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
17 static inline unsigned long
18 get_ex_fixup(const struct exception_table_entry *ex)
19 {
20 return ((unsigned long)&ex->fixup + ex->fixup);
21 }
22
23 static 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
30 static 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
38 static 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
48 static 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
61 static bool
62 ex_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
82 bool 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
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