arch/loongarch/kernel/process.c

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