Kbuild: fix # escaping in .cmd files for future Make

BugLink: http://bugs.launchpad.net/bugs/1808399
commit 9564a8cf422d7b58f6e857e3546d346fa970191e upstream.

I tried building using a freshly built Make (4.2.1-69-g8a731d1), but
already the objtool build broke with

orc_dump.c: In function ‘orc_dump’:
orc_dump.c:106:2: error: ‘elf_getshnum’ is deprecated [-Werror=deprecated-declarations]
  if (elf_getshdrnum(elf, &nr_sections)) {

Turns out that with that new Make, the backslash was not removed, so cpp
didn't see a #include directive, grep found nothing, and
-DLIBELF_USE_DEPRECATED was wrongly put in CFLAGS.

Now, that new Make behaviour is documented in their NEWS file:

  * WARNING: Backward-incompatibility!
    Number signs (#) appearing inside a macro reference or function invocation
    no longer introduce comments and should not be escaped with backslashes:
    thus a call such as:
      foo := $(shell echo '#')
    is legal.  Previously the number sign needed to be escaped, for example:
      foo := $(shell echo '\#')
    Now this latter will resolve to "\#".  If you want to write makefiles
    portable to both versions, assign the number sign to a variable:
      C := \#
      foo := $(shell echo '$C')
    This was claimed to be fixed in 3.81, but wasn't, for some reason.
    To detect this change search for 'nocomment' in the .FEATURES variable.

This also fixes up the two make-cmd instances to replace # with $(pound)
rather than with \#. There might very well be other places that need
similar fixup in preparation for whatever future Make release contains
the above change, but at least this builds an x86_64 defconfig with the
new make.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=197847
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 065324a8046ff8e0af179e6e90f335afb8d99179..f7bb1e4c2111b20ce28e2ebb10d864ea012f9b69 100644 (file)
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -8,6 +8,7 @@ squote  := '
 empty   :=
 space   := $(empty) $(empty)
 space_escape := _-_SPACE_-_
+pound := \#
 right_paren := )
 left_paren := (
 
@@ -324,11 +325,11 @@ endif
 
 # Replace >$< with >$$< to preserve $ when reloading the .cmd file
 # (needed for make)
-# Replace >#< with >\#< to avoid starting a comment in the .cmd file
+# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file
 # (needed for make)
 # Replace >'< with >'\''< to be able to enclose the whole string in '...'
 # (needed for the shell)
-make-cmd = $(call escsq,$(subst \#,\\\#,$(subst $$,$$$$,$(cmd_$(1)))))
+make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))
 
 # Find any prerequisites that is newer than target or that does not exist.
 # PHONY targets skipped in both cases.

diff --git a/tools/build/Build.include b/tools/build/Build.include
index 418871d02ebf2eeffc924fbc1eac6774dcd098ad..a4bbb984941df2c150ec7209e4905ac1baacbf81 100644 (file)
--- a/tools/build/Build.include
+++ b/tools/build/Build.include
@@ -12,6 +12,7 @@
 # Convenient variables
 comma   := ,
 squote  := '
+pound   := \#
 
 ###
 # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o
@@ -43,11 +44,11 @@ echo-cmd = $(if $($(quiet)cmd_$(1)),\
 ###
 # Replace >$< with >$$< to preserve $ when reloading the .cmd file
 # (needed for make)
-# Replace >#< with >\#< to avoid starting a comment in the .cmd file
+# Replace >#< with >$(pound)< to avoid starting a comment in the .cmd file
 # (needed for make)
 # Replace >'< with >'\''< to be able to enclose the whole string in '...'
 # (needed for the shell)
-make-cmd = $(call escsq,$(subst \#,\\\#,$(subst $$,$$$$,$(cmd_$(1)))))
+make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))))
 
 ###
 # Find any prerequisites that is newer than target or that does not exist.

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index e6acc281dd3757dbd03ba32c69a89b76ed690800..8ae824dbfca3fea24889064aca1fd46d60f0cbf2 100644 (file)
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -35,7 +35,7 @@ CFLAGS   += -Wall -Werror $(WARNINGS) -fomit-frame-pointer -O2 -g $(INCLUDES)
 LDFLAGS  += -lelf $(LIBSUBCMD)
 
 # Allow old libelf to be used:
-elfshdr := $(shell echo '\#include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
+elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
 CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
 
 AWK = awk

diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index 3fab179b1abac797a55952dd69b78848f74fdc64..e6cdc08b58c0867203b8069fcfb8ff566fb85baf 100644 (file)
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -101,3 +101,5 @@ ifneq ($(silent),1)
        QUIET_INSTALL  = @printf '  INSTALL  %s\n' $1;
   endif
 endif
+
+pound := \#