1/* $Id: fault.c,v 1.1.1.1 2007/08/03 18:52:19 Exp $ 2 * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc. 3 * 4 * Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu) 5 * Copyright (C) 1997, 1999 Jakub Jelinek (jj@ultra.linux.cz) 6 */ 7 8#include <asm/head.h> 9 10#include <linux/string.h> 11#include <linux/types.h> 12#include <linux/sched.h> 13#include <linux/ptrace.h> 14#include <linux/mman.h> 15#include <linux/signal.h> 16#include <linux/mm.h> 17#include <linux/module.h> 18#include <linux/init.h> 19#include <linux/interrupt.h> 20#include <linux/kprobes.h> 21#include <linux/kallsyms.h> 22#include <linux/kdebug.h> 23 24#include <asm/page.h> 25#include <asm/pgtable.h> 26#include <asm/openprom.h> 27#include <asm/oplib.h> 28#include <asm/uaccess.h> 29#include <asm/asi.h> 30#include <asm/lsu.h> 31#include <asm/sections.h> 32#include <asm/mmu_context.h> 33 34#ifdef CONFIG_KPROBES 35static inline int notify_page_fault(struct pt_regs *regs) 36{ 37 int ret = 0; 38 39 /* kprobe_running() needs smp_processor_id() */ 40 if (!user_mode(regs)) { 41 preempt_disable(); 42 if (kprobe_running() && kprobe_fault_handler(regs, 0)) 43 ret = 1; 44 preempt_enable(); 45 } 46 return ret; 47} 48#else 49static inline int notify_page_fault(struct pt_regs *regs) 50{ 51 return 0; 52} 53#endif 54 55/* 56 * To debug kernel to catch accesses to certain virtual/physical addresses. 57 * Mode = 0 selects physical watchpoints, mode = 1 selects virtual watchpoints. 58 * flags = VM_READ watches memread accesses, flags = VM_WRITE watches memwrite accesses. 59 * Caller passes in a 64bit aligned addr, with mask set to the bytes that need to be 60 * watched. This is only useful on a single cpu machine for now. After the watchpoint 61 * is detected, the process causing it will be killed, thus preventing an infinite loop. 62 */ 63void set_brkpt(unsigned long addr, unsigned char mask, int flags, int mode) 64{ 65 unsigned long lsubits; 66 67 __asm__ __volatile__("ldxa [%%g0] %1, %0" 68 : "=r" (lsubits) 69 : "i" (ASI_LSU_CONTROL)); 70 lsubits &= ~(LSU_CONTROL_PM | LSU_CONTROL_VM | 71 LSU_CONTROL_PR | LSU_CONTROL_VR | 72 LSU_CONTROL_PW | LSU_CONTROL_VW); 73 74 __asm__ __volatile__("stxa %0, [%1] %2\n\t" 75 "membar #Sync" 76 : /* no outputs */ 77 : "r" (addr), "r" (mode ? VIRT_WATCHPOINT : PHYS_WATCHPOINT), 78 "i" (ASI_DMMU)); 79 80 lsubits |= ((unsigned long)mask << (mode ? 25 : 33)); 81 if (flags & VM_READ) 82 lsubits |= (mode ? LSU_CONTROL_VR : LSU_CONTROL_PR); 83 if (flags & VM_WRITE) 84 lsubits |= (mode ? LSU_CONTROL_VW : LSU_CONTROL_PW); 85 __asm__ __volatile__("stxa %0, [%%g0] %1\n\t" 86 "membar #Sync" 87 : /* no outputs */ 88 : "r" (lsubits), "i" (ASI_LSU_CONTROL) 89 : "memory"); 90} 91 92static void __kprobes unhandled_fault(unsigned long address, 93 struct task_struct *tsk, 94 struct pt_regs *regs) 95{ 96 if ((unsigned long) address < PAGE_SIZE) { 97 printk(KERN_ALERT "Unable to handle kernel NULL " 98 "pointer dereference\n"); 99 } else { 100 printk(KERN_ALERT "Unable to handle kernel paging request " 101 "at virtual address %016lx\n", (unsigned long)address); 102 } 103 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n", 104 (tsk->mm ? 105 CTX_HWBITS(tsk->mm->context) : 106 CTX_HWBITS(tsk->active_mm->context))); 107 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n", 108 (tsk->mm ? (unsigned long) tsk->mm->pgd : 109 (unsigned long) tsk->active_mm->pgd)); 110 die_if_kernel("Oops", regs); 111} 112 113static void bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr) 114{ 115 unsigned long *ksp; 116 117 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n", 118 regs->tpc); 119 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]); 120 print_symbol("RPC: <%s>\n", regs->u_regs[15]); 121 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr); 122 __asm__("mov %%sp, %0" : "=r" (ksp)); 123 show_stack(current, ksp); 124 unhandled_fault(regs->tpc, current, regs); 125} 126 127/* 128 * We now make sure that mmap_sem is held in all paths that call 129 * this. Additionally, to prevent kswapd from ripping ptes from 130 * under us, raise interrupts around the time that we look at the 131 * pte, kswapd will have to wait to get his smp ipi response from 132 * us. vmtruncate likewise. This saves us having to get pte lock. 133 */ 134static unsigned int get_user_insn(unsigned long tpc) 135{ 136 pgd_t *pgdp = pgd_offset(current->mm, tpc); 137 pud_t *pudp; 138 pmd_t *pmdp; 139 pte_t *ptep, pte; 140 unsigned long pa; 141 u32 insn = 0; 142 unsigned long pstate; 143 144 if (pgd_none(*pgdp)) 145 goto outret; 146 pudp = pud_offset(pgdp, tpc); 147 if (pud_none(*pudp)) 148 goto outret; 149 pmdp = pmd_offset(pudp, tpc); 150 if (pmd_none(*pmdp)) 151 goto outret; 152 153 /* This disables preemption for us as well. */ 154 __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate)); 155 __asm__ __volatile__("wrpr %0, %1, %%pstate" 156 : : "r" (pstate), "i" (PSTATE_IE)); 157 ptep = pte_offset_map(pmdp, tpc); 158 pte = *ptep; 159 if (!pte_present(pte)) 160 goto out; 161 162 pa = (pte_pfn(pte) << PAGE_SHIFT); 163 pa += (tpc & ~PAGE_MASK); 164 165 /* Use phys bypass so we don't pollute dtlb/dcache. */ 166 __asm__ __volatile__("lduwa [%1] %2, %0" 167 : "=r" (insn) 168 : "r" (pa), "i" (ASI_PHYS_USE_EC)); 169 170out: 171 pte_unmap(ptep); 172 __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate)); 173outret: 174 return insn; 175} 176 177extern unsigned long compute_effective_address(struct pt_regs *, unsigned int, unsigned int); 178 179static void do_fault_siginfo(int code, int sig, struct pt_regs *regs, 180 unsigned int insn, int fault_code) 181{ 182 siginfo_t info; 183 184 info.si_code = code; 185 info.si_signo = sig; 186 info.si_errno = 0; 187 if (fault_code & FAULT_CODE_ITLB) 188 info.si_addr = (void __user *) regs->tpc; 189 else 190 info.si_addr = (void __user *) 191 compute_effective_address(regs, insn, 0); 192 info.si_trapno = 0; 193 force_sig_info(sig, &info, current); 194} 195 196extern int handle_ldf_stq(u32, struct pt_regs *); 197extern int handle_ld_nf(u32, struct pt_regs *); 198 199static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn) 200{ 201 if (!insn) { 202 if (!regs->tpc || (regs->tpc & 0x3)) 203 return 0; 204 if (regs->tstate & TSTATE_PRIV) { 205 insn = *(unsigned int *) regs->tpc; 206 } else { 207 insn = get_user_insn(regs->tpc); 208 } 209 } 210 return insn; 211} 212 213static void do_kernel_fault(struct pt_regs *regs, int si_code, int fault_code, 214 unsigned int insn, unsigned long address) 215{ 216 unsigned char asi = ASI_P; 217 218 if ((!insn) && (regs->tstate & TSTATE_PRIV)) 219 goto cannot_handle; 220 221 /* If user insn could be read (thus insn is zero), that 222 * is fine. We will just gun down the process with a signal 223 * in that case. 224 */ 225 226 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) && 227 (insn & 0xc0800000) == 0xc0800000) { 228 if (insn & 0x2000) 229 asi = (regs->tstate >> 24); 230 else 231 asi = (insn >> 5); 232 if ((asi & 0xf2) == 0x82) { 233 if (insn & 0x1000000) { 234 handle_ldf_stq(insn, regs); 235 } else { 236 /* This was a non-faulting load. Just clear the 237 * destination register(s) and continue with the next 238 * instruction. -jj 239 */ 240 handle_ld_nf(insn, regs); 241 } 242 return; 243 } 244 } 245 246 /* Is this in ex_table? */ 247 if (regs->tstate & TSTATE_PRIV) { 248 const struct exception_table_entry *entry; 249 250 if (asi == ASI_P && (insn & 0xc0800000) == 0xc0800000) { 251 if (insn & 0x2000) 252 asi = (regs->tstate >> 24); 253 else 254 asi = (insn >> 5); 255 } 256 257 /* Look in asi.h: All _S asis have LS bit set */ 258 if ((asi & 0x1) && 259 (entry = search_exception_tables(regs->tpc))) { 260 regs->tpc = entry->fixup; 261 regs->tnpc = regs->tpc + 4; 262 return; 263 } 264 } else { 265 /* The si_code was set to make clear whether 266 * this was a SEGV_MAPERR or SEGV_ACCERR fault. 267 */ 268 do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code); 269 return; 270 } 271 272cannot_handle: 273 unhandled_fault (address, current, regs); 274} 275 276asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) 277{ 278 struct mm_struct *mm = current->mm; 279 struct vm_area_struct *vma; 280 unsigned int insn = 0; 281 int si_code, fault_code; 282 unsigned long address, mm_rss; 283 284 fault_code = get_thread_fault_code(); 285 286 if (notify_page_fault(regs)) 287 return; 288 289 si_code = SEGV_MAPERR; 290 address = current_thread_info()->fault_address; 291 292 if ((fault_code & FAULT_CODE_ITLB) && 293 (fault_code & FAULT_CODE_DTLB)) 294 BUG(); 295 296 if (regs->tstate & TSTATE_PRIV) { 297 unsigned long tpc = regs->tpc; 298 299 /* Sanity check the PC. */ 300 if ((tpc >= KERNBASE && tpc < (unsigned long) _etext) || 301 (tpc >= MODULES_VADDR && tpc < MODULES_END)) { 302 /* Valid, no problems... */ 303 } else { 304 bad_kernel_pc(regs, address); 305 return; 306 } 307 } 308 309 /* 310 * If we're in an interrupt or have no user 311 * context, we must not take the fault.. 312 */ 313 if (in_atomic() || !mm) 314 goto intr_or_no_mm; 315 316 if (test_thread_flag(TIF_32BIT)) { 317 if (!(regs->tstate & TSTATE_PRIV)) 318 regs->tpc &= 0xffffffff; 319 address &= 0xffffffff; 320 } 321 322 if (!down_read_trylock(&mm->mmap_sem)) { 323 if ((regs->tstate & TSTATE_PRIV) && 324 !search_exception_tables(regs->tpc)) { 325 insn = get_fault_insn(regs, insn); 326 goto handle_kernel_fault; 327 } 328 down_read(&mm->mmap_sem); 329 } 330 331 vma = find_vma(mm, address); 332 if (!vma) 333 goto bad_area; 334 335 /* Pure DTLB misses do not tell us whether the fault causing 336 * load/store/atomic was a write or not, it only says that there 337 * was no match. So in such a case we (carefully) read the 338 * instruction to try and figure this out. It's an optimization 339 * so it's ok if we can't do this. 340 * 341 * Special hack, window spill/fill knows the exact fault type. 342 */ 343 if (((fault_code & 344 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) && 345 (vma->vm_flags & VM_WRITE) != 0) { 346 insn = get_fault_insn(regs, 0); 347 if (!insn) 348 goto continue_fault; 349 /* All loads, stores and atomics have bits 30 and 31 both set 350 * in the instruction. Bit 21 is set in all stores, but we 351 * have to avoid prefetches which also have bit 21 set. 352 */ 353 if ((insn & 0xc0200000) == 0xc0200000 && 354 (insn & 0x01780000) != 0x01680000) { 355 /* Don't bother updating thread struct value, 356 * because update_mmu_cache only cares which tlb 357 * the access came from. 358 */ 359 fault_code |= FAULT_CODE_WRITE; 360 } 361 } 362continue_fault: 363 364 if (vma->vm_start <= address) 365 goto good_area; 366 if (!(vma->vm_flags & VM_GROWSDOWN)) 367 goto bad_area; 368 if (!(fault_code & FAULT_CODE_WRITE)) { 369 /* Non-faulting loads shouldn't expand stack. */ 370 insn = get_fault_insn(regs, insn); 371 if ((insn & 0xc0800000) == 0xc0800000) { 372 unsigned char asi; 373 374 if (insn & 0x2000) 375 asi = (regs->tstate >> 24); 376 else 377 asi = (insn >> 5); 378 if ((asi & 0xf2) == 0x82) 379 goto bad_area; 380 } 381 } 382 if (expand_stack(vma, address)) 383 goto bad_area; 384 /* 385 * Ok, we have a good vm_area for this memory access, so 386 * we can handle it.. 387 */ 388good_area: 389 si_code = SEGV_ACCERR; 390 391 /* If we took a ITLB miss on a non-executable page, catch 392 * that here. 393 */ 394 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) { 395 BUG_ON(address != regs->tpc); 396 BUG_ON(regs->tstate & TSTATE_PRIV); 397 goto bad_area; 398 } 399 400 if (fault_code & FAULT_CODE_WRITE) { 401 if (!(vma->vm_flags & VM_WRITE)) 402 goto bad_area; 403 404 /* Spitfire has an icache which does not snoop 405 * processor stores. Later processors do... 406 */ 407 if (tlb_type == spitfire && 408 (vma->vm_flags & VM_EXEC) != 0 && 409 vma->vm_file != NULL) 410 set_thread_fault_code(fault_code | 411 FAULT_CODE_BLKCOMMIT); 412 } else { 413 /* Allow reads even for write-only mappings */ 414 if (!(vma->vm_flags & (VM_READ | VM_EXEC))) 415 goto bad_area; 416 } 417 418 switch (handle_mm_fault(mm, vma, address, (fault_code & FAULT_CODE_WRITE))) { 419 case VM_FAULT_MINOR: 420 current->min_flt++; 421 break; 422 case VM_FAULT_MAJOR: 423 current->maj_flt++; 424 break; 425 case VM_FAULT_SIGBUS: 426 goto do_sigbus; 427 case VM_FAULT_OOM: 428 goto out_of_memory; 429 default: 430 BUG(); 431 } 432 433 up_read(&mm->mmap_sem); 434 435 mm_rss = get_mm_rss(mm); 436#ifdef CONFIG_HUGETLB_PAGE 437 mm_rss -= (mm->context.huge_pte_count * (HPAGE_SIZE / PAGE_SIZE)); 438#endif 439 if (unlikely(mm_rss > 440 mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit)) 441 tsb_grow(mm, MM_TSB_BASE, mm_rss); 442#ifdef CONFIG_HUGETLB_PAGE 443 mm_rss = mm->context.huge_pte_count; 444 if (unlikely(mm_rss > 445 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) 446 tsb_grow(mm, MM_TSB_HUGE, mm_rss); 447#endif 448 return; 449 450 /* 451 * Something tried to access memory that isn't in our memory map.. 452 * Fix it, but check if it's kernel or user first.. 453 */ 454bad_area: 455 insn = get_fault_insn(regs, insn); 456 up_read(&mm->mmap_sem); 457 458handle_kernel_fault: 459 do_kernel_fault(regs, si_code, fault_code, insn, address); 460 return; 461 462/* 463 * We ran out of memory, or some other thing happened to us that made 464 * us unable to handle the page fault gracefully. 465 */ 466out_of_memory: 467 insn = get_fault_insn(regs, insn); 468 up_read(&mm->mmap_sem); 469 printk("VM: killing process %s\n", current->comm); 470 if (!(regs->tstate & TSTATE_PRIV)) 471 do_exit(SIGKILL); 472 goto handle_kernel_fault; 473 474intr_or_no_mm: 475 insn = get_fault_insn(regs, 0); 476 goto handle_kernel_fault; 477 478do_sigbus: 479 insn = get_fault_insn(regs, insn); 480 up_read(&mm->mmap_sem); 481 482 /* 483 * Send a sigbus, regardless of whether we were in kernel 484 * or user mode. 485 */ 486 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code); 487 488 /* Kernel mode? Handle exceptions or die */ 489 if (regs->tstate & TSTATE_PRIV) 490 goto handle_kernel_fault; 491} 492