On 4/4/21 10:25 AM, Sedat Dilek wrote:
On Sun, Apr 4, 2021 at 6:40 PM Yonghong Song <yhs@xxxxxx> wrote:
On 4/4/21 5:46 AM, Sedat Dilek wrote:
[...]
Next build-error:
g++ -g -rdynamic -Wall -O2 -DHAVE_GENHDR
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/b
pf/tools/include -I/home/dileks/src/linux-kernel/git/include/generated
-I/home/dileks/src/linux-kernel/git/tools/lib
-I/home/dileks/src/linux-kernel/git/tools/include
-I/home/dileks/src/linux-kernel/git/tools/include/uapi
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-Dbpf_prog_load=bpf_prog_test_load
-Dbpf_load_program=bpf_test_load_program test_cpp.cpp
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_core_extern.skel.h
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.a
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_stub.o
-lcap -lelf -lz -lrt -lpthread -o
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp
/usr/bin/ld: /home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.a(libbpf-in.o):
relocation R_X86_64_32 against `.rodata.str1.1' ca
n not be used when making a PIE object; recompile with -fPIE
collect2: error: ld returned 1 exit status
make: *** [Makefile:455:
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp]
Error 1
make: Leaving directory
'/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf'
LOL, I was not aware that there is usage of *** CXX*** in tools
directory (see g++ line and /usr/bin/ld ?).
So, I changed my $MAKE_OPTS to use "CXX=clang++".
In kernel, if LLVM=1 is set, we have:
ifneq ($(LLVM),)
HOSTCC = clang
HOSTCXX = clang++
else
HOSTCC = gcc
HOSTCXX = g++
endif
ifneq ($(LLVM),)
CC = clang
LD = ld.lld
AR = llvm-ar
NM = llvm-nm
OBJCOPY = llvm-objcopy
OBJDUMP = llvm-objdump
READELF = llvm-readelf
STRIP = llvm-strip
else
CC = $(CROSS_COMPILE)gcc
LD = $(CROSS_COMPILE)ld
AR = $(CROSS_COMPILE)ar
NM = $(CROSS_COMPILE)nm
OBJCOPY = $(CROSS_COMPILE)objcopy
OBJDUMP = $(CROSS_COMPILE)objdump
READELF = $(CROSS_COMPILE)readelf
STRIP = $(CROSS_COMPILE)strip
endif
So if you have right path, you don't need to set HOSTCC and HOSTCXX
explicitly.
That is all correct with HOSTCXX but there is no CXX=... assignment
otherwise test_cpp will use g++ as demonstrated.
This is not a kernel Makefile issue.
We have:
testing/selftests/bpf/Makefile:CXX ?= $(CROSS_COMPILE)g++
So you need to explicit add CXX=clang++ when compiling
bpf selftests with LLVM=1 LLVM_IAS=1.
$ echo $PATH
/opt/llvm-toolchain/bin:/opt/proxychains-ng/bin:/home/dileks/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
$ echo $MAKE $MAKE_OPTS
make V=1 HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang
CXX=clang++ LD=ld.lld LLVM=1 LLVM_IAS=1 PAHOLE=/opt/pahole/bin/pahole
$ clang --version
dileks clang version 12.0.0 (https://github.com/llvm/llvm-project.git
04ba60cfe598e41084fb848daae47e0ed910fa7d)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/llvm-toolchain/bin
$ ld.lld --version
LLD 12.0.0 (https://github.com/llvm/llvm-project.git
04ba60cfe598e41084fb848daae47e0ed910fa7d) (compatible with GNU
linkers)
$ LC_ALL=C $MAKE $MAKE_OPTS -C tools/testing/selftests/bpf/
This breaks like this:
clang++ -g -rdynamic -Wall -O2 -DHAVE_GENHDR
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-I/home/dileks/src/linux-kernel/git/tools/testing/selftes
ts/bpf/tools/include
-I/home/dileks/src/linux-kernel/git/include/generated
-I/home/dileks/src/linux-kernel/git/tools/lib
-I/home/dileks/src/linux-kernel/git/tools/incl
ude -I/home/dileks/src/linux-kernel/git/tools/include/uapi
-I/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf
-Dbpf_prog_load=bpf_prog_test_load -Dbpf_loa
d_program=bpf_test_load_program test_cpp.cpp
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_core_extern.skel.h
/home/dileks/src/linux-kernel/git/to
ols/testing/selftests/bpf/tools/build/libbpf/libbpf.a
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_stub.o
-lcap -lelf -lz -lrt -lpthread -o /home
/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp
clang-12: warning: treating 'c-header' input as 'c++-header' when in
C++ mode, this behavior is deprecated [-Wdeprecated]
clang-12: error: cannot specify -o when generating multiple output files
make: *** [Makefile:455:
/home/dileks/src/linux-kernel/git/tools/testing/selftests/bpf/test_cpp]
Error 1
OK, I see in bpf-next includes several fixes like:
commit a0964f526df6facd4e12a4c416185013026eecf9
"selftests/bpf: Add multi-file statically linked BPF object file test"
...and to "selftests: xsk".
Finally, I was able to build by suppressing the build of "test_cpp"
and "xdpxceiver":
[...]
OK, I started a fresh build with LLVM/Clang v13-git from <apt.llvm.org>...
$ /usr/lib/llvm-13/bin/clang --version
Debian clang version
13.0.0-++20210404092853+c4c511337247-1~exp1~20210404073605.3891
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-13/bin
...with latest bpf-next as new base.
I applied your/this pahole patch "[PATCH dwarves] dwarf_loader: handle
DWARF5 DW_OP_addrx properly".
Will report later...
- Sedat -
[1] https://git.kernel.org/bpf/bpf-next/c/2ba4badca9977b64c966b0177920daadbd5501fe
[2] https://git.kernel.org/bpf/bpf-next/c/a0964f526df6facd4e12a4c416185013026eecf9
