bpf_jit_asm.S
6.26 KB
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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
/* bpf_jit.S: Packet/header access helper functions
* for PPC64 BPF compiler.
*
* Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
#include <asm/ppc_asm.h>
#include "bpf_jit32.h"
/*
* All of these routines are called directly from generated code,
* whose register usage is:
*
* r3 skb
* r4,r5 A,X
* r6 *** address parameter to helper ***
* r7-r10 scratch
* r14 skb->data
* r15 skb headlen
* r16-31 M[]
*/
/*
* To consider: These helpers are so small it could be better to just
* generate them inline. Inline code can do the simple headlen check
* then branch directly to slow_path_XXX if required. (In fact, could
* load a spare GPR with the address of slow_path_generic and pass size
* as an argument, making the call site a mtlr, li and bllr.)
*/
.globl sk_load_word
sk_load_word:
PPC_LCMPI r_addr, 0
blt bpf_slow_path_word_neg
.globl sk_load_word_positive_offset
sk_load_word_positive_offset:
/* Are we accessing past headlen? */
subi r_scratch1, r_HL, 4
PPC_LCMP r_scratch1, r_addr
blt bpf_slow_path_word
/* Nope, just hitting the header. cr0 here is eq or gt! */
#ifdef __LITTLE_ENDIAN__
lwbrx r_A, r_D, r_addr
#else
lwzx r_A, r_D, r_addr
#endif
blr /* Return success, cr0 != LT */
.globl sk_load_half
sk_load_half:
PPC_LCMPI r_addr, 0
blt bpf_slow_path_half_neg
.globl sk_load_half_positive_offset
sk_load_half_positive_offset:
subi r_scratch1, r_HL, 2
PPC_LCMP r_scratch1, r_addr
blt bpf_slow_path_half
#ifdef __LITTLE_ENDIAN__
lhbrx r_A, r_D, r_addr
#else
lhzx r_A, r_D, r_addr
#endif
blr
.globl sk_load_byte
sk_load_byte:
PPC_LCMPI r_addr, 0
blt bpf_slow_path_byte_neg
.globl sk_load_byte_positive_offset
sk_load_byte_positive_offset:
PPC_LCMP r_HL, r_addr
ble bpf_slow_path_byte
lbzx r_A, r_D, r_addr
blr
/*
* BPF_LDX | BPF_B | BPF_MSH: ldxb 4*([offset]&0xf)
* r_addr is the offset value
*/
.globl sk_load_byte_msh
sk_load_byte_msh:
PPC_LCMPI r_addr, 0
blt bpf_slow_path_byte_msh_neg
.globl sk_load_byte_msh_positive_offset
sk_load_byte_msh_positive_offset:
PPC_LCMP r_HL, r_addr
ble bpf_slow_path_byte_msh
lbzx r_X, r_D, r_addr
rlwinm r_X, r_X, 2, 32-4-2, 31-2
blr
/* Call out to skb_copy_bits:
* We'll need to back up our volatile regs first; we have
* local variable space at r1+(BPF_PPC_STACK_BASIC).
* Allocate a new stack frame here to remain ABI-compliant in
* stashing LR.
*/
#define bpf_slow_path_common(SIZE) \
mflr r0; \
PPC_STL r0, PPC_LR_STKOFF(r1); \
/* R3 goes in parameter space of caller's frame */ \
PPC_STL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \
PPC_STL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \
PPC_STL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \
addi r5, r1, BPF_PPC_STACK_BASIC+(2*REG_SZ); \
PPC_STLU r1, -BPF_PPC_SLOWPATH_FRAME(r1); \
/* R3 = r_skb, as passed */ \
mr r4, r_addr; \
li r6, SIZE; \
bl skb_copy_bits; \
nop; \
/* R3 = 0 on success */ \
addi r1, r1, BPF_PPC_SLOWPATH_FRAME; \
PPC_LL r0, PPC_LR_STKOFF(r1); \
PPC_LL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \
PPC_LL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \
mtlr r0; \
PPC_LCMPI r3, 0; \
blt bpf_error; /* cr0 = LT */ \
PPC_LL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \
/* Great success! */
bpf_slow_path_word:
bpf_slow_path_common(4)
/* Data value is on stack, and cr0 != LT */
lwz r_A, BPF_PPC_STACK_BASIC+(2*REG_SZ)(r1)
blr
bpf_slow_path_half:
bpf_slow_path_common(2)
lhz r_A, BPF_PPC_STACK_BASIC+(2*8)(r1)
blr
bpf_slow_path_byte:
bpf_slow_path_common(1)
lbz r_A, BPF_PPC_STACK_BASIC+(2*8)(r1)
blr
bpf_slow_path_byte_msh:
bpf_slow_path_common(1)
lbz r_X, BPF_PPC_STACK_BASIC+(2*8)(r1)
rlwinm r_X, r_X, 2, 32-4-2, 31-2
blr
/* Call out to bpf_internal_load_pointer_neg_helper:
* We'll need to back up our volatile regs first; we have
* local variable space at r1+(BPF_PPC_STACK_BASIC).
* Allocate a new stack frame here to remain ABI-compliant in
* stashing LR.
*/
#define sk_negative_common(SIZE) \
mflr r0; \
PPC_STL r0, PPC_LR_STKOFF(r1); \
/* R3 goes in parameter space of caller's frame */ \
PPC_STL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \
PPC_STL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \
PPC_STL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \
PPC_STLU r1, -BPF_PPC_SLOWPATH_FRAME(r1); \
/* R3 = r_skb, as passed */ \
mr r4, r_addr; \
li r5, SIZE; \
bl bpf_internal_load_pointer_neg_helper; \
nop; \
/* R3 != 0 on success */ \
addi r1, r1, BPF_PPC_SLOWPATH_FRAME; \
PPC_LL r0, PPC_LR_STKOFF(r1); \
PPC_LL r_A, (BPF_PPC_STACK_BASIC+(0*REG_SZ))(r1); \
PPC_LL r_X, (BPF_PPC_STACK_BASIC+(1*REG_SZ))(r1); \
mtlr r0; \
PPC_LCMPLI r3, 0; \
beq bpf_error_slow; /* cr0 = EQ */ \
mr r_addr, r3; \
PPC_LL r_skb, (BPF_PPC_STACKFRAME+BPF_PPC_STACK_R3_OFF)(r1); \
/* Great success! */
bpf_slow_path_word_neg:
lis r_scratch1,-32 /* SKF_LL_OFF */
PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */
blt bpf_error /* cr0 = LT */
.globl sk_load_word_negative_offset
sk_load_word_negative_offset:
sk_negative_common(4)
lwz r_A, 0(r_addr)
blr
bpf_slow_path_half_neg:
lis r_scratch1,-32 /* SKF_LL_OFF */
PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */
blt bpf_error /* cr0 = LT */
.globl sk_load_half_negative_offset
sk_load_half_negative_offset:
sk_negative_common(2)
lhz r_A, 0(r_addr)
blr
bpf_slow_path_byte_neg:
lis r_scratch1,-32 /* SKF_LL_OFF */
PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */
blt bpf_error /* cr0 = LT */
.globl sk_load_byte_negative_offset
sk_load_byte_negative_offset:
sk_negative_common(1)
lbz r_A, 0(r_addr)
blr
bpf_slow_path_byte_msh_neg:
lis r_scratch1,-32 /* SKF_LL_OFF */
PPC_LCMP r_addr, r_scratch1 /* addr < SKF_* */
blt bpf_error /* cr0 = LT */
.globl sk_load_byte_msh_negative_offset
sk_load_byte_msh_negative_offset:
sk_negative_common(1)
lbz r_X, 0(r_addr)
rlwinm r_X, r_X, 2, 32-4-2, 31-2
blr
bpf_error_slow:
/* fabricate a cr0 = lt */
li r_scratch1, -1
PPC_LCMPI r_scratch1, 0
bpf_error:
/* Entered with cr0 = lt */
li r3, 0
/* Generated code will 'blt epilogue', returning 0. */
blr