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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
4 */
5#include <linux/bitfield.h>
6#include <linux/extable.h>
7#include <linux/uaccess.h>
8#include <asm/asm-extable.h>
9#include <asm/branch.h>
10
11static inline unsigned long
12get_ex_fixup(const struct exception_table_entry *ex)
13{
14 return ((unsigned long)&ex->fixup + ex->fixup);
15}
16
17static inline void regs_set_gpr(struct pt_regs *regs,
18 unsigned int offset, unsigned long val)
19{
20 if (offset && offset <= MAX_REG_OFFSET)
21 *(unsigned long *)((unsigned long)regs + offset) = val;
22}
23
24static bool ex_handler_fixup(const struct exception_table_entry *ex,
25 struct pt_regs *regs)
26{
27 regs->csr_era = get_ex_fixup(ex);
28
29 return true;
30}
31
32static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
33 struct pt_regs *regs)
34{
35 int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
36 int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
37
38 regs_set_gpr(regs, reg_err * sizeof(unsigned long), -EFAULT);
39 regs_set_gpr(regs, reg_zero * sizeof(unsigned long), 0);
40 regs->csr_era = get_ex_fixup(ex);
41
42 return true;
43}
44
45bool fixup_exception(struct pt_regs *regs)
46{
47 const struct exception_table_entry *ex;
48
49 ex = search_exception_tables(exception_era(regs));
50 if (!ex)
51 return false;
52
53 switch (ex->type) {
54 case EX_TYPE_FIXUP:
55 return ex_handler_fixup(ex, regs);
56 case EX_TYPE_UACCESS_ERR_ZERO:
57 return ex_handler_uaccess_err_zero(ex, regs);
58 case EX_TYPE_BPF:
59 return ex_handler_bpf(ex, regs);
60 }
61
62 BUG();
63}