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powerpc: Avoid unaligned loads and stores in boot memcpy code
The 601 processor will generate an alignment exception for accesses
which cross a page boundary. In the boot wrapper code, OF is still
handling all exceptions, and it doesn't have an alignment exception
handler that emulates the instruction and continues.
This changes the memcpy and memmove routines in the boot wrapper to
avoid doing unaligned accesses. If the source and destination are
misaligned with respect to each other, we just copy one byte at a
time.
Signed-off-by: Paul Mackerras <paulus@samba.org>
+17
-3
arch/powerpc/boot/string.S
+17
-3
arch/powerpc/boot/string.S
···
107
107
rlwinm. r7,r5,32-3,3,31 /* r7 = r5 >> 3 */
108
108
addi r6,r3,-4
109
109
addi r4,r4,-4
110
-
beq 2f /* if less than 8 bytes to do */
110
+
beq 3f /* if less than 8 bytes to do */
111
111
andi. r0,r6,3 /* get dest word aligned */
112
112
mtctr r7
113
113
bne 5f
114
+
andi. r0,r4,3 /* check src word aligned too */
115
+
bne 3f
114
116
1: lwz r7,4(r4)
115
117
lwzu r8,8(r4)
116
118
stw r7,4(r6)
···
134
132
bdnz 4b
135
133
blr
136
134
5: subfic r0,r0,4
135
+
cmpw cr1,r0,r5
136
+
add r7,r0,r4
137
+
andi. r7,r7,3 /* will source be word-aligned too? */
138
+
ble cr1,3b
139
+
bne 3b /* do byte-by-byte if not */
137
140
mtctr r0
138
141
6: lbz r7,4(r4)
139
142
addi r4,r4,1
···
156
149
rlwinm. r7,r5,32-3,3,31 /* r7 = r5 >> 3 */
157
150
add r6,r3,r5
158
151
add r4,r4,r5
159
-
beq 2f
152
+
beq 3f
160
153
andi. r0,r6,3
161
154
mtctr r7
162
155
bne 5f
156
+
andi. r0,r4,3
157
+
bne 3f
163
158
1: lwz r7,-4(r4)
164
159
lwzu r8,-8(r4)
165
160
stw r7,-4(r6)
···
180
171
stbu r0,-1(r6)
181
172
bdnz 4b
182
173
blr
183
-
5: mtctr r0
174
+
5: cmpw cr1,r0,r5
175
+
subf r7,r0,r4
176
+
andi. r7,r7,3
177
+
ble cr1,3b
178
+
bne 3b
179
+
mtctr r0
184
180
6: lbzu r7,-1(r4)
185
181
stbu r7,-1(r6)
186
182
bdnz 6b