1 // SPDX-License-Identifier: GPL-2.0
3 * Meta page fault handling.
5 * Copyright (C) 2005-2012 Imagination Technologies Ltd.
8 #include <linux/mman.h>
10 #include <linux/kernel.h>
11 #include <linux/ptrace.h>
12 #include <linux/sched/debug.h>
13 #include <linux/interrupt.h>
14 #include <linux/uaccess.h>
16 #include <asm/tlbflush.h>
18 #include <asm/traps.h>
20 /* Clear any pending catch buffer state. */
21 static void clear_cbuf_entry(struct pt_regs *regs, unsigned long addr,
24 PTBICTXEXTCB0 cbuf = regs->extcb0;
27 /* Instruction fetch faults leave no catch buffer state. */
28 case TBIXXF_SIGNUM_IGF:
29 case TBIXXF_SIGNUM_IPF:
32 if (cbuf[0].CBAddr == addr) {
34 cbuf[0].CBFlags &= ~TXCATCH0_FAULT_BITS;
36 /* And, as this is the ONLY catch entry, we
37 * need to clear the cbuf bit from the context!
39 regs->ctx.SaveMask &= ~(TBICTX_CBUF_BIT |
44 pr_err("Failed to clear cbuf entry!\n");
48 int show_unhandled_signals = 1;
50 int do_page_fault(struct pt_regs *regs, unsigned long address,
51 unsigned int write_access, unsigned int trapno)
53 struct task_struct *tsk;
55 struct vm_area_struct *vma, *prev_vma;
58 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
62 if ((address >= VMALLOC_START) && (address < VMALLOC_END)) {
64 * Synchronize this task's top level page-table
65 * with the 'reference' page table.
67 * Do _not_ use "tsk" here. We might be inside
68 * an interrupt in the middle of a task switch..
70 int offset = pgd_index(address);
76 pgd = ((pgd_t *)mmu_get_base()) + offset;
77 pgd_k = swapper_pg_dir + offset;
79 /* This will never happen with the folded page table. */
80 if (!pgd_present(*pgd)) {
81 if (!pgd_present(*pgd_k))
82 goto bad_area_nosemaphore;
87 pud = pud_offset(pgd, address);
88 pud_k = pud_offset(pgd_k, address);
89 if (!pud_present(*pud_k))
90 goto bad_area_nosemaphore;
93 pmd = pmd_offset(pud, address);
94 pmd_k = pmd_offset(pud_k, address);
95 if (!pmd_present(*pmd_k))
96 goto bad_area_nosemaphore;
99 pte_k = pte_offset_kernel(pmd_k, address);
100 if (!pte_present(*pte_k))
101 goto bad_area_nosemaphore;
103 /* May only be needed on Chorus2 */
110 if (faulthandler_disabled() || !mm)
114 flags |= FAULT_FLAG_USER;
116 down_read(&mm->mmap_sem);
118 vma = find_vma_prev(mm, address, &prev_vma);
120 if (!vma || address < vma->vm_start)
121 goto check_expansion;
125 if (!(vma->vm_flags & VM_WRITE))
127 flags |= FAULT_FLAG_WRITE;
129 if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
134 * If for any reason at all we couldn't handle the fault,
135 * make sure we exit gracefully rather than endlessly redo
138 fault = handle_mm_fault(vma, address, flags);
140 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
143 if (unlikely(fault & VM_FAULT_ERROR)) {
144 if (fault & VM_FAULT_OOM)
146 else if (fault & VM_FAULT_SIGSEGV)
148 else if (fault & VM_FAULT_SIGBUS)
152 if (flags & FAULT_FLAG_ALLOW_RETRY) {
153 if (fault & VM_FAULT_MAJOR)
157 if (fault & VM_FAULT_RETRY) {
158 flags &= ~FAULT_FLAG_ALLOW_RETRY;
159 flags |= FAULT_FLAG_TRIED;
162 * No need to up_read(&mm->mmap_sem) as we would
163 * have already released it in __lock_page_or_retry
171 up_read(&mm->mmap_sem);
176 if (vma && (expand_stack(vma, address) == 0))
180 up_read(&mm->mmap_sem);
182 bad_area_nosemaphore:
183 if (user_mode(regs)) {
184 info.si_signo = SIGSEGV;
186 info.si_code = SEGV_MAPERR;
187 info.si_addr = (__force void __user *)address;
188 info.si_trapno = trapno;
190 if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
191 printk_ratelimit()) {
192 printk("%s%s[%d]: segfault at %lx pc %08x sp %08x write %d trap %#x (%s)",
193 task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
194 tsk->comm, task_pid_nr(tsk), address,
195 regs->ctx.CurrPC, regs->ctx.AX[0].U0,
196 write_access, trapno, trap_name(trapno));
197 print_vma_addr(" in ", regs->ctx.CurrPC);
198 print_vma_addr(" rtp in ", regs->ctx.DX[4].U1);
202 force_sig_info(SIGSEGV, &info, tsk);
208 up_read(&mm->mmap_sem);
211 * Send a sigbus, regardless of whether we were in kernel
214 info.si_signo = SIGBUS;
216 info.si_code = BUS_ADRERR;
217 info.si_addr = (__force void __user *)address;
218 info.si_trapno = trapno;
219 force_sig_info(SIGBUS, &info, tsk);
221 /* Kernel mode? Handle exceptions or die */
222 if (!user_mode(regs))
228 * We ran out of memory, or some other thing happened to us that made
229 * us unable to handle the page fault gracefully.
232 up_read(&mm->mmap_sem);
233 if (user_mode(regs)) {
234 pagefault_out_of_memory();
239 /* Are we prepared to handle this kernel fault? */
240 if (fixup_exception(regs)) {
241 clear_cbuf_entry(regs, address, trapno);
245 die("Oops", regs, (write_access << 15) | trapno, address);