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
get_ex_fixup(const struct exception_table_entry * ex)18 get_ex_fixup(const struct exception_table_entry *ex)
19 {
20 return ((unsigned long)&ex->fixup + ex->fixup);
21 }
22
ex_handler_fixup(const struct exception_table_entry * ex,struct pt_regs * regs)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
regs_set_gpr(struct pt_regs * regs,unsigned int offset,unsigned long val)30 static 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
ex_handler_uaccess_err_zero(const struct exception_table_entry * ex,struct pt_regs * regs)40 static 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
fixup_exception(struct pt_regs * regs)53 bool 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 }
72