arch/arm/kernel/process.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/kernel/process.c
   4  *
   5  *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
   6  *  Original Copyright (C) 1995  Linus Torvalds
   7  */
   8 #include <stdarg.h>
   9
  10 #include <linux/export.h>
  11 #include <linux/sched.h>
  12 #include <linux/sched/debug.h>
  13 #include <linux/sched/task.h>
  14 #include <linux/sched/task_stack.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mm.h>
  17 #include <linux/stddef.h>
  18 #include <linux/unistd.h>
  19 #include <linux/user.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/init.h>
  22 #include <linux/elfcore.h>
  23 #include <linux/pm.h>
  24 #include <linux/tick.h>
  25 #include <linux/utsname.h>
  26 #include <linux/uaccess.h>
  27 #include <linux/random.h>
  28 #include <linux/hw_breakpoint.h>
  29 #include <linux/leds.h>
  30
  31 #include <asm/processor.h>
  32 #include <asm/thread_notify.h>
  33 #include <asm/stacktrace.h>
  34 #include <asm/system_misc.h>
  35 #include <asm/mach/time.h>
  36 #include <asm/tls.h>
  37 #include <asm/vdso.h>
  38
  39 #include "signal.h"
  40
  41 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
  42 #include <linux/stackprotector.h>
  43 unsigned long __stack_chk_guard __read_mostly;
  44 EXPORT_SYMBOL(__stack_chk_guard);
  45 #endif
  46
  47 static const char *processor_modes[] __maybe_unused = {
  48   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  49   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  50   "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "MON_32" , "ABT_32" ,
  51   "UK8_32" , "UK9_32" , "HYP_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
  52 };
  53
  54 static const char *isa_modes[] __maybe_unused = {
  55   "ARM" , "Thumb" , "Jazelle", "ThumbEE"
  56 };
  57
  58 /*
  59  * This is our default idle handler.
  60  */
  61
  62 void (*arm_pm_idle)(void);
  63
  64 /*
  65  * Called from the core idle loop.
  66  */
  67
  68 void arch_cpu_idle(void)
  69 {
  70         if (arm_pm_idle)
  71                 arm_pm_idle();
  72         else
  73                 cpu_do_idle();
  74         local_irq_enable();
  75 }
  76
  77 void arch_cpu_idle_prepare(void)
  78 {
  79         local_fiq_enable();
  80 }
  81
  82 void arch_cpu_idle_enter(void)
  83 {
  84         ledtrig_cpu(CPU_LED_IDLE_START);
  85 #ifdef CONFIG_PL310_ERRATA_769419
  86         wmb();
  87 #endif
  88 }
  89
  90 void arch_cpu_idle_exit(void)
  91 {
  92         ledtrig_cpu(CPU_LED_IDLE_END);
  93 }
  94
  95 void __show_regs(struct pt_regs *regs)
  96 {
  97         unsigned long flags;
  98         char buf[64];
  99 #ifndef CONFIG_CPU_V7M
 100         unsigned int domain, fs;
 101 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
 102         /*
 103          * Get the domain register for the parent context. In user
 104          * mode, we don't save the DACR, so lets use what it should
 105          * be. For other modes, we place it after the pt_regs struct.
 106          */
 107         if (user_mode(regs)) {
 108                 domain = DACR_UACCESS_ENABLE;
 109                 fs = get_fs();
 110         } else {
 111                 domain = to_svc_pt_regs(regs)->dacr;
 112                 fs = to_svc_pt_regs(regs)->addr_limit;
 113         }
 114 #else
 115         domain = get_domain();
 116         fs = get_fs();
 117 #endif
 118 #endif
 119
 120         show_regs_print_info(KERN_DEFAULT);
 121
 122         printk("PC is at %pS\n", (void *)instruction_pointer(regs));
 123         printk("LR is at %pS\n", (void *)regs->ARM_lr);
 124         printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n",
 125                regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr);
 126         printk("sp : %08lx  ip : %08lx  fp : %08lx\n",
 127                regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
 128         printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
 129                 regs->ARM_r10, regs->ARM_r9,
 130                 regs->ARM_r8);
 131         printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
 132                 regs->ARM_r7, regs->ARM_r6,
 133                 regs->ARM_r5, regs->ARM_r4);
 134         printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
 135                 regs->ARM_r3, regs->ARM_r2,
 136                 regs->ARM_r1, regs->ARM_r0);
 137
 138         flags = regs->ARM_cpsr;
 139         buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
 140         buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
 141         buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
 142         buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
 143         buf[4] = '\0';
 144
 145 #ifndef CONFIG_CPU_V7M
 146         {
 147                 const char *segment;
 148
 149                 if ((domain & domain_mask(DOMAIN_USER)) ==
 150                     domain_val(DOMAIN_USER, DOMAIN_NOACCESS))
 151                         segment = "none";
 152                 else if (fs == KERNEL_DS)
 153                         segment = "kernel";
 154                 else
 155                         segment = "user";
 156
 157                 printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
 158                         buf, interrupts_enabled(regs) ? "n" : "ff",
 159                         fast_interrupts_enabled(regs) ? "n" : "ff",
 160                         processor_modes[processor_mode(regs)],
 161                         isa_modes[isa_mode(regs)], segment);
 162         }
 163 #else
 164         printk("xPSR: %08lx\n", regs->ARM_cpsr);
 165 #endif
 166
 167 #ifdef CONFIG_CPU_CP15
 168         {
 169                 unsigned int ctrl;
 170
 171                 buf[0] = '\0';
 172 #ifdef CONFIG_CPU_CP15_MMU
 173                 {
 174                         unsigned int transbase;
 175                         asm("mrc p15, 0, %0, c2, c0\n\t"
 176                             : "=r" (transbase));
 177                         snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
 178                                 transbase, domain);
 179                 }
 180 #endif
 181                 asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
 182
 183                 printk("Control: %08x%s\n", ctrl, buf);
 184         }
 185 #endif
 186 }
 187
 188 void show_regs(struct pt_regs * regs)
 189 {
 190         __show_regs(regs);
 191         dump_stack();
 192 }
 193
 194 ATOMIC_NOTIFIER_HEAD(thread_notify_head);
 195
 196 EXPORT_SYMBOL_GPL(thread_notify_head);
 197
 198 /*
 199  * Free current thread data structures etc..
 200  */
 201 void exit_thread(struct task_struct *tsk)
 202 {
 203         thread_notify(THREAD_NOTIFY_EXIT, task_thread_info(tsk));
 204 }
 205
 206 void flush_thread(void)
 207 {
 208         struct thread_info *thread = current_thread_info();
 209         struct task_struct *tsk = current;
 210
 211         flush_ptrace_hw_breakpoint(tsk);
 212
 213         memset(thread->used_cp, 0, sizeof(thread->used_cp));
 214         memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
 215         memset(&thread->fpstate, 0, sizeof(union fp_state));
 216
 217         flush_tls();
 218
 219         thread_notify(THREAD_NOTIFY_FLUSH, thread);
 220 }
 221
 222 void release_thread(struct task_struct *dead_task)
 223 {
 224 }
 225
 226 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 227
 228 int
 229 copy_thread_tls(unsigned long clone_flags, unsigned long stack_start,
 230             unsigned long stk_sz, struct task_struct *p, unsigned long tls)
 231 {
 232         struct thread_info *thread = task_thread_info(p);
 233         struct pt_regs *childregs = task_pt_regs(p);
 234
 235         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
 236
 237 #ifdef CONFIG_CPU_USE_DOMAINS
 238         /*
 239          * Copy the initial value of the domain access control register
 240          * from the current thread: thread->addr_limit will have been
 241          * copied from the current thread via setup_thread_stack() in
 242          * kernel/fork.c
 243          */
 244         thread->cpu_domain = get_domain();
 245 #endif
 246
 247         if (likely(!(p->flags & PF_KTHREAD))) {
 248                 *childregs = *current_pt_regs();
 249                 childregs->ARM_r0 = 0;
 250                 if (stack_start)
 251                         childregs->ARM_sp = stack_start;
 252         } else {
 253                 memset(childregs, 0, sizeof(struct pt_regs));
 254                 thread->cpu_context.r4 = stk_sz;
 255                 thread->cpu_context.r5 = stack_start;
 256                 childregs->ARM_cpsr = SVC_MODE;
 257         }
 258         thread->cpu_context.pc = (unsigned long)ret_from_fork;
 259         thread->cpu_context.sp = (unsigned long)childregs;
 260
 261         clear_ptrace_hw_breakpoint(p);
 262
 263         if (clone_flags & CLONE_SETTLS)
 264                 thread->tp_value[0] = tls;
 265         thread->tp_value[1] = get_tpuser();
 266
 267         thread_notify(THREAD_NOTIFY_COPY, thread);
 268
 269 #ifdef CONFIG_STACKPROTECTOR_PER_TASK
 270         thread->stack_canary = p->stack_canary;
 271 #endif
 272
 273         return 0;
 274 }
 275
 276 /*
 277  * Fill in the task's elfregs structure for a core dump.
 278  */
 279 int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
 280 {
 281         elf_core_copy_regs(elfregs, task_pt_regs(t));
 282         return 1;
 283 }
 284
 285 /*
 286  * fill in the fpe structure for a core dump...
 287  */
 288 int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
 289 {
 290         struct thread_info *thread = current_thread_info();
 291         int used_math = thread->used_cp[1] | thread->used_cp[2];
 292
 293         if (used_math)
 294                 memcpy(fp, &thread->fpstate.soft, sizeof (*fp));
 295
 296         return used_math != 0;
 297 }
 298 EXPORT_SYMBOL(dump_fpu);
 299
 300 unsigned long get_wchan(struct task_struct *p)
 301 {
 302         struct stackframe frame;
 303         unsigned long stack_page;
 304         int count = 0;
 305         if (!p || p == current || p->state == TASK_RUNNING)
 306                 return 0;
 307
 308         frame.fp = thread_saved_fp(p);
 309         frame.sp = thread_saved_sp(p);
 310         frame.lr = 0;                   /* recovered from the stack */
 311         frame.pc = thread_saved_pc(p);
 312         stack_page = (unsigned long)task_stack_page(p);
 313         do {
 314                 if (frame.sp < stack_page ||
 315                     frame.sp >= stack_page + THREAD_SIZE ||
 316                     unwind_frame(&frame) < 0)
 317                         return 0;
 318                 if (!in_sched_functions(frame.pc))
 319                         return frame.pc;
 320         } while (count ++ < 16);
 321         return 0;
 322 }
 323
 324 #ifdef CONFIG_MMU
 325 #ifdef CONFIG_KUSER_HELPERS
 326 /*
 327  * The vectors page is always readable from user space for the
 328  * atomic helpers. Insert it into the gate_vma so that it is visible
 329  * through ptrace and /proc/<pid>/mem.
 330  */
 331 static struct vm_area_struct gate_vma;
 332
 333 static int __init gate_vma_init(void)
 334 {
 335         vma_init(&gate_vma, NULL);
 336         gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
 337         gate_vma.vm_start = 0xffff0000;
 338         gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
 339         gate_vma.vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC;
 340         return 0;
 341 }
 342 arch_initcall(gate_vma_init);
 343
 344 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
 345 {
 346         return &gate_vma;
 347 }
 348
 349 int in_gate_area(struct mm_struct *mm, unsigned long addr)
 350 {
 351         return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
 352 }
 353
 354 int in_gate_area_no_mm(unsigned long addr)
 355 {
 356         return in_gate_area(NULL, addr);
 357 }
 358 #define is_gate_vma(vma)        ((vma) == &gate_vma)
 359 #else
 360 #define is_gate_vma(vma)        0
 361 #endif
 362
 363 const char *arch_vma_name(struct vm_area_struct *vma)
 364 {
 365         return is_gate_vma(vma) ? "[vectors]" : NULL;
 366 }
 367
 368 /* If possible, provide a placement hint at a random offset from the
 369  * stack for the sigpage and vdso pages.
 370  */
 371 static unsigned long sigpage_addr(const struct mm_struct *mm,
 372                                   unsigned int npages)
 373 {
 374         unsigned long offset;
 375         unsigned long first;
 376         unsigned long last;
 377         unsigned long addr;
 378         unsigned int slots;
 379
 380         first = PAGE_ALIGN(mm->start_stack);
 381
 382         last = TASK_SIZE - (npages << PAGE_SHIFT);
 383
 384         /* No room after stack? */
 385         if (first > last)
 386                 return 0;
 387
 388         /* Just enough room? */
 389         if (first == last)
 390                 return first;
 391
 392         slots = ((last - first) >> PAGE_SHIFT) + 1;
 393
 394         offset = get_random_int() % slots;
 395
 396         addr = first + (offset << PAGE_SHIFT);
 397
 398         return addr;
 399 }
 400
 401 static struct page *signal_page;
 402 extern struct page *get_signal_page(void);
 403
 404 static int sigpage_mremap(const struct vm_special_mapping *sm,
 405                 struct vm_area_struct *new_vma)
 406 {
 407         current->mm->context.sigpage = new_vma->vm_start;
 408         return 0;
 409 }
 410
 411 static const struct vm_special_mapping sigpage_mapping = {
 412         .name = "[sigpage]",
 413         .pages = &signal_page,
 414         .mremap = sigpage_mremap,
 415 };
 416
 417 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 418 {
 419         struct mm_struct *mm = current->mm;
 420         struct vm_area_struct *vma;
 421         unsigned long npages;
 422         unsigned long addr;
 423         unsigned long hint;
 424         int ret = 0;
 425
 426         if (!signal_page)
 427                 signal_page = get_signal_page();
 428         if (!signal_page)
 429                 return -ENOMEM;
 430
 431         npages = 1; /* for sigpage */
 432         npages += vdso_total_pages;
 433
 434         if (down_write_killable(&mm->mmap_sem))
 435                 return -EINTR;
 436         hint = sigpage_addr(mm, npages);
 437         addr = get_unmapped_area(NULL, hint, npages << PAGE_SHIFT, 0, 0);
 438         if (IS_ERR_VALUE(addr)) {
 439                 ret = addr;
 440                 goto up_fail;
 441         }
 442
 443         vma = _install_special_mapping(mm, addr, PAGE_SIZE,
 444                 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 445                 &sigpage_mapping);
 446
 447         if (IS_ERR(vma)) {
 448                 ret = PTR_ERR(vma);
 449                 goto up_fail;
 450         }
 451
 452         mm->context.sigpage = addr;
 453
 454         /* Unlike the sigpage, failure to install the vdso is unlikely
 455          * to be fatal to the process, so no error check needed
 456          * here.
 457          */
 458         arm_install_vdso(mm, addr + PAGE_SIZE);
 459
 460  up_fail:
 461         up_write(&mm->mmap_sem);
 462         return ret;
 463 }
 464 #endif