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/hw_breakpoint.h>
22#include <linux/mm.h>
23#include <linux/stddef.h>
24#include <linux/unistd.h>
25#include <linux/export.h>
26#include <linux/ptrace.h>
27#include <linux/mman.h>
28#include <linux/personality.h>
29#include <linux/sys.h>
30#include <linux/completion.h>
31#include <linux/kallsyms.h>
32#include <linux/random.h>
33#include <linux/prctl.h>
34#include <linux/nmi.h>
35
36#include <asm/asm.h>
37#include <asm/bootinfo.h>
38#include <asm/cpu.h>
39#include <asm/elf.h>
40#include <asm/exec.h>
41#include <asm/fpu.h>
42#include <asm/lbt.h>
43#include <asm/io.h>
44#include <asm/irq.h>
45#include <asm/irq_regs.h>
46#include <asm/loongarch.h>
47#include <asm/pgtable.h>
48#include <asm/processor.h>
49#include <asm/reg.h>
50#include <asm/unwind.h>
51#include <asm/vdso.h>
52
53#ifdef CONFIG_STACKPROTECTOR
54#include <linux/stackprotector.h>
55unsigned long __stack_chk_guard __read_mostly;
56EXPORT_SYMBOL(__stack_chk_guard);
57#endif
58
59/*
60 * Idle related variables and functions
61 */
62
63unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
64EXPORT_SYMBOL(boot_option_idle_override);
65
66asmlinkage void ret_from_fork(void);
67asmlinkage void ret_from_kernel_thread(void);
68
69void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
70{
71 unsigned long crmd;
72 unsigned long prmd;
73 unsigned long euen;
74
75 /* New thread loses kernel privileges. */
76 crmd = regs->csr_crmd & ~(PLV_MASK);
77 crmd |= PLV_USER;
78 regs->csr_crmd = crmd;
79
80 prmd = regs->csr_prmd & ~(PLV_MASK);
81 prmd |= PLV_USER;
82 regs->csr_prmd = prmd;
83
84 euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
85 regs->csr_euen = euen;
86 lose_fpu(0);
87 lose_lbt(0);
88
89 clear_thread_flag(TIF_LSX_CTX_LIVE);
90 clear_thread_flag(TIF_LASX_CTX_LIVE);
91 clear_thread_flag(TIF_LBT_CTX_LIVE);
92 clear_used_math();
93 regs->csr_era = pc;
94 regs->regs[3] = sp;
95}
96
97void flush_thread(void)
98{
99 flush_ptrace_hw_breakpoint(current);
100}
101
102void exit_thread(struct task_struct *tsk)
103{
104}
105
106int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
107{
108 /*
109 * Save any process state which is live in hardware registers to the
110 * parent context prior to duplication. This prevents the new child
111 * state becoming stale if the parent is preempted before copy_thread()
112 * gets a chance to save the parent's live hardware registers to the
113 * child context.
114 */
115 preempt_disable();
116
117 if (is_fpu_owner()) {
118 if (is_lasx_enabled())
119 save_lasx(current);
120 else if (is_lsx_enabled())
121 save_lsx(current);
122 else
123 save_fp(current);
124 }
125
126 preempt_enable();
127
128 if (!used_math())
129 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));
130 else
131 memcpy(dst, src, offsetof(struct task_struct, thread.lbt.scr0));
132
133#ifdef CONFIG_CPU_HAS_LBT
134 memcpy(&dst->thread.lbt, &src->thread.lbt, sizeof(struct loongarch_lbt));
135#endif
136
137 return 0;
138}
139
140/*
141 * Copy architecture-specific thread state
142 */
143int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
144{
145 unsigned long childksp;
146 unsigned long tls = args->tls;
147 unsigned long usp = args->stack;
148 unsigned long clone_flags = args->flags;
149 struct pt_regs *childregs, *regs = current_pt_regs();
150
151 childksp = (unsigned long)task_stack_page(task: p) + THREAD_SIZE;
152
153 /* set up new TSS. */
154 childregs = (struct pt_regs *) childksp - 1;
155 /* Put the stack after the struct pt_regs. */
156 childksp = (unsigned long) childregs;
157 p->thread.sched_cfa = 0;
158 p->thread.csr_euen = 0;
159 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
160 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
161 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
162 if (unlikely(args->fn)) {
163 /* kernel thread */
164 p->thread.reg03 = childksp;
165 p->thread.reg23 = (unsigned long)args->fn;
166 p->thread.reg24 = (unsigned long)args->fn_arg;
167 p->thread.reg01 = (unsigned long)ret_from_kernel_thread;
168 p->thread.sched_ra = (unsigned long)ret_from_kernel_thread;
169 memset(childregs, 0, sizeof(struct pt_regs));
170 childregs->csr_euen = p->thread.csr_euen;
171 childregs->csr_crmd = p->thread.csr_crmd;
172 childregs->csr_prmd = p->thread.csr_prmd;
173 childregs->csr_ecfg = p->thread.csr_ecfg;
174 goto out;
175 }
176
177 /* user thread */
178 *childregs = *regs;
179 childregs->regs[4] = 0; /* Child gets zero as return value */
180 if (usp)
181 childregs->regs[3] = usp;
182
183 p->thread.reg03 = (unsigned long) childregs;
184 p->thread.reg01 = (unsigned long) ret_from_fork;
185 p->thread.sched_ra = (unsigned long) ret_from_fork;
186
187 /*
188 * New tasks lose permission to use the fpu. This accelerates context
189 * switching for most programs since they don't use the fpu.
190 */
191 childregs->csr_euen = 0;
192
193 if (clone_flags & CLONE_SETTLS)
194 childregs->regs[2] = tls;
195
196out:
197 ptrace_hw_copy_thread(p);
198 clear_tsk_thread_flag(p, TIF_USEDFPU);
199 clear_tsk_thread_flag(p, TIF_USEDSIMD);
200 clear_tsk_thread_flag(p, TIF_USEDLBT);
201 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
202 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
203 clear_tsk_thread_flag(p, TIF_LBT_CTX_LIVE);
204
205 return 0;
206}
207
208unsigned long __get_wchan(struct task_struct *task)
209{
210 unsigned long pc = 0;
211 struct unwind_state state;
212
213 if (!try_get_task_stack(tsk: task))
214 return 0;
215
216 for (unwind_start(&state, task, NULL);
217 !unwind_done(state: &state); unwind_next_frame(state: &state)) {
218 pc = unwind_get_return_address(state: &state);
219 if (!pc)
220 break;
221 if (in_sched_functions(addr: pc))
222 continue;
223 break;
224 }
225
226 put_task_stack(tsk: task);
227
228 return pc;
229}
230
231bool in_irq_stack(unsigned long stack, struct stack_info *info)
232{
233 unsigned long nextsp;
234 unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
235 unsigned long end = begin + IRQ_STACK_START;
236
237 if (stack < begin || stack >= end)
238 return false;
239
240 nextsp = *(unsigned long *)end;
241 if (nextsp & (SZREG - 1))
242 return false;
243
244 info->begin = begin;
245 info->end = end;
246 info->next_sp = nextsp;
247 info->type = STACK_TYPE_IRQ;
248
249 return true;
250}
251
252bool in_task_stack(unsigned long stack, struct task_struct *task,
253 struct stack_info *info)
254{
255 unsigned long begin = (unsigned long)task_stack_page(task);
256 unsigned long end = begin + THREAD_SIZE;
257
258 if (stack < begin || stack >= end)
259 return false;
260
261 info->begin = begin;
262 info->end = end;
263 info->next_sp = 0;
264 info->type = STACK_TYPE_TASK;
265
266 return true;
267}
268
269int get_stack_info(unsigned long stack, struct task_struct *task,
270 struct stack_info *info)
271{
272 task = task ? : current;
273
274 if (!stack || stack & (SZREG - 1))
275 goto unknown;
276
277 if (in_task_stack(stack, task, info))
278 return 0;
279
280 if (task != current)
281 goto unknown;
282
283 if (in_irq_stack(stack, info))
284 return 0;
285
286unknown:
287 info->type = STACK_TYPE_UNKNOWN;
288 return -EINVAL;
289}
290
291unsigned long stack_top(void)
292{
293 unsigned long top = TASK_SIZE & PAGE_MASK;
294
295 /* Space for the VDSO & data page */
296 top -= PAGE_ALIGN(current->thread.vdso->size);
297 top -= VVAR_SIZE;
298
299 /* Space to randomize the VDSO base */
300 if (current->flags & PF_RANDOMIZE)
301 top -= VDSO_RANDOMIZE_SIZE;
302
303 return top;
304}
305
306/*
307 * Don't forget that the stack pointer must be aligned on a 8 bytes
308 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
309 */
310unsigned long arch_align_stack(unsigned long sp)
311{
312 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
313 sp -= get_random_u32_below(PAGE_SIZE);
314
315 return sp & STACK_ALIGN;
316}
317
318static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
319static struct cpumask backtrace_csd_busy;
320
321static void handle_backtrace(void *info)
322{
323 nmi_cpu_backtrace(regs: get_irq_regs());
324 cpumask_clear_cpu(smp_processor_id(), dstp: &backtrace_csd_busy);
325}
326
327static void raise_backtrace(cpumask_t *mask)
328{
329 call_single_data_t *csd;
330 int cpu;
331
332 for_each_cpu(cpu, mask) {
333 /*
334 * If we previously sent an IPI to the target CPU & it hasn't
335 * cleared its bit in the busy cpumask then it didn't handle
336 * our previous IPI & it's not safe for us to reuse the
337 * call_single_data_t.
338 */
339 if (cpumask_test_and_set_cpu(cpu, cpumask: &backtrace_csd_busy)) {
340 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
341 cpu);
342 continue;
343 }
344
345 csd = &per_cpu(backtrace_csd, cpu);
346 csd->func = handle_backtrace;
347 smp_call_function_single_async(cpu, csd);
348 }
349}
350
351void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
352{
353 nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise: raise_backtrace);
354}
355
356#ifdef CONFIG_64BIT
357void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
358{
359 unsigned int i;
360
361 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
362 uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
363 }
364
365 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
366 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
367 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
368 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
369 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
370 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
371 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
372 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
373}
374#endif /* CONFIG_64BIT */
375

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