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