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Message-ID: <cd1147a8-25ba-47d2-a59a-0a686469a808@csgroup.eu>
Date: Mon, 3 Feb 2025 12:23:29 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>,
 Kees Cook <kees@...nel.org>, Eric Biederman <ebiederm@...ssion.com>,
 Shuah Khan <shuah@...nel.org>, Nathan Chancellor <nathan@...nel.org>,
 Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling
 <morbo@...gle.com>, Justin Stitt <justinstitt@...gle.com>,
 Andy Lutomirski <luto@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 Vincenzo Frascino <vincenzo.frascino@....com>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH 00/16] selftests: vDSO: parse_vdso: Make compatible with
 nolibc



Le 03/02/2025 à 10:05, Thomas Weißschuh a écrit :
> For testing the functionality of the vDSO, it is necessary to build
> userspace programs for multiple different architectures.
> It is additional work to acquire matching userspace cross-compilers with
> full C libraries and then building root images out of those.
> The kernel tree already contains nolibc, a small, header-only C library.
> By using it, it is possible to build userspace programs without any
> additional dependencies.
> For example the kernel.org crosstools or multi-target clang can be used
> to build test programs for a multitude of architectures.
> While nolibc is very limited, it is enough for many selftests.
> With some minor adjustments it is possible to make parse_vdso.c
> compatible with nolibc.
> As an example, vdso_standalone_test_x86 is now built from the same C
> code as the regular vdso_test_gettimeofday, while still being completely
> standalone.
> 
> This should probably go through the kselftest tree.

Not sure what are the expectations with this series.

I gave it a try with vdso_test_gettimeofday and get the following:

$ powerpc64-linux-gcc -nostdlib -nostdinc -ffreestanding 
-fno-asynchronous-unwind-tables -fno-stack-protector -include 
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include/nolibc/nolibc.h 
-I/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include/nolibc/ 
-isystem 
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../usr/include 
-std=gnu99 -O2 -D_GNU_SOURCE= -isystem 
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include/uapi 
    vdso_test_gettimeofday.c parse_vdso.c  -o 
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_gettimeofday

make: Entering directory 
'/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO'
powerpc64-linux-gcc -nostdlib -nostdinc -ffreestanding 
-fno-asynchronous-unwind-tables -fno-stack-protector -include 
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include/nolibc/nolibc.h 
-I/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include/nolibc/ 
-isystem 
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../usr/include 
-std=gnu99 -O2 -D_GNU_SOURCE= -isystem 
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include/uapi 
    vdso_test_gettimeofday.c parse_vdso.c  -o 
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_gettimeofday
parse_vdso.c:38:34: error: unknown type name 'Elf64_Versym'
    38 | #define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
       |                                  ^~~
parse_vdso.c:39:33: note: in expansion of macro 'ELF_BITS_XFORM2'
    39 | #define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
       |                                 ^~~~~~~~~~~~~~~
parse_vdso.c:40:16: note: in expansion of macro 'ELF_BITS_XFORM'
    40 | #define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
       |                ^~~~~~~~~~~~~~
parse_vdso.c:63:9: note: in expansion of macro 'ELF'
    63 |         ELF(Versym) *versym;
       |         ^~~
parse_vdso.c:38:34: error: unknown type name 'Elf64_Verdef'
    38 | #define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
       |                                  ^~~
parse_vdso.c:39:33: note: in expansion of macro 'ELF_BITS_XFORM2'
    39 | #define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
       |                                 ^~~~~~~~~~~~~~~
parse_vdso.c:40:16: note: in expansion of macro 'ELF_BITS_XFORM'
    40 | #define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
       |                ^~~~~~~~~~~~~~
parse_vdso.c:64:9: note: in expansion of macro 'ELF'
    64 |         ELF(Verdef) *verdef;
       |         ^~~
parse_vdso.c: In function 'vdso_init_from_sysinfo_ehdr':
parse_vdso.c:38:34: error: 'Elf64_Versym' undeclared (first use in this 
function); did you mean 'Elf64_Sym'?
    38 | #define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
       |                                  ^~~
parse_vdso.c:39:33: note: in expansion of macro 'ELF_BITS_XFORM2'
    39 | #define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
       |                                 ^~~~~~~~~~~~~~~
parse_vdso.c:40:16: note: in expansion of macro 'ELF_BITS_XFORM'
    40 | #define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
       |                ^~~~~~~~~~~~~~
parse_vdso.c:150:45: note: in expansion of macro 'ELF'
   150 |                         vdso_info.versym = (ELF(Versym) *)
       |                                             ^~~
parse_vdso.c:38:34: note: each undeclared identifier is reported only 
once for each function it appears in
    38 | #define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
       |                                  ^~~
parse_vdso.c:39:33: note: in expansion of macro 'ELF_BITS_XFORM2'
    39 | #define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
       |                                 ^~~~~~~~~~~~~~~
parse_vdso.c:40:16: note: in expansion of macro 'ELF_BITS_XFORM'
    40 | #define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
       |                ^~~~~~~~~~~~~~
parse_vdso.c:150:45: note: in expansion of macro 'ELF'
   150 |                         vdso_info.versym = (ELF(Versym) *)
       |                                             ^~~
parse_vdso.c:150:58: error: expected expression before ')' token
   150 |                         vdso_info.versym = (ELF(Versym) *)
       |                                                          ^
parse_vdso.c:38:34: error: 'Elf64_Verdef' undeclared (first use in this 
function); did you mean 'Elf64_Word'?
    38 | #define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
       |                                  ^~~
parse_vdso.c:39:33: note: in expansion of macro 'ELF_BITS_XFORM2'
    39 | #define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
       |                                 ^~~~~~~~~~~~~~~
parse_vdso.c:40:16: note: in expansion of macro 'ELF_BITS_XFORM'
    40 | #define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
       |                ^~~~~~~~~~~~~~
parse_vdso.c:155:45: note: in expansion of macro 'ELF'
   155 |                         vdso_info.verdef = (ELF(Verdef) *)
       |                                             ^~~
parse_vdso.c:155:58: error: expected expression before ')' token
   155 |                         vdso_info.verdef = (ELF(Verdef) *)
       |                                                          ^
parse_vdso.c: At top level:
parse_vdso.c:38:34: error: unknown type name 'Elf64_Versym'; did you 
mean 'Elf64_Sym'?
    38 | #define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
       |                                  ^~~
parse_vdso.c:39:33: note: in expansion of macro 'ELF_BITS_XFORM2'
    39 | #define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
       |                                 ^~~~~~~~~~~~~~~
parse_vdso.c:40:16: note: in expansion of macro 'ELF_BITS_XFORM'
    40 | #define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
       |                ^~~~~~~~~~~~~~
parse_vdso.c:177:32: note: in expansion of macro 'ELF'
   177 | static bool vdso_match_version(ELF(Versym) ver,
       |                                ^~~
parse_vdso.c: In function 'vdso_sym':
parse_vdso.c:224:25: error: 'STN_UNDEF' undeclared (first use in this 
function); did you mean 'SHN_UNDEF'?
   224 |         for (; chain != STN_UNDEF; chain = 
vdso_info.chain[chain]) {
       |                         ^~~~~~~~~
       |                         SHN_UNDEF
parse_vdso.c:240:25: warning: implicit declaration of function 
'vdso_match_version' [-Wimplicit-function-declaration]
   240 |                     && !vdso_match_version(vdso_info.versym[chain],
       |                         ^~~~~~~~~~~~~~~~~~
make: *** [../lib.mk:222: 
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_gettimeofday] 
Error 1
make: Leaving directory 
'/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO'

Christophe

> 
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
> ---
> Thomas Weißschuh (16):
>        MAINTAINERS: Add vDSO selftests
>        elf, uapi: Add definition for STN_UNDEF
>        elf, uapi: Add definition for DT_GNU_HASH
>        elf, uapi: Add definitions for VER_FLG_BASE and VER_FLG_WEAK
>        elf, uapi: Add type ElfXX_Versym
>        elf, uapi: Add types ElfXX_Verdef and ElfXX_Veraux
>        tools/include: Add uapi/linux/elf.h
>        selftests: Add headers target
>        selftests: vDSO: vdso_standalone_test_x86: Use vdso_init_form_sysinfo_ehdr
>        selftests: vDSO: parse_vdso: Drop vdso_init_from_auxv()
>        selftests: vDSO: parse_vdso: Use UAPI headers instead of libc headers
>        selftests: vDSO: parse_vdso: Test __SIZEOF_LONG__ instead of ULONG_MAX
>        selftests: vDSO: parse_vdso: Make compatible with nolibc
>        selftests: vDSO: vdso_test_gettimeofday: Clean up includes
>        selftests: vDSO: vdso_test_gettimeofday: Make compatible with nolibc
>        selftests: vDSO: vdso_standalone_test_x86: Switch to nolibc
> 
>   MAINTAINERS                                        |   1 +
>   include/uapi/linux/elf.h                           |  38 ++
>   tools/include/uapi/linux/elf.h                     | 524 +++++++++++++++++++++
>   tools/testing/selftests/lib.mk                     |   5 +-
>   tools/testing/selftests/vDSO/Makefile              |  11 +-
>   tools/testing/selftests/vDSO/parse_vdso.c          |  21 +-
>   tools/testing/selftests/vDSO/parse_vdso.h          |   1 -
>   .../selftests/vDSO/vdso_standalone_test_x86.c      | 143 +-----
>   .../selftests/vDSO/vdso_test_gettimeofday.c        |   4 +-
>   9 files changed, 584 insertions(+), 164 deletions(-)
> ---
> base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
> change-id: 20241017-parse_vdso-nolibc-e069baa7ff48
> 
> Best regards,


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