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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 void regs_set_gpr(struct pt_regs *regs, unsigned int offset,
31 unsigned long val)
32{
33 if (unlikely(offset > MAX_REG_OFFSET))
34 return;
35
36 if (offset)
37 *(unsigned long *)((unsigned long)regs + offset) = val;
38}
39
40static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
41 struct pt_regs *regs)
42{
43 int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
44 int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
45
46 regs_set_gpr(regs, reg_err * sizeof(unsigned long), -EFAULT);
47 regs_set_gpr(regs, reg_zero * sizeof(unsigned long), 0);
48
49 regs->epc = get_ex_fixup(ex);
50 return true;
51}
52
53bool fixup_exception(struct pt_regs *regs)
54{
55 const struct exception_table_entry *ex;
56
57 ex = search_exception_tables(regs->epc);
58 if (!ex)
59 return false;
60
61 switch (ex->type) {
62 case EX_TYPE_FIXUP:
63 return ex_handler_fixup(ex, regs);
64 case EX_TYPE_BPF:
65 return ex_handler_bpf(ex, regs);
66 case EX_TYPE_UACCESS_ERR_ZERO:
67 return ex_handler_uaccess_err_zero(ex, regs);
68 }
69
70 BUG();
71}