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 /*
  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
  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
  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
  93 void exit_thread(struct task_struct *tsk)
  94 {
  95 }
  96
  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  */
 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                 return 0;
 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         clear_tsk_thread_flag(p, TIF_USEDFPU);
 175         clear_tsk_thread_flag(p, TIF_USEDSIMD);
 176         clear_tsk_thread_flag(p, TIF_LSX_CTX_LIVE);
 177         clear_tsk_thread_flag(p, TIF_LASX_CTX_LIVE);
 178
 179         if (clone_flags & CLONE_SETTLS)
 180                 childregs->regs[2] = tls;
 181
 182         return 0;
 183 }
 184
 185 unsigned long __get_wchan(struct task_struct *task)
 186 {
 187         unsigned long pc;
 188         struct unwind_state state;
 189
 190         if (!try_get_task_stack(task))
 191                 return 0;
 192
 193         unwind_start(&state, task, NULL);
 194         state.sp = thread_saved_fp(task);
 195         get_stack_info(state.sp, state.task, &state.stack_info);
 196         state.pc = thread_saved_ra(task);
 197 #ifdef CONFIG_UNWINDER_PROLOGUE
 198         state.type = UNWINDER_PROLOGUE;
 199 #endif
 200         for (; !unwind_done(&state); unwind_next_frame(&state)) {
 201                 pc = unwind_get_return_address(&state);
 202                 if (!pc)
 203                         break;
 204                 if (in_sched_functions(pc))
 205                         continue;
 206                 break;
 207         }
 208
 209         put_task_stack(task);
 210
 211         return pc;
 212 }
 213
 214 bool in_irq_stack(unsigned long stack, struct stack_info *info)
 215 {
 216         unsigned long nextsp;
 217         unsigned long begin = (unsigned long)this_cpu_read(irq_stack);
 218         unsigned long end = begin + IRQ_STACK_START;
 219
 220         if (stack < begin || stack >= end)
 221                 return false;
 222
 223         nextsp = *(unsigned long *)end;
 224         if (nextsp & (SZREG - 1))
 225                 return false;
 226
 227         info->begin = begin;
 228         info->end = end;
 229         info->next_sp = nextsp;
 230         info->type = STACK_TYPE_IRQ;
 231
 232         return true;
 233 }
 234
 235 bool in_task_stack(unsigned long stack, struct task_struct *task,
 236                         struct stack_info *info)
 237 {
 238         unsigned long begin = (unsigned long)task_stack_page(task);
 239         unsigned long end = begin + THREAD_SIZE;
 240
 241         if (stack < begin || stack >= end)
 242                 return false;
 243
 244         info->begin = begin;
 245         info->end = end;
 246         info->next_sp = 0;
 247         info->type = STACK_TYPE_TASK;
 248
 249         return true;
 250 }
 251
 252 int get_stack_info(unsigned long stack, struct task_struct *task,
 253                    struct stack_info *info)
 254 {
 255         task = task ? : current;
 256
 257         if (!stack || stack & (SZREG - 1))
 258                 goto unknown;
 259
 260         if (in_task_stack(stack, task, info))
 261                 return 0;
 262
 263         if (task != current)
 264                 goto unknown;
 265
 266         if (in_irq_stack(stack, info))
 267                 return 0;
 268
 269 unknown:
 270         info->type = STACK_TYPE_UNKNOWN;
 271         return -EINVAL;
 272 }
 273
 274 unsigned long stack_top(void)
 275 {
 276         unsigned long top = TASK_SIZE & PAGE_MASK;
 277
 278         /* Space for the VDSO & data page */
 279         top -= PAGE_ALIGN(current->thread.vdso->size);
 280         top -= PAGE_SIZE;
 281
 282         /* Space to randomize the VDSO base */
 283         if (current->flags & PF_RANDOMIZE)
 284                 top -= VDSO_RANDOMIZE_SIZE;
 285
 286         return top;
 287 }
 288
 289 /*
 290  * Don't forget that the stack pointer must be aligned on a 8 bytes
 291  * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
 292  */
 293 unsigned long arch_align_stack(unsigned long sp)
 294 {
 295         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 296                 sp -= prandom_u32_max(PAGE_SIZE);
 297
 298         return sp & STACK_ALIGN;
 299 }
 300
 301 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
 302 static struct cpumask backtrace_csd_busy;
 303
 304 static void handle_backtrace(void *info)
 305 {
 306         nmi_cpu_backtrace(get_irq_regs());
 307         cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
 308 }
 309
 310 static void raise_backtrace(cpumask_t *mask)
 311 {
 312         call_single_data_t *csd;
 313         int cpu;
 314
 315         for_each_cpu(cpu, mask) {
 316                 /*
 317                  * If we previously sent an IPI to the target CPU & it hasn't
 318                  * cleared its bit in the busy cpumask then it didn't handle
 319                  * our previous IPI & it's not safe for us to reuse the
 320                  * call_single_data_t.
 321                  */
 322                 if (cpumask_test_and_set_cpu(cpu, &backtrace_csd_busy)) {
 323                         pr_warn("Unable to send backtrace IPI to CPU%u - perhaps it hung?\n",
 324                                 cpu);
 325                         continue;
 326                 }
 327
 328                 csd = &per_cpu(backtrace_csd, cpu);
 329                 csd->func = handle_backtrace;
 330                 smp_call_function_single_async(cpu, csd);
 331         }
 332 }
 333
 334 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
 335 {
 336         nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_backtrace);
 337 }
 338
 339 #ifdef CONFIG_64BIT
 340 void loongarch_dump_regs64(u64 *uregs, const struct pt_regs *regs)
 341 {
 342         unsigned int i;
 343
 344         for (i = LOONGARCH_EF_R1; i <= LOONGARCH_EF_R31; i++) {
 345                 uregs[i] = regs->regs[i - LOONGARCH_EF_R0];
 346         }
 347
 348         uregs[LOONGARCH_EF_ORIG_A0] = regs->orig_a0;
 349         uregs[LOONGARCH_EF_CSR_ERA] = regs->csr_era;
 350         uregs[LOONGARCH_EF_CSR_BADV] = regs->csr_badvaddr;
 351         uregs[LOONGARCH_EF_CSR_CRMD] = regs->csr_crmd;
 352         uregs[LOONGARCH_EF_CSR_PRMD] = regs->csr_prmd;
 353         uregs[LOONGARCH_EF_CSR_EUEN] = regs->csr_euen;
 354         uregs[LOONGARCH_EF_CSR_ECFG] = regs->csr_ecfg;
 355         uregs[LOONGARCH_EF_CSR_ESTAT] = regs->csr_estat;
 356 }
 357 #endif /* CONFIG_64BIT */