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         if (!from_user && address >= PAGE_OFFSET)
 147                 goto no_context;
 148
 149         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 150
 151 retry:
 152         vma = lock_mm_and_find_vma(mm, address, regs);
 153         if (!vma)
 154                 goto bad_area_nosemaphore;
 155         /*
 156          * Ok, we have a good vm_area for this memory access, so
 157          * we can handle it..
 158          */
 159         code = SEGV_ACCERR;
 160         if (write) {
 161                 if (!(vma->vm_flags & VM_WRITE))
 162                         goto bad_area;
 163         } else {
 164                 /* Allow reads even for write-only mappings */
 165                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 166                         goto bad_area;
 167         }
 168
 169         if (from_user)
 170                 flags |= FAULT_FLAG_USER;
 171         if (write)
 172                 flags |= FAULT_FLAG_WRITE;
 173
 174         /*
 175          * If for any reason at all we couldn't handle the fault,
 176          * make sure we exit gracefully rather than endlessly redo
 177          * the fault.
 178          */
 179         fault = handle_mm_fault(vma, address, flags, regs);
 180
 181         if (fault_signal_pending(fault, regs)) {
 182                 if (!from_user)
 183                         goto no_context;
 184                 return;
 185         }
 186
 187         /* The fault is fully completed (including releasing mmap lock) */
 188         if (fault & VM_FAULT_COMPLETED)
 189                 return;
 190
 191         if (unlikely(fault & VM_FAULT_ERROR)) {
 192                 if (fault & VM_FAULT_OOM)
 193                         goto out_of_memory;
 194                 else if (fault & VM_FAULT_SIGSEGV)
 195                         goto bad_area;
 196                 else if (fault & VM_FAULT_SIGBUS)
 197                         goto do_sigbus;
 198                 BUG();
 199         }
 200
 201         if (fault & VM_FAULT_RETRY) {
 202                 flags |= FAULT_FLAG_TRIED;
 203
 204                 /* No need to mmap_read_unlock(mm) as we would
 205                  * have already released it in __lock_page_or_retry
 206                  * in mm/filemap.c.
 207                  */
 208
 209                 goto retry;
 210         }
 211
 212         mmap_read_unlock(mm);
 213         return;
 214
 215         /*
 216          * Something tried to access memory that isn't in our memory map..
 217          * Fix it, but check if it's kernel or user first..
 218          */
 219 bad_area:
 220         mmap_read_unlock(mm);
 221
 222 bad_area_nosemaphore:
 223         /* User mode accesses just cause a SIGSEGV */
 224         if (from_user) {
 225                 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
 226                 return;
 227         }
 228
 229         /* Is this in ex_table? */
 230 no_context:
 231         if (!from_user) {
 232                 const struct exception_table_entry *entry;
 233
 234                 entry = search_exception_tables(regs->pc);
 235 #ifdef DEBUG_EXCEPTIONS
 236                 printk("Exception: PC<%08lx> faddr<%08lx>\n",
 237                        regs->pc, address);
 238                 printk("EX_TABLE: insn<%08lx> fixup<%08x>\n",
 239                         regs->pc, entry->fixup);
 240 #endif
 241                 regs->pc = entry->fixup;
 242                 regs->npc = regs->pc + 4;
 243                 return;
 244         }
 245
 246         unhandled_fault(address, tsk, regs);
 247
 248 /*
 249  * We ran out of memory, or some other thing happened to us that made
 250  * us unable to handle the page fault gracefully.
 251  */
 252 out_of_memory:
 253         mmap_read_unlock(mm);
 254         if (from_user) {
 255                 pagefault_out_of_memory();
 256                 return;
 257         }
 258         goto no_context;
 259
 260 do_sigbus:
 261         mmap_read_unlock(mm);
 262         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
 263         if (!from_user)
 264                 goto no_context;
 265
 266 vmalloc_fault:
 267         {
 268                 /*
 269                  * Synchronize this task's top level page-table
 270                  * with the 'reference' page table.
 271                  */
 272                 int offset = pgd_index(address);
 273                 pgd_t *pgd, *pgd_k;
 274                 p4d_t *p4d, *p4d_k;
 275                 pud_t *pud, *pud_k;
 276                 pmd_t *pmd, *pmd_k;
 277
 278                 pgd = tsk->active_mm->pgd + offset;
 279                 pgd_k = init_mm.pgd + offset;
 280
 281                 if (!pgd_present(*pgd)) {
 282                         if (!pgd_present(*pgd_k))
 283                                 goto bad_area_nosemaphore;
 284                         pgd_val(*pgd) = pgd_val(*pgd_k);
 285                         return;
 286                 }
 287
 288                 p4d = p4d_offset(pgd, address);
 289                 pud = pud_offset(p4d, address);
 290                 pmd = pmd_offset(pud, address);
 291
 292                 p4d_k = p4d_offset(pgd_k, address);
 293                 pud_k = pud_offset(p4d_k, address);
 294                 pmd_k = pmd_offset(pud_k, address);
 295
 296                 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
 297                         goto bad_area_nosemaphore;
 298
 299                 *pmd = *pmd_k;
 300                 return;
 301         }
 302 }
 303
 304 /* This always deals with user addresses. */
 305 static void force_user_fault(unsigned long address, int write)
 306 {
 307         struct vm_area_struct *vma;
 308         struct task_struct *tsk = current;
 309         struct mm_struct *mm = tsk->mm;
 310         unsigned int flags = FAULT_FLAG_USER;
 311         int code;
 312
 313         code = SEGV_MAPERR;
 314
 315         vma = lock_mm_and_find_vma(mm, address, NULL);
 316         if (!vma)
 317                 goto bad_area_nosemaphore;
 318         code = SEGV_ACCERR;
 319         if (write) {
 320                 if (!(vma->vm_flags & VM_WRITE))
 321                         goto bad_area;
 322                 flags |= FAULT_FLAG_WRITE;
 323         } else {
 324                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 325                         goto bad_area;
 326         }
 327         switch (handle_mm_fault(vma, address, flags, NULL)) {
 328         case VM_FAULT_SIGBUS:
 329         case VM_FAULT_OOM:
 330                 goto do_sigbus;
 331         }
 332         mmap_read_unlock(mm);
 333         return;
 334 bad_area:
 335         mmap_read_unlock(mm);
 336 bad_area_nosemaphore:
 337         __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
 338         return;
 339
 340 do_sigbus:
 341         mmap_read_unlock(mm);
 342         __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
 343 }
 344
 345 static void check_stack_aligned(unsigned long sp)
 346 {
 347         if (sp & 0x7UL)
 348                 force_sig(SIGILL);
 349 }
 350
 351 void window_overflow_fault(void)
 352 {
 353         unsigned long sp;
 354
 355         sp = current_thread_info()->rwbuf_stkptrs[0];
 356         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 357                 force_user_fault(sp + 0x38, 1);
 358         force_user_fault(sp, 1);
 359
 360         check_stack_aligned(sp);
 361 }
 362
 363 void window_underflow_fault(unsigned long sp)
 364 {
 365         if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
 366                 force_user_fault(sp + 0x38, 0);
 367         force_user_fault(sp, 0);
 368
 369         check_stack_aligned(sp);
 370 }
 371
 372 void window_ret_fault(struct pt_regs *regs)
 373 {
 374         unsigned long sp;
 375
 376         sp = regs->u_regs[UREG_FP];
 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 }