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/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>
  55 unsigned long __stack_chk_guard __read_mostly;
  56 EXPORT_SYMBOL(__stack_chk_guard);
  57 #endif
  58
  59 /*
  60  * Idle related variables and functions
  61  */
  62
  63 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
  64 EXPORT_SYMBOL(boot_option_idle_override);
  65
  66 asmlinkage void ret_from_fork(void);
  67 asmlinkage void ret_from_kernel_thread(void);
  68
  69 void 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
  97 void flush_thread(void)
  98 {
  99         flush_ptrace_hw_breakpoint(current);
 100 }
 101
 102 void exit_thread(struct task_struct *tsk)
 103 {
 104 }
 105
 106 int 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  */
 143 int 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(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
 196 out:
 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
 208 unsigned 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(task))
 214                 return 0;
 215
 216         for (unwind_start(&state, task, NULL);
 217              !unwind_done(&state); unwind_next_frame(&state)) {
 218                 pc = unwind_get_return_address(&state);
 219                 if (!pc)
 220                         break;
 221                 if (in_sched_functions(pc))
 222                         continue;
 223                 break;
 224         }
 225
 226         put_task_stack(task);
 227
 228         return pc;
 229 }
 230
 231 bool 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
 252 bool 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
 269 int 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
 286 unknown:
 287         info->type = STACK_TYPE_UNKNOWN;
 288         return -EINVAL;
 289 }
 290
 291 unsigned 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  */
 310 unsigned 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
 318 static DEFINE_PER_CPU(call_single_data_t, backtrace_csd);
 319 static struct cpumask backtrace_csd_busy;
 320
 321 static void handle_backtrace(void *info)
 322 {
 323         nmi_cpu_backtrace(get_irq_regs());
 324         cpumask_clear_cpu(smp_processor_id(), &backtrace_csd_busy);
 325 }
 326
 327 static 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, &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
 351 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
 352 {
 353         nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_backtrace);
 354 }
 355
 356 #ifdef CONFIG_64BIT
 357 void 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 */