2 * fault.c: Page fault handlers for the Sparc.
4 * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
5 * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be)
6 * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
11 #include <linux/string.h>
12 #include <linux/types.h>
13 #include <linux/sched.h>
14 #include <linux/ptrace.h>
15 #include <linux/mman.h>
16 #include <linux/threads.h>
17 #include <linux/kernel.h>
18 #include <linux/signal.h>
20 #include <linux/smp.h>
21 #include <linux/perf_event.h>
22 #include <linux/interrupt.h>
23 #include <linux/kdebug.h>
26 #include <asm/pgtable.h>
27 #include <asm/openprom.h>
28 #include <asm/oplib.h>
30 #include <asm/traps.h>
31 #include <asm/uaccess.h>
33 int show_unhandled_signals = 1;
35 /* At boot time we determine these two values necessary for setting
36 * up the segment maps and page table entries (pte's).
41 /* Return how much physical memory we have. */
42 unsigned long probe_memory(void)
44 unsigned long total = 0;
47 for (i = 0; sp_banks[i].num_bytes; i++)
48 total += sp_banks[i].num_bytes;
53 static void unhandled_fault(unsigned long, struct task_struct *,
54 struct pt_regs *) __attribute__ ((noreturn));
56 static void __noreturn unhandled_fault(unsigned long address,
57 struct task_struct *tsk,
60 if ((unsigned long) address < PAGE_SIZE) {
62 "Unable to handle kernel NULL pointer dereference\n");
64 printk(KERN_ALERT "Unable to handle kernel paging request at virtual address %08lx\n",
67 printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n",
68 (tsk->mm ? tsk->mm->context : tsk->active_mm->context));
69 printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n",
70 (tsk->mm ? (unsigned long) tsk->mm->pgd :
71 (unsigned long) tsk->active_mm->pgd));
72 die_if_kernel("Oops", regs);
75 asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc,
76 unsigned long address)
83 i = search_extables_range(ret_pc, &g2);
86 /* load & store will be handled by fixup */
90 /* store will be handled by fixup, load will bump out */
92 insn = *((unsigned int *) pc);
98 /* load will be handled by fixup, store will bump out */
99 /* for _from_ macros */
100 insn = *((unsigned int *) pc);
101 if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15)
109 memset(®s, 0, sizeof(regs));
112 __asm__ __volatile__(
116 "nop\n" : "=r" (regs.psr));
117 unhandled_fault(address, current, ®s);
124 show_signal_msg(struct pt_regs *regs, int sig, int code,
125 unsigned long address, struct task_struct *tsk)
127 if (!unhandled_signal(tsk, sig))
130 if (!printk_ratelimit())
133 printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x",
134 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
135 tsk->comm, task_pid_nr(tsk), address,
136 (void *)regs->pc, (void *)regs->u_regs[UREG_I7],
137 (void *)regs->u_regs[UREG_FP], code);
139 print_vma_addr(KERN_CONT " in ", regs->pc);
141 printk(KERN_CONT "\n");
144 static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs,
152 info.si_addr = (void __user *) addr;
155 if (unlikely(show_unhandled_signals))
156 show_signal_msg(regs, sig, info.si_code,
159 force_sig_info (sig, &info, current);
162 extern unsigned long safe_compute_effective_address(struct pt_regs *,
165 static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault)
172 if (regs->psr & PSR_PS)
173 insn = *(unsigned int *) regs->pc;
175 __get_user(insn, (unsigned int *) regs->pc);
177 return safe_compute_effective_address(regs, insn);
180 static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs,
183 unsigned long addr = compute_si_addr(regs, text_fault);
185 __do_fault_siginfo(code, sig, regs, addr);
188 asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
189 unsigned long address)
191 struct vm_area_struct *vma;
192 struct task_struct *tsk = current;
193 struct mm_struct *mm = tsk->mm;
196 int from_user = !(regs->psr & PSR_PS);
198 unsigned int flags = (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
199 (write ? FAULT_FLAG_WRITE : 0));
205 * We fault-in kernel-space virtual memory on-demand. The
206 * 'reference' page table is init_mm.pgd.
208 * NOTE! We MUST NOT take any locks for this case. We may
209 * be in an interrupt or a critical region, and should
210 * only copy the information from the master page table,
214 if (address >= TASK_SIZE)
218 * If we're in an interrupt or have no user
219 * context, we must not take the fault..
221 if (in_atomic() || !mm)
224 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
227 down_read(&mm->mmap_sem);
229 if (!from_user && address >= PAGE_OFFSET)
232 vma = find_vma(mm, address);
235 if (vma->vm_start <= address)
237 if (!(vma->vm_flags & VM_GROWSDOWN))
239 if (expand_stack(vma, address))
242 * Ok, we have a good vm_area for this memory access, so
248 if (!(vma->vm_flags & VM_WRITE))
251 /* Allow reads even for write-only mappings */
252 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
257 * If for any reason at all we couldn't handle the fault,
258 * make sure we exit gracefully rather than endlessly redo
261 fault = handle_mm_fault(mm, vma, address, flags);
263 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
266 if (unlikely(fault & VM_FAULT_ERROR)) {
267 if (fault & VM_FAULT_OOM)
269 else if (fault & VM_FAULT_SIGBUS)
274 if (flags & FAULT_FLAG_ALLOW_RETRY) {
275 if (fault & VM_FAULT_MAJOR) {
277 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ,
281 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN,
284 if (fault & VM_FAULT_RETRY) {
285 flags &= ~FAULT_FLAG_ALLOW_RETRY;
287 /* No need to up_read(&mm->mmap_sem) as we would
288 * have already released it in __lock_page_or_retry
296 up_read(&mm->mmap_sem);
300 * Something tried to access memory that isn't in our memory map..
301 * Fix it, but check if it's kernel or user first..
304 up_read(&mm->mmap_sem);
306 bad_area_nosemaphore:
307 /* User mode accesses just cause a SIGSEGV */
309 do_fault_siginfo(code, SIGSEGV, regs, text_fault);
313 /* Is this in ex_table? */
315 g2 = regs->u_regs[UREG_G2];
317 fixup = search_extables_range(regs->pc, &g2);
318 /* Values below 10 are reserved for other things */
320 extern const unsigned __memset_start[];
321 extern const unsigned __memset_end[];
322 extern const unsigned __csum_partial_copy_start[];
323 extern const unsigned __csum_partial_copy_end[];
325 #ifdef DEBUG_EXCEPTIONS
326 printk("Exception: PC<%08lx> faddr<%08lx>\n",
328 printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n",
329 regs->pc, fixup, g2);
331 if ((regs->pc >= (unsigned long)__memset_start &&
332 regs->pc < (unsigned long)__memset_end) ||
333 (regs->pc >= (unsigned long)__csum_partial_copy_start &&
334 regs->pc < (unsigned long)__csum_partial_copy_end)) {
335 regs->u_regs[UREG_I4] = address;
336 regs->u_regs[UREG_I5] = regs->pc;
338 regs->u_regs[UREG_G2] = g2;
340 regs->npc = regs->pc + 4;
345 unhandled_fault(address, tsk, regs);
349 * We ran out of memory, or some other thing happened to us that made
350 * us unable to handle the page fault gracefully.
353 up_read(&mm->mmap_sem);
355 pagefault_out_of_memory();
361 up_read(&mm->mmap_sem);
362 do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault);
369 * Synchronize this task's top level page-table
370 * with the 'reference' page table.
372 int offset = pgd_index(address);
376 pgd = tsk->active_mm->pgd + offset;
377 pgd_k = init_mm.pgd + offset;
379 if (!pgd_present(*pgd)) {
380 if (!pgd_present(*pgd_k))
381 goto bad_area_nosemaphore;
382 pgd_val(*pgd) = pgd_val(*pgd_k);
386 pmd = pmd_offset(pgd, address);
387 pmd_k = pmd_offset(pgd_k, address);
389 if (pmd_present(*pmd) || !pmd_present(*pmd_k))
390 goto bad_area_nosemaphore;
397 /* This always deals with user addresses. */
398 static void force_user_fault(unsigned long address, int write)
400 struct vm_area_struct *vma;
401 struct task_struct *tsk = current;
402 struct mm_struct *mm = tsk->mm;
407 down_read(&mm->mmap_sem);
408 vma = find_vma(mm, address);
411 if (vma->vm_start <= address)
413 if (!(vma->vm_flags & VM_GROWSDOWN))
415 if (expand_stack(vma, address))
420 if (!(vma->vm_flags & VM_WRITE))
423 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
426 switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) {
427 case VM_FAULT_SIGBUS:
431 up_read(&mm->mmap_sem);
434 up_read(&mm->mmap_sem);
435 __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address);
439 up_read(&mm->mmap_sem);
440 __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address);
443 static void check_stack_aligned(unsigned long sp)
446 force_sig(SIGILL, current);
449 void window_overflow_fault(void)
453 sp = current_thread_info()->rwbuf_stkptrs[0];
454 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
455 force_user_fault(sp + 0x38, 1);
456 force_user_fault(sp, 1);
458 check_stack_aligned(sp);
461 void window_underflow_fault(unsigned long sp)
463 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
464 force_user_fault(sp + 0x38, 0);
465 force_user_fault(sp, 0);
467 check_stack_aligned(sp);
470 void window_ret_fault(struct pt_regs *regs)
474 sp = regs->u_regs[UREG_FP];
475 if (((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK))
476 force_user_fault(sp + 0x38, 0);
477 force_user_fault(sp, 0);
479 check_stack_aligned(sp);