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 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
  40 #include <linux/stackprotector.h>
  41 unsigned long __stack_chk_guard __read_mostly;
  42 EXPORT_SYMBOL(__stack_chk_guard);
  43 #endif
  44
  45 static const char *processor_modes[] __maybe_unused = {
  46   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  47   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  48   "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "MON_32" , "ABT_32" ,
  49   "UK8_32" , "UK9_32" , "HYP_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
  50 };
  51
  52 static const char *isa_modes[] __maybe_unused = {
  53   "ARM" , "Thumb" , "Jazelle", "ThumbEE"
  54 };
  55
  56 /*
  57  * This is our default idle handler.
  58  */
  59
  60 void (*arm_pm_idle)(void);
  61
  62 /*
  63  * Called from the core idle loop.
  64  */
  65
  66 void arch_cpu_idle(void)
  67 {
  68         if (arm_pm_idle)
  69                 arm_pm_idle();
  70         else
  71                 cpu_do_idle();
  72         local_irq_enable();
  73 }
  74
  75 void arch_cpu_idle_prepare(void)
  76 {
  77         local_fiq_enable();
  78 }
  79
  80 void arch_cpu_idle_enter(void)
  81 {
  82         ledtrig_cpu(CPU_LED_IDLE_START);
  83 #ifdef CONFIG_PL310_ERRATA_769419
  84         wmb();
  85 #endif
  86 }
  87
  88 void arch_cpu_idle_exit(void)
  89 {
  90         ledtrig_cpu(CPU_LED_IDLE_END);
  91 }
  92
  93 void __show_regs(struct pt_regs *regs)
  94 {
  95         unsigned long flags;
  96         char buf[64];
  97 #ifndef CONFIG_CPU_V7M
  98         unsigned int domain, fs;
  99 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
 100         /*
 101          * Get the domain register for the parent context. In user
 102          * mode, we don't save the DACR, so lets use what it should
 103          * be. For other modes, we place it after the pt_regs struct.
 104          */
 105         if (user_mode(regs)) {
 106                 domain = DACR_UACCESS_ENABLE;
 107                 fs = get_fs();
 108         } else {
 109                 domain = to_svc_pt_regs(regs)->dacr;
 110                 fs = to_svc_pt_regs(regs)->addr_limit;
 111         }
 112 #else
 113         domain = get_domain();
 114         fs = get_fs();
 115 #endif
 116 #endif
 117
 118         show_regs_print_info(KERN_DEFAULT);
 119
 120         printk("PC is at %pS\n", (void *)instruction_pointer(regs));
 121         printk("LR is at %pS\n", (void *)regs->ARM_lr);
 122         printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n",
 123                regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr);
 124         printk("sp : %08lx  ip : %08lx  fp : %08lx\n",
 125                regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
 126         printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
 127                 regs->ARM_r10, regs->ARM_r9,
 128                 regs->ARM_r8);
 129         printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
 130                 regs->ARM_r7, regs->ARM_r6,
 131                 regs->ARM_r5, regs->ARM_r4);
 132         printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
 133                 regs->ARM_r3, regs->ARM_r2,
 134                 regs->ARM_r1, regs->ARM_r0);
 135
 136         flags = regs->ARM_cpsr;
 137         buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
 138         buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
 139         buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
 140         buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
 141         buf[4] = '\0';
 142
 143 #ifndef CONFIG_CPU_V7M
 144         {
 145                 const char *segment;
 146
 147                 if ((domain & domain_mask(DOMAIN_USER)) ==
 148                     domain_val(DOMAIN_USER, DOMAIN_NOACCESS))
 149                         segment = "none";
 150                 else if (fs == KERNEL_DS)
 151                         segment = "kernel";
 152                 else
 153                         segment = "user";
 154
 155                 printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
 156                         buf, interrupts_enabled(regs) ? "n" : "ff",
 157                         fast_interrupts_enabled(regs) ? "n" : "ff",
 158                         processor_modes[processor_mode(regs)],
 159                         isa_modes[isa_mode(regs)], segment);
 160         }
 161 #else
 162         printk("xPSR: %08lx\n", regs->ARM_cpsr);
 163 #endif
 164
 165 #ifdef CONFIG_CPU_CP15
 166         {
 167                 unsigned int ctrl;
 168
 169                 buf[0] = '\0';
 170 #ifdef CONFIG_CPU_CP15_MMU
 171                 {
 172                         unsigned int transbase;
 173                         asm("mrc p15, 0, %0, c2, c0\n\t"
 174                             : "=r" (transbase));
 175                         snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
 176                                 transbase, domain);
 177                 }
 178 #endif
 179                 asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
 180
 181                 printk("Control: %08x%s\n", ctrl, buf);
 182         }
 183 #endif
 184 }
 185
 186 void show_regs(struct pt_regs * regs)
 187 {
 188         __show_regs(regs);
 189         dump_stack();
 190 }
 191
 192 ATOMIC_NOTIFIER_HEAD(thread_notify_head);
 193
 194 EXPORT_SYMBOL_GPL(thread_notify_head);
 195
 196 /*
 197  * Free current thread data structures etc..
 198  */
 199 void exit_thread(struct task_struct *tsk)
 200 {
 201         thread_notify(THREAD_NOTIFY_EXIT, task_thread_info(tsk));
 202 }
 203
 204 void flush_thread(void)
 205 {
 206         struct thread_info *thread = current_thread_info();
 207         struct task_struct *tsk = current;
 208
 209         flush_ptrace_hw_breakpoint(tsk);
 210
 211         memset(thread->used_cp, 0, sizeof(thread->used_cp));
 212         memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
 213         memset(&thread->fpstate, 0, sizeof(union fp_state));
 214
 215         flush_tls();
 216
 217         thread_notify(THREAD_NOTIFY_FLUSH, thread);
 218 }
 219
 220 void release_thread(struct task_struct *dead_task)
 221 {
 222 }
 223
 224 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 225
 226 int
 227 copy_thread(unsigned long clone_flags, unsigned long stack_start,
 228             unsigned long stk_sz, struct task_struct *p)
 229 {
 230         struct thread_info *thread = task_thread_info(p);
 231         struct pt_regs *childregs = task_pt_regs(p);
 232
 233         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
 234
 235 #ifdef CONFIG_CPU_USE_DOMAINS
 236         /*
 237          * Copy the initial value of the domain access control register
 238          * from the current thread: thread->addr_limit will have been
 239          * copied from the current thread via setup_thread_stack() in
 240          * kernel/fork.c
 241          */
 242         thread->cpu_domain = get_domain();
 243 #endif
 244
 245         if (likely(!(p->flags & PF_KTHREAD))) {
 246                 *childregs = *current_pt_regs();
 247                 childregs->ARM_r0 = 0;
 248                 if (stack_start)
 249                         childregs->ARM_sp = stack_start;
 250         } else {
 251                 memset(childregs, 0, sizeof(struct pt_regs));
 252                 thread->cpu_context.r4 = stk_sz;
 253                 thread->cpu_context.r5 = stack_start;
 254                 childregs->ARM_cpsr = SVC_MODE;
 255         }
 256         thread->cpu_context.pc = (unsigned long)ret_from_fork;
 257         thread->cpu_context.sp = (unsigned long)childregs;
 258
 259         clear_ptrace_hw_breakpoint(p);
 260
 261         if (clone_flags & CLONE_SETTLS)
 262                 thread->tp_value[0] = childregs->ARM_r3;
 263         thread->tp_value[1] = get_tpuser();
 264
 265         thread_notify(THREAD_NOTIFY_COPY, thread);
 266
 267 #ifdef CONFIG_STACKPROTECTOR_PER_TASK
 268         thread->stack_canary = p->stack_canary;
 269 #endif
 270
 271         return 0;
 272 }
 273
 274 /*
 275  * Fill in the task's elfregs structure for a core dump.
 276  */
 277 int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
 278 {
 279         elf_core_copy_regs(elfregs, task_pt_regs(t));
 280         return 1;
 281 }
 282
 283 /*
 284  * fill in the fpe structure for a core dump...
 285  */
 286 int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
 287 {
 288         struct thread_info *thread = current_thread_info();
 289         int used_math = thread->used_cp[1] | thread->used_cp[2];
 290
 291         if (used_math)
 292                 memcpy(fp, &thread->fpstate.soft, sizeof (*fp));
 293
 294         return used_math != 0;
 295 }
 296 EXPORT_SYMBOL(dump_fpu);
 297
 298 unsigned long get_wchan(struct task_struct *p)
 299 {
 300         struct stackframe frame;
 301         unsigned long stack_page;
 302         int count = 0;
 303         if (!p || p == current || p->state == TASK_RUNNING)
 304                 return 0;
 305
 306         frame.fp = thread_saved_fp(p);
 307         frame.sp = thread_saved_sp(p);
 308         frame.lr = 0;                   /* recovered from the stack */
 309         frame.pc = thread_saved_pc(p);
 310         stack_page = (unsigned long)task_stack_page(p);
 311         do {
 312                 if (frame.sp < stack_page ||
 313                     frame.sp >= stack_page + THREAD_SIZE ||
 314                     unwind_frame(&frame) < 0)
 315                         return 0;
 316                 if (!in_sched_functions(frame.pc))
 317                         return frame.pc;
 318         } while (count ++ < 16);
 319         return 0;
 320 }
 321
 322 unsigned long arch_randomize_brk(struct mm_struct *mm)
 323 {
 324         return randomize_page(mm->brk, 0x02000000);
 325 }
 326
 327 #ifdef CONFIG_MMU
 328 #ifdef CONFIG_KUSER_HELPERS
 329 /*
 330  * The vectors page is always readable from user space for the
 331  * atomic helpers. Insert it into the gate_vma so that it is visible
 332  * through ptrace and /proc/<pid>/mem.
 333  */
 334 static struct vm_area_struct gate_vma;
 335
 336 static int __init gate_vma_init(void)
 337 {
 338         vma_init(&gate_vma, NULL);
 339         gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
 340         gate_vma.vm_start = 0xffff0000;
 341         gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
 342         gate_vma.vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC;
 343         return 0;
 344 }
 345 arch_initcall(gate_vma_init);
 346
 347 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
 348 {
 349         return &gate_vma;
 350 }
 351
 352 int in_gate_area(struct mm_struct *mm, unsigned long addr)
 353 {
 354         return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
 355 }
 356
 357 int in_gate_area_no_mm(unsigned long addr)
 358 {
 359         return in_gate_area(NULL, addr);
 360 }
 361 #define is_gate_vma(vma)        ((vma) == &gate_vma)
 362 #else
 363 #define is_gate_vma(vma)        0
 364 #endif
 365
 366 const char *arch_vma_name(struct vm_area_struct *vma)
 367 {
 368         return is_gate_vma(vma) ? "[vectors]" : NULL;
 369 }
 370
 371 /* If possible, provide a placement hint at a random offset from the
 372  * stack for the sigpage and vdso pages.
 373  */
 374 static unsigned long sigpage_addr(const struct mm_struct *mm,
 375                                   unsigned int npages)
 376 {
 377         unsigned long offset;
 378         unsigned long first;
 379         unsigned long last;
 380         unsigned long addr;
 381         unsigned int slots;
 382
 383         first = PAGE_ALIGN(mm->start_stack);
 384
 385         last = TASK_SIZE - (npages << PAGE_SHIFT);
 386
 387         /* No room after stack? */
 388         if (first > last)
 389                 return 0;
 390
 391         /* Just enough room? */
 392         if (first == last)
 393                 return first;
 394
 395         slots = ((last - first) >> PAGE_SHIFT) + 1;
 396
 397         offset = get_random_int() % slots;
 398
 399         addr = first + (offset << PAGE_SHIFT);
 400
 401         return addr;
 402 }
 403
 404 static struct page *signal_page;
 405 extern struct page *get_signal_page(void);
 406
 407 static int sigpage_mremap(const struct vm_special_mapping *sm,
 408                 struct vm_area_struct *new_vma)
 409 {
 410         current->mm->context.sigpage = new_vma->vm_start;
 411         return 0;
 412 }
 413
 414 static const struct vm_special_mapping sigpage_mapping = {
 415         .name = "[sigpage]",
 416         .pages = &signal_page,
 417         .mremap = sigpage_mremap,
 418 };
 419
 420 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 421 {
 422         struct mm_struct *mm = current->mm;
 423         struct vm_area_struct *vma;
 424         unsigned long npages;
 425         unsigned long addr;
 426         unsigned long hint;
 427         int ret = 0;
 428
 429         if (!signal_page)
 430                 signal_page = get_signal_page();
 431         if (!signal_page)
 432                 return -ENOMEM;
 433
 434         npages = 1; /* for sigpage */
 435         npages += vdso_total_pages;
 436
 437         if (down_write_killable(&mm->mmap_sem))
 438                 return -EINTR;
 439         hint = sigpage_addr(mm, npages);
 440         addr = get_unmapped_area(NULL, hint, npages << PAGE_SHIFT, 0, 0);
 441         if (IS_ERR_VALUE(addr)) {
 442                 ret = addr;
 443                 goto up_fail;
 444         }
 445
 446         vma = _install_special_mapping(mm, addr, PAGE_SIZE,
 447                 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 448                 &sigpage_mapping);
 449
 450         if (IS_ERR(vma)) {
 451                 ret = PTR_ERR(vma);
 452                 goto up_fail;
 453         }
 454
 455         mm->context.sigpage = addr;
 456
 457         /* Unlike the sigpage, failure to install the vdso is unlikely
 458          * to be fatal to the process, so no error check needed
 459          * here.
 460          */
 461         arm_install_vdso(mm, addr + PAGE_SIZE);
 462
 463  up_fail:
 464         up_write(&mm->mmap_sem);
 465         return ret;
 466 }
 467 #endif