x86/efi: Enforce CONFIG_RELOCATABLE for EFI boot stub
[linux/fpc-iii.git] / arch / microblaze / mm / fault.c
blobfa4cf52aa7a6d386711690005a314ece7d67fc53
1 /*
2 * arch/microblaze/mm/fault.c
4 * Copyright (C) 2007 Xilinx, Inc. All rights reserved.
6 * Derived from "arch/ppc/mm/fault.c"
7 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
9 * Derived from "arch/i386/mm/fault.c"
10 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
12 * Modified by Cort Dougan and Paul Mackerras.
14 * This file is subject to the terms and conditions of the GNU General
15 * Public License. See the file COPYING in the main directory of this
16 * archive for more details.
20 #include <linux/module.h>
21 #include <linux/signal.h>
22 #include <linux/sched.h>
23 #include <linux/kernel.h>
24 #include <linux/errno.h>
25 #include <linux/string.h>
26 #include <linux/types.h>
27 #include <linux/ptrace.h>
28 #include <linux/mman.h>
29 #include <linux/mm.h>
30 #include <linux/interrupt.h>
32 #include <asm/page.h>
33 #include <asm/pgtable.h>
34 #include <asm/mmu.h>
35 #include <linux/mmu_context.h>
36 #include <linux/uaccess.h>
37 #include <asm/exceptions.h>
39 static unsigned long pte_misses; /* updated by do_page_fault() */
40 static unsigned long pte_errors; /* updated by do_page_fault() */
43 * Check whether the instruction at regs->pc is a store using
44 * an update addressing form which will update r1.
46 static int store_updates_sp(struct pt_regs *regs)
48 unsigned int inst;
50 if (get_user(inst, (unsigned int __user *)regs->pc))
51 return 0;
52 /* check for 1 in the rD field */
53 if (((inst >> 21) & 0x1f) != 1)
54 return 0;
55 /* check for store opcodes */
56 if ((inst & 0xd0000000) == 0xd0000000)
57 return 1;
58 return 0;
63 * bad_page_fault is called when we have a bad access from the kernel.
64 * It is called from do_page_fault above and from some of the procedures
65 * in traps.c.
67 void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
69 const struct exception_table_entry *fixup;
70 /* MS: no context */
71 /* Are we prepared to handle this fault? */
72 fixup = search_exception_tables(regs->pc);
73 if (fixup) {
74 regs->pc = fixup->fixup;
75 return;
78 /* kernel has accessed a bad area */
79 die("kernel access of bad area", regs, sig);
83 * The error_code parameter is ESR for a data fault,
84 * 0 for an instruction fault.
86 void do_page_fault(struct pt_regs *regs, unsigned long address,
87 unsigned long error_code)
89 struct vm_area_struct *vma;
90 struct mm_struct *mm = current->mm;
91 siginfo_t info;
92 int code = SEGV_MAPERR;
93 int is_write = error_code & ESR_S;
94 int fault;
95 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
97 regs->ear = address;
98 regs->esr = error_code;
100 /* On a kernel SLB miss we can only check for a valid exception entry */
101 if (unlikely(kernel_mode(regs) && (address >= TASK_SIZE))) {
102 pr_warn("kernel task_size exceed");
103 _exception(SIGSEGV, regs, code, address);
106 /* for instr TLB miss and instr storage exception ESR_S is undefined */
107 if ((error_code & 0x13) == 0x13 || (error_code & 0x11) == 0x11)
108 is_write = 0;
110 if (unlikely(in_atomic() || !mm)) {
111 if (kernel_mode(regs))
112 goto bad_area_nosemaphore;
114 /* in_atomic() in user mode is really bad,
115 as is current->mm == NULL. */
116 pr_emerg("Page fault in user mode with in_atomic(), mm = %p\n",
117 mm);
118 pr_emerg("r15 = %lx MSR = %lx\n",
119 regs->r15, regs->msr);
120 die("Weird page fault", regs, SIGSEGV);
123 if (user_mode(regs))
124 flags |= FAULT_FLAG_USER;
126 /* When running in the kernel we expect faults to occur only to
127 * addresses in user space. All other faults represent errors in the
128 * kernel and should generate an OOPS. Unfortunately, in the case of an
129 * erroneous fault occurring in a code path which already holds mmap_sem
130 * we will deadlock attempting to validate the fault against the
131 * address space. Luckily the kernel only validly references user
132 * space from well defined areas of code, which are listed in the
133 * exceptions table.
135 * As the vast majority of faults will be valid we will only perform
136 * the source reference check when there is a possibility of a deadlock.
137 * Attempt to lock the address space, if we cannot we then validate the
138 * source. If this is invalid we can skip the address space check,
139 * thus avoiding the deadlock.
141 if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
142 if (kernel_mode(regs) && !search_exception_tables(regs->pc))
143 goto bad_area_nosemaphore;
145 retry:
146 down_read(&mm->mmap_sem);
149 vma = find_vma(mm, address);
150 if (unlikely(!vma))
151 goto bad_area;
153 if (vma->vm_start <= address)
154 goto good_area;
156 if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
157 goto bad_area;
159 if (unlikely(!is_write))
160 goto bad_area;
163 * N.B. The ABI allows programs to access up to
164 * a few hundred bytes below the stack pointer (TBD).
165 * The kernel signal delivery code writes up to about 1.5kB
166 * below the stack pointer (r1) before decrementing it.
167 * The exec code can write slightly over 640kB to the stack
168 * before setting the user r1. Thus we allow the stack to
169 * expand to 1MB without further checks.
171 if (unlikely(address + 0x100000 < vma->vm_end)) {
173 /* get user regs even if this fault is in kernel mode */
174 struct pt_regs *uregs = current->thread.regs;
175 if (uregs == NULL)
176 goto bad_area;
179 * A user-mode access to an address a long way below
180 * the stack pointer is only valid if the instruction
181 * is one which would update the stack pointer to the
182 * address accessed if the instruction completed,
183 * i.e. either stwu rs,n(r1) or stwux rs,r1,rb
184 * (or the byte, halfword, float or double forms).
186 * If we don't check this then any write to the area
187 * between the last mapped region and the stack will
188 * expand the stack rather than segfaulting.
190 if (address + 2048 < uregs->r1
191 && (kernel_mode(regs) || !store_updates_sp(regs)))
192 goto bad_area;
194 if (expand_stack(vma, address))
195 goto bad_area;
197 good_area:
198 code = SEGV_ACCERR;
200 /* a write */
201 if (unlikely(is_write)) {
202 if (unlikely(!(vma->vm_flags & VM_WRITE)))
203 goto bad_area;
204 flags |= FAULT_FLAG_WRITE;
205 /* a read */
206 } else {
207 /* protection fault */
208 if (unlikely(error_code & 0x08000000))
209 goto bad_area;
210 if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC))))
211 goto bad_area;
215 * If for any reason at all we couldn't handle the fault,
216 * make sure we exit gracefully rather than endlessly redo
217 * the fault.
219 fault = handle_mm_fault(mm, vma, address, flags);
221 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
222 return;
224 if (unlikely(fault & VM_FAULT_ERROR)) {
225 if (fault & VM_FAULT_OOM)
226 goto out_of_memory;
227 else if (fault & VM_FAULT_SIGBUS)
228 goto do_sigbus;
229 BUG();
232 if (flags & FAULT_FLAG_ALLOW_RETRY) {
233 if (unlikely(fault & VM_FAULT_MAJOR))
234 current->maj_flt++;
235 else
236 current->min_flt++;
237 if (fault & VM_FAULT_RETRY) {
238 flags &= ~FAULT_FLAG_ALLOW_RETRY;
239 flags |= FAULT_FLAG_TRIED;
242 * No need to up_read(&mm->mmap_sem) as we would
243 * have already released it in __lock_page_or_retry
244 * in mm/filemap.c.
247 goto retry;
251 up_read(&mm->mmap_sem);
254 * keep track of tlb+htab misses that are good addrs but
255 * just need pte's created via handle_mm_fault()
256 * -- Cort
258 pte_misses++;
259 return;
261 bad_area:
262 up_read(&mm->mmap_sem);
264 bad_area_nosemaphore:
265 pte_errors++;
267 /* User mode accesses cause a SIGSEGV */
268 if (user_mode(regs)) {
269 _exception(SIGSEGV, regs, code, address);
270 /* info.si_signo = SIGSEGV;
271 info.si_errno = 0;
272 info.si_code = code;
273 info.si_addr = (void *) address;
274 force_sig_info(SIGSEGV, &info, current);*/
275 return;
278 bad_page_fault(regs, address, SIGSEGV);
279 return;
282 * We ran out of memory, or some other thing happened to us that made
283 * us unable to handle the page fault gracefully.
285 out_of_memory:
286 up_read(&mm->mmap_sem);
287 if (!user_mode(regs))
288 bad_page_fault(regs, address, SIGKILL);
289 else
290 pagefault_out_of_memory();
291 return;
293 do_sigbus:
294 up_read(&mm->mmap_sem);
295 if (user_mode(regs)) {
296 info.si_signo = SIGBUS;
297 info.si_errno = 0;
298 info.si_code = BUS_ADRERR;
299 info.si_addr = (void __user *)address;
300 force_sig_info(SIGBUS, &info, current);
301 return;
303 bad_page_fault(regs, address, SIGBUS);