2 * Meta page fault handling.
4 * Copyright (C) 2005-2012 Imagination Technologies Ltd.
7 #include <linux/mman.h>
9 #include <linux/kernel.h>
10 #include <linux/ptrace.h>
11 #include <linux/interrupt.h>
12 #include <linux/uaccess.h>
14 #include <asm/tlbflush.h>
16 #include <asm/traps.h>
18 /* Clear any pending catch buffer state. */
19 static void clear_cbuf_entry(struct pt_regs *regs, unsigned long addr,
22 PTBICTXEXTCB0 cbuf = regs->extcb0;
25 /* Instruction fetch faults leave no catch buffer state. */
26 case TBIXXF_SIGNUM_IGF:
27 case TBIXXF_SIGNUM_IPF:
30 if (cbuf[0].CBAddr == addr) {
32 cbuf[0].CBFlags &= ~TXCATCH0_FAULT_BITS;
34 /* And, as this is the ONLY catch entry, we
35 * need to clear the cbuf bit from the context!
37 regs->ctx.SaveMask &= ~(TBICTX_CBUF_BIT |
42 pr_err("Failed to clear cbuf entry!\n");
46 int show_unhandled_signals = 1;
48 int do_page_fault(struct pt_regs *regs, unsigned long address,
49 unsigned int write_access, unsigned int trapno)
51 struct task_struct *tsk;
53 struct vm_area_struct *vma, *prev_vma;
56 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE |
57 (write_access ? FAULT_FLAG_WRITE : 0);
61 if ((address >= VMALLOC_START) && (address < VMALLOC_END)) {
63 * Synchronize this task's top level page-table
64 * with the 'reference' page table.
66 * Do _not_ use "tsk" here. We might be inside
67 * an interrupt in the middle of a task switch..
69 int offset = pgd_index(address);
75 pgd = ((pgd_t *)mmu_get_base()) + offset;
76 pgd_k = swapper_pg_dir + offset;
78 /* This will never happen with the folded page table. */
79 if (!pgd_present(*pgd)) {
80 if (!pgd_present(*pgd_k))
81 goto bad_area_nosemaphore;
86 pud = pud_offset(pgd, address);
87 pud_k = pud_offset(pgd_k, address);
88 if (!pud_present(*pud_k))
89 goto bad_area_nosemaphore;
92 pmd = pmd_offset(pud, address);
93 pmd_k = pmd_offset(pud_k, address);
94 if (!pmd_present(*pmd_k))
95 goto bad_area_nosemaphore;
98 pte_k = pte_offset_kernel(pmd_k, address);
99 if (!pte_present(*pte_k))
100 goto bad_area_nosemaphore;
102 /* May only be needed on Chorus2 */
109 if (in_atomic() || !mm)
113 down_read(&mm->mmap_sem);
115 vma = find_vma_prev(mm, address, &prev_vma);
117 if (!vma || address < vma->vm_start)
118 goto check_expansion;
122 if (!(vma->vm_flags & VM_WRITE))
125 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
130 * If for any reason at all we couldn't handle the fault,
131 * make sure we exit gracefully rather than endlessly redo
134 fault = handle_mm_fault(mm, vma, address, flags);
136 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
139 if (unlikely(fault & VM_FAULT_ERROR)) {
140 if (fault & VM_FAULT_OOM)
142 else if (fault & VM_FAULT_SIGBUS)
146 if (flags & FAULT_FLAG_ALLOW_RETRY) {
147 if (fault & VM_FAULT_MAJOR)
151 if (fault & VM_FAULT_RETRY) {
152 flags &= ~FAULT_FLAG_ALLOW_RETRY;
153 flags |= FAULT_FLAG_TRIED;
156 * No need to up_read(&mm->mmap_sem) as we would
157 * have already released it in __lock_page_or_retry
165 up_read(&mm->mmap_sem);
170 if (vma && (expand_stack(vma, address) == 0))
174 up_read(&mm->mmap_sem);
176 bad_area_nosemaphore:
177 if (user_mode(regs)) {
178 info.si_signo = SIGSEGV;
180 info.si_code = SEGV_MAPERR;
181 info.si_addr = (__force void __user *)address;
182 info.si_trapno = trapno;
184 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
185 printk_ratelimit()) {
186 pr_info("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)",
187 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
188 tsk->comm, task_pid_nr(tsk), address,
189 regs->ctx.CurrPC, regs->ctx.AX[0].U0,
190 write_access, trapno, trap_name(trapno));
191 print_vma_addr(" in ", regs->ctx.CurrPC);
192 print_vma_addr(" rtp in ", regs->ctx.DX[4].U1);
196 force_sig_info(SIGSEGV, &info, tsk);
202 up_read(&mm->mmap_sem);
205 * Send a sigbus, regardless of whether we were in kernel
208 info.si_signo = SIGBUS;
210 info.si_code = BUS_ADRERR;
211 info.si_addr = (__force void __user *)address;
212 info.si_trapno = trapno;
213 force_sig_info(SIGBUS, &info, tsk);
215 /* Kernel mode? Handle exceptions or die */
216 if (!user_mode(regs))
222 * We ran out of memory, or some other thing happened to us that made
223 * us unable to handle the page fault gracefully.
226 up_read(&mm->mmap_sem);
227 if (user_mode(regs)) {
228 pagefault_out_of_memory();
233 /* Are we prepared to handle this kernel fault? */
234 if (fixup_exception(regs)) {
235 clear_cbuf_entry(regs, address, trapno);
239 die("Oops", regs, (write_access << 15) | trapno, address);