arch/sparc/mm/fault_32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * fault.c:  Page fault handlers for the Sparc.
   4  *
   5  * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
   6  * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
   7  * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
   8  */
   9
  10 #include <asm/head.h>
  11
  12 #include <linux/string.h>
  13 #include <linux/types.h>
  14 #include <linux/sched.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/mman.h>
  17 #include <linux/threads.h>
  18 #include <linux/kernel.h>
  19 #include <linux/signal.h>
  20 #include <linux/mm.h>
  21 #include <linux/smp.h>
  22 #include <linux/perf_event.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/kdebug.h>
  25 #include <linux/uaccess.h>
  26
  27 #include <asm/page.h>
  28 #include <asm/pgtable.h>
  29 #include <asm/openprom.h>
  30 #include <asm/oplib.h>
  31 #include <asm/setup.h>
  32 #include <asm/smp.h>
  33 #include <asm/traps.h>
  34
  35 #include "mm_32.h"
  36
  37 int show_unhandled_signals = 1;
  38
  39 static void __noreturn unhandled_fault(unsigned long address,
  40                                        struct task_struct *tsk,
  41                                        struct pt_regs *regs)
  42 {
  43         if ((unsigned long) address < PAGE_SIZE) {
  44                 printk(KERN_ALERT
  45                     "Unable to handle kernel NULL pointer dereference\n");
  46         } else {
  47                 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
  48                        address);
  49         }
  50         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
  51                 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
  52         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
  53                 (tsk->mm ? (unsigned long) tsk->mm->pgd :
  54                         (unsigned long) tsk->active_mm->pgd));
  55         die_if_kernel("Oops", regs);
  56 }
  57
  58 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
  59                             unsigned long address)
  60 {
  61         struct pt_regs regs;
  62         unsigned long g2;
  63         unsigned int insn;
  64         int i;
  65
  66         i = search_extables_range(ret_pc, &g2);
  67         switch (i) {
  68         case 3:
  69                 /* load & store will be handled by fixup */
  70                 return 3;
  71
  72         case 1:
  73                 /* store will be handled by fixup, load will bump out */
  74                 /* for _to_ macros */
  75                 insn = *((unsigned int *) pc);
  76                 if ((insn >> 21) & 1)
  77                         return 1;
  78                 break;
  79
  80         case 2:
  81                 /* load will be handled by fixup, store will bump out */
  82                 /* for _from_ macros */
  83                 insn = *((unsigned int *) pc);
  84                 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
  85                         return 2;
  86                 break;
  87
  88         default:
  89                 break;
  90         }
  91
  92         memset(&regs, 0, sizeof(regs));
  93         regs.pc = pc;
  94         regs.npc = pc + 4;
  95         __asm__ __volatile__(
  96                 "rd %%psr, %0\n\t"
  97                 "nop\n\t"
  98                 "nop\n\t"
  99                 "nop\n" : "=r" (regs.psr));
 100         unhandled_fault(address, current, &regs);
 101
 102         /* Not reached */
 103         return 0;
 104 }
 105
 106 static inline void
 107 show_signal_msg(struct pt_regs *regs, int sig, int code,
 108                 unsigned long address, struct task_struct *tsk)
 109 {
 110         if (!unhandled_signal(tsk, sig))
 111                 return;
 112
 113         if (!printk_ratelimit())
 114                 return;
 115
 116         printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
 117                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 118                tsk->comm, task_pid_nr(tsk), address,
 119                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
 120                (void *)regs->u_regs[UREG_FP], code);
 121
 122         print_vma_addr(KERN_CONT " in ", regs->pc);
 123
 124         printk(KERN_CONT "\n");
 125 }
 126
 127 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 128                                unsigned long addr)
 129 {
 130         if (unlikely(show_unhandled_signals))
 131                 show_signal_msg(regs, sig, code,
 132                                 addr, current);
 133
 134         force_sig_fault(sig, code, (void __user *) addr, 0);
 135 }
 136
 137 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
 138 {
 139         unsigned int insn;
 140
 141         if (text_fault)
 142                 return regs->pc;
 143
 144         if (regs->psr & PSR_PS)
 145                 insn = *(unsigned int *) regs->pc;
 146         else
 147                 __get_user(insn, (unsigned int *) regs->pc);
 148
 149         return safe_compute_effective_address(regs, insn);
 150 }
 151
 152 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 153                                       int text_fault)
 154 {
 155         unsigned long addr = compute_si_addr(regs, text_fault);
 156
 157         __do_fault_siginfo(code, sig, regs, addr);
 158 }
 159
 160 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 161                                unsigned long address)
 162 {
 163         struct vm_area_struct *vma;
 164         struct task_struct *tsk = current;
 165         struct mm_struct *mm = tsk->mm;
 166         unsigned int fixup;
 167         unsigned long g2;
 168         int from_user = !(regs->psr & PSR_PS);
 169         int code;
 170         vm_fault_t fault;
 171         unsigned int flags = FAULT_FLAG_DEFAULT;
 172
 173         if (text_fault)
 174                 address = regs->pc;
 175
 176         /*
 177          * We fault-in kernel-space virtual memory on-demand. The
 178          * 'reference' page table is init_mm.pgd.
 179          *
 180          * NOTE! We MUST NOT take any locks for this case. We may
 181          * be in an interrupt or a critical region, and should
 182          * only copy the information from the master page table,
 183          * nothing more.
 184          */
 185         code = SEGV_MAPERR;
 186         if (address >= TASK_SIZE)
 187                 goto vmalloc_fault;
 188
 189         /*
 190          * If we're in an interrupt or have no user
 191          * context, we must not take the fault..
 192          */
 193         if (pagefault_disabled() || !mm)
 194                 goto no_context;
 195
 196         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 197
 198 retry:
 199         down_read(&mm->mmap_sem);
 200
 201         if (!from_user && address >= PAGE_OFFSET)
 202                 goto bad_area;
 203
 204         vma = find_vma(mm, address);
 205         if (!vma)
 206                 goto bad_area;
 207         if (vma->vm_start <= address)
 208                 goto good_area;
 209         if (!(vma->vm_flags & VM_GROWSDOWN))
 210                 goto bad_area;
 211         if (expand_stack(vma, address))
 212                 goto bad_area;
 213         /*
 214          * Ok, we have a good vm_area for this memory access, so
 215          * we can handle it..
 216          */
 217 good_area:
 218         code = SEGV_ACCERR;
 219         if (write) {
 220                 if (!(vma->vm_flags & VM_WRITE))
 221                         goto bad_area;
 222         } else {
 223                 /* Allow reads even for write-only mappings */
 224                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 225                         goto bad_area;
 226         }
 227
 228         if (from_user)
 229                 flags |= FAULT_FLAG_USER;
 230         if (write)
 231                 flags |= FAULT_FLAG_WRITE;
 232
 233         /*
 234          * If for any reason at all we couldn't handle the fault,
 235          * make sure we exit gracefully rather than endlessly redo
 236          * the fault.
 237          */
 238         fault = handle_mm_fault(vma, address, flags);
 239
 240         if (fault_signal_pending(fault, regs))
 241                 return;
 242
 243         if (unlikely(fault & VM_FAULT_ERROR)) {
 244                 if (fault & VM_FAULT_OOM)
 245                         goto out_of_memory;
 246                 else if (fault & VM_FAULT_SIGSEGV)
 247                         goto bad_area;
 248                 else if (fault & VM_FAULT_SIGBUS)
 249                         goto do_sigbus;
 250                 BUG();
 251         }
 252
 253         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 254                 if (fault & VM_FAULT_MAJOR) {
 255                         current->maj_flt++;
 256                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
 257                                       1, regs, address);
 258                 } else {
 259                         current->min_flt++;
 260                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
 261                                       1, regs, address);
 262                 }
 263                 if (fault & VM_FAULT_RETRY) {
 264                         flags |= FAULT_FLAG_TRIED;
 265
 266                         /* No need to up_read(&mm->mmap_sem) as we would
 267                          * have already released it in __lock_page_or_retry
 268                          * in mm/filemap.c.
 269                          */
 270
 271                         goto retry;
 272                 }
 273         }
 274
 275         up_read(&mm->mmap_sem);
 276         return;
 277
 278         /*
 279          * Something tried to access memory that isn't in our memory map..
 280          * Fix it, but check if it's kernel or user first..
 281          */
 282 bad_area:
 283         up_read(&mm->mmap_sem);
 284
 285 bad_area_nosemaphore:
 286         /* User mode accesses just cause a SIGSEGV */
 287         if (from_user) {
 288                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 289                 return;
 290         }
 291
 292         /* Is this in ex_table? */
 293 no_context:
 294         g2 = regs->u_regs[UREG_G2];
 295         if (!from_user) {
 296                 fixup = search_extables_range(regs->pc, &g2);
 297                 /* Values below 10 are reserved for other things */
 298                 if (fixup > 10) {
 299                         extern const unsigned int __memset_start[];
 300                         extern const unsigned int __memset_end[];
 301                         extern const unsigned int __csum_partial_copy_start[];
 302                         extern const unsigned int __csum_partial_copy_end[];
 303
 304 #ifdef DEBUG_EXCEPTIONS
 305                         printk("Exception: PC<%08lx> faddr<%08lx>\n",
 306                                regs->pc, address);
 307                         printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
 308                                 regs->pc, fixup, g2);
 309 #endif
 310                         if ((regs->pc >= (unsigned long)__memset_start &&
 311                              regs->pc < (unsigned long)__memset_end) ||
 312                             (regs->pc >= (unsigned long)__csum_partial_copy_start &&
 313                              regs->pc < (unsigned long)__csum_partial_copy_end)) {
 314                                 regs->u_regs[UREG_I4] = address;
 315                                 regs->u_regs[UREG_I5] = regs->pc;
 316                         }
 317                         regs->u_regs[UREG_G2] = g2;
 318                         regs->pc = fixup;
 319                         regs->npc = regs->pc + 4;
 320                         return;
 321                 }
 322         }
 323
 324         unhandled_fault(address, tsk, regs);
 325         do_exit(SIGKILL);
 326
 327 /*
 328  * We ran out of memory, or some other thing happened to us that made
 329  * us unable to handle the page fault gracefully.
 330  */
 331 out_of_memory:
 332         up_read(&mm->mmap_sem);
 333         if (from_user) {
 334                 pagefault_out_of_memory();
 335                 return;
 336         }
 337         goto no_context;
 338
 339 do_sigbus:
 340         up_read(&mm->mmap_sem);
 341         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 342         if (!from_user)
 343                 goto no_context;
 344
 345 vmalloc_fault:
 346         {
 347                 /*
 348                  * Synchronize this task's top level page-table
 349                  * with the 'reference' page table.
 350                  */
 351                 int offset = pgd_index(address);
 352                 pgd_t *pgd, *pgd_k;
 353                 p4d_t *p4d, *p4d_k;
 354                 pud_t *pud, *pud_k;
 355                 pmd_t *pmd, *pmd_k;
 356
 357                 pgd = tsk->active_mm->pgd + offset;
 358                 pgd_k = init_mm.pgd + offset;
 359
 360                 if (!pgd_present(*pgd)) {
 361                         if (!pgd_present(*pgd_k))
 362                                 goto bad_area_nosemaphore;
 363                         pgd_val(*pgd) = pgd_val(*pgd_k);
 364                         return;
 365                 }
 366
 367                 p4d = p4d_offset(pgd, address);
 368                 pud = pud_offset(p4d, address);
 369                 pmd = pmd_offset(pud, address);
 370
 371                 p4d_k = p4d_offset(pgd_k, address);
 372                 pud_k = pud_offset(p4d_k, address);
 373                 pmd_k = pmd_offset(pud_k, address);
 374
 375                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 376                         goto bad_area_nosemaphore;
 377
 378                 *pmd = *pmd_k;
 379                 return;
 380         }
 381 }
 382
 383 /* This always deals with user addresses. */
 384 static void force_user_fault(unsigned long address, int write)
 385 {
 386         struct vm_area_struct *vma;
 387         struct task_struct *tsk = current;
 388         struct mm_struct *mm = tsk->mm;
 389         unsigned int flags = FAULT_FLAG_USER;
 390         int code;
 391
 392         code = SEGV_MAPERR;
 393
 394         down_read(&mm->mmap_sem);
 395         vma = find_vma(mm, address);
 396         if (!vma)
 397                 goto bad_area;
 398         if (vma->vm_start <= address)
 399                 goto good_area;
 400         if (!(vma->vm_flags & VM_GROWSDOWN))
 401                 goto bad_area;
 402         if (expand_stack(vma, address))
 403                 goto bad_area;
 404 good_area:
 405         code = SEGV_ACCERR;
 406         if (write) {
 407                 if (!(vma->vm_flags & VM_WRITE))
 408                         goto bad_area;
 409                 flags |= FAULT_FLAG_WRITE;
 410         } else {
 411                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 412                         goto bad_area;
 413         }
 414         switch (handle_mm_fault(vma, address, flags)) {
 415         case VM_FAULT_SIGBUS:
 416         case VM_FAULT_OOM:
 417                 goto do_sigbus;
 418         }
 419         up_read(&mm->mmap_sem);
 420         return;
 421 bad_area:
 422         up_read(&mm->mmap_sem);
 423         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 424         return;
 425
 426 do_sigbus:
 427         up_read(&mm->mmap_sem);
 428         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 429 }
 430
 431 static void check_stack_aligned(unsigned long sp)
 432 {
 433         if (sp & 0x7UL)
 434                 force_sig(SIGILL);
 435 }
 436
 437 void window_overflow_fault(void)
 438 {
 439         unsigned long sp;
 440
 441         sp = current_thread_info()->rwbuf_stkptrs[0];
 442         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 443                 force_user_fault(sp + 0x38, 1);
 444         force_user_fault(sp, 1);
 445
 446         check_stack_aligned(sp);
 447 }
 448
 449 void window_underflow_fault(unsigned long sp)
 450 {
 451         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 452                 force_user_fault(sp + 0x38, 0);
 453         force_user_fault(sp, 0);
 454
 455         check_stack_aligned(sp);
 456 }
 457
 458 void window_ret_fault(struct pt_regs *regs)
 459 {
 460         unsigned long sp;
 461
 462         sp = regs->u_regs[UREG_FP];
 463         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 464                 force_user_fault(sp + 0x38, 0);
 465         force_user_fault(sp, 0);
 466
 467         check_stack_aligned(sp);
 468 }