIZE_SIZE;
197
198 return top;
199 }
200
201 /*
202 * Don't forget that the stack pointer must be aligned on a 8 bytes
203 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
204 */
arch_align_stack(unsigned long sp)205 unsigned long arch_align_stack(unsigned long sp)
206 {
207 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
208 sp -= get_random_int() & ~PAGE_MASK;
209
210 return sp & STACK_ALIGN;
211 }
212
213 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
214 static struct cpumask backtrace_csd_busy;
215
handle_backtrace(void * info)216 static void handle_backtrace(void *info)
217 {
218 nmi_cpu_backtrace(get_irq_regs());
219 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
220 }
221
raise_backtrace(cpumask_t * mask)222 static void raise_backtrace(cpumask_t *mask)
223 {
224 call_single_data_t *csd;
225 int cpu;
226
227 for_each_cpu(cpu, mask) {
228 /*
229 * If we previously sent an IPI to the target CPU & it hasn't
230 * cleared its bit in the busy cpumask then it didn't handle
231 * our previous IPI & it's not safe for us to reuse the
232 * call_single_data_t.
233 */
234 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
235 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
236 cpu);
237 continue;
238 }
239
240 csd = &per_cpu(backtrace_csd, cpu);
241 csd->func = handle_backtrace;
242 smp_call_function_single_async(cpu, csd);
243 }
244 }
245
arch_trigger_cpumask_backtrace(const cpumask_t * mask,bool exclude_self)246 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
247 {
248 nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
249 }
250
251 #ifdef CONFIG_64BIT
loongarch_dump_regs64(u64 * uregs,const struct pt_regs * regs)252 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
253 {
254 unsigned int i;
255
256 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
257 uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
258 }
259
260 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
261 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
262 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
263 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
264 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
265 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
266 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
267 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
268 }
269 #endif /* CONFIG_64BIT */
270