2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
7 #include <linux/sched.h>
8 #include <linux/hardirq.h>
9 #include <linux/module.h>
10 #include <asm/current.h>
11 #include <asm/pgtable.h>
12 #include <asm/tlbflush.h>
14 #include "as-layout.h"
15 #include "kern_util.h"
20 * Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by
23 int handle_page_fault(unsigned long address, unsigned long ip,
24 int is_write, int is_user, int *code_out)
26 struct mm_struct *mm = current->mm;
27 struct vm_area_struct *vma;
33 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
34 (is_write ? FAULT_FLAG_WRITE : 0);
36 *code_out = SEGV_MAPERR;
39 * If the fault was during atomic operation, don't take the fault, just
46 down_read(&mm->mmap_sem);
47 vma = find_vma(mm, address);
50 else if (vma->vm_start <= address)
52 else if (!(vma->vm_flags & VM_GROWSDOWN))
54 else if (is_user && !ARCH_IS_STACKGROW(address))
56 else if (expand_stack(vma, address))
60 *code_out = SEGV_ACCERR;
61 if (is_write && !(vma->vm_flags & VM_WRITE))
64 /* Don't require VM_READ|VM_EXEC for write faults! */
65 if (!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
71 fault = handle_mm_fault(mm, vma, address, flags);
73 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
76 if (unlikely(fault & VM_FAULT_ERROR)) {
77 if (fault & VM_FAULT_OOM) {
79 } else if (fault & VM_FAULT_SIGBUS) {
85 if (flags & FAULT_FLAG_ALLOW_RETRY) {
86 if (fault & VM_FAULT_MAJOR)
90 if (fault & VM_FAULT_RETRY) {
91 flags &= ~FAULT_FLAG_ALLOW_RETRY;
92 flags |= FAULT_FLAG_TRIED;
98 pgd = pgd_offset(mm, address);
99 pud = pud_offset(pgd, address);
100 pmd = pmd_offset(pud, address);
101 pte = pte_offset_kernel(pmd, address);
102 } while (!pte_present(*pte));
105 * The below warning was added in place of
106 * pte_mkyoung(); if (is_write) pte_mkdirty();
107 * If it's triggered, we'd see normally a hang here (a clean pte is
108 * marked read-only to emulate the dirty bit).
109 * However, the generic code can mark a PTE writable but clean on a
110 * concurrent read fault, triggering this harmlessly. So comment it out.
113 WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
115 flush_tlb_page(vma, address);
117 up_read(&mm->mmap_sem);
123 * We ran out of memory, call the OOM killer, and return the userspace
124 * (which will retry the fault, or kill us if we got oom-killed).
126 up_read(&mm->mmap_sem);
127 pagefault_out_of_memory();
130 EXPORT_SYMBOL(handle_page_fault);
132 static void show_segv_info(struct uml_pt_regs *regs)
134 struct task_struct *tsk = current;
135 struct faultinfo *fi = UPT_FAULTINFO(regs);
137 if (!unhandled_signal(tsk, SIGSEGV))
140 if (!printk_ratelimit())
143 printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
144 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
145 tsk->comm, task_pid_nr(tsk), FAULT_ADDRESS(*fi),
146 (void *)UPT_IP(regs), (void *)UPT_SP(regs),
149 print_vma_addr(KERN_CONT " in ", UPT_IP(regs));
150 printk(KERN_CONT "\n");
153 static void bad_segv(struct faultinfo fi, unsigned long ip)
157 si.si_signo = SIGSEGV;
158 si.si_code = SEGV_ACCERR;
159 si.si_addr = (void __user *) FAULT_ADDRESS(fi);
160 current->thread.arch.faultinfo = fi;
161 force_sig_info(SIGSEGV, &si, current);
164 void fatal_sigsegv(void)
166 force_sigsegv(SIGSEGV, current);
169 * This is to tell gcc that we're not returning - do_signal
170 * can, in general, return, but in this case, it's not, since
171 * we just got a fatal SIGSEGV queued.
176 void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
178 struct faultinfo * fi = UPT_FAULTINFO(regs);
180 if (UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)) {
181 show_segv_info(regs);
182 bad_segv(*fi, UPT_IP(regs));
185 segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
189 * We give a *copy* of the faultinfo in the regs to segv.
190 * This must be done, since nesting SEGVs could overwrite
191 * the info in the regs. A pointer to the info then would
194 unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
195 struct uml_pt_regs *regs)
200 int is_write = FAULT_WRITE(fi);
201 unsigned long address = FAULT_ADDRESS(fi);
203 if (!is_user && (address >= start_vm) && (address < end_vm)) {
204 flush_tlb_kernel_vm();
207 else if (current->mm == NULL) {
208 show_regs(container_of(regs, struct pt_regs, regs));
209 panic("Segfault with no mm");
212 if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
213 err = handle_page_fault(address, ip, is_write, is_user,
218 * A thread accessed NULL, we get a fault, but CR2 is invalid.
219 * This code is used in __do_copy_from_user() of TT mode.
220 * XXX tt mode is gone, so maybe this isn't needed any more
225 catcher = current->thread.fault_catcher;
228 else if (catcher != NULL) {
229 current->thread.fault_addr = (void *) address;
230 UML_LONGJMP(catcher, 1);
232 else if (current->thread.fault_addr != NULL)
233 panic("fault_addr set but no fault catcher");
234 else if (!is_user && arch_fixup(ip, regs))
238 show_regs(container_of(regs, struct pt_regs, regs));
239 panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
243 show_segv_info(regs);
245 if (err == -EACCES) {
246 si.si_signo = SIGBUS;
248 si.si_code = BUS_ADRERR;
249 si.si_addr = (void __user *)address;
250 current->thread.arch.faultinfo = fi;
251 force_sig_info(SIGBUS, &si, current);
253 BUG_ON(err != -EFAULT);
254 si.si_signo = SIGSEGV;
255 si.si_addr = (void __user *) address;
256 current->thread.arch.faultinfo = fi;
257 force_sig_info(SIGSEGV, &si, current);
262 void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs)
264 struct faultinfo *fi;
265 struct siginfo clean_si;
267 if (!UPT_IS_USER(regs)) {
269 printk(KERN_ERR "Bus error - the host /dev/shm or /tmp "
270 "mount likely just ran out of space\n");
271 panic("Kernel mode signal %d", sig);
274 arch_examine_signal(sig, regs);
276 memset(&clean_si, 0, sizeof(clean_si));
277 clean_si.si_signo = si->si_signo;
278 clean_si.si_errno = si->si_errno;
279 clean_si.si_code = si->si_code;
286 fi = UPT_FAULTINFO(regs);
287 clean_si.si_addr = (void __user *) FAULT_ADDRESS(*fi);
288 current->thread.arch.faultinfo = *fi;
289 #ifdef __ARCH_SI_TRAPNO
290 clean_si.si_trapno = si->si_trapno;
294 printk(KERN_ERR "Attempted to relay unknown signal %d (si_code = %d)\n",
298 force_sig_info(sig, &clean_si, current);
301 void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs)
303 if (current->thread.fault_catcher != NULL)
304 UML_LONGJMP(current->thread.fault_catcher, 1);
306 relay_signal(sig, si, regs);
309 void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
311 do_IRQ(WINCH_IRQ, regs);