The following linker construct is problematic with linkers of
binutils < 2.28:
EXCLUDE_FILE (*piggy.o) *(.rodata.*)
from 8f1732fc2a11dc of binutils:
"though the linker accepts this without complaint the
EXCLUDE_FILE part is silently ignored and has no effect."
Silent ignoring of EXCLUDE_FILE construct made .rodata.compressed be
part of .rodata, and in case of .rodata.compressed following some
unaligned data, input_len would also become unaligned.
from arch/s390/boot/compressed/vmlinux.map:
.rodata.compressed
0x0000000000012fea 0x4d57e7 arch/s390/boot/compressed/piggy.o
0x0000000000012fea input_len
0x0000000000012fee input_data
input_len is later used here:
arch/s390/boot/compressed/misc.c:113
__decompress(input_data, input_len, NULL, NULL, output, 0, NULL, error);
asm generated by gcc looks like:
.loc 3 113 0
egfrl %r11,input_len
from what assembler generates invalid (the second operand must be aligned
on a doubleword boundary):
0x00000000000129b4 <+148>: c4 bc 00 00 03 1b lgfrl %r11,0x12fea
hence specification exception is recognized.
To avoid an issue use EXCLUDE_FILE construct which is recognized by
older linkers (since at least binutils-2_11)
*(EXCLUDE_FILE (*piggy.o) .rodata.compressed)
Also ensure that .rodata.compressed is at least doubleword aligned.
Fixes: 89b5202e81 ("s390/decompressor: support uncompressed kernel")
Reported-by: Halil Pasic <pasic@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2d6f74f797