arm64/neon: Disable -Wincompatible-pointer-types when building with Clang

mainline inclusion
from mainline-5.0
commit 0738c8b5915c
category: bugfix
bugzilla: 11024
CVE: NA

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

After commit cc9f8349cb33 ("arm64: crypto: add NEON accelerated XOR
implementation"), Clang builds for arm64 started failing with the
following error message.

arch/arm64/lib/xor-neon.c:58:28: error: incompatible pointer types
assigning to 'const unsigned long *' from 'uint64_t *' (aka 'unsigned
long long *') [-Werror,-Wincompatible-pointer-types]
                v3 = veorq_u64(vld1q_u64(dp1 +  6), vld1q_u64(dp2 + 6));
                                         ^~~~~~~~
/usr/lib/llvm-9/lib/clang/9.0.0/include/arm_neon.h:7538:47: note:
expanded from macro 'vld1q_u64'
  __ret = (uint64x2_t) __builtin_neon_vld1q_v(__p0, 51); \
                                              ^~~~

There has been quite a bit of debate and triage that has gone into
figuring out what the proper fix is, viewable at the link below, which
is still ongoing. Ard suggested disabling this warning with Clang with a
pragma so no neon code will have this type of error. While this is not
at all an ideal solution, this build error is the only thing preventing
KernelCI from having successful arm64 defconfig and allmodconfig builds
on linux-next. Getting continuous integration running is more important
so new warnings/errors or boot failures can be caught and fixed quickly.

Link: https://github.com/ClangBuiltLinux/linux/issues/283Suggested-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
(cherry picked from commit 0738c8b5915c7eaf1e6007b441008e8f3b460443)
Signed-off-by: NXie XiuQi <xiexiuqi@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/include/asm/neon-intrinsics.h

@@ -36,4 +36,8 @@
 #include <arm_neon.h>
 #endif
 
+#ifdef CONFIG_CC_IS_CLANG
+#pragma clang diagnostic ignored "-Wincompatible-pointer-types"
+#endif
+
 #endif /* __ASM_NEON_INTRINSICS_H */