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         raw_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 copy_thread(unsigned long clone_flags, unsigned long stack_start,
 229                 unsigned long stk_sz, struct task_struct *p, unsigned long tls)
 230 {
 231         struct thread_info *thread = task_thread_info(p);
 232         struct pt_regs *childregs = task_pt_regs(p);
 233
 234         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
 235
 236 #ifdef CONFIG_CPU_USE_DOMAINS
 237         /*
 238          * Copy the initial value of the domain access control register
 239          * from the current thread: thread->addr_limit will have been
 240          * copied from the current thread via setup_thread_stack() in
 241          * kernel/fork.c
 242          */
 243         thread->cpu_domain = get_domain();
 244 #endif
 245
 246         if (likely(!(p->flags & PF_KTHREAD))) {
 247                 *childregs = *current_pt_regs();
 248                 childregs->ARM_r0 = 0;
 249                 if (stack_start)
 250                         childregs->ARM_sp = stack_start;
 251         } else {
 252                 memset(childregs, 0, sizeof(struct pt_regs));
 253                 thread->cpu_context.r4 = stk_sz;
 254                 thread->cpu_context.r5 = stack_start;
 255                 childregs->ARM_cpsr = SVC_MODE;
 256         }
 257         thread->cpu_context.pc = (unsigned long)ret_from_fork;
 258         thread->cpu_context.sp = (unsigned long)childregs;
 259
 260         clear_ptrace_hw_breakpoint(p);
 261
 262         if (clone_flags & CLONE_SETTLS)
 263                 thread->tp_value[0] = tls;
 264         thread->tp_value[1] = get_tpuser();
 265
 266         thread_notify(THREAD_NOTIFY_COPY, thread);
 267
 268 #ifdef CONFIG_STACKPROTECTOR_PER_TASK
 269         thread->stack_canary = p->stack_canary;
 270 #endif
 271
 272         return 0;
 273 }
 274
 275 unsigned long get_wchan(struct task_struct *p)
 276 {
 277         struct stackframe frame;
 278         unsigned long stack_page;
 279         int count = 0;
 280         if (!p || p == current || p->state == TASK_RUNNING)
 281                 return 0;
 282
 283         frame.fp = thread_saved_fp(p);
 284         frame.sp = thread_saved_sp(p);
 285         frame.lr = 0;                   /* recovered from the stack */
 286         frame.pc = thread_saved_pc(p);
 287         stack_page = (unsigned long)task_stack_page(p);
 288         do {
 289                 if (frame.sp < stack_page ||
 290                     frame.sp >= stack_page + THREAD_SIZE ||
 291                     unwind_frame(&frame) < 0)
 292                         return 0;
 293                 if (!in_sched_functions(frame.pc))
 294                         return frame.pc;
 295         } while (count ++ < 16);
 296         return 0;
 297 }
 298
 299 #ifdef CONFIG_MMU
 300 #ifdef CONFIG_KUSER_HELPERS
 301 /*
 302  * The vectors page is always readable from user space for the
 303  * atomic helpers. Insert it into the gate_vma so that it is visible
 304  * through ptrace and /proc/<pid>/mem.
 305  */
 306 static struct vm_area_struct gate_vma;
 307
 308 static int __init gate_vma_init(void)
 309 {
 310         vma_init(&gate_vma, NULL);
 311         gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
 312         gate_vma.vm_start = 0xffff0000;
 313         gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
 314         gate_vma.vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC;
 315         return 0;
 316 }
 317 arch_initcall(gate_vma_init);
 318
 319 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
 320 {
 321         return &gate_vma;
 322 }
 323
 324 int in_gate_area(struct mm_struct *mm, unsigned long addr)
 325 {
 326         return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
 327 }
 328
 329 int in_gate_area_no_mm(unsigned long addr)
 330 {
 331         return in_gate_area(NULL, addr);
 332 }
 333 #define is_gate_vma(vma)        ((vma) == &gate_vma)
 334 #else
 335 #define is_gate_vma(vma)        0
 336 #endif
 337
 338 const char *arch_vma_name(struct vm_area_struct *vma)
 339 {
 340         return is_gate_vma(vma) ? "[vectors]" : NULL;
 341 }
 342
 343 /* If possible, provide a placement hint at a random offset from the
 344  * stack for the sigpage and vdso pages.
 345  */
 346 static unsigned long sigpage_addr(const struct mm_struct *mm,
 347                                   unsigned int npages)
 348 {
 349         unsigned long offset;
 350         unsigned long first;
 351         unsigned long last;
 352         unsigned long addr;
 353         unsigned int slots;
 354
 355         first = PAGE_ALIGN(mm->start_stack);
 356
 357         last = TASK_SIZE - (npages << PAGE_SHIFT);
 358
 359         /* No room after stack? */
 360         if (first > last)
 361                 return 0;
 362
 363         /* Just enough room? */
 364         if (first == last)
 365                 return first;
 366
 367         slots = ((last - first) >> PAGE_SHIFT) + 1;
 368
 369         offset = get_random_int() % slots;
 370
 371         addr = first + (offset << PAGE_SHIFT);
 372
 373         return addr;
 374 }
 375
 376 static struct page *signal_page;
 377 extern struct page *get_signal_page(void);
 378
 379 static int sigpage_mremap(const struct vm_special_mapping *sm,
 380                 struct vm_area_struct *new_vma)
 381 {
 382         current->mm->context.sigpage = new_vma->vm_start;
 383         return 0;
 384 }
 385
 386 static const struct vm_special_mapping sigpage_mapping = {
 387         .name = "[sigpage]",
 388         .pages = &signal_page,
 389         .mremap = sigpage_mremap,
 390 };
 391
 392 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 393 {
 394         struct mm_struct *mm = current->mm;
 395         struct vm_area_struct *vma;
 396         unsigned long npages;
 397         unsigned long addr;
 398         unsigned long hint;
 399         int ret = 0;
 400
 401         if (!signal_page)
 402                 signal_page = get_signal_page();
 403         if (!signal_page)
 404                 return -ENOMEM;
 405
 406         npages = 1; /* for sigpage */
 407         npages += vdso_total_pages;
 408
 409         if (mmap_write_lock_killable(mm))
 410                 return -EINTR;
 411         hint = sigpage_addr(mm, npages);
 412         addr = get_unmapped_area(NULL, hint, npages << PAGE_SHIFT, 0, 0);
 413         if (IS_ERR_VALUE(addr)) {
 414                 ret = addr;
 415                 goto up_fail;
 416         }
 417
 418         vma = _install_special_mapping(mm, addr, PAGE_SIZE,
 419                 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 420                 &sigpage_mapping);
 421
 422         if (IS_ERR(vma)) {
 423                 ret = PTR_ERR(vma);
 424                 goto up_fail;
 425         }
 426
 427         mm->context.sigpage = addr;
 428
 429         /* Unlike the sigpage, failure to install the vdso is unlikely
 430          * to be fatal to the process, so no error check needed
 431          * here.
 432          */
 433         arm_install_vdso(mm, addr + PAGE_SIZE);
 434
 435  up_fail:
 436         mmap_write_unlock(mm);
 437         return ret;
 438 }
 439 #endif