1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
// SPDX-License-Identifier: GPL-2.0
/*
* Based on arch/arm/mm/extable.c
*/
#include <linux/bitfield.h>
#include <linux/extable.h>
#include <linux/uaccess.h>
#include <asm/asm-extable.h>
#include <asm/ptrace.h>
static inline unsigned long
get_ex_fixup(const struct exception_table_entry *ex)
{
return ((unsigned long)&ex->fixup + ex->fixup);
}
static bool ex_handler_fixup(const struct exception_table_entry *ex,
struct pt_regs *regs)
{
regs->pc = get_ex_fixup(ex);
return true;
}
static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
struct pt_regs *regs)
{
int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
pt_regs_write_reg(regs, reg_err, -EFAULT);
pt_regs_write_reg(regs, reg_zero, 0);
regs->pc = get_ex_fixup(ex);
return true;
}
static bool
ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
struct pt_regs *regs)
{
int reg_data = FIELD_GET(EX_DATA_REG_DATA, ex->type);
int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->type);
unsigned long data, addr, offset;
addr = pt_regs_read_reg(regs, reg_addr);
offset = addr & 0x7UL;
addr &= ~0x7UL;
data = *(unsigned long*)addr;
#ifndef __AARCH64EB__
data >>= 8 * offset;
#else
data <<= 8 * offset;
#endif
pt_regs_write_reg(regs, reg_data, data);
regs->pc = get_ex_fixup(ex);
return true;
}
bool fixup_exception(struct pt_regs *regs)
{
const struct exception_table_entry *ex;
ex = search_exception_tables(instruction_pointer(regs));
if (!ex)
return false;
switch (ex->type) {
case EX_TYPE_FIXUP:
return ex_handler_fixup(ex, regs);
case EX_TYPE_BPF:
return ex_handler_bpf(ex, regs);
case EX_TYPE_UACCESS_ERR_ZERO:
return ex_handler_uaccess_err_zero(ex, regs);
case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
return ex_handler_load_unaligned_zeropad(ex, regs);
}
BUG();
}
|
