[PATCH bpf-next v3 0/3] selftests/bpf: Improve building with extra

[PATCH bpf-next v3 0/3] selftests/bpf: Improve building with extra

[Viktor Malik]

When trying to build BPF selftests with additional compiler and linker
flags, we're running into multiple problems. This series addresses all
of them:

- CFLAGS are not passed to sub-makes of bpftool and libbpf. This is a
  problem when compiling with PIE as libbpf.a ends up being non-PIE and
  cannot be linked with other binaries (patch #1).

- bpftool Makefile runs `llvm-config --cflags` and appends the result to
  CFLAGS. The result typically contains `-D_GNU_SOURCE` which may be
  already set in CFLAGS. That causes a compilation error (patch #2).

- Some GCC flags are not supported by Clang but there are binaries which
  are always built with Clang but reuse user-defined CFLAGS. When CFLAGS
  contain such flags, compilation fails (patch #3).

Changelog:
----------
v2 -> v3:
- resolve conflicts between patch #1 and 4192bb294f80 ("selftests/bpf:
  Provide a generic [un]load_module helper")
- add Quentin's and Jiri's acks for patches #2 and #3

v1 -> v2:
- cover forgotten case in patch#1 (noted by Eduard)
- remove -D_GNU_SOURCE unconditionally in patch#2 (suggested by Andrii)
- rewrite patch#3 to just add -Wno-unused-command-line-argument
  (suggested by Andrii)

Viktor Malik (3):
  selftests/bpf: Allow building with extra flags
  bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile
  selftests/bpf: Disable warnings on unused flags for Clang builds

 tools/bpf/bpftool/Makefile           |  6 ++++-
 tools/testing/selftests/bpf/Makefile | 36 +++++++++++++++++++---------
 2 files changed, 30 insertions(+), 12 deletions(-)

-- 
2.47.0

[PATCH bpf-next v3 1/3] selftests/bpf: Allow building with extra flags

[Viktor Malik]

In order to specify extra compilation or linking flags to BPF selftests,
it is possible to set EXTRA_CFLAGS and EXTRA_LDFLAGS from the command
line. The problem is that they are not propagated to sub-make calls
(runqslower, bpftool, libbpf) and in the better case are not applied, in
the worse case cause the entire build fail.

Propagate EXTRA_CFLAGS and EXTRA_LDFLAGS to the sub-makes.

This, for instance, allows to build selftests as PIE with

    $ make EXTRA_CFLAGS='-fPIE' EXTRA_LDFLAGS='-pie'

Without this change, the command would fail because libbpf.a would not
be built with -fPIE and other PIE binaries would not link against it.

The only problem is that we have to explicitly provide empty
EXTRA_CFLAGS='' and EXTRA_LDFLAGS='' to the builds of kernel modules as
we don't want to build modules with flags used for userspace (the above
example would fail as kernel doesn't support PIE).

Signed-off-by: Viktor Malik <vmalik@redhat.com>
---
 tools/testing/selftests/bpf/Makefile | 34 +++++++++++++++++++---------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index a226d0647c4e..3b43d7db8d2c 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -295,25 +295,33 @@ $(OUTPUT)/sign-file: ../../../../scripts/sign-file.c
 $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_testmod/Makefile bpf_testmod/*.[ch])
 	$(call msg,MOD,,$@)
 	$(Q)$(RM) bpf_testmod/bpf_testmod.ko # force re-compilation
-	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_testmod
+	$(Q)$(MAKE) $(submake_extras) -C bpf_testmod \
+		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)     \
+		EXTRA_CFLAGS='' EXTRA_LDFLAGS=''
 	$(Q)cp bpf_testmod/bpf_testmod.ko $@
 
 $(OUTPUT)/bpf_test_no_cfi.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_test_no_cfi/Makefile bpf_test_no_cfi/*.[ch])
 	$(call msg,MOD,,$@)
 	$(Q)$(RM) bpf_test_no_cfi/bpf_test_no_cfi.ko # force re-compilation
-	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_test_no_cfi
+	$(Q)$(MAKE) $(submake_extras) -C bpf_test_no_cfi \
+		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)	 \
+		EXTRA_CFLAGS='' EXTRA_LDFLAGS=''
 	$(Q)cp bpf_test_no_cfi/bpf_test_no_cfi.ko $@
 
 $(OUTPUT)/bpf_test_modorder_x.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_test_modorder_x/Makefile bpf_test_modorder_x/*.[ch])
 	$(call msg,MOD,,$@)
 	$(Q)$(RM) bpf_test_modorder_x/bpf_test_modorder_x.ko # force re-compilation
-	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_test_modorder_x
+	$(Q)$(MAKE) $(submake_extras) -C bpf_test_modorder_x \
+		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)	     \
+		EXTRA_CFLAGS='' EXTRA_LDFLAGS=''
 	$(Q)cp bpf_test_modorder_x/bpf_test_modorder_x.ko $@
 
 $(OUTPUT)/bpf_test_modorder_y.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_test_modorder_y/Makefile bpf_test_modorder_y/*.[ch])
 	$(call msg,MOD,,$@)
 	$(Q)$(RM) bpf_test_modorder_y/bpf_test_modorder_y.ko # force re-compilation
-	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_test_modorder_y
+	$(Q)$(MAKE) $(submake_extras) -C bpf_test_modorder_y \
+		RESOLVE_BTFIDS=$(RESOLVE_BTFIDS)	     \
+		EXTRA_CFLAGS='' EXTRA_LDFLAGS=''
 	$(Q)cp bpf_test_modorder_y/bpf_test_modorder_y.ko $@
 
 
@@ -333,8 +341,8 @@ $(OUTPUT)/runqslower: $(BPFOBJ) | $(DEFAULT_BPFTOOL) $(RUNQSLOWER_OUTPUT)
 		    BPFTOOL_OUTPUT=$(HOST_BUILD_DIR)/bpftool/		       \
 		    BPFOBJ_OUTPUT=$(BUILD_DIR)/libbpf/			       \
 		    BPFOBJ=$(BPFOBJ) BPF_INCLUDE=$(INCLUDE_DIR)		       \
-		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS)'	       \
-		    EXTRA_LDFLAGS='$(SAN_LDFLAGS)' &&			       \
+		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS) $(EXTRA_CFLAGS)' \
+		    EXTRA_LDFLAGS='$(SAN_LDFLAGS) $(EXTRA_LDFLAGS)' &&	       \
 		    cp $(RUNQSLOWER_OUTPUT)runqslower $@
 
 TEST_GEN_PROGS_EXTENDED += $(TRUNNER_BPFTOOL)
@@ -367,7 +375,8 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)    \
 		    $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool
 	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)			       \
 		    ARCH= CROSS_COMPILE= CC="$(HOSTCC)" LD="$(HOSTLD)" 	       \
-		    EXTRA_CFLAGS='-g $(OPT_FLAGS)'			       \
+		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)'	       \
+		    EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)'			       \
 		    OUTPUT=$(HOST_BUILD_DIR)/bpftool/			       \
 		    LIBBPF_OUTPUT=$(HOST_BUILD_DIR)/libbpf/		       \
 		    LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/			       \
@@ -378,7 +387,8 @@ $(CROSS_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)	\
 		    $(BPFOBJ) | $(BUILD_DIR)/bpftool
 	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)				\
 		    ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE)			\
-		    EXTRA_CFLAGS='-g $(OPT_FLAGS)'				\
+		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)'		\
+		    EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)'				\
 		    OUTPUT=$(BUILD_DIR)/bpftool/				\
 		    LIBBPF_OUTPUT=$(BUILD_DIR)/libbpf/				\
 		    LIBBPF_DESTDIR=$(SCRATCH_DIR)/				\
@@ -401,8 +411,8 @@ $(BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
 	   $(APIDIR)/linux/bpf.h					       \
 	   | $(BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR) OUTPUT=$(BUILD_DIR)/libbpf/ \
-		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS)'	       \
-		    EXTRA_LDFLAGS='$(SAN_LDFLAGS)'			       \
+		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS) $(EXTRA_CFLAGS)' \
+		    EXTRA_LDFLAGS='$(SAN_LDFLAGS) $(EXTRA_LDFLAGS)'	       \
 		    DESTDIR=$(SCRATCH_DIR) prefix= all install_headers
 
 ifneq ($(BPFOBJ),$(HOST_BPFOBJ))
@@ -410,7 +420,9 @@ $(HOST_BPFOBJ): $(wildcard $(BPFDIR)/*.[ch] $(BPFDIR)/Makefile)		       \
 		$(APIDIR)/linux/bpf.h					       \
 		| $(HOST_BUILD_DIR)/libbpf
 	$(Q)$(MAKE) $(submake_extras) -C $(BPFDIR)                             \
-		    EXTRA_CFLAGS='-g $(OPT_FLAGS)' ARCH= CROSS_COMPILE=	       \
+		    ARCH= CROSS_COMPILE=				       \
+		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)'	       \
+		    EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)'			       \
 		    OUTPUT=$(HOST_BUILD_DIR)/libbpf/			       \
 		    CC="$(HOSTCC)" LD="$(HOSTLD)"			       \
 		    DESTDIR=$(HOST_SCRATCH_DIR)/ prefix= all install_headers
-- 
2.47.0

Re: [PATCH bpf-next v3 1/3] selftests/bpf: Allow building with extra flags

[Andrii Nakryiko]

On Fri, Nov 1, 2024 at 1:29 AM Viktor Malik <vmalik@redhat.com> wrote:
>
> In order to specify extra compilation or linking flags to BPF selftests,
> it is possible to set EXTRA_CFLAGS and EXTRA_LDFLAGS from the command
> line. The problem is that they are not propagated to sub-make calls
> (runqslower, bpftool, libbpf) and in the better case are not applied, in
> the worse case cause the entire build fail.
>
> Propagate EXTRA_CFLAGS and EXTRA_LDFLAGS to the sub-makes.
>
> This, for instance, allows to build selftests as PIE with
>
>     $ make EXTRA_CFLAGS='-fPIE' EXTRA_LDFLAGS='-pie'
>
> Without this change, the command would fail because libbpf.a would not
> be built with -fPIE and other PIE binaries would not link against it.
>
> The only problem is that we have to explicitly provide empty
> EXTRA_CFLAGS='' and EXTRA_LDFLAGS='' to the builds of kernel modules as
> we don't want to build modules with flags used for userspace (the above
> example would fail as kernel doesn't support PIE).
>
> Signed-off-by: Viktor Malik <vmalik@redhat.com>
> ---
>  tools/testing/selftests/bpf/Makefile | 34 +++++++++++++++++++---------
>  1 file changed, 23 insertions(+), 11 deletions(-)
>

Ok, so this will conflict with Toke's [0]. Who should go first? :)

And given you guys touch these more obscure parts of BPF selftests
Makefile, I'd really appreciate it if you can help reviewing them for
each other :)


  [0] https://patchwork.kernel.org/project/netdevbpf/patch/20241031-bpf-selftests-mod-compile-v1-1-1a63af2385f1@redhat.com/

[...]

Re: [PATCH bpf-next v3 1/3] selftests/bpf: Allow building with extra flags

[Toke Høiland-Jørgensen]

Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:

> On Fri, Nov 1, 2024 at 1:29 AM Viktor Malik <vmalik@redhat.com> wrote:
>>
>> In order to specify extra compilation or linking flags to BPF selftests,
>> it is possible to set EXTRA_CFLAGS and EXTRA_LDFLAGS from the command
>> line. The problem is that they are not propagated to sub-make calls
>> (runqslower, bpftool, libbpf) and in the better case are not applied, in
>> the worse case cause the entire build fail.
>>
>> Propagate EXTRA_CFLAGS and EXTRA_LDFLAGS to the sub-makes.
>>
>> This, for instance, allows to build selftests as PIE with
>>
>>     $ make EXTRA_CFLAGS='-fPIE' EXTRA_LDFLAGS='-pie'
>>
>> Without this change, the command would fail because libbpf.a would not
>> be built with -fPIE and other PIE binaries would not link against it.
>>
>> The only problem is that we have to explicitly provide empty
>> EXTRA_CFLAGS='' and EXTRA_LDFLAGS='' to the builds of kernel modules as
>> we don't want to build modules with flags used for userspace (the above
>> example would fail as kernel doesn't support PIE).
>>
>> Signed-off-by: Viktor Malik <vmalik@redhat.com>
>> ---
>>  tools/testing/selftests/bpf/Makefile | 34 +++++++++++++++++++---------
>>  1 file changed, 23 insertions(+), 11 deletions(-)
>>
>
> Ok, so this will conflict with Toke's [0]. Who should go first? :)

I'm OK with rebasing on top of Viktor's patch :)
>
> And given you guys touch these more obscure parts of BPF selftests
> Makefile, I'd really appreciate it if you can help reviewing them for
> each other :)

Sure, can do!

-Toke

Re: [PATCH bpf-next v3 1/3] selftests/bpf: Allow building with extra flags

[Andrii Nakryiko]

On Mon, Nov 4, 2024 at 5:43 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
>
> > On Fri, Nov 1, 2024 at 1:29 AM Viktor Malik <vmalik@redhat.com> wrote:
> >>
> >> In order to specify extra compilation or linking flags to BPF selftests,
> >> it is possible to set EXTRA_CFLAGS and EXTRA_LDFLAGS from the command
> >> line. The problem is that they are not propagated to sub-make calls
> >> (runqslower, bpftool, libbpf) and in the better case are not applied, in
> >> the worse case cause the entire build fail.
> >>
> >> Propagate EXTRA_CFLAGS and EXTRA_LDFLAGS to the sub-makes.
> >>
> >> This, for instance, allows to build selftests as PIE with
> >>
> >>     $ make EXTRA_CFLAGS='-fPIE' EXTRA_LDFLAGS='-pie'
> >>
> >> Without this change, the command would fail because libbpf.a would not
> >> be built with -fPIE and other PIE binaries would not link against it.
> >>
> >> The only problem is that we have to explicitly provide empty
> >> EXTRA_CFLAGS='' and EXTRA_LDFLAGS='' to the builds of kernel modules as
> >> we don't want to build modules with flags used for userspace (the above
> >> example would fail as kernel doesn't support PIE).
> >>
> >> Signed-off-by: Viktor Malik <vmalik@redhat.com>
> >> ---
> >>  tools/testing/selftests/bpf/Makefile | 34 +++++++++++++++++++---------
> >>  1 file changed, 23 insertions(+), 11 deletions(-)
> >>
> >
> > Ok, so this will conflict with Toke's [0]. Who should go first? :)
>
> I'm OK with rebasing on top of Viktor's patch :)

Ok, then. Thanks for the review! I've applied this patch to
bpf-next/master as well. Please rebase and resend your change.

> >
> > And given you guys touch these more obscure parts of BPF selftests
> > Makefile, I'd really appreciate it if you can help reviewing them for
> > each other :)
>
> Sure, can do!
>
> -Toke
>

Re: [PATCH bpf-next v3 1/3] selftests/bpf: Allow building with extra flags

[Toke Høiland-Jørgensen]

Viktor Malik <vmalik@redhat.com> writes:

> In order to specify extra compilation or linking flags to BPF selftests,
> it is possible to set EXTRA_CFLAGS and EXTRA_LDFLAGS from the command
> line. The problem is that they are not propagated to sub-make calls
> (runqslower, bpftool, libbpf) and in the better case are not applied, in
> the worse case cause the entire build fail.
>
> Propagate EXTRA_CFLAGS and EXTRA_LDFLAGS to the sub-makes.
>
> This, for instance, allows to build selftests as PIE with
>
>     $ make EXTRA_CFLAGS='-fPIE' EXTRA_LDFLAGS='-pie'
>
> Without this change, the command would fail because libbpf.a would not
> be built with -fPIE and other PIE binaries would not link against it.
>
> The only problem is that we have to explicitly provide empty
> EXTRA_CFLAGS='' and EXTRA_LDFLAGS='' to the builds of kernel modules as
> we don't want to build modules with flags used for userspace (the above
> example would fail as kernel doesn't support PIE).
>
> Signed-off-by: Viktor Malik <vmalik@redhat.com>

That last bit is a bit ugly, but I couldn't think of a better way of
doing it, so with that:

Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>

[PATCH bpf-next v3 2/3] bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile

[Viktor Malik]

When building selftests with CFLAGS set via env variable, the value of
CFLAGS is propagated into bpftool Makefile (called from selftests
Makefile). This makes the compilation fail as _GNU_SOURCE is defined two
times - once from selftests Makefile (by including lib.mk) and once from
bpftool Makefile (by calling `llvm-config --cflags`):

    $ CFLAGS="" make -C tools/testing/selftests/bpf
    [...]
    CC      /bpf-next/tools/testing/selftests/bpf/tools/build/bpftool/btf.o
    <command-line>: error: "_GNU_SOURCE" redefined [-Werror]
    <command-line>: note: this is the location of the previous definition
    cc1: all warnings being treated as errors
    [...]

Filter out -D_GNU_SOURCE from the result of `llvm-config --cflags` in
bpftool Makefile to prevent this error.

Signed-off-by: Viktor Malik <vmalik@redhat.com>
Acked-by: Quentin Monnet <qmo@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/bpf/bpftool/Makefile | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index ba927379eb20..a4263dfb5e03 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -147,7 +147,11 @@ ifeq ($(feature-llvm),1)
   # If LLVM is available, use it for JIT disassembly
   CFLAGS  += -DHAVE_LLVM_SUPPORT
   LLVM_CONFIG_LIB_COMPONENTS := mcdisassembler all-targets
-  CFLAGS  += $(shell $(LLVM_CONFIG) --cflags)
+  # llvm-config always adds -D_GNU_SOURCE, however, it may already be in CFLAGS
+  # (e.g. when bpftool build is called from selftests build as selftests
+  # Makefile includes lib.mk which sets -D_GNU_SOURCE) which would cause
+  # compilation error due to redefinition. Let's filter it out here.
+  CFLAGS  += $(filter-out -D_GNU_SOURCE,$(shell $(LLVM_CONFIG) --cflags))
   LIBS    += $(shell $(LLVM_CONFIG) --libs $(LLVM_CONFIG_LIB_COMPONENTS))
   ifeq ($(shell $(LLVM_CONFIG) --shared-mode),static)
     LIBS += $(shell $(LLVM_CONFIG) --system-libs $(LLVM_CONFIG_LIB_COMPONENTS))
-- 
2.47.0

Re: [PATCH bpf-next v3 2/3] bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile

[Toke Høiland-Jørgensen]

Viktor Malik <vmalik@redhat.com> writes:

> When building selftests with CFLAGS set via env variable, the value of
> CFLAGS is propagated into bpftool Makefile (called from selftests
> Makefile). This makes the compilation fail as _GNU_SOURCE is defined two
> times - once from selftests Makefile (by including lib.mk) and once from
> bpftool Makefile (by calling `llvm-config --cflags`):
>
>     $ CFLAGS="" make -C tools/testing/selftests/bpf
>     [...]
>     CC      /bpf-next/tools/testing/selftests/bpf/tools/build/bpftool/btf.o
>     <command-line>: error: "_GNU_SOURCE" redefined [-Werror]
>     <command-line>: note: this is the location of the previous definition
>     cc1: all warnings being treated as errors
>     [...]
>
> Filter out -D_GNU_SOURCE from the result of `llvm-config --cflags` in
> bpftool Makefile to prevent this error.
>
> Signed-off-by: Viktor Malik <vmalik@redhat.com>
> Acked-by: Quentin Monnet <qmo@kernel.org>
> Acked-by: Jiri Olsa <jolsa@kernel.org>

Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>

[PATCH bpf-next v3 3/3] selftests/bpf: Disable warnings on unused flags for Clang builds

[Viktor Malik]

There exist compiler flags supported by GCC but not supported by Clang
(e.g. -specs=...). Currently, these cannot be passed to BPF selftests
builds, even when building with GCC, as some binaries (urandom_read and
liburandom_read.so) are always built with Clang and the unsupported
flags make the compilation fail (as -Werror is turned on).

Add -Wno-unused-command-line-argument to these rules to suppress such
errors.

This allows to do things like:

    $ CFLAGS="-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1" \
      make -C tools/testing/selftests/bpf

Without this patch, the compilation would fail with:

    [...]
    clang: error: argument unused during compilation: '-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1' [-Werror,-Wunused-command-line-argument]
    make: *** [Makefile:273: /bpf-next/tools/testing/selftests/bpf/liburandom_read.so] Error 1
    [...]

Signed-off-by: Viktor Malik <vmalik@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/testing/selftests/bpf/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 3b43d7db8d2c..edef5df08cb2 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -274,6 +274,7 @@ $(OUTPUT)/liburandom_read.so: urandom_read_lib1.c urandom_read_lib2.c liburandom
 	$(Q)$(CLANG) $(CLANG_TARGET_ARCH) \
 		     $(filter-out -static,$(CFLAGS) $(LDFLAGS)) \
 		     $(filter %.c,$^) $(filter-out -static,$(LDLIBS)) \
+		     -Wno-unused-command-line-argument \
 		     -fuse-ld=$(LLD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
 		     -Wl,--version-script=liburandom_read.map \
 		     -fPIC -shared -o $@
@@ -282,6 +283,7 @@ $(OUTPUT)/urandom_read: urandom_read.c urandom_read_aux.c $(OUTPUT)/liburandom_r
 	$(call msg,BINARY,,$@)
 	$(Q)$(CLANG) $(CLANG_TARGET_ARCH) \
 		     $(filter-out -static,$(CFLAGS) $(LDFLAGS)) $(filter %.c,$^) \
+		     -Wno-unused-command-line-argument \
 		     -lurandom_read $(filter-out -static,$(LDLIBS)) -L$(OUTPUT) \
 		     -fuse-ld=$(LLD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
 		     -Wl,-rpath=. -o $@
-- 
2.47.0

Re: [PATCH bpf-next v3 0/3] selftests/bpf: Improve building with extra

[Andrii Nakryiko]

On Fri, Nov 1, 2024 at 1:38 AM Viktor Malik <vmalik@redhat.com> wrote:
>
> When trying to build BPF selftests with additional compiler and linker
> flags, we're running into multiple problems. This series addresses all
> of them:
>
> - CFLAGS are not passed to sub-makes of bpftool and libbpf. This is a
>   problem when compiling with PIE as libbpf.a ends up being non-PIE and
>   cannot be linked with other binaries (patch #1).
>
> - bpftool Makefile runs `llvm-config --cflags` and appends the result to
>   CFLAGS. The result typically contains `-D_GNU_SOURCE` which may be
>   already set in CFLAGS. That causes a compilation error (patch #2).
>
> - Some GCC flags are not supported by Clang but there are binaries which
>   are always built with Clang but reuse user-defined CFLAGS. When CFLAGS
>   contain such flags, compilation fails (patch #3).
>
> Changelog:
> ----------
> v2 -> v3:
> - resolve conflicts between patch #1 and 4192bb294f80 ("selftests/bpf:
>   Provide a generic [un]load_module helper")
> - add Quentin's and Jiri's acks for patches #2 and #3
>
> v1 -> v2:
> - cover forgotten case in patch#1 (noted by Eduard)
> - remove -D_GNU_SOURCE unconditionally in patch#2 (suggested by Andrii)
> - rewrite patch#3 to just add -Wno-unused-command-line-argument
>   (suggested by Andrii)
>
> Viktor Malik (3):
>   selftests/bpf: Allow building with extra flags
>   bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile
>   selftests/bpf: Disable warnings on unused flags for Clang builds
>

I've applied the last two patches, they seem to be independent from
the first, right?


>  tools/bpf/bpftool/Makefile           |  6 ++++-
>  tools/testing/selftests/bpf/Makefile | 36 +++++++++++++++++++---------
>  2 files changed, 30 insertions(+), 12 deletions(-)
>
> --
> 2.47.0
>
>

Re: [PATCH bpf-next v3 0/3] selftests/bpf: Improve building with extra

[Viktor Malik]

On 11/1/24 20:46, Andrii Nakryiko wrote:
> On Fri, Nov 1, 2024 at 1:38 AM Viktor Malik <vmalik@redhat.com> wrote:
>>
>> When trying to build BPF selftests with additional compiler and linker
>> flags, we're running into multiple problems. This series addresses all
>> of them:
>>
>> - CFLAGS are not passed to sub-makes of bpftool and libbpf. This is a
>>   problem when compiling with PIE as libbpf.a ends up being non-PIE and
>>   cannot be linked with other binaries (patch #1).
>>
>> - bpftool Makefile runs `llvm-config --cflags` and appends the result to
>>   CFLAGS. The result typically contains `-D_GNU_SOURCE` which may be
>>   already set in CFLAGS. That causes a compilation error (patch #2).
>>
>> - Some GCC flags are not supported by Clang but there are binaries which
>>   are always built with Clang but reuse user-defined CFLAGS. When CFLAGS
>>   contain such flags, compilation fails (patch #3).
>>
>> Changelog:
>> ----------
>> v2 -> v3:
>> - resolve conflicts between patch #1 and 4192bb294f80 ("selftests/bpf:
>>   Provide a generic [un]load_module helper")
>> - add Quentin's and Jiri's acks for patches #2 and #3
>>
>> v1 -> v2:
>> - cover forgotten case in patch#1 (noted by Eduard)
>> - remove -D_GNU_SOURCE unconditionally in patch#2 (suggested by Andrii)
>> - rewrite patch#3 to just add -Wno-unused-command-line-argument
>>   (suggested by Andrii)
>>
>> Viktor Malik (3):
>>   selftests/bpf: Allow building with extra flags
>>   bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile
>>   selftests/bpf: Disable warnings on unused flags for Clang builds
>>
> 
> I've applied the last two patches, they seem to be independent from
> the first, right?

Yes, they are independent, thanks. I'll sync with Toke on the first one.

Viktor

> 
> 
>>  tools/bpf/bpftool/Makefile           |  6 ++++-
>>  tools/testing/selftests/bpf/Makefile | 36 +++++++++++++++++++---------
>>  2 files changed, 30 insertions(+), 12 deletions(-)
>>
>> --
>> 2.47.0
>>
>>
> 

Re: [PATCH bpf-next v3 0/3] selftests/bpf: Improve building with extra

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Fri,  1 Nov 2024 09:27:10 +0100 you wrote:
> When trying to build BPF selftests with additional compiler and linker
> flags, we're running into multiple problems. This series addresses all
> of them:
> 
> - CFLAGS are not passed to sub-makes of bpftool and libbpf. This is a
>   problem when compiling with PIE as libbpf.a ends up being non-PIE and
>   cannot be linked with other binaries (patch #1).
> 
> [...]

Here is the summary with links:
  - [bpf-next,v3,1/3] selftests/bpf: Allow building with extra flags
    (no matching commit)
  - [bpf-next,v3,2/3] bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile
    https://git.kernel.org/bpf/bpf-next/c/0513eeee86d6
  - [bpf-next,v3,3/3] selftests/bpf: Disable warnings on unused flags for Clang builds
    https://git.kernel.org/bpf/bpf-next/c/77017b9c4682

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH bpf-next v3 0/3] selftests/bpf: Improve building with extra

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Fri,  1 Nov 2024 09:27:10 +0100 you wrote:
> When trying to build BPF selftests with additional compiler and linker
> flags, we're running into multiple problems. This series addresses all
> of them:
> 
> - CFLAGS are not passed to sub-makes of bpftool and libbpf. This is a
>   problem when compiling with PIE as libbpf.a ends up being non-PIE and
>   cannot be linked with other binaries (patch #1).
> 
> [...]

Here is the summary with links:
  - [bpf-next,v3,1/3] selftests/bpf: Allow building with extra flags
    https://git.kernel.org/bpf/bpf-next/c/9a28559932d2
  - [bpf-next,v3,2/3] bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile
    (no matching commit)
  - [bpf-next,v3,3/3] selftests/bpf: Disable warnings on unused flags for Clang builds
    (no matching commit)

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html