1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
4 *  Lennox Wu <lennox.wu@sunplusct.com>
5 *  Chen Liqin <liqin.chen@sunplusct.com>
6 * Copyright (C) 2013 Regents of the University of California
7 */
8
9
10#include <linux/bitfield.h>
11#include <linux/extable.h>
12#include <linux/module.h>
13#include <linux/uaccess.h>
14#include <asm/asm-extable.h>
15#include <asm/ptrace.h>
16
17static inline unsigned long
18get_ex_fixup(const struct exception_table_entry *ex)
19{
20	return ((unsigned long)&ex->fixup + ex->fixup);
21}
22
23static bool ex_handler_fixup(const struct exception_table_entry *ex,
24			     struct pt_regs *regs)
25{
26	regs->epc = get_ex_fixup(ex);
27	return true;
28}
29
30static inline unsigned long regs_get_gpr(struct pt_regs *regs, unsigned int offset)
31{
32	if (unlikely(!offset || offset > MAX_REG_OFFSET))
33		return 0;
34
35	return *(unsigned long *)((unsigned long)regs + offset);
36}
37
38static inline void regs_set_gpr(struct pt_regs *regs, unsigned int offset,
39				unsigned long val)
40{
41	if (unlikely(offset > MAX_REG_OFFSET))
42		return;
43
44	if (offset)
45		*(unsigned long *)((unsigned long)regs + offset) = val;
46}
47
48static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
49					struct pt_regs *regs)
50{
51	int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
52	int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
53
54	regs_set_gpr(regs, reg_err * sizeof(unsigned long), -EFAULT);
55	regs_set_gpr(regs, reg_zero * sizeof(unsigned long), 0);
56
57	regs->epc = get_ex_fixup(ex);
58	return true;
59}
60
61static bool
62ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
63				  struct pt_regs *regs)
64{
65	int reg_data = FIELD_GET(EX_DATA_REG_DATA, ex->data);
66	int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
67	unsigned long data, addr, offset;
68
69	addr = regs_get_gpr(regs, reg_addr * sizeof(unsigned long));
70
71	offset = addr & 0x7UL;
72	addr &= ~0x7UL;
73
74	data = *(unsigned long *)addr >> (offset * 8);
75
76	regs_set_gpr(regs, reg_data * sizeof(unsigned long), data);
77
78	regs->epc = get_ex_fixup(ex);
79	return true;
80}
81
82bool fixup_exception(struct pt_regs *regs)
83{
84	const struct exception_table_entry *ex;
85
86	ex = search_exception_tables(regs->epc);
87	if (!ex)
88		return false;
89
90	switch (ex->type) {
91	case EX_TYPE_FIXUP:
92		return ex_handler_fixup(ex, regs);
93	case EX_TYPE_BPF:
94		return ex_handler_bpf(ex, regs);
95	case EX_TYPE_UACCESS_ERR_ZERO:
96		return ex_handler_uaccess_err_zero(ex, regs);
97	case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
98		return ex_handler_load_unaligned_zeropad(ex, regs);
99	}
100
101	BUG();
102}
103