linux/scripts/Kbuild.include, branch v4.20

Revert "kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs"

2018-12-19T11:00:28Z

This reverts commit 77b0bf55bc675233d22cd5df97605d516d64525e. See this commit for details about the revert: e769742d3584 ("Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"") Conflicts: arch/x86/Makefile Reported-by: Masahiro Yamada Reviewed-by: Borislav Petkov Reviewed-by: Thomas Gleixner Cc: Juergen Gross Cc: Richard Biener Cc: Kees Cook Cc: Segher Boessenkool Cc: Ard Biesheuvel Cc: Peter Zijlstra Cc: Josh Poimboeuf Cc: Nadav Amit Cc: Linus Torvalds Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

kbuild: remove cc-name variable

2018-11-02T13:49:01Z

There is one more user of $(cc-name) in the top Makefile. It is supposed to detect Clang before invoking Kconfig, so it should still be there in the $(shell ...) form. All the other users of $(cc-name) have been replaced with $(CONFIG_CC_IS_CLANG). Hence, scripts/Kbuild.include does not need to define cc-name any more. Signed-off-by: Masahiro Yamada

kbuild: remove unused cc-fullversion variable

2018-11-01T15:15:26Z

The last user of cc-fullversion was removed by commit f2910f0e6835 ("powerpc: remove old GCC version checks"). Signed-off-by: Masahiro Yamada

Merge tag 'kbuild-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2018-10-28T20:22:35Z

Pull Kbuild updates from Masahiro Yamada: - optimize kallsyms slightly - remove check for old CFLAGS usage - add some compiler flags unconditionally instead of evaluating $(call cc-option,...) - fix variable shadowing in host tools - refactor scripts/mkmakefile - refactor various makefiles * tag 'kbuild-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: modpost: Create macro to avoid variable shadowing ASN.1: Remove unnecessary shadowed local variable kbuild: use 'else ifeq' for checksrc to improve readability kbuild: remove unneeded link_multi_deps kbuild: add -Wno-unused-but-set-variable flag unconditionally kbuild: add -Wdeclaration-after-statement flag unconditionally kbuild: add -Wno-pointer-sign flag unconditionally modpost: remove leftover symbol prefix handling for module device table kbuild: simplify command line creation in scripts/mkmakefile kbuild: do not pass $(objtree) to scripts/mkmakefile kbuild: remove user ID check in scripts/mkmakefile kbuild: remove VERSION and PATCHLEVEL from $(objtree)/Makefile kbuild: add --include-dir flag only for out-of-tree build kbuild: remove dead code in cmd_files calculation in top Makefile kbuild: hide most of targets when running config or mixed targets kbuild: remove old check for CFLAGS use kbuild: prefix Makefile.dtbinst path with $(srctree) unconditionally kallsyms: remove left-over Blackfin code kallsyms: reduce size a little on 64-bit

kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs

2018-10-04T08:57:09Z

Using macros in inline assembly allows us to work around bugs in GCC's inlining decisions. Compile macros.S and use it to assemble all C files. Currently only x86 will use it. Background: The inlining pass of GCC doesn't include an assembler, so it's not aware of basic properties of the generated code, such as its size in bytes, or that there are such things as discontiuous blocks of code and data due to the newfangled linker feature called 'sections' ... Instead GCC uses a lazy and fragile heuristic: it does a linear count of certain syntactic and whitespace elements in inlined assembly block source code, such as a count of new-lines and semicolons (!), as a poor substitute for "code size and complexity". Unsurprisingly this heuristic falls over and breaks its neck whith certain common types of kernel code that use inline assembly, such as the frequent practice of putting useful information into alternative sections. As a result of this fresh, 20+ years old GCC bug, GCC's inlining decisions are effectively disabled for inlined functions that make use of such asm() blocks, because GCC thinks those sections of code are "large" - when in reality they are often result in just a very low number of machine instructions. This absolute lack of inlining provess when GCC comes across such asm() blocks both increases generated kernel code size and causes performance overhead, which is particularly noticeable on paravirt kernels, which make frequent use of these inlining facilities in attempt to stay out of the way when running on baremetal hardware. Instead of fixing the compiler we use a workaround: we set an assembly macro and call it from the inlined assembly block. As a result GCC considers the inline assembly block as a single instruction. (Which it often isn't but I digress.) This uglifies and bloats the source code - for example just the refcount related changes have this impact: Makefile | 9 +++++++-- arch/x86/Makefile | 7 +++++++ arch/x86/kernel/macros.S | 7 +++++++ scripts/Kbuild.include | 4 +++- scripts/mod/Makefile | 2 ++ 5 files changed, 26 insertions(+), 3 deletions(-) Yay readability and maintainability, it's not like assembly code is hard to read and maintain ... We also hope that GCC will eventually get fixed, but we are not holding our breath for that. Yet we are optimistic, it might still happen, any decade now. [ mingo: Wrote new changelog describing the background. ] Tested-by: Kees Cook Signed-off-by: Nadav Amit Acked-by: Masahiro Yamada Acked-by: Peter Zijlstra (Intel) Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Michal Marek Cc: Peter Zijlstra Cc: Sam Ravnborg Cc: Thomas Gleixner Cc: linux-kbuild@vger.kernel.org Link: http://lkml.kernel.org/r/20181003213100.189959-3-namit@vmware.com Signed-off-by: Ingo Molnar

kbuild: prefix Makefile.dtbinst path with $(srctree) unconditionally

2018-09-12T15:00:43Z

$(srctree) always points to the top of the source tree whether KBUILD_SRC is set or not. Signed-off-by: Masahiro Yamada

x86/build: Remove jump label quirk for GCC older than 4.5.2

2018-08-30T09:37:08Z

Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6") bumped the minimum GCC version to 4.6 for all architectures. Remove the workaround code. It was the only user of cc-if-fullversion. Remove the macro as well. Signed-off-by: Masahiro Yamada Signed-off-by: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Michal Marek Cc: linux-kbuild@vger.kernel.org Link: https://lkml.kernel.org/r/1535348714-25457-1-git-send-email-yamada.masahiro@socionext.com

kbuild: rename LDFLAGS to KBUILD_LDFLAGS

2018-08-23T23:22:08Z

Commit a0f97e06a43c ("kbuild: enable 'make CFLAGS=...' to add additional options to CC") renamed CFLAGS to KBUILD_CFLAGS. Commit 222d394d30e7 ("kbuild: enable 'make AFLAGS=...' to add additional options to AS") renamed AFLAGS to KBUILD_AFLAGS. Commit 06c5040cdb13 ("kbuild: enable 'make CPPFLAGS=...' to add additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS. For some reason, LDFLAGS was not renamed. Using a well-known variable like LDFLAGS may result in accidental override of the variable. Kbuild generally uses KBUILD_ prefixed variables for the internally appended options, so here is one more conversion to sanitize the naming convention. I did not touch Makefiles under tools/ since the tools build system is a different world. Signed-off-by: Masahiro Yamada Acked-by: Kirill A. Shutemov Reviewed-by: Palmer Dabbelt

Merge tag 'kconfig-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2018-08-15T19:50:10Z

Pull Kconfig updates from Masahiro Yamada: - show clearer error messages where pkg-config is needed, but not installed - rename SYMBOL_AUTO to SYMBOL_NO_WRITE to reflect its semantics - create all necessary directories by Kconfig tool itself instead of Makefile - update the .config unconditionally when syncconfig is invoked - use 'include' directive instead of '-include' where include/config/{auto,tristate}.conf is mandatory - do not try to update the .config when running install targets - add .DELETE_ON_ERROR to delete partially updated files - misc cleanups and fixes * tag 'kconfig-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kconfig: remove P_ENV property type kconfig: remove unused sym_get_env_prop() function kconfig: fix the rule of mainmenu_stmt symbol init/Kconfig: Use short unix-style option instead of --longname Kbuild: Makefile.modbuiltin: include auto.conf and tristate.conf mandatory kbuild: remove auto.conf from prerequisite of phony targets kbuild: do not update config for 'make kernelrelease' kbuild: do not update config when running install targets kbuild: add .DELETE_ON_ERROR special target kbuild: use 'include' directive to load auto.conf from top Makefile kconfig: allow all config targets to write auto.conf if missing kconfig: make syncconfig update .config regardless of sym_change_count kconfig: create directories needed for syncconfig by itself kconfig: remove unneeded directory generation from local*config kconfig: split out useful helpers in confdata.c kconfig: rename file_write_dep and move it to confdata.c kconfig: fix typos in description of "choice" in kconfig-language.txt kconfig: handle format string before calling conf_message_callback() kconfig: rename SYMBOL_AUTO to SYMBOL_NO_WRITE kconfig: check for pkg-config on make {menu,n,g,x}config

Merge tag 'kbuild-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2018-08-15T19:09:03Z

Pull Kbuild updates from Masahiro Yamada: - verify depmod is installed before modules_install - support build salt in case build ids must be unique between builds - allow users to specify additional host compiler flags via HOST*FLAGS, and rename internal variables to KBUILD_HOST*FLAGS - update buildtar script to drop vax support, add arm64 support - update builddeb script for better debarch support - document the pit-fall of if_changed usage - fix parallel build of UML with O= option - make 'samples' target depend on headers_install to fix build errors - remove deprecated host-progs variable - add a new coccinelle script for refcount_t vs atomic_t check - improve double-test coccinelle script - misc cleanups and fixes * tag 'kbuild-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (41 commits) coccicheck: return proper error code on fail Coccinelle: doubletest: reduce side effect false positives kbuild: remove deprecated host-progs variable kbuild: make samples really depend on headers_install um: clean up archheaders recipe kbuild: add %asm-generic to no-dot-config-targets um: fix parallel building with O= option scripts: Add Python 3 support to tracing/draw_functrace.py builddeb: Add automatic support for sh{3,4}{,eb} architectures builddeb: Add automatic support for riscv* architectures builddeb: Add automatic support for m68k architecture builddeb: Add automatic support for or1k architecture builddeb: Add automatic support for sparc64 architecture builddeb: Add automatic support for mips{,64}r6{,el} architectures builddeb: Add automatic support for mips64el architecture builddeb: Add automatic support for ppc64 and powerpcspe architectures builddeb: Introduce functions to simplify kconfig tests in set_debarch builddeb: Drop check for 32-bit s390 builddeb: Change architecture detection fallback to use dpkg-architecture builddeb: Skip architecture detection when KBUILD_DEBARCH is set ...