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/unwind.h>
48 #include <asm/vdso.h>
49
50 /*
51 * Idle related variables and functions
52 */
53
54 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
55 EXPORT_SYMBOL(boot_option_idle_override);
56
57 #ifdef CONFIG_HOTPLUG_CPU
arch_cpu_idle_dead(void)58 void arch_cpu_idle_dead(void)
59 {
60 play_dead();
61 }
62 #endif
63
64 asmlinkage void ret_from_fork(void);
65 asmlinkage void ret_from_kernel_thread(void);
66
start_thread(struct pt_regs * regs,unsigned long pc,unsigned long sp)67 void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
68 {
69 unsigned long crmd;
70 unsigned long prmd;
71 unsigned long euen;
72
73 /* New thread loses kernel privileges. */
74 crmd = regs->csr_crmd & ~(PLV_MASK);
75 crmd |= PLV_USER;
76 regs->csr_crmd = crmd;
77
78 prmd = regs->csr_prmd & ~(PLV_MASK);
79 prmd |= PLV_USER;
80 regs->csr_prmd = prmd;
81
82 euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
83 regs->csr_euen = euen;
84 lose_fpu(0);
85
86 clear_thread_flag(TIF_LSX_CTX_LIVE);
87 clear_thread_flag(TIF_LASX_CTX_LIVE);
88 clear_used_math();
89 regs->csr_era = pc;
90 regs->regs[3] = sp;
91 }
92
exit_thread(struct task_struct * tsk)93 void exit_thread(struct task_struct *tsk)
94 {
95 }
96
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)97 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
98 {
99 /*
100 * Save any process state which is live in hardware registers to the
101 * parent context prior to duplication. This prevents the new child
102 * state becoming stale if the parent is preempted before copy_thread()
103 * gets a chance to save the parent's live hardware registers to the
104 * child context.
105 */
106 preempt_disable();
107
108 if (is_fpu_owner())
109 save_fp(current);
110
111 preempt_enable();
112
113 if (used_math())
114 memcpy(dst, src, sizeof(struct task_struct));
115 else
116 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));
117
118 return 0;
119 }
120
121 /*
122 * Copy architecture-specific thread state
123 */
copy_thread(struct task_struct * p,const struct kernel_clone_args * args)124 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
125 {
126 unsigned long childksp;
127 unsigned long tls = args->tls;
128 unsigned long usp = args->stack;
129 unsigned long clone_flags = args->flags;
130 struct pt_regs *childregs, *regs = current_pt_regs();
131
132 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
133
134 /* set up new TSS. */
135 childregs = (struct pt_regs *) childksp - 1;
136 /* Put the stack after the struct pt_regs. */
137 childksp = (unsigned long) childregs;
138 p->thread.sched_cfa = 0;
139 p->thread.csr_euen = 0;
140 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
141 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
142 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
143 if (unlikely(args->fn)) {
144 /* kernel thread */
145 p->thread.reg03 = childksp;
146 p->thread.reg23 = (unsigned long)args->fn;
147 p->thread.reg24 = (unsigned long)args->fn_arg;
148 p->thread.reg01 = (unsigned long)ret_from_kernel_thread;
149 p->thread.sched_ra = (unsigned long)ret_from_kernel_thread;
150 memset(childregs, 0, sizeof(struct pt_regs));
151 childregs->csr_euen = p->thread.csr_euen;
152 childregs->csr_crmd = p->thread.csr_crmd;
153 childregs->csr_prmd = p->thread.csr_prmd;
154 childregs->csr_ecfg = p->thread.csr_ecfg;
155 goto out;
156 }
157
158 /* user thread */
159 *childregs = *regs;
160 childregs->regs[4] = 0; /* Child gets zero as return value */
161 if (usp)
162 childregs->regs[3] = usp;
163
164 p->thread.reg03 = (unsigned long) childregs;
165 p->thread.reg01 = (unsigned long) ret_from_fork;
166 p->thread.sched_ra = (unsigned long) ret_from_fork;
167
168 /*
169 * New tasks lose permission to use the fpu. This accelerates context
170 * switching for most programs since they don't use the fpu.
171 */
172 childregs->csr_euen = 0;
173
174 if (clone_flags & CLONE_SETTLS)
175 childregs->regs[2] = tls;
176
177 out:
178 clear_tsk_thread_flag(p, TIF_USEDFPU);
179 clear_tsk_thread_flag(p, TIF_USEDSIMD);
180 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
181 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
182
183 return 0;
184 }
185
__get_wchan(struct task_struct * task)186 unsigned long __get_wchan(struct task_struct *task)
187 {
188 unsigned long pc;
189 struct unwind_state state;
190
191 if (!try_get_task_stack(task))
192 return 0;
193
194 unwind_start(&state, task, NULL);
195 state.sp = thread_saved_fp(task);
196 get_stack_info(state.sp, state.task, &state.stack_info);
197 state.pc = thread_saved_ra(task);
198 #ifdef CONFIG_UNWINDER_PROLOGUE
199 state.type = UNWINDER_PROLOGUE;
200 #endif
201 for (; !unwind_done(&state); unwind_next_frame(&state)) {
202 pc = unwind_get_return_address(&state);
203 if (!pc)
204 break;
205 if (in_sched_functions(pc))
206 continue;
207 break;
208 }
209
210 put_task_stack(task);
211
212 return pc;
213 }
214
in_irq_stack(unsigned long stack,struct stack_info * info)215 bool in_irq_stack(unsigned long stack, struct stack_info *info)
216 {
217 unsigned long nextsp;
218 unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
219 unsigned long end = begin + IRQ_STACK_START;
220
221 if (stack < begin || stack >= end)
222 return false;
223
224 nextsp = *(unsigned long *)end;
225 if (nextsp & (SZREG - 1))
226 return false;
227
228 info->begin = begin;
229 info->end = end;
230 info->next_sp = nextsp;
231 info->type = STACK_TYPE_IRQ;
232
233 return true;
234 }
235
in_task_stack(unsigned long stack,struct task_struct * task,struct stack_info * info)236 bool in_task_stack(unsigned long stack, struct task_struct *task,
237 struct stack_info *info)
238 {
239 unsigned long begin = (unsigned long)task_stack_page(task);
240 unsigned long end = begin + THREAD_SIZE;
241
242 if (stack < begin || stack >= end)
243 return false;
244
245 info->begin = begin;
246 info->end = end;
247 info->next_sp = 0;
248 info->type = STACK_TYPE_TASK;
249
250 return true;
251 }
252
get_stack_info(unsigned long stack,struct task_struct * task,struct stack_info * info)253 int get_stack_info(unsigned long stack, struct task_struct *task,
254 struct stack_info *info)
255 {
256 task = task ? : current;
257
258 if (!stack || stack & (SZREG - 1))
259 goto unknown;
260
261 if (in_task_stack(stack, task, info))
262 return 0;
263
264 if (task != current)
265 goto unknown;
266
267 if (in_irq_stack(stack, info))
268 return 0;
269
270 unknown:
271 info->type = STACK_TYPE_UNKNOWN;
272 return -EINVAL;
273 }
274
stack_top(void)275 unsigned long stack_top(void)
276 {
277 unsigned long top = TASK_SIZE & PAGE_MASK;
278
279 /* Space for the VDSO & data page */
280 top -= PAGE_ALIGN(current->thread.vdso->size);
281 top -= PAGE_SIZE;
282
283 /* Space to randomize the VDSO base */
284 if (current->flags & PF_RANDOMIZE)
285 top -= VDSO_RANDOMIZE_SIZE;
286
287 return top;
288 }
289
290 /*
291 * Don't forget that the stack pointer must be aligned on a 8 bytes
292 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
293 */
arch_align_stack(unsigned long sp)294 unsigned long arch_align_stack(unsigned long sp)
295 {
296 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
297 sp -= prandom_u32_max(PAGE_SIZE);
298
299 return sp & STACK_ALIGN;
300 }
301
302 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
303 static struct cpumask backtrace_csd_busy;
304
handle_backtrace(void * info)305 static void handle_backtrace(void *info)
306 {
307 nmi_cpu_backtrace(get_irq_regs());
308 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
309 }
310
raise_backtrace(cpumask_t * mask)311 static void raise_backtrace(cpumask_t *mask)
312 {
313 call_single_data_t *csd;
314 int cpu;
315
316 for_each_cpu(cpu, mask) {
317 /*
318 * If we previously sent an IPI to the target CPU & it hasn't
319 * cleared its bit in the busy cpumask then it didn't handle
320 * our previous IPI & it's not safe for us to reuse the
321 * call_single_data_t.
322 */
323 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
324 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
325 cpu);
326 continue;
327 }
328
329 csd = &per_cpu(backtrace_csd, cpu);
330 csd->func = handle_backtrace;
331 smp_call_function_single_async(cpu, csd);
332 }
333 }
334
arch_trigger_cpumask_backtrace(const cpumask_t * mask,bool exclude_self)335 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
336 {
337 nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
338 }
339
340 #ifdef CONFIG_64BIT
loongarch_dump_regs64(u64 * uregs,const struct pt_regs * regs)341 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
342 {
343 unsigned int i;
344
345 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
346 uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
347 }
348
349 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
350 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
351 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
352 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
353 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
354 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
355 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
356 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
357 }
358 #endif /* CONFIG_64BIT */
359