| Message ID | 1492803404-17837-1-git-send-email-yamada.masahiro@socionext.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Dne 21.4.2017 v 21:36 Masahiro Yamada napsal(a): > Since Kbuild runs in the objtree, __FILE__ can be a very long path > depending of $(srctree). > > Commit 9da0763bdd82 ("kbuild: Use relative path when building in a > subdir of the source tree") made the situation better for cases > where objtree is a child of srctree. ($(srctree) is "..") > > For other cases of out-of-tree build, filenames in WARN_ON() etc. > are still an absolute path. It also means the kernel image depends > on where it was built. > > Here, the idea is to redefine __FILE__ as the relative path from > $(srctree), but doing so causes a compiler warning: > warning: "__FILE__" redefined [-Wbuiltin-macro-redefined] > > We can suppress it with -Wno-builtin-macro-redefined. However, > this option is not recognized by old compilers. So, __FILE__ > is re-defined only when the option is supported. I actually like the KBUILD_FILE approach more, even if it means patching various users. > Please note __FILE__ is always an absolute path for external > modules. We can strip KBUILD_EXTMOD from the path if we want, > but I am not doing that. It would make it difficult to figure out > the module in question in case of WARN_ON(). Agreed. OOT modules are potential source of trouble, so let them stand out. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Makefile b/Makefile index 8804aae..293ef6d 100644 --- a/Makefile +++ b/Makefile @@ -798,6 +798,9 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=strict-prototypes) # Prohibit date/time macros, which would make the build non-deterministic KBUILD_CFLAGS += $(call cc-option,-Werror=date-time) +# Is is possible to redefine __FILE__? +KBUILD_CFLAGS += $(call cc-disable-warning, builtin-macro-redefined) + # enforce correct pointer usage KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types) diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 61f87a9..7fc3841 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -31,6 +31,10 @@ baseprereq = $(basename $(notdir $<)) escsq = $(subst $(squote),'\$(squote)',$1) ### +# Quote a string to pass it to C files. foo => '"foo"' +stringify = $(squote)$(quote)$1$(quote)$(squote) + +### # Easy method for doing a status message kecho := : quiet_kecho := echo diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 9e70196..1d789df 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -96,10 +96,12 @@ obj-dirs := $(addprefix $(obj)/,$(obj-dirs)) # Note: Files that end up in two or more modules are compiled without the # KBUILD_MODNAME definition. The reason is that any made-up name would # differ in different configs. -name-fix = $(squote)$(quote)$(subst $(comma),_,$(subst -,_,$1))$(quote)$(squote) +name-fix = $(call stringify,$(subst $(comma),_,$(subst -,_,$1))) basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget)) modname_flags = $(if $(filter 1,$(words $(modname))),\ -DKBUILD_MODNAME=$(call name-fix,$(modname))) +filepath_flags = $(if $(filter -Wno-builtin-macro-redefined, $(KBUILD_CFLAGS)), \ + -D__FILE__=$(call stringify,$(src)/$(notdir $<))) orig_c_flags = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(KBUILD_SUBDIR_CCFLAGS) \ $(ccflags-y) $(CFLAGS_$(basetarget).o) @@ -163,7 +165,7 @@ endif c_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \ $(__c_flags) $(modkern_cflags) \ - $(basename_flags) $(modname_flags) + $(basename_flags) $(modname_flags) $(filepath_flags) a_flags = -Wp,-MD,$(depfile) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) \ $(__a_flags) $(modkern_aflags)
Since Kbuild runs in the objtree, __FILE__ can be a very long path depending of $(srctree). Commit 9da0763bdd82 ("kbuild: Use relative path when building in a subdir of the source tree") made the situation better for cases where objtree is a child of srctree. ($(srctree) is "..") For other cases of out-of-tree build, filenames in WARN_ON() etc. are still an absolute path. It also means the kernel image depends on where it was built. Here, the idea is to redefine __FILE__ as the relative path from $(srctree), but doing so causes a compiler warning: warning: "__FILE__" redefined [-Wbuiltin-macro-redefined] We can suppress it with -Wno-builtin-macro-redefined. However, this option is not recognized by old compilers. So, __FILE__ is re-defined only when the option is supported. I am adding stringify helper because '"..."' wrapping is the same pattern as in KBUILD_BASENAME, KBUILD_MODNAME. Please note __FILE__ is always an absolute path for external modules. We can strip KBUILD_EXTMOD from the path if we want, but I am not doing that. It would make it difficult to figure out the module in question in case of WARN_ON(). Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- This is another possible approach. Please see these as well: https://patchwork.kernel.org/patch/9693559/ https://patchwork.kernel.org/patch/9693563/ Pro: this is only touching 3 makefiles. Con: this does not work for old compilers. Makefile | 3 +++ scripts/Kbuild.include | 4 ++++ scripts/Makefile.lib | 6 ++++-- 3 files changed, 11 insertions(+), 2 deletions(-)