blob: db6913094be3c9b2bc9ad87e91f7aab779da728d [file] [log] [blame]
Vineet Guptafbd70532013-01-18 15:12:20 +05301/* Page Fault Handling for ARC (TLB Miss / ProtV)
2 *
3 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 */
9
10#include <linux/signal.h>
11#include <linux/interrupt.h>
Ingo Molnar3f07c012017-02-08 18:51:30 +010012#include <linux/sched/signal.h>
Vineet Guptafbd70532013-01-18 15:12:20 +053013#include <linux/errno.h>
14#include <linux/ptrace.h>
Vineet Guptafbd70532013-01-18 15:12:20 +053015#include <linux/uaccess.h>
16#include <linux/kdebug.h>
Vineet Guptaceed97a2014-10-02 12:30:42 +053017#include <linux/perf_event.h>
Souptick Joarder50a7ca32018-08-17 15:44:47 -070018#include <linux/mm_types.h>
Vineet Guptafbd70532013-01-18 15:12:20 +053019#include <asm/pgalloc.h>
Vineet Guptada1677b02013-05-14 13:28:17 +053020#include <asm/mmu.h>
Vineet Guptafbd70532013-01-18 15:12:20 +053021
Vineet Gupta336e2132015-03-05 17:06:31 +053022/*
23 * kernel virtual address is required to implement vmalloc/pkmap/fixmap
24 * Refer to asm/processor.h for System Memory Map
25 *
26 * It simply copies the PMD entry (pointer to 2nd level page table or hugepage)
27 * from swapper pgdir to task pgdir. The 2nd level table/page is thus shared
28 */
29noinline static int handle_kernel_vaddr_fault(unsigned long address)
Vineet Guptafbd70532013-01-18 15:12:20 +053030{
31 /*
32 * Synchronize this task's top level page-table
33 * with the 'reference' page table.
34 */
35 pgd_t *pgd, *pgd_k;
36 pud_t *pud, *pud_k;
37 pmd_t *pmd, *pmd_k;
38
Vineet Gupta9c41f4e2013-11-02 17:47:49 +053039 pgd = pgd_offset_fast(current->active_mm, address);
Vineet Guptafbd70532013-01-18 15:12:20 +053040 pgd_k = pgd_offset_k(address);
41
42 if (!pgd_present(*pgd_k))
43 goto bad_area;
44
45 pud = pud_offset(pgd, address);
46 pud_k = pud_offset(pgd_k, address);
47 if (!pud_present(*pud_k))
48 goto bad_area;
49
50 pmd = pmd_offset(pud, address);
51 pmd_k = pmd_offset(pud_k, address);
52 if (!pmd_present(*pmd_k))
53 goto bad_area;
54
55 set_pmd(pmd, *pmd_k);
56
57 /* XXX: create the TLB entry here */
58 return 0;
59
60bad_area:
61 return 1;
62}
63
Vineet Gupta21a63b52013-09-18 16:25:40 +053064void do_page_fault(unsigned long address, struct pt_regs *regs)
Vineet Guptafbd70532013-01-18 15:12:20 +053065{
66 struct vm_area_struct *vma = NULL;
67 struct task_struct *tsk = current;
68 struct mm_struct *mm = tsk->mm;
69 siginfo_t info;
Souptick Joarder50a7ca32018-08-17 15:44:47 -070070 int ret;
71 vm_fault_t fault;
Vineet Gupta38a9ff62013-06-12 15:13:40 +053072 int write = regs->ecr_cause & ECR_C_PROTV_STORE; /* ST/EX */
Johannes Weiner759496b2013-09-12 15:13:39 -070073 unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
Vineet Guptafbd70532013-01-18 15:12:20 +053074
Eric W. Biederman3eb0f512018-04-17 15:26:37 -050075 clear_siginfo(&info);
76
Vineet Guptafbd70532013-01-18 15:12:20 +053077 /*
78 * We fault-in kernel-space virtual memory on-demand. The
79 * 'reference' page table is init_mm.pgd.
80 *
81 * NOTE! We MUST NOT take any locks for this case. We may
82 * be in an interrupt or a critical region, and should
83 * only copy the information from the master page table,
84 * nothing more.
85 */
Vineet Gupta336e2132015-03-05 17:06:31 +053086 if (address >= VMALLOC_START) {
87 ret = handle_kernel_vaddr_fault(address);
Vineet Guptafbd70532013-01-18 15:12:20 +053088 if (unlikely(ret))
89 goto bad_area_nosemaphore;
90 else
91 return;
92 }
93
94 info.si_code = SEGV_MAPERR;
95
96 /*
97 * If we're in an interrupt or have no user
98 * context, we must not take the fault..
99 */
David Hildenbrand70ffdb92015-05-11 17:52:11 +0200100 if (faulthandler_disabled() || !mm)
Vineet Guptafbd70532013-01-18 15:12:20 +0530101 goto no_context;
102
Johannes Weiner759496b2013-09-12 15:13:39 -0700103 if (user_mode(regs))
104 flags |= FAULT_FLAG_USER;
Vineet Guptafbd70532013-01-18 15:12:20 +0530105retry:
106 down_read(&mm->mmap_sem);
107 vma = find_vma(mm, address);
108 if (!vma)
109 goto bad_area;
110 if (vma->vm_start <= address)
111 goto good_area;
112 if (!(vma->vm_flags & VM_GROWSDOWN))
113 goto bad_area;
114 if (expand_stack(vma, address))
115 goto bad_area;
116
117 /*
118 * Ok, we have a good vm_area for this memory access, so
119 * we can handle it..
120 */
121good_area:
122 info.si_code = SEGV_ACCERR;
123
124 /* Handle protection violation, execute on heap or stack */
125
Vineet Gupta38a9ff62013-06-12 15:13:40 +0530126 if ((regs->ecr_vec == ECR_V_PROTV) &&
127 (regs->ecr_cause == ECR_C_PROTV_INST_FETCH))
Vineet Guptafbd70532013-01-18 15:12:20 +0530128 goto bad_area;
129
130 if (write) {
131 if (!(vma->vm_flags & VM_WRITE))
132 goto bad_area;
Johannes Weiner759496b2013-09-12 15:13:39 -0700133 flags |= FAULT_FLAG_WRITE;
Vineet Guptafbd70532013-01-18 15:12:20 +0530134 } else {
135 if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
136 goto bad_area;
137 }
138
Vineet Guptafbd70532013-01-18 15:12:20 +0530139 /*
140 * If for any reason at all we couldn't handle the fault,
141 * make sure we exit gracefully rather than endlessly redo
142 * the fault.
143 */
Kirill A. Shutemovdcddffd2016-07-26 15:25:18 -0700144 fault = handle_mm_fault(vma, address, flags);
Vineet Guptafbd70532013-01-18 15:12:20 +0530145
146 /* If Pagefault was interrupted by SIGKILL, exit page fault "early" */
147 if (unlikely(fatal_signal_pending(current))) {
148 if ((fault & VM_FAULT_ERROR) && !(fault & VM_FAULT_RETRY))
149 up_read(&mm->mmap_sem);
150 if (user_mode(regs))
151 return;
152 }
153
Vineet Guptaceed97a2014-10-02 12:30:42 +0530154 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
155
Vineet Guptafbd70532013-01-18 15:12:20 +0530156 if (likely(!(fault & VM_FAULT_ERROR))) {
157 if (flags & FAULT_FLAG_ALLOW_RETRY) {
158 /* To avoid updating stats twice for retry case */
Vineet Guptaceed97a2014-10-02 12:30:42 +0530159 if (fault & VM_FAULT_MAJOR) {
Vineet Guptafbd70532013-01-18 15:12:20 +0530160 tsk->maj_flt++;
Vineet Guptaceed97a2014-10-02 12:30:42 +0530161 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
162 regs, address);
163 } else {
Vineet Guptafbd70532013-01-18 15:12:20 +0530164 tsk->min_flt++;
Vineet Guptaceed97a2014-10-02 12:30:42 +0530165 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
166 regs, address);
167 }
Vineet Guptafbd70532013-01-18 15:12:20 +0530168
169 if (fault & VM_FAULT_RETRY) {
170 flags &= ~FAULT_FLAG_ALLOW_RETRY;
171 flags |= FAULT_FLAG_TRIED;
172 goto retry;
173 }
174 }
175
176 /* Fault Handled Gracefully */
177 up_read(&mm->mmap_sem);
178 return;
179 }
180
Vineet Guptafbd70532013-01-18 15:12:20 +0530181 if (fault & VM_FAULT_OOM)
182 goto out_of_memory;
Guenter Roecke262eb92015-01-29 19:15:33 -0800183 else if (fault & VM_FAULT_SIGSEGV)
Linus Torvalds33692f22015-01-29 10:51:32 -0800184 goto bad_area;
Vineet Guptafbd70532013-01-18 15:12:20 +0530185 else if (fault & VM_FAULT_SIGBUS)
186 goto do_sigbus;
187
188 /* no man's land */
189 BUG();
190
191 /*
192 * Something tried to access memory that isn't in our memory map..
193 * Fix it, but check if it's kernel or user first..
194 */
195bad_area:
196 up_read(&mm->mmap_sem);
197
198bad_area_nosemaphore:
199 /* User mode accesses just cause a SIGSEGV */
200 if (user_mode(regs)) {
201 tsk->thread.fault_address = address;
Vineet Guptafbd70532013-01-18 15:12:20 +0530202 info.si_signo = SIGSEGV;
203 info.si_errno = 0;
204 /* info.si_code has been set above */
205 info.si_addr = (void __user *)address;
206 force_sig_info(SIGSEGV, &info, tsk);
207 return;
208 }
209
210no_context:
211 /* Are we prepared to handle this kernel fault?
212 *
213 * (The kernel has valid exception-points in the source
Liav Rehanaddf720f2017-05-28 09:52:00 +0300214 * when it accesses user-memory. When it fails in one
Vineet Guptafbd70532013-01-18 15:12:20 +0530215 * of those points, we find it in a table and do a jump
216 * to some fixup code that loads an appropriate error
217 * code)
218 */
219 if (fixup_exception(regs))
220 return;
221
Vineet Gupta38a9ff62013-06-12 15:13:40 +0530222 die("Oops", regs, address);
Vineet Guptafbd70532013-01-18 15:12:20 +0530223
224out_of_memory:
Vineet Guptafbd70532013-01-18 15:12:20 +0530225 up_read(&mm->mmap_sem);
226
Johannes Weiner609838c2013-07-08 15:59:50 -0700227 if (user_mode(regs)) {
228 pagefault_out_of_memory();
229 return;
230 }
Vineet Guptafbd70532013-01-18 15:12:20 +0530231
232 goto no_context;
233
234do_sigbus:
235 up_read(&mm->mmap_sem);
236
237 if (!user_mode(regs))
238 goto no_context;
239
240 tsk->thread.fault_address = address;
Vineet Guptafbd70532013-01-18 15:12:20 +0530241 info.si_signo = SIGBUS;
242 info.si_errno = 0;
243 info.si_code = BUS_ADRERR;
244 info.si_addr = (void __user *)address;
245 force_sig_info(SIGBUS, &info, tsk);
246}