On Thu, Oct 1, 2020 at 4:57 PM Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx> wrote: > > During an investigation to fix up the execute bits of scripts in the kernel > repository, Andrew Morton and Kees Cook pointed out that the execute bit > should not matter, and that build scripts cannot rely on that. Kees could > not point to any documentation, though. > > Masahiro Yamada explained the convention of setting execute bits to make it > easier for manual script invocation. > > Provide some basic documentation how the build shall invoke scripts, such > that the execute bits do not matter, and acknowledge that execute bits > are useful nonetheless. > > This serves as reference for further clean-up patches in the future. > > Link: https://lore.kernel.org/lkml/20200830174409.c24c3f67addcce0cea9a9d4c@xxxxxxxxxxxxxxxxxxxx/ > Link: https://lore.kernel.org/lkml/202008271102.FEB906C88@keescook/ > Link: https://lore.kernel.org/linux-kbuild/CAK7LNAQdrvMkDA6ApDJCGr+5db8SiPo=G+p8EiOvnnGvEN80gA@xxxxxxxxxxxxxx/ > > Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx> > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@xxxxxxxxx> Applied to linux-kbuild. Thanks. > --- > RFC v1 -> RFC v2: > explain why execute bits are still convenient. > > Kees, Andrew, please ack. > > Masahiro-san, I have taken your feedback into account. Please pick this small > documentation update into your kbuild tree. > > Ujjwal Kumar, a potential future mentee, will follow up with further fixes to > the build scripts. > > Documentation/kbuild/makefiles.rst | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst > index 58d513a0fa95..bd3e1baf58be 100644 > --- a/Documentation/kbuild/makefiles.rst > +++ b/Documentation/kbuild/makefiles.rst > @@ -21,6 +21,7 @@ This document describes the Linux kernel Makefiles. > --- 3.10 Special Rules > --- 3.11 $(CC) support functions > --- 3.12 $(LD) support functions > + --- 3.13 Script Invocation > > === 4 Host Program support > --- 4.1 Simple Host Program > @@ -605,6 +606,25 @@ more details, with real examples. > #Makefile > LDFLAGS_vmlinux += $(call ld-option, -X) > > +3.13 Script invocation > +---------------------- > + > + Make rules may invoke scripts to build the kernel. The rules shall > + always provide the appropriate interpreter to execute the script. They > + shall not rely on the execute bits being set, and shall not invoke the > + script directly. For the convenience of manual script invocation, such > + as invoking ./scripts/checkpatch.pl, it is recommended to set execute > + bits on the scripts nonetheless. > + > + Kbuild provides variables $(CONFIG_SHELL), $(AWK), $(PERL), > + $(PYTHON) and $(PYTHON3) to refer to interpreters for the respective > + scripts. > + > + Example:: > + > + #Makefile > + cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \ > + $(KERNELRELEASE) > > 4 Host Program support > ====================== > -- > 2.17.1 > -- Best Regards Masahiro Yamada
