[v2] bpf: Remove custom build rule

Commit Message

Alexey Gladkov Aug. 28, 2024, 5:06 p.m. UTC

According to the documentation, when building a kernel with the C=2
parameter, all source files should be checked. But this does not happen
for the kernel/bpf/ directory.

$ touch kernel/bpf/core.o
$ make C=2 CHECK=true kernel/bpf/core.o

Outputs:

  CHECK   scripts/mod/empty.c
  CALL    scripts/checksyscalls.sh
  DESCEND objtool
  INSTALL libsubcmd_headers
  CC      kernel/bpf/core.o

As can be seen the compilation is done, but CHECK is not executed. This
happens because kernel/bpf/Makefile has defined its own rule for
compilation and forgotten the macro that does the check.

There is no need to duplicate the build code, and this rule can be
removed to use generic rules.

Signed-off-by: Alexey Gladkov <[e-mail]>
---
 kernel/bpf/Makefile | 6 ------
 1 file changed, 6 deletions(-)

Comments

Masahiro Yamada Aug. 28, 2024, 5:22 p.m. UTC | #1

On Thu, Aug 29, 2024 at 2:07 AM Alexey Gladkov <[e-mail]> wrote:
>
> According to the documentation, when building a kernel with the C=2
> parameter, all source files should be checked. But this does not happen
> for the kernel/bpf/ directory.
>
> $ touch kernel/bpf/core.o
> $ make C=2 CHECK=true kernel/bpf/core.o
>
> Outputs:
>
>   CHECK   scripts/mod/empty.c
>   CALL    scripts/checksyscalls.sh
>   DESCEND objtool
>   INSTALL libsubcmd_headers
>   CC      kernel/bpf/core.o
>
> As can be seen the compilation is done, but CHECK is not executed. This
> happens because kernel/bpf/Makefile has defined its own rule for
> compilation and forgotten the macro that does the check.
>
> There is no need to duplicate the build code, and this rule can be
> removed to use generic rules.
>
> Signed-off-by: Alexey Gladkov <[e-mail]>


Did you compile-test this?

See my previous email.




I said this:

$ cat kernel/bpf/btf_iter.c
#include "../../tools/lib/bpf/btf_iter.c"


Same for
kernel/bpf/btf_relocate.c
kernel/bpf/relo_core.c











> ---
>  kernel/bpf/Makefile | 6 ------
>  1 file changed, 6 deletions(-)
>
> diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
> index 0291eef9ce92..9b9c151b5c82 100644
> --- a/kernel/bpf/Makefile
> +++ b/kernel/bpf/Makefile
> @@ -52,9 +52,3 @@ obj-$(CONFIG_BPF_PRELOAD) += preload/
>  obj-$(CONFIG_BPF_SYSCALL) += relo_core.o
>  obj-$(CONFIG_BPF_SYSCALL) += btf_iter.o
>  obj-$(CONFIG_BPF_SYSCALL) += btf_relocate.o
> -
> -# Some source files are common to libbpf.
> -vpath %.c $(srctree)/kernel/bpf:$(srctree)/tools/lib/bpf
> -
> -$(obj)/%.o: %.c FORCE
> -       $(call if_changed_rule,cc_o_c)
> --
> 2.46.0
>


--
Best Regards
Masahiro Yamada

Alexey Gladkov Aug. 28, 2024, 5:49 p.m. UTC | #2

On Thu, Aug 29, 2024 at 02:22:33AM +0900, Masahiro Yamada wrote:
> On Thu, Aug 29, 2024 at 2:07 AM Alexey Gladkov <[e-mail]> wrote:
> >
> > According to the documentation, when building a kernel with the C=2
> > parameter, all source files should be checked. But this does not happen
> > for the kernel/bpf/ directory.
> >
> > $ touch kernel/bpf/core.o
> > $ make C=2 CHECK=true kernel/bpf/core.o
> >
> > Outputs:
> >
> >   CHECK   scripts/mod/empty.c
> >   CALL    scripts/checksyscalls.sh
> >   DESCEND objtool
> >   INSTALL libsubcmd_headers
> >   CC      kernel/bpf/core.o
> >
> > As can be seen the compilation is done, but CHECK is not executed. This
> > happens because kernel/bpf/Makefile has defined its own rule for
> > compilation and forgotten the macro that does the check.
> >
> > There is no need to duplicate the build code, and this rule can be
> > removed to use generic rules.
> >
> > Signed-off-by: Alexey Gladkov <[e-mail]>
> 
> 
> Did you compile-test this?

Yes. I repeated my steps for reproduce:

$ touch kernel/bpf/core.c
$ make C=2 CHECK=true |grep kernel/bpf/core
  CC      kernel/bpf/core.o
  CHECK   kernel/bpf/core.c

but maybe my config is too small.

> 
> See my previous email.
> 
> 
> 
> 
> I said this:
> 
> $ cat kernel/bpf/btf_iter.c
> #include "../../tools/lib/bpf/btf_iter.c"
> 
> 
> Same for
> kernel/bpf/btf_relocate.c
> kernel/bpf/relo_core.c
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> > ---
> >  kernel/bpf/Makefile | 6 ------
> >  1 file changed, 6 deletions(-)
> >
> > diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
> > index 0291eef9ce92..9b9c151b5c82 100644
> > --- a/kernel/bpf/Makefile
> > +++ b/kernel/bpf/Makefile
> > @@ -52,9 +52,3 @@ obj-$(CONFIG_BPF_PRELOAD) += preload/
> >  obj-$(CONFIG_BPF_SYSCALL) += relo_core.o
> >  obj-$(CONFIG_BPF_SYSCALL) += btf_iter.o
> >  obj-$(CONFIG_BPF_SYSCALL) += btf_relocate.o
> > -
> > -# Some source files are common to libbpf.
> > -vpath %.c $(srctree)/kernel/bpf:$(srctree)/tools/lib/bpf
> > -
> > -$(obj)/%.o: %.c FORCE
> > -       $(call if_changed_rule,cc_o_c)
> > --
> > 2.46.0
> >
> 
> 
> --
> Best Regards
> Masahiro Yamada
>

Patch

diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 0291eef9ce92..9b9c151b5c82 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -52,9 +52,3 @@  obj-$(CONFIG_BPF_PRELOAD) += preload/
 obj-$(CONFIG_BPF_SYSCALL) += relo_core.o
 obj-$(CONFIG_BPF_SYSCALL) += btf_iter.o
 obj-$(CONFIG_BPF_SYSCALL) += btf_relocate.o
-
-# Some source files are common to libbpf.
-vpath %.c $(srctree)/kernel/bpf:$(srctree)/tools/lib/bpf
-
-$(obj)/%.o: %.c FORCE
-	$(call if_changed_rule,cc_o_c)