mips: always link byteswap helpers into decompressor

stable inclusion
from stable-5.10.52
commit 4e2764e96a1561d44635eb4d2c27f8b9bd000cd0
bugzilla: 175542 https://gitee.com/openeuler/kernel/issues/I4DTKU

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4e2764e96a1561d44635eb4d2c27f8b9bd000cd0

--------------------------------

[ Upstream commit cddc40f5 ]

My series to clean up the unaligned access implementation
across architectures caused some mips randconfig builds to
fail with:

   mips64-linux-ld: arch/mips/boot/compressed/decompress.o: in function `decompress_kernel':
   decompress.c:(.text.decompress_kernel+0x54): undefined reference to `__bswapsi2'

It turns out that this problem has already been fixed for the XZ
decompressor but now it also shows up in (at least) LZO and LZ4.  From my
analysis I concluded that the compiler could always have emitted those
calls, but the different implementation allowed it to make otherwise
better decisions about not inlining the byteswap, which results in the
link error when the out-of-line code is missing.

While it could be addressed by adding it to the two decompressor
implementations that are known to be affected, but as this only adds
112 bytes to the kernel, the safer choice is to always add them.

Fixes: c50ec678 ("MIPS: zboot: Fix the build with XZ compression on older GCC versions")
Fixes: 0652035a ("asm-generic: unaligned: remove byteshift helpers")
Link: https://lore.kernel.org/linux-mm/202106301304.gz2wVY9w-lkp@intel.com/
Link: https://lore.kernel.org/linux-mm/202106260659.TyMe8mjr-lkp@intel.com/
Link: https://lore.kernel.org/linux-mm/202106172016.onWT6Tza-lkp@intel.com/
Link: https://lore.kernel.org/linux-mm/202105231743.JJcALnhS-lkp@intel.com/Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/mips/boot/compressed/Makefile

@@ -39,7 +39,7 @@ KCOV_INSTRUMENT		:= n
 UBSAN_SANITIZE := n
 
 # decompressor objects (linked with vmlinuz)
-vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o
+vmlinuzobjs-y := $(obj)/head.o $(obj)/decompress.o $(obj)/string.o $(obj)/bswapsi.o
 
 ifdef CONFIG_DEBUG_ZBOOT
 vmlinuzobjs-$(CONFIG_DEBUG_ZBOOT)		   += $(obj)/dbg.o
@@ -53,7 +53,7 @@ extra-y += uart-ath79.c
 $(obj)/uart-ath79.c: $(srctree)/arch/mips/ath79/early_printk.c
 	$(call cmd,shipped)
 
-vmlinuzobjs-$(CONFIG_KERNEL_XZ) += $(obj)/ashldi3.o $(obj)/bswapsi.o
+vmlinuzobjs-$(CONFIG_KERNEL_XZ) += $(obj)/ashldi3.o
 
 extra-y += ashldi3.c
 $(obj)/ashldi3.c: $(obj)/%.c: $(srctree)/lib/%.c FORCE