arch/sparc/mm/fault

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This source file includes following definitions.
unhandled_fault
bad_kernel_pc
get_user_insn
show_signal_msg
do_fault_siginfo
get_fault_insn
do_kernel_fault
bogus_32bit_fault_tpc
do_sparc64_fault
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
   4  *
   5  * Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
   6  * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz)
   7  */
   8 
   9 #include <asm/head.h>
  10 
  11 #include <linux/string.h>
  12 #include <linux/types.h>
  13 #include <linux/sched.h>
  14 #include <linux/sched/debug.h>
  15 #include <linux/ptrace.h>
  16 #include <linux/mman.h>
  17 #include <linux/signal.h>
  18 #include <linux/mm.h>
  19 #include <linux/extable.h>
  20 #include <linux/init.h>
  21 #include <linux/perf_event.h>
  22 #include <linux/interrupt.h>
  23 #include <linux/kprobes.h>
  24 #include <linux/kdebug.h>
  25 #include <linux/percpu.h>
  26 #include <linux/context_tracking.h>
  27 #include <linux/uaccess.h>
  28 
  29 #include <asm/page.h>
  30 #include <asm/pgtable.h>
  31 #include <asm/openprom.h>
  32 #include <asm/oplib.h>
  33 #include <asm/asi.h>
  34 #include <asm/lsu.h>
  35 #include <asm/sections.h>
  36 #include <asm/mmu_context.h>
  37 #include <asm/setup.h>
  38 
  39 int show_unhandled_signals = 1;
  40 
  41 static void __kprobes unhandled_fault(unsigned long address,
  42                                       struct task_struct *tsk,
  43                                       struct pt_regs *regs)
  44 {
  45         if ((unsigned long) address < PAGE_SIZE) {
  46                 printk(KERN_ALERT "Unable to handle kernel NULL "
  47                        "pointer dereference\n");
  48         } else {
  49                 printk(KERN_ALERT "Unable to handle kernel paging request "
  50                        "at virtual address %016lx\n", (unsigned long)address);
  51         }
  52         printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",
  53                (tsk->mm ?
  54                 CTX_HWBITS(tsk->mm->context) :
  55                 CTX_HWBITS(tsk->active_mm->context)));
  56         printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
  57                (tsk->mm ? (unsigned long) tsk->mm->pgd :
  58                           (unsigned long) tsk->active_mm->pgd));
  59         die_if_kernel("Oops", regs);
  60 }
  61 
  62 static void __kprobes bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr)
  63 {
  64         printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
  65                regs->tpc);
  66         printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]);
  67         printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]);
  68         printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr);
  69         dump_stack();
  70         unhandled_fault(regs->tpc, current, regs);
  71 }
  72 
  73 /*
  74  * We now make sure that mmap_sem is held in all paths that call 
  75  * this. Additionally, to prevent kswapd from ripping ptes from
  76  * under us, raise interrupts around the time that we look at the
  77  * pte, kswapd will have to wait to get his smp ipi response from
  78  * us. vmtruncate likewise. This saves us having to get pte lock.
  79  */
  80 static unsigned int get_user_insn(unsigned long tpc)
  81 {
  82         pgd_t *pgdp = pgd_offset(current->mm, tpc);
  83         pud_t *pudp;
  84         pmd_t *pmdp;
  85         pte_t *ptep, pte;
  86         unsigned long pa;
  87         u32 insn = 0;
  88 
  89         if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp)))
  90                 goto out;
  91         pudp = pud_offset(pgdp, tpc);
  92         if (pud_none(*pudp) || unlikely(pud_bad(*pudp)))
  93                 goto out;
  94 
  95         /* This disables preemption for us as well. */
  96         local_irq_disable();
  97 
  98         pmdp = pmd_offset(pudp, tpc);
  99         if (pmd_none(*pmdp) || unlikely(pmd_bad(*pmdp)))
 100                 goto out_irq_enable;
 101 
 102 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 103         if (is_hugetlb_pmd(*pmdp)) {
 104                 pa  = pmd_pfn(*pmdp) << PAGE_SHIFT;
 105                 pa += tpc & ~HPAGE_MASK;
 106 
 107                 /* Use phys bypass so we don't pollute dtlb/dcache. */
 108                 __asm__ __volatile__("lduwa [%1] %2, %0"
 109                                      : "=r" (insn)
 110                                      : "r" (pa), "i" (ASI_PHYS_USE_EC));
 111         } else
 112 #endif
 113         {
 114                 ptep = pte_offset_map(pmdp, tpc);
 115                 pte = *ptep;
 116                 if (pte_present(pte)) {
 117                         pa  = (pte_pfn(pte) << PAGE_SHIFT);
 118                         pa += (tpc & ~PAGE_MASK);
 119 
 120                         /* Use phys bypass so we don't pollute dtlb/dcache. */
 121                         __asm__ __volatile__("lduwa [%1] %2, %0"
 122                                              : "=r" (insn)
 123                                              : "r" (pa), "i" (ASI_PHYS_USE_EC));
 124                 }
 125                 pte_unmap(ptep);
 126         }
 127 out_irq_enable:
 128         local_irq_enable();
 129 out:
 130         return insn;
 131 }
 132 
 133 static inline void
 134 show_signal_msg(struct pt_regs *regs, int sig, int code,
 135                 unsigned long address, struct task_struct *tsk)
 136 {
 137         if (!unhandled_signal(tsk, sig))
 138                 return;
 139 
 140         if (!printk_ratelimit())
 141                 return;
 142 
 143         printk("%s%s[%d]: segfault at %lx ip %px (rpc %px) sp %px error %x",
 144                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 145                tsk->comm, task_pid_nr(tsk), address,
 146                (void *)regs->tpc, (void *)regs->u_regs[UREG_I7],
 147                (void *)regs->u_regs[UREG_FP], code);
 148 
 149         print_vma_addr(KERN_CONT " in ", regs->tpc);
 150 
 151         printk(KERN_CONT "\n");
 152 }
 153 
 154 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
 155                              unsigned long fault_addr, unsigned int insn,
 156                              int fault_code)
 157 {
 158         unsigned long addr;
 159 
 160         if (fault_code & FAULT_CODE_ITLB) {
 161                 addr = regs->tpc;
 162         } else {
 163                 /* If we were able to probe the faulting instruction, use it
 164                  * to compute a precise fault address.  Otherwise use the fault
 165                  * time provided address which may only have page granularity.
 166                  */
 167                 if (insn)
 168                         addr = compute_effective_address(regs, insn, 0);
 169                 else
 170                         addr = fault_addr;
 171         }
 172 
 173         if (unlikely(show_unhandled_signals))
 174                 show_signal_msg(regs, sig, code, addr, current);
 175 
 176         force_sig_fault(sig, code, (void __user *) addr, 0);
 177 }
 178 
 179 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
 180 {
 181         if (!insn) {
 182                 if (!regs->tpc || (regs->tpc & 0x3))
 183                         return 0;
 184                 if (regs->tstate & TSTATE_PRIV) {
 185                         insn = *(unsigned int *) regs->tpc;
 186                 } else {
 187                         insn = get_user_insn(regs->tpc);
 188                 }
 189         }
 190         return insn;
 191 }
 192 
 193 static void __kprobes do_kernel_fault(struct pt_regs *regs, int si_code,
 194                                       int fault_code, unsigned int insn,
 195                                       unsigned long address)
 196 {
 197         unsigned char asi = ASI_P;
 198  
 199         if ((!insn) && (regs->tstate & TSTATE_PRIV))
 200                 goto cannot_handle;
 201 
 202         /* If user insn could be read (thus insn is zero), that
 203          * is fine.  We will just gun down the process with a signal
 204          * in that case.
 205          */
 206 
 207         if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) &&
 208             (insn & 0xc0800000) == 0xc0800000) {
 209                 if (insn & 0x2000)
 210                         asi = (regs->tstate >> 24);
 211                 else
 212                         asi = (insn >> 5);
 213                 if ((asi & 0xf2) == 0x82) {
 214                         if (insn & 0x1000000) {
 215                                 handle_ldf_stq(insn, regs);
 216                         } else {
 217                                 /* This was a non-faulting load. Just clear the
 218                                  * destination register(s) and continue with the next
 219                                  * instruction. -jj
 220                                  */
 221                                 handle_ld_nf(insn, regs);
 222                         }
 223                         return;
 224                 }
 225         }
 226                 
 227         /* Is this in ex_table? */
 228         if (regs->tstate & TSTATE_PRIV) {
 229                 const struct exception_table_entry *entry;
 230 
 231                 entry = search_exception_tables(regs->tpc);
 232                 if (entry) {
 233                         regs->tpc = entry->fixup;
 234                         regs->tnpc = regs->tpc + 4;
 235                         return;
 236                 }
 237         } else {
 238                 /* The si_code was set to make clear whether
 239                  * this was a SEGV_MAPERR or SEGV_ACCERR fault.
 240                  */
 241                 do_fault_siginfo(si_code, SIGSEGV, regs, address, insn, fault_code);
 242                 return;
 243         }
 244 
 245 cannot_handle:
 246         unhandled_fault (address, current, regs);
 247 }
 248 
 249 static void noinline __kprobes bogus_32bit_fault_tpc(struct pt_regs *regs)
 250 {
 251         static int times;
 252 
 253         if (times++ < 10)
 254                 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports "
 255                        "64-bit TPC [%lx]\n",
 256                        current->comm, current->pid,
 257                        regs->tpc);
 258         show_regs(regs);
 259 }
 260 
 261 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
 262 {
 263         enum ctx_state prev_state = exception_enter();
 264         struct mm_struct *mm = current->mm;
 265         struct vm_area_struct *vma;
 266         unsigned int insn = 0;
 267         int si_code, fault_code;
 268         vm_fault_t fault;
 269         unsigned long address, mm_rss;
 270         unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 271 
 272         fault_code = get_thread_fault_code();
 273 
 274         if (kprobe_page_fault(regs, 0))
 275                 goto exit_exception;
 276 
 277         si_code = SEGV_MAPERR;
 278         address = current_thread_info()->fault_address;
 279 
 280         if ((fault_code & FAULT_CODE_ITLB) &&
 281             (fault_code & FAULT_CODE_DTLB))
 282                 BUG();
 283 
 284         if (test_thread_flag(TIF_32BIT)) {
 285                 if (!(regs->tstate & TSTATE_PRIV)) {
 286                         if (unlikely((regs->tpc >> 32) != 0)) {
 287                                 bogus_32bit_fault_tpc(regs);
 288                                 goto intr_or_no_mm;
 289                         }
 290                 }
 291                 if (unlikely((address >> 32) != 0))
 292                         goto intr_or_no_mm;
 293         }
 294 
 295         if (regs->tstate & TSTATE_PRIV) {
 296                 unsigned long tpc = regs->tpc;
 297 
 298                 /* Sanity check the PC. */
 299                 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) ||
 300                     (tpc >= MODULES_VADDR && tpc < MODULES_END)) {
 301                         /* Valid, no problems... */
 302                 } else {
 303                         bad_kernel_pc(regs, address);
 304                         goto exit_exception;
 305                 }
 306         } else
 307                 flags |= FAULT_FLAG_USER;
 308 
 309         /*
 310          * If we're in an interrupt or have no user
 311          * context, we must not take the fault..
 312          */
 313         if (faulthandler_disabled() || !mm)
 314                 goto intr_or_no_mm;
 315 
 316         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
 317 
 318         if (!down_read_trylock(&mm->mmap_sem)) {
 319                 if ((regs->tstate & TSTATE_PRIV) &&
 320                     !search_exception_tables(regs->tpc)) {
 321                         insn = get_fault_insn(regs, insn);
 322                         goto handle_kernel_fault;
 323                 }
 324 
 325 retry:
 326                 down_read(&mm->mmap_sem);
 327         }
 328 
 329         if (fault_code & FAULT_CODE_BAD_RA)
 330                 goto do_sigbus;
 331 
 332         vma = find_vma(mm, address);
 333         if (!vma)
 334                 goto bad_area;
 335 
 336         /* Pure DTLB misses do not tell us whether the fault causing
 337          * load/store/atomic was a write or not, it only says that there
 338          * was no match.  So in such a case we (carefully) read the
 339          * instruction to try and figure this out.  It's an optimization
 340          * so it's ok if we can't do this.
 341          *
 342          * Special hack, window spill/fill knows the exact fault type.
 343          */
 344         if (((fault_code &
 345               (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&
 346             (vma->vm_flags & VM_WRITE) != 0) {
 347                 insn = get_fault_insn(regs, 0);
 348                 if (!insn)
 349                         goto continue_fault;
 350                 /* All loads, stores and atomics have bits 30 and 31 both set
 351                  * in the instruction.  Bit 21 is set in all stores, but we
 352                  * have to avoid prefetches which also have bit 21 set.
 353                  */
 354                 if ((insn & 0xc0200000) == 0xc0200000 &&
 355                     (insn & 0x01780000) != 0x01680000) {
 356                         /* Don't bother updating thread struct value,
 357                          * because update_mmu_cache only cares which tlb
 358                          * the access came from.
 359                          */
 360                         fault_code |= FAULT_CODE_WRITE;
 361                 }
 362         }
 363 continue_fault:
 364 
 365         if (vma->vm_start <= address)
 366                 goto good_area;
 367         if (!(vma->vm_flags & VM_GROWSDOWN))
 368                 goto bad_area;
 369         if (!(fault_code & FAULT_CODE_WRITE)) {
 370                 /* Non-faulting loads shouldn't expand stack. */
 371                 insn = get_fault_insn(regs, insn);
 372                 if ((insn & 0xc0800000) == 0xc0800000) {
 373                         unsigned char asi;
 374 
 375                         if (insn & 0x2000)
 376                                 asi = (regs->tstate >> 24);
 377                         else
 378                                 asi = (insn >> 5);
 379                         if ((asi & 0xf2) == 0x82)
 380                                 goto bad_area;
 381                 }
 382         }
 383         if (expand_stack(vma, address))
 384                 goto bad_area;
 385         /*
 386          * Ok, we have a good vm_area for this memory access, so
 387          * we can handle it..
 388          */
 389 good_area:
 390         si_code = SEGV_ACCERR;
 391 
 392         /* If we took a ITLB miss on a non-executable page, catch
 393          * that here.
 394          */
 395         if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
 396                 WARN(address != regs->tpc,
 397                      "address (%lx) != regs->tpc (%lx)\n", address, regs->tpc);
 398                 WARN_ON(regs->tstate & TSTATE_PRIV);
 399                 goto bad_area;
 400         }
 401 
 402         if (fault_code & FAULT_CODE_WRITE) {
 403                 if (!(vma->vm_flags & VM_WRITE))
 404                         goto bad_area;
 405 
 406                 /* Spitfire has an icache which does not snoop
 407                  * processor stores.  Later processors do...
 408                  */
 409                 if (tlb_type == spitfire &&
 410                     (vma->vm_flags & VM_EXEC) != 0 &&
 411                     vma->vm_file != NULL)
 412                         set_thread_fault_code(fault_code |
 413                                               FAULT_CODE_BLKCOMMIT);
 414 
 415                 flags |= FAULT_FLAG_WRITE;
 416         } else {
 417                 /* Allow reads even for write-only mappings */
 418                 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
 419                         goto bad_area;
 420         }
 421 
 422         fault = handle_mm_fault(vma, address, flags);
 423 
 424         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 425                 goto exit_exception;
 426 
 427         if (unlikely(fault & VM_FAULT_ERROR)) {
 428                 if (fault & VM_FAULT_OOM)
 429                         goto out_of_memory;
 430                 else if (fault & VM_FAULT_SIGSEGV)
 431                         goto bad_area;
 432                 else if (fault & VM_FAULT_SIGBUS)
 433                         goto do_sigbus;
 434                 BUG();
 435         }
 436 
 437         if (flags & FAULT_FLAG_ALLOW_RETRY) {
 438                 if (fault & VM_FAULT_MAJOR) {
 439                         current->maj_flt++;
 440                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
 441                                       1, regs, address);
 442                 } else {
 443                         current->min_flt++;
 444                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
 445                                       1, regs, address);
 446                 }
 447                 if (fault & VM_FAULT_RETRY) {
 448                         flags &= ~FAULT_FLAG_ALLOW_RETRY;
 449                         flags |= FAULT_FLAG_TRIED;
 450 
 451                         /* No need to up_read(&mm->mmap_sem) as we would
 452                          * have already released it in __lock_page_or_retry
 453                          * in mm/filemap.c.
 454                          */
 455 
 456                         goto retry;
 457                 }
 458         }
 459         up_read(&mm->mmap_sem);
 460 
 461         mm_rss = get_mm_rss(mm);
 462 #if defined(CONFIG_TRANSPARENT_HUGEPAGE)
 463         mm_rss -= (mm->context.thp_pte_count * (HPAGE_SIZE / PAGE_SIZE));
 464 #endif
 465         if (unlikely(mm_rss >
 466                      mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit))
 467                 tsb_grow(mm, MM_TSB_BASE, mm_rss);
 468 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 469         mm_rss = mm->context.hugetlb_pte_count + mm->context.thp_pte_count;
 470         mm_rss *= REAL_HPAGE_PER_HPAGE;
 471         if (unlikely(mm_rss >
 472                      mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) {
 473                 if (mm->context.tsb_block[MM_TSB_HUGE].tsb)
 474                         tsb_grow(mm, MM_TSB_HUGE, mm_rss);
 475                 else
 476                         hugetlb_setup(regs);
 477 
 478         }
 479 #endif
 480 exit_exception:
 481         exception_exit(prev_state);
 482         return;
 483 
 484         /*
 485          * Something tried to access memory that isn't in our memory map..
 486          * Fix it, but check if it's kernel or user first..
 487          */
 488 bad_area:
 489         insn = get_fault_insn(regs, insn);
 490         up_read(&mm->mmap_sem);
 491 
 492 handle_kernel_fault:
 493         do_kernel_fault(regs, si_code, fault_code, insn, address);
 494         goto exit_exception;
 495 
 496 /*
 497  * We ran out of memory, or some other thing happened to us that made
 498  * us unable to handle the page fault gracefully.
 499  */
 500 out_of_memory:
 501         insn = get_fault_insn(regs, insn);
 502         up_read(&mm->mmap_sem);
 503         if (!(regs->tstate & TSTATE_PRIV)) {
 504                 pagefault_out_of_memory();
 505                 goto exit_exception;
 506         }
 507         goto handle_kernel_fault;
 508 
 509 intr_or_no_mm:
 510         insn = get_fault_insn(regs, 0);
 511         goto handle_kernel_fault;
 512 
 513 do_sigbus:
 514         insn = get_fault_insn(regs, insn);
 515         up_read(&mm->mmap_sem);
 516 
 517         /*
 518          * Send a sigbus, regardless of whether we were in kernel
 519          * or user mode.
 520          */
 521         do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, address, insn, fault_code);
 522 
 523         /* Kernel mode? Handle exceptions or die */
 524         if (regs->tstate & TSTATE_PRIV)
 525                 goto handle_kernel_fault;
 526 }
/* [<][>][^][v][top][bottom][index][help] */
root/arch/sparc/mm/fault_64.c

DEFINITIONS
