summaryrefslogtreecommitdiffstats
path: root/arch/blackfin/kernel/fixed_code.S
blob: 4b03ba025488edd4ec55d0f2cc9c92d3d9c2313b (plain)
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
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/*
 * This file contains sequences of code that will be copied to a
 * fixed location, defined in <asm/fixed_code.h>.  The interrupt
 * handlers ensure that these sequences appear to be atomic when
 * executed from userspace.
 * These are aligned to 16 bytes, so that we have some space to replace
 * these sequences with something else (e.g. kernel traps if we ever do
 * BF561 SMP).
 */
#include <linux/linkage.h>
#include <linux/unistd.h>
#include <asm/entry.h>

.text
ENTRY(_fixed_code_start)

.align 16
ENTRY(_sigreturn_stub)
	P0 = __NR_rt_sigreturn;
	EXCPT 0;
	/* Speculative execution paranoia.  */
0:	JUMP.S 0b;
ENDPROC (_sigreturn_stub)

.align 16
	/*
	 * Atomic swap, 8 bit.
	 * Inputs:	P0: memory address to use
	 *		R1: value to store
	 * Output:	R0: old contents of the memory address, zero extended.
	 */
ENTRY(_atomic_xchg32)
	R0 = [P0];
	[P0] = R1;
	rts;
ENDPROC (_atomic_xchg32)

.align 16
	/*
	 * Compare and swap, 32 bit.
	 * Inputs:	P0: memory address to use
	 *		R1: compare value
	 *		R2: new value to store
	 * The new value is stored if the contents of the memory
	 * address is equal to the compare value.
	 * Output:	R0: old contents of the memory address.
	 */
ENTRY(_atomic_cas32)
	R0 = [P0];
	CC = R0 == R1;
	IF !CC JUMP 1f;
	[P0] = R2;
1:
	rts;
ENDPROC (_atomic_cas32)

.align 16
	/*
	 * Atomic add, 32 bit.
	 * Inputs:	P0: memory address to use
	 *		R0: value to add
	 * Outputs:	R0: new contents of the memory address.
	 *		R1: previous contents of the memory address.
	 */
ENTRY(_atomic_add32)
	R1 = [P0];
	R0 = R1 + R0;
	[P0] = R0;
	rts;
ENDPROC (_atomic_add32)

.align 16
	/*
	 * Atomic sub, 32 bit.
	 * Inputs:	P0: memory address to use
	 *		R0: value to subtract
	 * Outputs:	R0: new contents of the memory address.
	 *		R1: previous contents of the memory address.
	 */
ENTRY(_atomic_sub32)
	R1 = [P0];
	R0 = R1 - R0;
	[P0] = R0;
	rts;
ENDPROC (_atomic_sub32)

.align 16
	/*
	 * Atomic ior, 32 bit.
	 * Inputs:	P0: memory address to use
	 *		R0: value to ior
	 * Outputs:	R0: new contents of the memory address.
	 *		R1: previous contents of the memory address.
	 */
ENTRY(_atomic_ior32)
	R1 = [P0];
	R0 = R1 | R0;
	[P0] = R0;
	rts;
ENDPROC (_atomic_ior32)

.align 16
	/*
	 * Atomic and, 32 bit.
	 * Inputs:	P0: memory address to use
	 *		R0: value to and
	 * Outputs:	R0: new contents of the memory address.
	 *		R1: previous contents of the memory address.
	 */
ENTRY(_atomic_and32)
	R1 = [P0];
	R0 = R1 & R0;
	[P0] = R0;
	rts;
ENDPROC (_atomic_and32)

.align 16
	/*
	 * Atomic xor, 32 bit.
	 * Inputs:	P0: memory address to use
	 *		R0: value to xor
	 * Outputs:	R0: new contents of the memory address.
	 *		R1: previous contents of the memory address.
	 */
ENTRY(_atomic_xor32)
	R1 = [P0];
	R0 = R1 ^ R0;
	[P0] = R0;
	rts;
ENDPROC (_atomic_xor32)

.align 16
	/*
	 * safe_user_instruction
	 * Four NOPS are enough to allow the pipeline to speculativily load
	 * execute anything it wants. After that, things have gone bad, and
	 * we are stuck - so panic. Since we might be in user space, we can't
	 * call panic, so just cause a unhandled exception, this should cause
	 * a dump of the trace buffer so we can tell were we are, and a reboot
	 */
ENTRY(_safe_user_instruction)
	NOP; NOP; NOP; NOP;
	EXCPT 0x4;
ENDPROC(_safe_user_instruction)

ENTRY(_fixed_code_end)