2 * linux/arch/unicore32/mm/fault.c
4 * Code specific to PKUnity SoC and UniCore ISA
6 * Copyright (C) 2001-2010 GUAN Xue-tao
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
12 #include <linux/extable.h>
13 #include <linux/signal.h>
15 #include <linux/hardirq.h>
16 #include <linux/init.h>
17 #include <linux/kprobes.h>
18 #include <linux/uaccess.h>
19 #include <linux/page-flags.h>
20 #include <linux/sched/signal.h>
23 #include <asm/pgtable.h>
24 #include <asm/tlbflush.h>
27 * Fault status register encodings. We steal bit 31 for our own purposes.
29 #define FSR_LNX_PF (1 << 31)
31 static inline int fsr_fs(unsigned int fsr)
33 /* xyabcde will be abcde+xy */
34 return (fsr & 31) + ((fsr & (3 << 5)) >> 5);
38 * This is useful to dump out the page tables associated with
41 void show_pte(struct mm_struct *mm, unsigned long addr)
48 printk(KERN_ALERT "pgd = %p\n", mm->pgd);
49 pgd = pgd_offset(mm, addr);
50 printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
64 pmd = pmd_offset((pud_t *) pgd, addr);
65 if (PTRS_PER_PMD != 1)
66 printk(", *pmd=%08lx", pmd_val(*pmd));
76 /* We must not map this if we have highmem enabled */
77 if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
80 pte = pte_offset_map(pmd, addr);
81 printk(", *pte=%08lx", pte_val(*pte));
89 * Oops. The kernel tried to access some page that wasn't present.
91 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
92 unsigned int fsr, struct pt_regs *regs)
95 * Are we prepared to handle this kernel fault?
97 if (fixup_exception(regs))
101 * No handler, we'll have to terminate things with extreme prejudice.
105 "Unable to handle kernel %s at virtual address %08lx\n",
106 (addr < PAGE_SIZE) ? "NULL pointer dereference" :
107 "paging request", addr);
110 die("Oops", regs, fsr);
116 * Something tried to access memory that isn't in our memory map..
117 * User mode accesses just cause a SIGSEGV
119 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
120 unsigned int fsr, unsigned int sig, int code,
121 struct pt_regs *regs)
123 tsk->thread.address = addr;
124 tsk->thread.error_code = fsr;
125 tsk->thread.trap_no = 14;
126 force_sig_fault(sig, code, (void __user *)addr, tsk);
129 void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
131 struct task_struct *tsk = current;
132 struct mm_struct *mm = tsk->active_mm;
135 * If we are in kernel mode at this point, we
136 * have no context to handle this fault with.
139 __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
141 __do_kernel_fault(mm, addr, fsr, regs);
144 #define VM_FAULT_BADMAP 0x010000
145 #define VM_FAULT_BADACCESS 0x020000
148 * Check that the permissions on the VMA allow for the fault which occurred.
149 * If we encountered a write fault, we must have write permission, otherwise
150 * we allow any permission.
152 static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
154 unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
156 if (!(fsr ^ 0x12)) /* write? */
158 if (fsr & FSR_LNX_PF)
161 return vma->vm_flags & mask ? false : true;
164 static vm_fault_t __do_pf(struct mm_struct *mm, unsigned long addr,
165 unsigned int fsr, unsigned int flags, struct task_struct *tsk)
167 struct vm_area_struct *vma;
170 vma = find_vma(mm, addr);
171 fault = VM_FAULT_BADMAP;
174 if (unlikely(vma->vm_start > addr))
178 * Ok, we have a good vm_area for this
179 * memory access, so we can handle it.
182 if (access_error(fsr, vma)) {
183 fault = VM_FAULT_BADACCESS;
188 * If for any reason at all we couldn't handle the fault, make
189 * sure we exit gracefully rather than endlessly redo the fault.
191 fault = handle_mm_fault(vma, addr & PAGE_MASK, flags);
195 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
201 static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
203 struct task_struct *tsk;
204 struct mm_struct *mm;
207 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
213 * If we're in an interrupt or have no user
214 * context, we must not take the fault..
216 if (faulthandler_disabled() || !mm)
220 flags |= FAULT_FLAG_USER;
222 flags |= FAULT_FLAG_WRITE;
225 * As per x86, we may deadlock here. However, since the kernel only
226 * validly references user space from well defined areas of the code,
227 * we can bug out early if this is from code which shouldn't.
229 if (!down_read_trylock(&mm->mmap_sem)) {
231 && !search_exception_tables(regs->UCreg_pc))
234 down_read(&mm->mmap_sem);
237 * The above down_read_trylock() might have succeeded in
238 * which case, we'll have missed the might_sleep() from
242 #ifdef CONFIG_DEBUG_VM
243 if (!user_mode(regs) &&
244 !search_exception_tables(regs->UCreg_pc))
249 fault = __do_pf(mm, addr, fsr, flags, tsk);
251 /* If we need to retry but a fatal signal is pending, handle the
252 * signal first. We do not need to release the mmap_sem because
253 * it would already be released in __lock_page_or_retry in
255 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
258 if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
259 if (fault & VM_FAULT_MAJOR)
263 if (fault & VM_FAULT_RETRY) {
264 /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
266 flags &= ~FAULT_FLAG_ALLOW_RETRY;
271 up_read(&mm->mmap_sem);
274 * Handle the "normal" case first - VM_FAULT_MAJOR
277 (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
281 * If we are in kernel mode at this point, we
282 * have no context to handle this fault with.
284 if (!user_mode(regs))
287 if (fault & VM_FAULT_OOM) {
289 * We ran out of memory, call the OOM killer, and return to
290 * userspace (which will retry the fault, or kill us if we
293 pagefault_out_of_memory();
297 if (fault & VM_FAULT_SIGBUS) {
299 * We had some memory, but were unable to
300 * successfully fix up this page fault.
306 * Something tried to access memory that
307 * isn't in our memory map..
310 code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
313 __do_user_fault(tsk, addr, fsr, sig, code, regs);
317 __do_kernel_fault(mm, addr, fsr, regs);
322 * First Level Translation Fault Handler
324 * We enter here because the first level page table doesn't contain
325 * a valid entry for the address.
327 * If the address is in kernel space (>= TASK_SIZE), then we are
328 * probably faulting in the vmalloc() area.
330 * If the init_task's first level page tables contains the relevant
331 * entry, we copy the it to this task. If not, we send the process
332 * a signal, fixup the exception, or oops the kernel.
334 * NOTE! We MUST NOT take any locks for this case. We may be in an
335 * interrupt or a critical region, and should only copy the information
336 * from the master page table, nothing more.
338 static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
344 if (addr < TASK_SIZE)
345 return do_pf(addr, fsr, regs);
350 index = pgd_index(addr);
352 pgd = cpu_get_pgd() + index;
353 pgd_k = init_mm.pgd + index;
355 if (pgd_none(*pgd_k))
358 pmd_k = pmd_offset((pud_t *) pgd_k, addr);
359 pmd = pmd_offset((pud_t *) pgd, addr);
361 if (pmd_none(*pmd_k))
364 set_pmd(pmd, *pmd_k);
365 flush_pmd_entry(pmd);
369 do_bad_area(addr, fsr, regs);
374 * This abort handler always returns "fault".
376 static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
381 static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
383 unsigned int res1, res2;
385 printk("dabt exception but no error!\n");
387 __asm__ __volatile__(
390 : "=r"(res1), "=r"(res2)
394 printk(KERN_EMERG "r0 :%08x r1 :%08x\n", res1, res2);
399 static struct fsr_info {
400 int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
406 * The following are the standard Unicore-I and UniCore-II aborts.
408 { do_good, SIGBUS, 0, "no error" },
409 { do_bad, SIGBUS, BUS_ADRALN, "alignment exception" },
410 { do_bad, SIGBUS, BUS_OBJERR, "external exception" },
411 { do_bad, SIGBUS, 0, "burst operation" },
412 { do_bad, SIGBUS, 0, "unknown 00100" },
413 { do_ifault, SIGSEGV, SEGV_MAPERR, "2nd level pt non-exist"},
414 { do_bad, SIGBUS, 0, "2nd lvl large pt non-exist" },
415 { do_bad, SIGBUS, 0, "invalid pte" },
416 { do_pf, SIGSEGV, SEGV_MAPERR, "page miss" },
417 { do_bad, SIGBUS, 0, "middle page miss" },
418 { do_bad, SIGBUS, 0, "large page miss" },
419 { do_pf, SIGSEGV, SEGV_MAPERR, "super page (section) miss" },
420 { do_bad, SIGBUS, 0, "unknown 01100" },
421 { do_bad, SIGBUS, 0, "unknown 01101" },
422 { do_bad, SIGBUS, 0, "unknown 01110" },
423 { do_bad, SIGBUS, 0, "unknown 01111" },
424 { do_bad, SIGBUS, 0, "addr: up 3G or IO" },
425 { do_pf, SIGSEGV, SEGV_ACCERR, "read unreadable addr" },
426 { do_pf, SIGSEGV, SEGV_ACCERR, "write unwriteable addr"},
427 { do_pf, SIGSEGV, SEGV_ACCERR, "exec unexecutable addr"},
428 { do_bad, SIGBUS, 0, "unknown 10100" },
429 { do_bad, SIGBUS, 0, "unknown 10101" },
430 { do_bad, SIGBUS, 0, "unknown 10110" },
431 { do_bad, SIGBUS, 0, "unknown 10111" },
432 { do_bad, SIGBUS, 0, "unknown 11000" },
433 { do_bad, SIGBUS, 0, "unknown 11001" },
434 { do_bad, SIGBUS, 0, "unknown 11010" },
435 { do_bad, SIGBUS, 0, "unknown 11011" },
436 { do_bad, SIGBUS, 0, "unknown 11100" },
437 { do_bad, SIGBUS, 0, "unknown 11101" },
438 { do_bad, SIGBUS, 0, "unknown 11110" },
439 { do_bad, SIGBUS, 0, "unknown 11111" }
442 void __init hook_fault_code(int nr,
443 int (*fn) (unsigned long, unsigned int, struct pt_regs *),
444 int sig, int code, const char *name)
446 if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
449 fsr_info[nr].fn = fn;
450 fsr_info[nr].sig = sig;
451 fsr_info[nr].code = code;
452 fsr_info[nr].name = name;
456 * Dispatch a data abort to the relevant handler.
458 asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
459 struct pt_regs *regs)
461 const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
463 if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
466 printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
467 inf->name, fsr, addr);
469 uc32_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,
473 asmlinkage void do_PrefetchAbort(unsigned long addr,
474 unsigned int ifsr, struct pt_regs *regs)
476 const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);
478 if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
481 printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
482 inf->name, ifsr, addr);
484 uc32_notify_die("", regs, inf->sig, inf->code, (void __user *)addr,