1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Memory fault handling for Hexagon
4 *
5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
6 */
7
8/*
9 * Page fault handling for the Hexagon Virtual Machine.
10 * Can also be called by a native port emulating the HVM
11 * execptions.
12 */
13
14#include <asm/traps.h>
15#include <linux/uaccess.h>
16#include <linux/mm.h>
17#include <linux/sched/signal.h>
18#include <linux/signal.h>
19#include <linux/extable.h>
20#include <linux/hardirq.h>
21#include <linux/perf_event.h>
22
23/*
24 * Decode of hardware exception sends us to one of several
25 * entry points.  At each, we generate canonical arguments
26 * for handling by the abstract memory management code.
27 */
28#define FLT_IFETCH     -1
29#define FLT_LOAD        0
30#define FLT_STORE       1
31
32
33/*
34 * Canonical page fault handler
35 */
36void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
37{
38	struct vm_area_struct *vma;
39	struct mm_struct *mm = current->mm;
40	int si_signo;
41	int si_code = SEGV_MAPERR;
42	vm_fault_t fault;
43	const struct exception_table_entry *fixup;
44	unsigned int flags = FAULT_FLAG_DEFAULT;
45
46	/*
47	 * If we're in an interrupt or have no user context,
48	 * then must not take the fault.
49	 */
50	if (unlikely(in_interrupt() || !mm))
51		goto no_context;
52
53	local_irq_enable();
54
55	if (user_mode(regs))
56		flags |= FAULT_FLAG_USER;
57
58	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
59retry:
60	mmap_read_lock(mm);
61	vma = find_vma(mm, address);
62	if (!vma)
63		goto bad_area;
64
65	if (vma->vm_start <= address)
66		goto good_area;
67
68	if (!(vma->vm_flags & VM_GROWSDOWN))
69		goto bad_area;
70
71	if (expand_stack(vma, address))
72		goto bad_area;
73
74good_area:
75	/* Address space is OK.  Now check access rights. */
76	si_code = SEGV_ACCERR;
77
78	switch (cause) {
79	case FLT_IFETCH:
80		if (!(vma->vm_flags & VM_EXEC))
81			goto bad_area;
82		break;
83	case FLT_LOAD:
84		if (!(vma->vm_flags & VM_READ))
85			goto bad_area;
86		break;
87	case FLT_STORE:
88		if (!(vma->vm_flags & VM_WRITE))
89			goto bad_area;
90		flags |= FAULT_FLAG_WRITE;
91		break;
92	}
93
94	fault = handle_mm_fault(vma, address, flags, regs);
95
96	if (fault_signal_pending(fault, regs))
97		return;
98
99	/* The most common case -- we are done. */
100	if (likely(!(fault & VM_FAULT_ERROR))) {
101		if (flags & FAULT_FLAG_ALLOW_RETRY) {
102			if (fault & VM_FAULT_RETRY) {
103				flags |= FAULT_FLAG_TRIED;
104				goto retry;
105			}
106		}
107
108		mmap_read_unlock(mm);
109		return;
110	}
111
112	mmap_read_unlock(mm);
113
114	/* Handle copyin/out exception cases */
115	if (!user_mode(regs))
116		goto no_context;
117
118	if (fault & VM_FAULT_OOM) {
119		pagefault_out_of_memory();
120		return;
121	}
122
123	/* User-mode address is in the memory map, but we are
124	 * unable to fix up the page fault.
125	 */
126	if (fault & VM_FAULT_SIGBUS) {
127		si_signo = SIGBUS;
128		si_code = BUS_ADRERR;
129	}
130	/* Address is not in the memory map */
131	else {
132		si_signo = SIGSEGV;
133		si_code  = SEGV_ACCERR;
134	}
135	force_sig_fault(si_signo, si_code, (void __user *)address);
136	return;
137
138bad_area:
139	mmap_read_unlock(mm);
140
141	if (user_mode(regs)) {
142		force_sig_fault(SIGSEGV, si_code, (void __user *)address);
143		return;
144	}
145	/* Kernel-mode fault falls through */
146
147no_context:
148	fixup = search_exception_tables(pt_elr(regs));
149	if (fixup) {
150		pt_set_elr(regs, fixup->fixup);
151		return;
152	}
153
154	/* Things are looking very, very bad now */
155	bust_spinlocks(1);
156	printk(KERN_EMERG "Unable to handle kernel paging request at "
157		"virtual address 0x%08lx, regs %p\n", address, regs);
158	die("Bad Kernel VA", regs, SIGKILL);
159}
160
161
162void read_protection_fault(struct pt_regs *regs)
163{
164	unsigned long badvadr = pt_badva(regs);
165
166	do_page_fault(badvadr, FLT_LOAD, regs);
167}
168
169void write_protection_fault(struct pt_regs *regs)
170{
171	unsigned long badvadr = pt_badva(regs);
172
173	do_page_fault(badvadr, FLT_STORE, regs);
174}
175
176void execute_protection_fault(struct pt_regs *regs)
177{
178	unsigned long badvadr = pt_badva(regs);
179
180	do_page_fault(badvadr, FLT_IFETCH, regs);
181}
182