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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Author: Huacai Chen <[email protected]>
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 ([email protected])
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#include <asm/vdso/vdso.h>
56
57#ifdef CONFIG_STACKPROTECTOR
58#include <linux/stackprotector.h>
59unsigned long __stack_chk_guard __read_mostly;
60EXPORT_SYMBOL(__stack_chk_guard);
61#endif
62
63DEFINE_PER_CPU(struct task_struct *, cpu_tasks);
64
65/*
66 * Idle related variables and functions
67 */
68
69unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
70EXPORT_SYMBOL(boot_option_idle_override);
71
72asmlinkage void restore_and_ret(void);
73asmlinkage void ret_from_fork_asm(void);
74asmlinkage void ret_from_kernel_thread_asm(void);
75
76void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
77{
78 unsigned long crmd;
79 unsigned long prmd;
80 unsigned long euen;
81
82 /* New thread loses kernel privileges. */
83 crmd = regs->csr_crmd & ~(PLV_MASK);
84 crmd |= PLV_USER;
85 regs->csr_crmd = crmd;
86
87 prmd = regs->csr_prmd & ~(PLV_MASK);
88 prmd |= PLV_USER;
89 regs->csr_prmd = prmd;
90
91 euen = regs->csr_euen & ~(CSR_EUEN_FPEN);
92 regs->csr_euen = euen;
93 lose_fpu(0);
94 lose_lbt(0);
95 current->thread.fpu.fcsr = boot_cpu_data.fpu_csr0;
96
97 clear_thread_flag(TIF_LSX_CTX_LIVE);
98 clear_thread_flag(TIF_LASX_CTX_LIVE);
99 clear_thread_flag(TIF_LBT_CTX_LIVE);
100 clear_used_math();
101 regs->csr_era = pc;
102 regs->regs[3] = sp;
103}
104
105void flush_thread(void)
106{
107 flush_ptrace_hw_breakpoint(current);
108}
109
110void exit_thread(struct task_struct *tsk)
111{
112}
113
114int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
115{
116 /*
117 * Save any process state which is live in hardware registers to the
118 * parent context prior to duplication. This prevents the new child
119 * state becoming stale if the parent is preempted before copy_thread()
120 * gets a chance to save the parent's live hardware registers to the
121 * child context.
122 */
123 preempt_disable();
124
125 if (is_fpu_owner()) {
126 if (is_lasx_enabled())
127 save_lasx(current);
128 else if (is_lsx_enabled())
129 save_lsx(current);
130 else
131 save_fp(current);
132 }
133
134 preempt_enable();
135
136 if (IS_ENABLED(CONFIG_RANDSTRUCT)) {
137 memcpy(dst, src, sizeof(struct task_struct));
138 return 0;
139 }
140
141 dst->thread.fpu.fcsr = src->thread.fpu.fcsr;
142
143 if (!used_math())
144 memcpy(dst, src, offsetof(struct task_struct, thread.fpu.fpr));
145 else
146 memcpy(dst, src, offsetof(struct task_struct, thread.lbt.scr0));
147
148#ifdef CONFIG_CPU_HAS_LBT
149 memcpy(&dst->thread.lbt, &src->thread.lbt, sizeof(struct loongarch_lbt));
150#endif
151
152 return 0;
153}
154
155asmlinkage void noinstr __no_stack_protector ret_from_fork(struct task_struct *prev,
156 struct pt_regs *regs)
157{
158 schedule_tail(prev);
159 syscall_exit_to_user_mode(regs);
160}
161
162asmlinkage void noinstr __no_stack_protector ret_from_kernel_thread(struct task_struct *prev,
163 struct pt_regs *regs,
164 int (*fn)(void *),
165 void *fn_arg)
166{
167 schedule_tail(prev);
168 fn(fn_arg);
169 syscall_exit_to_user_mode(regs);
170}
171
172/*
173 * Copy architecture-specific thread state
174 */
175int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
176{
177 unsigned long childksp;
178 unsigned long tls = args->tls;
179 unsigned long usp = args->stack;
180 u64 clone_flags = args->flags;
181 struct pt_regs *childregs, *regs = current_pt_regs();
182
183 childksp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
184
185 /* set up new TSS. */
186 childregs = (struct pt_regs *) childksp - 1;
187 /* Put the stack after the struct pt_regs. */
188 childksp = (unsigned long) childregs;
189 p->thread.sched_cfa = 0;
190 p->thread.csr_euen = 0;
191 p->thread.csr_crmd = csr_read32(LOONGARCH_CSR_CRMD);
192 p->thread.csr_prmd = csr_read32(LOONGARCH_CSR_PRMD);
193 p->thread.csr_ecfg = csr_read32(LOONGARCH_CSR_ECFG);
194 if (unlikely(args->fn)) {
195 /* kernel thread */
196 p->thread.reg03 = childksp;
197 p->thread.reg23 = (unsigned long)args->fn;
198 p->thread.reg24 = (unsigned long)args->fn_arg;
199 p->thread.reg01 = (unsigned long)ret_from_kernel_thread_asm;
200 p->thread.sched_ra = (unsigned long)ret_from_kernel_thread_asm;
201 memset(childregs, 0, sizeof(struct pt_regs));
202 childregs->csr_euen = p->thread.csr_euen;
203 childregs->csr_crmd = p->thread.csr_crmd;
204 childregs->csr_prmd = p->thread.csr_prmd;
205 childregs->csr_ecfg = p->thread.csr_ecfg;
206 goto out;
207 }
208
209 /* user thread */
210 *childregs = *regs;
211 childregs->regs[4] = 0; /* Child gets zero as return value */
212 if (usp)
213 childregs->regs[3] = usp;
214
215 p->thread.reg03 = (unsigned long) childregs;
216 p->thread.reg01 = (unsigned long) ret_from_fork_asm;
217 p->thread.sched_ra = (unsigned long) ret_from_fork_asm;
218
219 /*
220 * New tasks lose permission to use the fpu. This accelerates context
221 * switching for most programs since they don't use the fpu.
222 */
223 childregs->csr_euen = 0;
224
225 if (clone_flags & CLONE_SETTLS)
226 childregs->regs[2] = tls;
227
228out:
229 ptrace_hw_copy_thread(p);
230 clear_tsk_thread_flag(p, TIF_USEDFPU);
231 clear_tsk_thread_flag(p, TIF_USEDSIMD);
232 clear_tsk_thread_flag(p, TIF_USEDLBT);
233 clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
234 clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
235 clear_tsk_thread_flag(p, TIF_LBT_CTX_LIVE);
236
237 return 0;
238}
239
240unsigned long __get_wchan(struct task_struct *task)
241{
242 unsigned long pc = 0;
243 struct unwind_state state;
244
245 if (!try_get_task_stack(task))
246 return 0;
247
248 for (unwind_start(&state, task, NULL);
249 !unwind_done(&state); unwind_next_frame(&state)) {
250 pc = unwind_get_return_address(&state);
251 if (!pc)
252 break;
253 if (in_sched_functions(pc))
254 continue;
255 break;
256 }
257
258 put_task_stack(task);
259
260 return pc;
261}
262
263bool in_irq_stack(unsigned long stack, struct stack_info *info)
264{
265 unsigned long nextsp;
266 unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
267 unsigned long end = begin + IRQ_STACK_START;
268
269 if (stack < begin || stack >= end)
270 return false;
271
272 nextsp = *(unsigned long *)end;
273 if (nextsp & (SZREG - 1))
274 return false;
275
276 info->begin = begin;
277 info->end = end;
278 info->next_sp = nextsp;
279 info->type = STACK_TYPE_IRQ;
280
281 return true;
282}
283
284bool in_task_stack(unsigned long stack, struct task_struct *task,
285 struct stack_info *info)
286{
287 unsigned long begin = (unsigned long)task_stack_page(task);
288 unsigned long end = begin + THREAD_SIZE;
289
290 if (stack < begin || stack >= end)
291 return false;
292
293 info->begin = begin;
294 info->end = end;
295 info->next_sp = 0;
296 info->type = STACK_TYPE_TASK;
297
298 return true;
299}
300
301int get_stack_info(unsigned long stack, struct task_struct *task,
302 struct stack_info *info)
303{
304 task = task ? : current;
305
306 if (!stack || stack & (SZREG - 1))
307 goto unknown;
308
309 if (in_task_stack(stack, task, info))
310 return 0;
311
312 if (task != current)
313 goto unknown;
314
315 if (in_irq_stack(stack, info))
316 return 0;
317
318unknown:
319 info->type = STACK_TYPE_UNKNOWN;
320 return -EINVAL;
321}
322
323unsigned long stack_top(void)
324{
325 unsigned long top = TASK_SIZE & PAGE_MASK;
326
327 if (current->thread.vdso) {
328 /* Space for the VDSO & data page */
329 top -= PAGE_ALIGN(current->thread.vdso->size);
330 top -= VVAR_SIZE;
331
332 /* Space to randomize the VDSO base */
333 if (current->flags & PF_RANDOMIZE)
334 top -= VDSO_RANDOMIZE_SIZE;
335 }
336
337 return top;
338}
339
340/*
341 * Don't forget that the stack pointer must be aligned on a 8 bytes
342 * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
343 */
344unsigned long arch_align_stack(unsigned long sp)
345{
346 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
347 sp -= get_random_u32_below(PAGE_SIZE);
348
349 return sp & STACK_ALIGN;
350}
351
352static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
353static struct cpumask backtrace_csd_busy;
354
355static void handle_backtrace(void *info)
356{
357 nmi_cpu_backtrace(get_irq_regs());
358 cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
359}
360
361static void raise_backtrace(cpumask_t *mask)
362{
363 call_single_data_t *csd;
364 int cpu;
365
366 for_each_cpu(cpu, mask) {
367 /*
368 * If we previously sent an IPI to the target CPU & it hasn't
369 * cleared its bit in the busy cpumask then it didn't handle
370 * our previous IPI & it's not safe for us to reuse the
371 * call_single_data_t.
372 */
373 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
374 pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
375 cpu);
376 continue;
377 }
378
379 csd = &per_cpu(backtrace_csd, cpu);
380 csd->func = handle_backtrace;
381 smp_call_function_single_async(cpu, csd);
382 }
383}
384
385void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
386{
387 nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace);
388}
389
390#ifdef CONFIG_32BIT
391void loongarch_dump_regs32(u32 *uregs, const struct pt_regs *regs)
392#else
393void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
394#endif
395{
396 unsigned int i;
397
398 for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
399 uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
400 }
401
402 uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
403 uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
404 uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
405 uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
406 uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
407 uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
408 uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
409 uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
410}