On 3/11/21 2:06 PM, kernel test robot wrote:
tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head: 98546348153dee5f8ced572fd6c4690461d20f51
commit: 797e78564634275ed4fe6b3f586c4b96eb1d86bc [1430/3917] platform/surface: aggregator_registry: Add base device hub
config: arm64-randconfig-r026-20210311 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 574a9dabc63ba1e7a04c08d4bde2eacd61b44ce1)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# install arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=797e78564634275ed4fe6b3f586c4b96eb1d86bc
git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git fetch --no-tags linux-next master
git checkout 797e78564634275ed4fe6b3f586c4b96eb1d86bc
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
In file included from drivers/platform/surface/surface_aggregator_registry.c:12:
In file included from include/linux/acpi.h:35:
In file included from include/acpi/acpi_io.h:7:
In file included from arch/arm64/include/asm/acpi.h:12:
include/linux/efi.h:1093:34: warning: passing 1-byte aligned argument to 4-byte aligned parameter 2 of 'get_var' may result in an unaligned pointer access [-Walign-mismatch]
status = get_var(L"SecureBoot", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size,
^
include/linux/efi.h:1101:24: warning: passing 1-byte aligned argument to 4-byte aligned parameter 2 of 'get_var' may result in an unaligned pointer access [-Walign-mismatch]
get_var(L"SetupMode", &EFI_GLOBAL_VARIABLE_GUID, NULL, &size, &setupmode);
^
>> drivers/platform/surface/surface_aggregator_registry.c:398:25: warning: implicit conversion from 'int' to '__u8' (aka 'unsigned char') changes value from 65535 to 255 [-Wconstant-conversion]
{ SSAM_VDEV(HUB, 0x02, SSAM_ANY_IID, 0x00) },
~ ^~~~~~~~~~~~
This is a false positive:
include/linux/surface_aggregator/device.h:71:23: note: expanded from macro 'SSAM_ANY_IID'
#define SSAM_ANY_IID 0xffff
^~~~~~
Here, clang complains that the input is SSAM_ANY_ID. That is a special
value which has special considerations below. The SSAM_DEVICE() and
thus SSAM_VDEV() macros are intended to only allow either __u8 or
SSAM_ANY_ID as input in this place.
include/linux/surface_aggregator/device.h:126:63: note: expanded from macro 'SSAM_VDEV'
SSAM_DEVICE(SSAM_DOMAIN_VIRTUAL, SSAM_VIRTUAL_TC_##cat, tid, iid, fun)
^~~
include/linux/surface_aggregator/device.h:102:41: note: expanded from macro 'SSAM_DEVICE'
.instance = ((iid) != SSAM_ANY_IID) ? (iid) : 0, \
^~~
Here is the special handling for SSAM_ANY_ID. So there is an implicit
conversion from iid, which may be __u8, to int (i.e. the type of
SSAM_ANY_ID), but there is at no point any implicit conversion of
SSAM_ANY_ID to __u8, as clang alleges.
Is there any way to silence this warning in particular without
suppressing it (e.g. by explicit casting) when users of this macro
_actually_ input any non-u8 and non-SSAM_ANY_ID value as iid,
leading to an _actual_ implicit value-changing cast?
I believe GCC does get this right and only emits a warning if a
non-u8 _and_ non-SSAM_ANY_ID value is input.
Regards,
Max
3 warnings generated.
vim +398 drivers/platform/surface/surface_aggregator_registry.c
396
397 static const struct ssam_device_id ssam_base_hub_match[] = {
> 398 { SSAM_VDEV(HUB, 0x02, SSAM_ANY_IID, 0x00) },
399 { },
400 };
401
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0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
