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 #include <linux/extable.h>
  27
  28 #include <asm/page.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 static inline void
  59 show_signal_msg(struct pt_regs *regs, int sig, int code,
  60                 unsigned long address, struct task_struct *tsk)
  61 {
  62         if (!unhandled_signal(tsk, sig))
  63                 return;
  64
  65         if (!printk_ratelimit())
  66                 return;
  67
  68         printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
  69                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
  70                tsk->comm, task_pid_nr(tsk), address,
  71                (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
  72                (void *)regs->u_regs[UREG_FP], code);
  73
  74         print_vma_addr(KERN_CONT " in ", regs->pc);
  75
  76         printk(KERN_CONT "\n");
  77 }
  78
  79 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
  80                                unsigned long addr)
  81 {
  82         if (unlikely(show_unhandled_signals))
  83                 show_signal_msg(regs, sig, code,
  84                                 addr, current);
  85
  86         force_sig_fault(sig, code, (void __user *) addr);
  87 }
  88
  89 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
  90 {
  91         unsigned int insn;
  92
  93         if (text_fault)
  94                 return regs->pc;
  95
  96         if (regs->psr & PSR_PS)
  97                 insn = *(unsigned int *) regs->pc;
  98         else
  99                 __get_user(insn, (unsigned int *) regs->pc);
 100
 101         return safe_compute_effective_address(regs, insn);
 102 }
 103
 104 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 105                                       int text_fault)
 106 {
 107         unsigned long addr = compute_si_addr(regs, text_fault);
 108
 109         __do_fault_siginfo(code, sig, regs, addr);
 110 }
 111
 112 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
 113                                unsigned long address)
 114 {
 115         struct vm_area_struct *vma;
 116         struct task_struct *tsk = current;
 117         struct mm_struct *mm = tsk->mm;
 118         int from_user = !(regs->psr & PSR_PS);
 119         int code;
 120         vm_fault_t fault;
 121         unsigned int flags = FAULT_FLAG_DEFAULT;
 122
 123         if (text_fault)
 124                 address = regs->pc;
 125
 126         /*
 127          * We fault-in kernel-space virtual memory on-demand. The
 128          * 'reference' page table is init_mm.pgd.
 129          *
 130          * NOTE! We MUST NOT take any locks for this case. We may
 131          * be in an interrupt or a critical region, and should
 132          * only copy the information from the master page table,
 133          * nothing more.
 134          */
 135         code = SEGV_MAPERR;
 136         if (address >= TASK_SIZE)
 137                 goto vmalloc_fault;
 138
 139         /*
 140          * If we're in an interrupt or have no user
 141          * context, we must not take the fault..
 142          */
 143         if (pagefault_disabled() || !mm)
 144                 goto no_context;
 145
 146         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 147
 148 retry:
 149         mmap_read_lock(mm);
 150
 151         if (!from_user && address >= PAGE_OFFSET)
 152                 goto bad_area;
 153
 154         vma = find_vma(mm, address);
 155         if (!vma)
 156                 goto bad_area;
 157         if (vma->vm_start <= address)
 158                 goto good_area;
 159         if (!(vma->vm_flags & VM_GROWSDOWN))
 160                 goto bad_area;
 161         if (expand_stack(vma, address))
 162                 goto bad_area;
 163         /*
 164          * Ok, we have a good vm_area for this memory access, so
 165          * we can handle it..
 166          */
 167 good_area:
 168         code = SEGV_ACCERR;
 169         if (write) {
 170                 if (!(vma->vm_flags & VM_WRITE))
 171                         goto bad_area;
 172         } else {
 173                 /* Allow reads even for write-only mappings */
 174                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 175                         goto bad_area;
 176         }
 177
 178         if (from_user)
 179                 flags |= FAULT_FLAG_USER;
 180         if (write)
 181                 flags |= FAULT_FLAG_WRITE;
 182
 183         /*
 184          * If for any reason at all we couldn't handle the fault,
 185          * make sure we exit gracefully rather than endlessly redo
 186          * the fault.
 187          */
 188         fault = handle_mm_fault(vma, address, flags, regs);
 189
 190         if (fault_signal_pending(fault, regs))
 191                 return;
 192
 193         if (unlikely(fault & VM_FAULT_ERROR)) {
 194                 if (fault & VM_FAULT_OOM)
 195                         goto out_of_memory;
 196                 else if (fault & VM_FAULT_SIGSEGV)
 197                         goto bad_area;
 198                 else if (fault & VM_FAULT_SIGBUS)
 199                         goto do_sigbus;
 200                 BUG();
 201         }
 202
 203         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 204                 if (fault & VM_FAULT_RETRY) {
 205                         flags |= FAULT_FLAG_TRIED;
 206
 207                         /* No need to mmap_read_unlock(mm) as we would
 208                          * have already released it in __lock_page_or_retry
 209                          * in mm/filemap.c.
 210                          */
 211
 212                         goto retry;
 213                 }
 214         }
 215
 216         mmap_read_unlock(mm);
 217         return;
 218
 219         /*
 220          * Something tried to access memory that isn't in our memory map..
 221          * Fix it, but check if it's kernel or user first..
 222          */
 223 bad_area:
 224         mmap_read_unlock(mm);
 225
 226 bad_area_nosemaphore:
 227         /* User mode accesses just cause a SIGSEGV */
 228         if (from_user) {
 229                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 230                 return;
 231         }
 232
 233         /* Is this in ex_table? */
 234 no_context:
 235         if (!from_user) {
 236                 const struct exception_table_entry *entry;
 237
 238                 entry = search_exception_tables(regs->pc);
 239 #ifdef DEBUG_EXCEPTIONS
 240                 printk("Exception: PC<%08lx> faddr<%08lx>\n",
 241                        regs->pc, address);
 242                 printk("EX_TABLE: insn<%08lx> fixup<%08x>\n",
 243                         regs->pc, entry->fixup);
 244 #endif
 245                 regs->pc = entry->fixup;
 246                 regs->npc = regs->pc + 4;
 247                 return;
 248         }
 249
 250         unhandled_fault(address, tsk, regs);
 251         do_exit(SIGKILL);
 252
 253 /*
 254  * We ran out of memory, or some other thing happened to us that made
 255  * us unable to handle the page fault gracefully.
 256  */
 257 out_of_memory:
 258         mmap_read_unlock(mm);
 259         if (from_user) {
 260                 pagefault_out_of_memory();
 261                 return;
 262         }
 263         goto no_context;
 264
 265 do_sigbus:
 266         mmap_read_unlock(mm);
 267         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 268         if (!from_user)
 269                 goto no_context;
 270
 271 vmalloc_fault:
 272         {
 273                 /*
 274                  * Synchronize this task's top level page-table
 275                  * with the 'reference' page table.
 276                  */
 277                 int offset = pgd_index(address);
 278                 pgd_t *pgd, *pgd_k;
 279                 p4d_t *p4d, *p4d_k;
 280                 pud_t *pud, *pud_k;
 281                 pmd_t *pmd, *pmd_k;
 282
 283                 pgd = tsk->active_mm->pgd + offset;
 284                 pgd_k = init_mm.pgd + offset;
 285
 286                 if (!pgd_present(*pgd)) {
 287                         if (!pgd_present(*pgd_k))
 288                                 goto bad_area_nosemaphore;
 289                         pgd_val(*pgd) = pgd_val(*pgd_k);
 290                         return;
 291                 }
 292
 293                 p4d = p4d_offset(pgd, address);
 294                 pud = pud_offset(p4d, address);
 295                 pmd = pmd_offset(pud, address);
 296
 297                 p4d_k = p4d_offset(pgd_k, address);
 298                 pud_k = pud_offset(p4d_k, address);
 299                 pmd_k = pmd_offset(pud_k, address);
 300
 301                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 302                         goto bad_area_nosemaphore;
 303
 304                 *pmd = *pmd_k;
 305                 return;
 306         }
 307 }
 308
 309 /* This always deals with user addresses. */
 310 static void force_user_fault(unsigned long address, int write)
 311 {
 312         struct vm_area_struct *vma;
 313         struct task_struct *tsk = current;
 314         struct mm_struct *mm = tsk->mm;
 315         unsigned int flags = FAULT_FLAG_USER;
 316         int code;
 317
 318         code = SEGV_MAPERR;
 319
 320         mmap_read_lock(mm);
 321         vma = find_vma(mm, address);
 322         if (!vma)
 323                 goto bad_area;
 324         if (vma->vm_start <= address)
 325                 goto good_area;
 326         if (!(vma->vm_flags & VM_GROWSDOWN))
 327                 goto bad_area;
 328         if (expand_stack(vma, address))
 329                 goto bad_area;
 330 good_area:
 331         code = SEGV_ACCERR;
 332         if (write) {
 333                 if (!(vma->vm_flags & VM_WRITE))
 334                         goto bad_area;
 335                 flags |= FAULT_FLAG_WRITE;
 336         } else {
 337                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 338                         goto bad_area;
 339         }
 340         switch (handle_mm_fault(vma, address, flags, NULL)) {
 341         case VM_FAULT_SIGBUS:
 342         case VM_FAULT_OOM:
 343                 goto do_sigbus;
 344         }
 345         mmap_read_unlock(mm);
 346         return;
 347 bad_area:
 348         mmap_read_unlock(mm);
 349         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 350         return;
 351
 352 do_sigbus:
 353         mmap_read_unlock(mm);
 354         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 355 }
 356
 357 static void check_stack_aligned(unsigned long sp)
 358 {
 359         if (sp & 0x7UL)
 360                 force_sig(SIGILL);
 361 }
 362
 363 void window_overflow_fault(void)
 364 {
 365         unsigned long sp;
 366
 367         sp = current_thread_info()->rwbuf_stkptrs[0];
 368         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 369                 force_user_fault(sp + 0x38, 1);
 370         force_user_fault(sp, 1);
 371
 372         check_stack_aligned(sp);
 373 }
 374
 375 void window_underflow_fault(unsigned long sp)
 376 {
 377         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 378                 force_user_fault(sp + 0x38, 0);
 379         force_user_fault(sp, 0);
 380
 381         check_stack_aligned(sp);
 382 }
 383
 384 void window_ret_fault(struct pt_regs *regs)
 385 {
 386         unsigned long sp;
 387
 388         sp = regs->u_regs[UREG_FP];
 389         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 390                 force_user_fault(sp + 0x38, 0);
 391         force_user_fault(sp, 0);
 392
 393         check_stack_aligned(sp);
 394 }