Unknown __always_inline in linux/swab.h

From: Petr Vaněk
Date: Fri Jul 16 2021 - 10:30:05 EST


Hi all,

I cannot build the kernel on my box with musl libc since release 5.12,
see the kernel 5.13.1 build log below. Bisect points to the commit
1d509f2a6ebc ("x86/insn: Support big endian cross-compiles") merged to
5.12-rc1, but it probably only triggers the issue from different place.

I searched through the mailing list [1] and it seems that people face to
a similar issue with perf tool as well [2-5]. Related issues were also
reported in Gentoo [6] and alpinelinux [7]. Both distributions basically
fixed it with the patch from [3] which works for me and it is the best
solution, in my opinion. I believe it should be applied to the upstream
and backported to 5.12 and 5.13.

Systems with glibc are not affected because glibc defines its own
__always_inline in sys/cdefs.h which is indirectly included with stdio.h
and/or stdlib.h in top of tools/objtool/arch/x86/decode.c file.

Note: I CCed you because your address was mentioned in [2-5] or in
bisected commit.

Thanks,
Petr

References:

[1] https://lore.kernel.org/lkml/?q=swab+__always_inline
[2] https://lore.kernel.org/lkml/20210204005810.GZ854763@xxxxxxxxxx/
[3] https://lore.kernel.org/lkml/1514973450-12447-1-git-send-email-matt.redfearn@xxxxxxxx/
[4] https://lore.kernel.org/lkml/20181213180129.1373-1-raj.khem@xxxxxxxxx/
[5] https://lore.kernel.org/lkml/20201210144844.72580-1-chanho61.park@xxxxxxxxxxx/
[6] https://bugs.gentoo.org/791364
[7] https://gitlab.alpinelinux.org/alpine/aports/-/issues/11119

Build log:

make[1]: Entering directory '/var/tmp/portage/linux'
GEN Makefile
DESCEND objtool
CALL /usr/src/linux-5.13.1-gentoo/scripts/atomic/check-atomics.sh
CALL /usr/src/linux-5.13.1-gentoo/scripts/checksyscalls.sh
CC /var/tmp/portage/linux/tools/objtool/arch/x86/decode.o
CC /var/tmp/portage/linux/tools/objtool/str_error_r.o
CC /var/tmp/portage/linux/tools/objtool/librbtree.o
In file included from /usr/include/linux/byteorder/little_endian.h:13,
from /usr/include/asm/byteorder.h:5,
from /usr/src/linux-5.13.1-gentoo/tools/arch/x86/include/asm/insn.h:10,
from arch/x86/decode.c:10:
/usr/include/linux/swab.h:136:23: error: expected ';' before 'unsigned'
136 | static __always_inline unsigned long __swab(const unsigned long y)
| ^~~~~~~~~
| ;
/usr/include/linux/swab.h:171:8: error: unknown type name '__always_inline'
171 | static __always_inline __u16 __swab16p(const __u16 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/swab.h:171:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__swab16p'
171 | static __always_inline __u16 __swab16p(const __u16 *p)
| ^~~~~~~~~
/usr/include/linux/swab.h:184:8: error: unknown type name '__always_inline'
184 | static __always_inline __u32 __swab32p(const __u32 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/swab.h:184:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__swab32p'
184 | static __always_inline __u32 __swab32p(const __u32 *p)
| ^~~~~~~~~
/usr/include/linux/swab.h:197:8: error: unknown type name '__always_inline'
197 | static __always_inline __u64 __swab64p(const __u64 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/swab.h:197:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__swab64p'
197 | static __always_inline __u64 __swab64p(const __u64 *p)
| ^~~~~~~~~
/usr/include/linux/swab.h:252:23: error: expected ';' before 'void'
252 | static __always_inline void __swab32s(__u32 *p)
| ^~~~~
| ;
/usr/include/linux/swab.h:265:23: error: expected ';' before 'void'
265 | static __always_inline void __swab64s(__u64 *p)
| ^~~~~
| ;
In file included from /usr/include/asm/byteorder.h:5,
from /usr/src/linux-5.13.1-gentoo/tools/arch/x86/include/asm/insn.h:10,
from arch/x86/decode.c:10:
/usr/include/linux/byteorder/little_endian.h:44:8: error: unknown type name '__always_inline'
44 | static __always_inline __le64 __cpu_to_le64p(const __u64 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:44:31: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__cpu_to_le64p'
44 | static __always_inline __le64 __cpu_to_le64p(const __u64 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:48:8: error: unknown type name '__always_inline'
48 | static __always_inline __u64 __le64_to_cpup(const __le64 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:48:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__le64_to_cpup'
48 | static __always_inline __u64 __le64_to_cpup(const __le64 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:52:8: error: unknown type name '__always_inline'
52 | static __always_inline __le32 __cpu_to_le32p(const __u32 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:52:31: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__cpu_to_le32p'
52 | static __always_inline __le32 __cpu_to_le32p(const __u32 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:56:8: error: unknown type name '__always_inline'
56 | static __always_inline __u32 __le32_to_cpup(const __le32 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:56:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__le32_to_cpup'
56 | static __always_inline __u32 __le32_to_cpup(const __le32 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:60:8: error: unknown type name '__always_inline'
60 | static __always_inline __le16 __cpu_to_le16p(const __u16 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:60:31: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__cpu_to_le16p'
60 | static __always_inline __le16 __cpu_to_le16p(const __u16 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:64:8: error: unknown type name '__always_inline'
64 | static __always_inline __u16 __le16_to_cpup(const __le16 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:64:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__le16_to_cpup'
64 | static __always_inline __u16 __le16_to_cpup(const __le16 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:68:8: error: unknown type name '__always_inline'
68 | static __always_inline __be64 __cpu_to_be64p(const __u64 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:68:31: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__cpu_to_be64p'
68 | static __always_inline __be64 __cpu_to_be64p(const __u64 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:72:8: error: unknown type name '__always_inline'
72 | static __always_inline __u64 __be64_to_cpup(const __be64 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:72:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__be64_to_cpup'
72 | static __always_inline __u64 __be64_to_cpup(const __be64 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:76:8: error: unknown type name '__always_inline'
76 | static __always_inline __be32 __cpu_to_be32p(const __u32 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:76:31: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__cpu_to_be32p'
76 | static __always_inline __be32 __cpu_to_be32p(const __u32 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:80:8: error: unknown type name '__always_inline'
80 | static __always_inline __u32 __be32_to_cpup(const __be32 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:80:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__be32_to_cpup'
80 | static __always_inline __u32 __be32_to_cpup(const __be32 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:84:8: error: unknown type name '__always_inline'
84 | static __always_inline __be16 __cpu_to_be16p(const __u16 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:84:31: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__cpu_to_be16p'
84 | static __always_inline __be16 __cpu_to_be16p(const __u16 *p)
| ^~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:88:8: error: unknown type name '__always_inline'
88 | static __always_inline __u16 __be16_to_cpup(const __be16 *p)
| ^~~~~~~~~~~~~~~
/usr/include/linux/byteorder/little_endian.h:88:30: error: expected '=', ',', ';', 'asm' or '__attribute__' before '__be16_to_cpup'
88 | static __always_inline __u16 __be16_to_cpup(const __be16 *p)
| ^~~~~~~~~~~~~~
make[5]: *** [/usr/src/linux-5.13.1-gentoo/tools/build/Makefile.build:97: /var/tmp/portage/linux/tools/objtool/arch/x86/decode.o] Error 1
make[4]: *** [/usr/src/linux-5.13.1-gentoo/tools/build/Makefile.build:139: arch/x86] Error 2
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [Makefile:56: /var/tmp/portage/linux/tools/objtool/objtool-in.o] Error 2
make[2]: *** [Makefile:69: objtool] Error 2
make[1]: *** [/usr/src/linux-5.13.1-gentoo/Makefile:1974: tools/objtool] Error 2
make[1]: Leaving directory '/var/tmp/portage/linux'
make: *** [Makefile:215: __sub-make] Error 2