1 /*
2 * arch/sparc64/mm/fault.c: Page fault handlers for the 64-bit Sparc.
3 *
4 * Copyright (C) 1996, 2008 David S. Miller (davem@davemloft.net)
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/kdebug.h>
22 #include <linux/percpu.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
notify_page_fault(struct pt_regs * regs)35 static 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
notify_page_fault(struct pt_regs * regs)49 static inline int notify_page_fault(struct pt_regs *regs)
50 {
51 return 0;
52 }
53 #endif
54
unhandled_fault(unsigned long address,struct task_struct * tsk,struct pt_regs * regs)55 static void __kprobes unhandled_fault(unsigned long address,
56 struct task_struct *tsk,
57 struct pt_regs *regs)
58 {
59 if ((unsigned long) address < PAGE_SIZE) {
60 printk(KERN_ALERT "Unable to handle kernel NULL "
61 "pointer dereference\n");
62 } else {
63 printk(KERN_ALERT "Unable to handle kernel paging request "
64 "at virtual address %016lx\n", (unsigned long)address);
65 }
66 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %016lx\n",
67 (tsk->mm ?
68 CTX_HWBITS(tsk->mm->context) :
69 CTX_HWBITS(tsk->active_mm->context)));
70 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %016lx\n",
71 (tsk->mm ? (unsigned long) tsk->mm->pgd :
72 (unsigned long) tsk->active_mm->pgd));
73 die_if_kernel("Oops", regs);
74 }
75
bad_kernel_pc(struct pt_regs * regs,unsigned long vaddr)76 static void bad_kernel_pc(struct pt_regs *regs, unsigned long vaddr)
77 {
78 printk(KERN_CRIT "OOPS: Bogus kernel PC [%016lx] in fault handler\n",
79 regs->tpc);
80 printk(KERN_CRIT "OOPS: RPC [%016lx]\n", regs->u_regs[15]);
81 printk("OOPS: RPC <%pS>\n", (void *) regs->u_regs[15]);
82 printk(KERN_CRIT "OOPS: Fault was to vaddr[%lx]\n", vaddr);
83 dump_stack();
84 unhandled_fault(regs->tpc, current, regs);
85 }
86
87 /*
88 * We now make sure that mmap_sem is held in all paths that call
89 * this. Additionally, to prevent kswapd from ripping ptes from
90 * under us, raise interrupts around the time that we look at the
91 * pte, kswapd will have to wait to get his smp ipi response from
92 * us. vmtruncate likewise. This saves us having to get pte lock.
93 */
get_user_insn(unsigned long tpc)94 static unsigned int get_user_insn(unsigned long tpc)
95 {
96 pgd_t *pgdp = pgd_offset(current->mm, tpc);
97 pud_t *pudp;
98 pmd_t *pmdp;
99 pte_t *ptep, pte;
100 unsigned long pa;
101 u32 insn = 0;
102 unsigned long pstate;
103
104 if (pgd_none(*pgdp))
105 goto outret;
106 pudp = pud_offset(pgdp, tpc);
107 if (pud_none(*pudp))
108 goto outret;
109 pmdp = pmd_offset(pudp, tpc);
110 if (pmd_none(*pmdp))
111 goto outret;
112
113 /* This disables preemption for us as well. */
114 __asm__ __volatile__("rdpr %%pstate, %0" : "=r" (pstate));
115 __asm__ __volatile__("wrpr %0, %1, %%pstate"
116 : : "r" (pstate), "i" (PSTATE_IE));
117 ptep = pte_offset_map(pmdp, tpc);
118 pte = *ptep;
119 if (!pte_present(pte))
120 goto out;
121
122 pa = (pte_pfn(pte) << PAGE_SHIFT);
123 pa += (tpc & ~PAGE_MASK);
124
125 /* Use phys bypass so we don't pollute dtlb/dcache. */
126 __asm__ __volatile__("lduwa [%1] %2, %0"
127 : "=r" (insn)
128 : "r" (pa), "i" (ASI_PHYS_USE_EC));
129
130 out:
131 pte_unmap(ptep);
132 __asm__ __volatile__("wrpr %0, 0x0, %%pstate" : : "r" (pstate));
133 outret:
134 return insn;
135 }
136
137 extern unsigned long compute_effective_address(struct pt_regs *, unsigned int, unsigned int);
138
do_fault_siginfo(int code,int sig,struct pt_regs * regs,unsigned int insn,int fault_code)139 static void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
140 unsigned int insn, int fault_code)
141 {
142 siginfo_t info;
143
144 info.si_code = code;
145 info.si_signo = sig;
146 info.si_errno = 0;
147 if (fault_code & FAULT_CODE_ITLB)
148 info.si_addr = (void __user *) regs->tpc;
149 else
150 info.si_addr = (void __user *)
151 compute_effective_address(regs, insn, 0);
152 info.si_trapno = 0;
153 force_sig_info(sig, &info, current);
154 }
155
156 extern int handle_ldf_stq(u32, struct pt_regs *);
157 extern int handle_ld_nf(u32, struct pt_regs *);
158
get_fault_insn(struct pt_regs * regs,unsigned int insn)159 static unsigned int get_fault_insn(struct pt_regs *regs, unsigned int insn)
160 {
161 if (!insn) {
162 if (!regs->tpc || (regs->tpc & 0x3))
163 return 0;
164 if (regs->tstate & TSTATE_PRIV) {
165 insn = *(unsigned int *) regs->tpc;
166 } else {
167 insn = get_user_insn(regs->tpc);
168 }
169 }
170 return insn;
171 }
172
do_kernel_fault(struct pt_regs * regs,int si_code,int fault_code,unsigned int insn,unsigned long address)173 static void do_kernel_fault(struct pt_regs *regs, int si_code, int fault_code,
174 unsigned int insn, unsigned long address)
175 {
176 unsigned char asi = ASI_P;
177
178 if ((!insn) && (regs->tstate & TSTATE_PRIV))
179 goto cannot_handle;
180
181 /* If user insn could be read (thus insn is zero), that
182 * is fine. We will just gun down the process with a signal
183 * in that case.
184 */
185
186 if (!(fault_code & (FAULT_CODE_WRITE|FAULT_CODE_ITLB)) &&
187 (insn & 0xc0800000) == 0xc0800000) {
188 if (insn & 0x2000)
189 asi = (regs->tstate >> 24);
190 else
191 asi = (insn >> 5);
192 if ((asi & 0xf2) == 0x82) {
193 if (insn & 0x1000000) {
194 handle_ldf_stq(insn, regs);
195 } else {
196 /* This was a non-faulting load. Just clear the
197 * destination register(s) and continue with the next
198 * instruction. -jj
199 */
200 handle_ld_nf(insn, regs);
201 }
202 return;
203 }
204 }
205
206 /* Is this in ex_table? */
207 if (regs->tstate & TSTATE_PRIV) {
208 const struct exception_table_entry *entry;
209
210 entry = search_exception_tables(regs->tpc);
211 if (entry) {
212 regs->tpc = entry->fixup;
213 regs->tnpc = regs->tpc + 4;
214 return;
215 }
216 } else {
217 /* The si_code was set to make clear whether
218 * this was a SEGV_MAPERR or SEGV_ACCERR fault.
219 */
220 do_fault_siginfo(si_code, SIGSEGV, regs, insn, fault_code);
221 return;
222 }
223
224 cannot_handle:
225 unhandled_fault (address, current, regs);
226 }
227
bogus_32bit_fault_tpc(struct pt_regs * regs)228 static void noinline bogus_32bit_fault_tpc(struct pt_regs *regs)
229 {
230 static int times;
231
232 if (times++ < 10)
233 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process reports "
234 "64-bit TPC [%lx]\n",
235 current->comm, current->pid,
236 regs->tpc);
237 show_regs(regs);
238 }
239
bogus_32bit_fault_address(struct pt_regs * regs,unsigned long addr)240 static void noinline bogus_32bit_fault_address(struct pt_regs *regs,
241 unsigned long addr)
242 {
243 static int times;
244
245 if (times++ < 10)
246 printk(KERN_ERR "FAULT[%s:%d]: 32-bit process "
247 "reports 64-bit fault address [%lx]\n",
248 current->comm, current->pid, addr);
249 show_regs(regs);
250 }
251
do_sparc64_fault(struct pt_regs * regs)252 asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
253 {
254 struct mm_struct *mm = current->mm;
255 struct vm_area_struct *vma;
256 unsigned int insn = 0;
257 int si_code, fault_code, fault;
258 unsigned long address, mm_rss;
259
260 fault_code = get_thread_fault_code();
261
262 if (notify_page_fault(regs))
263 return;
264
265 si_code = SEGV_MAPERR;
266 address = current_thread_info()->fault_address;
267
268 if ((fault_code & FAULT_CODE_ITLB) &&
269 (fault_code & FAULT_CODE_DTLB))
270 BUG();
271
272 if (test_thread_flag(TIF_32BIT)) {
273 if (!(regs->tstate & TSTATE_PRIV)) {
274 if (unlikely((regs->tpc >> 32) != 0)) {
275 bogus_32bit_fault_tpc(regs);
276 goto intr_or_no_mm;
277 }
278 }
279 if (unlikely((address >> 32) != 0)) {
280 bogus_32bit_fault_address(regs, address);
281 goto intr_or_no_mm;
282 }
283 }
284
285 if (regs->tstate & TSTATE_PRIV) {
286 unsigned long tpc = regs->tpc;
287
288 /* Sanity check the PC. */
289 if ((tpc >= KERNBASE && tpc < (unsigned long) __init_end) ||
290 (tpc >= MODULES_VADDR && tpc < MODULES_END)) {
291 /* Valid, no problems... */
292 } else {
293 bad_kernel_pc(regs, address);
294 return;
295 }
296 }
297
298 /*
299 * If we're in an interrupt or have no user
300 * context, we must not take the fault..
301 */
302 if (in_atomic() || !mm)
303 goto intr_or_no_mm;
304
305 if (!down_read_trylock(&mm->mmap_sem)) {
306 if ((regs->tstate & TSTATE_PRIV) &&
307 !search_exception_tables(regs->tpc)) {
308 insn = get_fault_insn(regs, insn);
309 goto handle_kernel_fault;
310 }
311 down_read(&mm->mmap_sem);
312 }
313
314 vma = find_vma(mm, address);
315 if (!vma)
316 goto bad_area;
317
318 /* Pure DTLB misses do not tell us whether the fault causing
319 * load/store/atomic was a write or not, it only says that there
320 * was no match. So in such a case we (carefully) read the
321 * instruction to try and figure this out. It's an optimization
322 * so it's ok if we can't do this.
323 *
324 * Special hack, window spill/fill knows the exact fault type.
325 */
326 if (((fault_code &
327 (FAULT_CODE_DTLB | FAULT_CODE_WRITE | FAULT_CODE_WINFIXUP)) == FAULT_CODE_DTLB) &&
328 (vma->vm_flags & VM_WRITE) != 0) {
329 insn = get_fault_insn(regs, 0);
330 if (!insn)
331 goto continue_fault;
332 /* All loads, stores and atomics have bits 30 and 31 both set
333 * in the instruction. Bit 21 is set in all stores, but we
334 * have to avoid prefetches which also have bit 21 set.
335 */
336 if ((insn & 0xc0200000) == 0xc0200000 &&
337 (insn & 0x01780000) != 0x01680000) {
338 /* Don't bother updating thread struct value,
339 * because update_mmu_cache only cares which tlb
340 * the access came from.
341 */
342 fault_code |= FAULT_CODE_WRITE;
343 }
344 }
345 continue_fault:
346
347 if (vma->vm_start <= address)
348 goto good_area;
349 if (!(vma->vm_flags & VM_GROWSDOWN))
350 goto bad_area;
351 if (!(fault_code & FAULT_CODE_WRITE)) {
352 /* Non-faulting loads shouldn't expand stack. */
353 insn = get_fault_insn(regs, insn);
354 if ((insn & 0xc0800000) == 0xc0800000) {
355 unsigned char asi;
356
357 if (insn & 0x2000)
358 asi = (regs->tstate >> 24);
359 else
360 asi = (insn >> 5);
361 if ((asi & 0xf2) == 0x82)
362 goto bad_area;
363 }
364 }
365 if (expand_stack(vma, address))
366 goto bad_area;
367 /*
368 * Ok, we have a good vm_area for this memory access, so
369 * we can handle it..
370 */
371 good_area:
372 si_code = SEGV_ACCERR;
373
374 /* If we took a ITLB miss on a non-executable page, catch
375 * that here.
376 */
377 if ((fault_code & FAULT_CODE_ITLB) && !(vma->vm_flags & VM_EXEC)) {
378 BUG_ON(address != regs->tpc);
379 BUG_ON(regs->tstate & TSTATE_PRIV);
380 goto bad_area;
381 }
382
383 if (fault_code & FAULT_CODE_WRITE) {
384 if (!(vma->vm_flags & VM_WRITE))
385 goto bad_area;
386
387 /* Spitfire has an icache which does not snoop
388 * processor stores. Later processors do...
389 */
390 if (tlb_type == spitfire &&
391 (vma->vm_flags & VM_EXEC) != 0 &&
392 vma->vm_file != NULL)
393 set_thread_fault_code(fault_code |
394 FAULT_CODE_BLKCOMMIT);
395 } else {
396 /* Allow reads even for write-only mappings */
397 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
398 goto bad_area;
399 }
400
401 fault = handle_mm_fault(mm, vma, address, (fault_code & FAULT_CODE_WRITE));
402 if (unlikely(fault & VM_FAULT_ERROR)) {
403 if (fault & VM_FAULT_OOM)
404 goto out_of_memory;
405 else if (fault & VM_FAULT_SIGBUS)
406 goto do_sigbus;
407 BUG();
408 }
409 if (fault & VM_FAULT_MAJOR)
410 current->maj_flt++;
411 else
412 current->min_flt++;
413
414 up_read(&mm->mmap_sem);
415
416 mm_rss = get_mm_rss(mm);
417 #ifdef CONFIG_HUGETLB_PAGE
418 mm_rss -= (mm->context.huge_pte_count * (HPAGE_SIZE / PAGE_SIZE));
419 #endif
420 if (unlikely(mm_rss >
421 mm->context.tsb_block[MM_TSB_BASE].tsb_rss_limit))
422 tsb_grow(mm, MM_TSB_BASE, mm_rss);
423 #ifdef CONFIG_HUGETLB_PAGE
424 mm_rss = mm->context.huge_pte_count;
425 if (unlikely(mm_rss >
426 mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit))
427 tsb_grow(mm, MM_TSB_HUGE, mm_rss);
428 #endif
429 return;
430
431 /*
432 * Something tried to access memory that isn't in our memory map..
433 * Fix it, but check if it's kernel or user first..
434 */
435 bad_area:
436 insn = get_fault_insn(regs, insn);
437 up_read(&mm->mmap_sem);
438
439 handle_kernel_fault:
440 do_kernel_fault(regs, si_code, fault_code, insn, address);
441 return;
442
443 /*
444 * We ran out of memory, or some other thing happened to us that made
445 * us unable to handle the page fault gracefully.
446 */
447 out_of_memory:
448 insn = get_fault_insn(regs, insn);
449 up_read(&mm->mmap_sem);
450 printk("VM: killing process %s\n", current->comm);
451 if (!(regs->tstate & TSTATE_PRIV))
452 do_group_exit(SIGKILL);
453 goto handle_kernel_fault;
454
455 intr_or_no_mm:
456 insn = get_fault_insn(regs, 0);
457 goto handle_kernel_fault;
458
459 do_sigbus:
460 insn = get_fault_insn(regs, insn);
461 up_read(&mm->mmap_sem);
462
463 /*
464 * Send a sigbus, regardless of whether we were in kernel
465 * or user mode.
466 */
467 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, insn, fault_code);
468
469 /* Kernel mode? Handle exceptions or die */
470 if (regs->tstate & TSTATE_PRIV)
471 goto handle_kernel_fault;
472 }
473