xref: /kernel/linux/linux-5.10/arch/sparc/mm/extable.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/arch/sparc/mm/extable.c
4 */
5
6#include <linux/module.h>
7#include <linux/extable.h>
8#include <linux/uaccess.h>
9
10void sort_extable(struct exception_table_entry *start,
11		  struct exception_table_entry *finish)
12{
13}
14
15/* Caller knows they are in a range if ret->fixup == 0 */
16const struct exception_table_entry *
17search_extable(const struct exception_table_entry *base,
18	       const size_t num,
19	       unsigned long value)
20{
21	int i;
22
23	/* Single insn entries are encoded as:
24	 *	word 1:	insn address
25	 *	word 2:	fixup code address
26	 *
27	 * Range entries are encoded as:
28	 *	word 1: first insn address
29	 *	word 2: 0
30	 *	word 3: last insn address + 4 bytes
31	 *	word 4: fixup code address
32	 *
33	 * Deleted entries are encoded as:
34	 *	word 1: unused
35	 *	word 2: -1
36	 *
37	 * See asm/uaccess.h for more details.
38	 */
39
40	/* 1. Try to find an exact match. */
41	for (i = 0; i < num; i++) {
42		if (base[i].fixup == 0) {
43			/* A range entry, skip both parts. */
44			i++;
45			continue;
46		}
47
48		/* A deleted entry; see trim_init_extable */
49		if (base[i].fixup == -1)
50			continue;
51
52		if (base[i].insn == value)
53			return &base[i];
54	}
55
56	/* 2. Try to find a range match. */
57	for (i = 0; i < (num - 1); i++) {
58		if (base[i].fixup)
59			continue;
60
61		if (base[i].insn <= value && base[i + 1].insn > value)
62			return &base[i];
63
64		i++;
65	}
66
67        return NULL;
68}
69
70#ifdef CONFIG_MODULES
71/* We could memmove them around; easier to mark the trimmed ones. */
72void trim_init_extable(struct module *m)
73{
74	unsigned int i;
75	bool range;
76
77	for (i = 0; i < m->num_exentries; i += range ? 2 : 1) {
78		range = m->extable[i].fixup == 0;
79
80		if (within_module_init(m->extable[i].insn, m)) {
81			m->extable[i].fixup = -1;
82			if (range)
83				m->extable[i+1].fixup = -1;
84		}
85		if (range)
86			i++;
87	}
88}
89#endif /* CONFIG_MODULES */
90
91/* Special extable search, which handles ranges.  Returns fixup */
92unsigned long search_extables_range(unsigned long addr, unsigned long *g2)
93{
94	const struct exception_table_entry *entry;
95
96	entry = search_exception_tables(addr);
97	if (!entry)
98		return 0;
99
100	/* Inside range?  Fix g2 and return correct fixup */
101	if (!entry->fixup) {
102		*g2 = (addr - entry->insn) / 4;
103		return (entry + 1)->fixup;
104	}
105
106	return entry->fixup;
107}
108