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 <linux/export.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/debug.h>
  11 #include <linux/sched/task.h>
  12 #include <linux/sched/task_stack.h>
  13 #include <linux/kernel.h>
  14 #include <linux/mm.h>
  15 #include <linux/stddef.h>
  16 #include <linux/unistd.h>
  17 #include <linux/user.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/init.h>
  20 #include <linux/elfcore.h>
  21 #include <linux/pm.h>
  22 #include <linux/tick.h>
  23 #include <linux/utsname.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/random.h>
  26 #include <linux/hw_breakpoint.h>
  27 #include <linux/leds.h>
  28
  29 #include <asm/processor.h>
  30 #include <asm/thread_notify.h>
  31 #include <asm/stacktrace.h>
  32 #include <asm/system_misc.h>
  33 #include <asm/mach/time.h>
  34 #include <asm/tls.h>
  35 #include <asm/vdso.h>
  36
  37 #include "signal.h"
  38
  39 #if defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
  40 DEFINE_PER_CPU(struct task_struct *, __entry_task);
  41 #endif
  42
  43 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
  44 #include <linux/stackprotector.h>
  45 unsigned long __stack_chk_guard __read_mostly;
  46 EXPORT_SYMBOL(__stack_chk_guard);
  47 #endif
  48
  49 #ifndef CONFIG_CURRENT_POINTER_IN_TPIDRURO
  50 asmlinkage struct task_struct *__current;
  51 EXPORT_SYMBOL(__current);
  52 #endif
  53
  54 static const char *processor_modes[] __maybe_unused = {
  55   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
  56   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
  57   "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "MON_32" , "ABT_32" ,
  58   "UK8_32" , "UK9_32" , "HYP_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
  59 };
  60
  61 static const char *isa_modes[] __maybe_unused = {
  62   "ARM" , "Thumb" , "Jazelle", "ThumbEE"
  63 };
  64
  65 /*
  66  * This is our default idle handler.
  67  */
  68
  69 void (*arm_pm_idle)(void);
  70
  71 /*
  72  * Called from the core idle loop.
  73  */
  74
  75 void arch_cpu_idle(void)
  76 {
  77         if (arm_pm_idle)
  78                 arm_pm_idle();
  79         else
  80                 cpu_do_idle();
  81 }
  82
  83 void arch_cpu_idle_prepare(void)
  84 {
  85         local_fiq_enable();
  86 }
  87
  88 void arch_cpu_idle_enter(void)
  89 {
  90         ledtrig_cpu(CPU_LED_IDLE_START);
  91 #ifdef CONFIG_PL310_ERRATA_769419
  92         wmb();
  93 #endif
  94 }
  95
  96 void arch_cpu_idle_exit(void)
  97 {
  98         ledtrig_cpu(CPU_LED_IDLE_END);
  99 }
 100
 101 void __show_regs_alloc_free(struct pt_regs *regs)
 102 {
 103         int i;
 104
 105         /* check for r0 - r12 only */
 106         for (i = 0; i < 13; i++) {
 107                 pr_alert("Register r%d information:", i);
 108                 mem_dump_obj((void *)regs->uregs[i]);
 109         }
 110 }
 111
 112 void __show_regs(struct pt_regs *regs)
 113 {
 114         unsigned long flags;
 115         char buf[64];
 116 #ifndef CONFIG_CPU_V7M
 117         unsigned int domain;
 118 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
 119         /*
 120          * Get the domain register for the parent context. In user
 121          * mode, we don't save the DACR, so lets use what it should
 122          * be. For other modes, we place it after the pt_regs struct.
 123          */
 124         if (user_mode(regs)) {
 125                 domain = DACR_UACCESS_ENABLE;
 126         } else {
 127                 domain = to_svc_pt_regs(regs)->dacr;
 128         }
 129 #else
 130         domain = get_domain();
 131 #endif
 132 #endif
 133
 134         show_regs_print_info(KERN_DEFAULT);
 135
 136         printk("PC is at %pS\n", (void *)instruction_pointer(regs));
 137         printk("LR is at %pS\n", (void *)regs->ARM_lr);
 138         printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n",
 139                regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr);
 140         printk("sp : %08lx  ip : %08lx  fp : %08lx\n",
 141                regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
 142         printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
 143                 regs->ARM_r10, regs->ARM_r9,
 144                 regs->ARM_r8);
 145         printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
 146                 regs->ARM_r7, regs->ARM_r6,
 147                 regs->ARM_r5, regs->ARM_r4);
 148         printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
 149                 regs->ARM_r3, regs->ARM_r2,
 150                 regs->ARM_r1, regs->ARM_r0);
 151
 152         flags = regs->ARM_cpsr;
 153         buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
 154         buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
 155         buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
 156         buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
 157         buf[4] = '\0';
 158
 159 #ifndef CONFIG_CPU_V7M
 160         {
 161                 const char *segment;
 162
 163                 if ((domain & domain_mask(DOMAIN_USER)) ==
 164                     domain_val(DOMAIN_USER, DOMAIN_NOACCESS))
 165                         segment = "none";
 166                 else
 167                         segment = "user";
 168
 169                 printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
 170                         buf, interrupts_enabled(regs) ? "n" : "ff",
 171                         fast_interrupts_enabled(regs) ? "n" : "ff",
 172                         processor_modes[processor_mode(regs)],
 173                         isa_modes[isa_mode(regs)], segment);
 174         }
 175 #else
 176         printk("xPSR: %08lx\n", regs->ARM_cpsr);
 177 #endif
 178
 179 #ifdef CONFIG_CPU_CP15
 180         {
 181                 unsigned int ctrl;
 182
 183                 buf[0] = '\0';
 184 #ifdef CONFIG_CPU_CP15_MMU
 185                 {
 186                         unsigned int transbase;
 187                         asm("mrc p15, 0, %0, c2, c0\n\t"
 188                             : "=r" (transbase));
 189                         snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
 190                                 transbase, domain);
 191                 }
 192 #endif
 193                 asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
 194
 195                 printk("Control: %08x%s\n", ctrl, buf);
 196         }
 197 #endif
 198 }
 199
 200 void show_regs(struct pt_regs * regs)
 201 {
 202         __show_regs(regs);
 203         dump_backtrace(regs, NULL, KERN_DEFAULT);
 204 }
 205
 206 ATOMIC_NOTIFIER_HEAD(thread_notify_head);
 207
 208 EXPORT_SYMBOL_GPL(thread_notify_head);
 209
 210 /*
 211  * Free current thread data structures etc..
 212  */
 213 void exit_thread(struct task_struct *tsk)
 214 {
 215         thread_notify(THREAD_NOTIFY_EXIT, task_thread_info(tsk));
 216 }
 217
 218 void flush_thread(void)
 219 {
 220         struct thread_info *thread = current_thread_info();
 221         struct task_struct *tsk = current;
 222
 223         flush_ptrace_hw_breakpoint(tsk);
 224
 225         memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
 226         memset(&thread->fpstate, 0, sizeof(union fp_state));
 227
 228         flush_tls();
 229
 230         thread_notify(THREAD_NOTIFY_FLUSH, thread);
 231 }
 232
 233 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
 234
 235 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 236 {
 237         unsigned long clone_flags = args->flags;
 238         unsigned long stack_start = args->stack;
 239         unsigned long tls = args->tls;
 240         struct thread_info *thread = task_thread_info(p);
 241         struct pt_regs *childregs = task_pt_regs(p);
 242
 243         memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
 244
 245 #ifdef CONFIG_CPU_USE_DOMAINS
 246         /*
 247          * Copy the initial value of the domain access control register
 248          * from the current thread: thread->addr_limit will have been
 249          * copied from the current thread via setup_thread_stack() in
 250          * kernel/fork.c
 251          */
 252         thread->cpu_domain = get_domain();
 253 #endif
 254
 255         if (likely(!args->fn)) {
 256                 *childregs = *current_pt_regs();
 257                 childregs->ARM_r0 = 0;
 258                 if (stack_start)
 259                         childregs->ARM_sp = stack_start;
 260         } else {
 261                 memset(childregs, 0, sizeof(struct pt_regs));
 262                 thread->cpu_context.r4 = (unsigned long)args->fn_arg;
 263                 thread->cpu_context.r5 = (unsigned long)args->fn;
 264                 childregs->ARM_cpsr = SVC_MODE;
 265         }
 266         thread->cpu_context.pc = (unsigned long)ret_from_fork;
 267         thread->cpu_context.sp = (unsigned long)childregs;
 268
 269         clear_ptrace_hw_breakpoint(p);
 270
 271         if (clone_flags & CLONE_SETTLS)
 272                 thread->tp_value[0] = tls;
 273         thread->tp_value[1] = get_tpuser();
 274
 275         thread_notify(THREAD_NOTIFY_COPY, thread);
 276
 277         return 0;
 278 }
 279
 280 unsigned long __get_wchan(struct task_struct *p)
 281 {
 282         struct stackframe frame;
 283         unsigned long stack_page;
 284         int count = 0;
 285
 286         frame.fp = thread_saved_fp(p);
 287         frame.sp = thread_saved_sp(p);
 288         frame.lr = 0;                   /* recovered from the stack */
 289         frame.pc = thread_saved_pc(p);
 290         stack_page = (unsigned long)task_stack_page(p);
 291         do {
 292                 if (frame.sp < stack_page ||
 293                     frame.sp >= stack_page + THREAD_SIZE ||
 294                     unwind_frame(&frame) < 0)
 295                         return 0;
 296                 if (!in_sched_functions(frame.pc))
 297                         return frame.pc;
 298         } while (count ++ < 16);
 299         return 0;
 300 }
 301
 302 #ifdef CONFIG_MMU
 303 #ifdef CONFIG_KUSER_HELPERS
 304 /*
 305  * The vectors page is always readable from user space for the
 306  * atomic helpers. Insert it into the gate_vma so that it is visible
 307  * through ptrace and /proc/<pid>/mem.
 308  */
 309 static struct vm_area_struct gate_vma;
 310
 311 static int __init gate_vma_init(void)
 312 {
 313         vma_init(&gate_vma, NULL);
 314         gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
 315         gate_vma.vm_start = 0xffff0000;
 316         gate_vma.vm_end = 0xffff0000 + PAGE_SIZE;
 317         vm_flags_init(&gate_vma, VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC);
 318         return 0;
 319 }
 320 arch_initcall(gate_vma_init);
 321
 322 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
 323 {
 324         return &gate_vma;
 325 }
 326
 327 int in_gate_area(struct mm_struct *mm, unsigned long addr)
 328 {
 329         return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
 330 }
 331
 332 int in_gate_area_no_mm(unsigned long addr)
 333 {
 334         return in_gate_area(NULL, addr);
 335 }
 336 #define is_gate_vma(vma)        ((vma) == &gate_vma)
 337 #else
 338 #define is_gate_vma(vma)        0
 339 #endif
 340
 341 const char *arch_vma_name(struct vm_area_struct *vma)
 342 {
 343         return is_gate_vma(vma) ? "[vectors]" : NULL;
 344 }
 345
 346 /* If possible, provide a placement hint at a random offset from the
 347  * stack for the sigpage and vdso pages.
 348  */
 349 static unsigned long sigpage_addr(const struct mm_struct *mm,
 350                                   unsigned int npages)
 351 {
 352         unsigned long offset;
 353         unsigned long first;
 354         unsigned long last;
 355         unsigned long addr;
 356         unsigned int slots;
 357
 358         first = PAGE_ALIGN(mm->start_stack);
 359
 360         last = TASK_SIZE - (npages << PAGE_SHIFT);
 361
 362         /* No room after stack? */
 363         if (first > last)
 364                 return 0;
 365
 366         /* Just enough room? */
 367         if (first == last)
 368                 return first;
 369
 370         slots = ((last - first) >> PAGE_SHIFT) + 1;
 371
 372         offset = get_random_u32_below(slots);
 373
 374         addr = first + (offset << PAGE_SHIFT);
 375
 376         return addr;
 377 }
 378
 379 static struct page *signal_page;
 380 extern struct page *get_signal_page(void);
 381
 382 static int sigpage_mremap(const struct vm_special_mapping *sm,
 383                 struct vm_area_struct *new_vma)
 384 {
 385         current->mm->context.sigpage = new_vma->vm_start;
 386         return 0;
 387 }
 388
 389 static const struct vm_special_mapping sigpage_mapping = {
 390         .name = "[sigpage]",
 391         .pages = &signal_page,
 392         .mremap = sigpage_mremap,
 393 };
 394
 395 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 396 {
 397         struct mm_struct *mm = current->mm;
 398         struct vm_area_struct *vma;
 399         unsigned long npages;
 400         unsigned long addr;
 401         unsigned long hint;
 402         int ret = 0;
 403
 404         if (!signal_page)
 405                 signal_page = get_signal_page();
 406         if (!signal_page)
 407                 return -ENOMEM;
 408
 409         npages = 1; /* for sigpage */
 410         npages += vdso_total_pages;
 411
 412         if (mmap_write_lock_killable(mm))
 413                 return -EINTR;
 414         hint = sigpage_addr(mm, npages);
 415         addr = get_unmapped_area(NULL, hint, npages << PAGE_SHIFT, 0, 0);
 416         if (IS_ERR_VALUE(addr)) {
 417                 ret = addr;
 418                 goto up_fail;
 419         }
 420
 421         vma = _install_special_mapping(mm, addr, PAGE_SIZE,
 422                 VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
 423                 &sigpage_mapping);
 424
 425         if (IS_ERR(vma)) {
 426                 ret = PTR_ERR(vma);
 427                 goto up_fail;
 428         }
 429
 430         mm->context.sigpage = addr;
 431
 432         /* Unlike the sigpage, failure to install the vdso is unlikely
 433          * to be fatal to the process, so no error check needed
 434          * here.
 435          */
 436         arm_install_vdso(mm, addr + PAGE_SIZE);
 437
 438  up_fail:
 439         mmap_write_unlock(mm);
 440         return ret;
 441 }
 442 #endif