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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/entry-common.h>
17#include <linux/errno.h>
18#include <linux/sched.h>
19#include <linux/sched/debug.h>
20#include <linux/sched/task.h>
21#include <linux/sched/task_stack.h>
22#include <linux/hw_breakpoint.h>
23#include <linux/mm.h>
24#include <linux/stddef.h>
25#include <linux/unistd.h>
26#include <linux/export.h>
27#include <linux/ptrace.h>
28#include <linux/mman.h>
29#include <linux/personality.h>
30#include <linux/sys.h>
31#include <linux/completion.h>
32#include <linux/kallsyms.h>
33#include <linux/random.h>
34#include <linux/prctl.h>
35#include <linux/nmi.h>
36
37#include <asm/asm.h>
38#include <asm/asm-prototypes.h>
39#include <asm/bootinfo.h>
40#include <asm/cpu.h>
41#include <asm/elf.h>
42#include <asm/exec.h>
43#include <asm/fpu.h>
44#include <asm/lbt.h>
45#include <asm/io.h>
46#include <asm/irq.h>
47#include <asm/irq_regs.h>
48#include <asm/loongarch.h>
49#include <asm/pgtable.h>
50#include <asm/processor.h>
51#include <asm/reg.h>
52#include <asm/switch_to.h>
53#include <asm/unwind.h>
54#include <asm/vdso.h>
55
56#ifdef CONFIG_STACKPROTECTOR
57#include <linux/stackprotector.h>
58unsigned long __stack_chk_guard __read_mostly;
59EXPORT_SYMBOL(__stack_chk_guard);
60#endif
61
62/*
63 * Idle related variables and functions
64 */
65
66unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
67EXPORT_SYMBOL(boot_option_idle_override);
68
69asmlinkage void restore_and_ret(void);
70asmlinkage void ret_from_fork_asm(void);
71asmlinkage void ret_from_kernel_thread_asm(void);
72
73void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
74{
75 unsigned long crmd;
76 unsigned long prmd;
77 unsigned long euen;
78
79 /* New thread loses kernel privileges. */
80 crmd = regs->csr_crmd & ~(PLV_MASK);
81 crmd |= PLV_USER;
82 regs->csr_crmd = crmd;
83
84 prmd = regs->csr_prmd & ~(PLV_MASK);
85 prmd |= PLV_USER;
86 regs->csr_prmd = prmd;
87
88 euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
89 regs->csr_euen = euen;
90 lose_fpu(0);
91 lose_lbt(0);
92 current->thread.fpu.fcsr = boot_cpu_data.fpu_csr0;
93
94 clear_thread_flag(TIF_LSX_CTX_LIVE);
95 clear_thread_flag(TIF_LASX_CTX_LIVE);
96 clear_thread_flag(TIF_LBT_CTX_LIVE);
97 clear_used_math();
98 regs->csr_era = pc;
99 regs->regs[3] = sp;
100}
101
102void flush_thread(void)
103{
104 flush_ptrace_hw_breakpoint(current);
105}
106
107void exit_thread(struct task_struct *tsk)
108{
109}
110
111int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
112{
113 /*
114 * Save any process state which is live in hardware registers to the
115 * parent context prior to duplication. This prevents the new child
116 * state becoming stale if the parent is preempted before copy_thread()
117 * gets a chance to save the parent's live hardware registers to the
118 * child context.
119 */
120 preempt_disable();
121
122 if (is_fpu_owner()) {
123 if (is_lasx_enabled())
124 save_lasx(current);
125 else if (is_lsx_enabled())
126 save_lsx(current);
127 else
128 save_fp(current);
129 }
130
131 preempt_enable();
132
133 if (IS_ENABLED(CONFIG_RANDSTRUCT)) {
134 memcpy(dst, src, sizeof(struct task_struct));
135 return 0;
136 }
137
138 if (!used_math())
139 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));
140 else
141 memcpy(dst, src, offsetof(struct task_struct, thread.lbt.scr0));
142
143#ifdef CONFIG_CPU_HAS_LBT
144 memcpy(&dst->thread.lbt, &src->thread.lbt, sizeof(struct loongarch_lbt));
145#endif
146
147 return 0;
148}
149
150asmlinkage void noinstr __no_stack_protector ret_from_fork(struct task_struct *prev,
151 struct pt_regs *regs)
152{
153 schedule_tail(prev);
154 syscall_exit_to_user_mode(regs);
155}
156
157asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev,
158 struct pt_regs *regs,
159 int (*fn)(void *),
160 void *fn_arg)
161{
162 schedule_tail(prev);
163 fn(fn_arg);
164 syscall_exit_to_user_mode(regs);
165}
166
167/*
168 * Copy architecture-specific thread state
169 */
170int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
171{
172 unsigned long childksp;
173 unsigned long tls = args->tls;
174 unsigned long usp = args->stack;
175 u64 clone_flags = args->flags;
176 struct pt_regs *childregs, *regs = current_pt_regs();
177
178 childksp = (unsigned long)task_stack_page(task: p) + THREAD_SIZE;
179
180 /* set up new TSS. */
181 childregs = (struct pt_regs *) childksp - 1;
182 /* Put the stack after the struct pt_regs. */
183 childksp = (unsigned long) childregs;
184 p->thread.sched_cfa = 0;
185 p->thread.csr_euen = 0;
186 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
187 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
188 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
189 if (unlikely(args->fn)) {
190 /* kernel thread */
191 p->thread.reg03 = childksp;
192 p->thread.reg23 = (unsigned long)args->fn;
193 p->thread.reg24 = (unsigned long)args->fn_arg;
194 p->thread.reg01 = (unsigned long)ret_from_kernel_thread_asm;
195 p->thread.sched_ra = (unsigned long)ret_from_kernel_thread_asm;
196 memset(childregs, 0, sizeof(struct pt_regs));
197 childregs->csr_euen = p->thread.csr_euen;
198 childregs->csr_crmd = p->thread.csr_crmd;
199 childregs->csr_prmd = p->thread.csr_prmd;
200 childregs->csr_ecfg = p->thread.csr_ecfg;
201 goto out;
202 }
203
204 /* user thread */
205 *childregs = *regs;
206 childregs->regs[4] = 0; /* Child gets zero as return value */
207 if (usp)
208 childregs->regs[3] = usp;
209
210 p->thread.reg03 = (unsigned long) childregs;
211 p->thread.reg01 = (unsigned long) ret_from_fork_asm;
212 p->thread.sched_ra = (unsigned long) ret_from_fork_asm;
213
214 /*
215 * New tasks lose permission to use the fpu. This accelerates context
216 * switching for most programs since they don't use the fpu.
217 */
218 childregs->csr_euen = 0;
219
220 if (clone_flags & CLONE_SETTLS)
221 childregs->regs[2] = tls;
222
223out:
224 ptrace_hw_copy_thread(p);
225 clear_tsk_thread_flag(p, TIF_USEDFPU);
226 clear_tsk_thread_flag(p, TIF_USEDSIMD);
227 clear_tsk_thread_flag(p, TIF_USEDLBT);
228 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
229 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
230 clear_tsk_thread_flag(p, TIF_LBT_CTX_LIVE);
231
232 return 0;
233}
234
235unsigned long __get_wchan(struct task_struct *task)
236{
237 unsigned long pc = 0;
238 struct unwind_state state;
239
240 if (!try_get_task_stack(tsk: task))
241 return 0;
242
243 for (unwind_start(&state, task, NULL);
244 !unwind_done(state: &state); unwind_next_frame(state: &state)) {
245 pc = unwind_get_return_address(state: &state);
246 if (!pc)
247 break;
248 if (in_sched_functions(addr: pc))
249 continue;
250 break;
251 }
252
253 put_task_stack(tsk: task);
254
255 return pc;
256}
257
258bool in_irq_stack(unsigned long stack, struct stack_info *info)
259{
260 unsigned long nextsp;
261 unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
262 unsigned long end = begin + IRQ_STACK_START;
263
264 if (stack < begin || stack >= end)
265 return false;
266
267 nextsp = *(unsigned long *)end;
268 if (nextsp & (SZREG - 1))
269 return false;
270
271 info->begin = begin;
272 info->end = end;
273 info->next_sp = nextsp;
274 info->type = STACK_TYPE_IRQ;
275
276 return true;
277}
278
279bool in_task_stack(unsigned long stack, struct task_struct *task,
280 struct stack_info *info)
281{
282 unsigned long begin = (unsigned long)task_stack_page(task);
283 unsigned long end = begin + THREAD_SIZE;
284
285 if (stack < begin || stack >= end)
286 return false;
287
288 info->begin = begin;
289 info->end = end;
290 info->next_sp = 0;
291 info->type = STACK_TYPE_TASK;
292
293 return true;
294}
295
296int get_stack_info(unsigned long stack, struct task_struct *task,
297 struct stack_info *info)
298{
299 task = task ? : current;
300
301 if (!stack || stack & (SZREG - 1))
302 goto unknown;
303
304 if (in_task_stack(stack, task, info))
305 return 0;
306
307 if (task != current)
308 goto unknown;
309
310 if (in_irq_stack(stack, info))
311 return 0;
312
313unknown:
314 info->type = STACK_TYPE_UNKNOWN;
315 return -EINVAL;
316}
317
318unsigned long stack_top(void)
319{
320 unsigned long top = TASK_SIZE & PAGE_MASK;
321
322 if (current->thread.vdso) {
323 /* Space for the VDSO & data page */
324 top -= PAGE_ALIGN(current->thread.vdso->size);
325 top -= VVAR_SIZE;
326
327 /* Space to randomize the VDSO base */
328 if (current->flags & PF_RANDOMIZE)
329 top -= VDSO_RANDOMIZE_SIZE;
330 }
331
332 return top;
333}
334
335/*
336 * Don't forget that the stack pointer must be aligned on a 8 bytes
337 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
338 */
339unsigned long arch_align_stack(unsigned long sp)
340{
341 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
342 sp -= get_random_u32_below(PAGE_SIZE);
343
344 return sp & STACK_ALIGN;
345}
346
347static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
348static struct cpumask backtrace_csd_busy;
349
350static void handle_backtrace(void *info)
351{
352 nmi_cpu_backtrace(regs: get_irq_regs());
353 cpumask_clear_cpu(smp_processor_id(), dstp: &backtrace_csd_busy);
354}
355
356static void raise_backtrace(cpumask_t *mask)
357{
358 call_single_data_t *csd;
359 int cpu;
360
361 for_each_cpu(cpu, mask) {
362 /*
363 * If we previously sent an IPI to the target CPU & it hasn't
364 * cleared its bit in the busy cpumask then it didn't handle
365 * our previous IPI & it's not safe for us to reuse the
366 * call_single_data_t.
367 */
368 if (cpumask_test_and_set_cpu(cpu, cpumask: &backtrace_csd_busy)) {
369 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
370 cpu);
371 continue;
372 }
373
374 csd = &per_cpu(backtrace_csd, cpu);
375 csd->func = handle_backtrace;
376 smp_call_function_single_async(cpu, csd);
377 }
378}
379
380void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
381{
382 nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise: raise_backtrace);
383}
384
385#ifdef CONFIG_32BIT
386void loongarch_dump_regs32(u32 *uregs, const struct pt_regs *regs)
387#else
388void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
389#endif
390{
391 unsigned int i;
392
393 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
394 uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
395 }
396
397 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
398 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
399 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
400 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
401 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
402 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
403 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
404 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
405}
406

source code of linux/arch/loongarch/kernel/process.c