user/sven/linux.git/scripts/Makefile.build, branch v4.9.181

kbuild: Add support to generate LLVM assembly files

2018-11-23T07:20:35Z

commit 433db3e260bc8134d4a46ddf20b3668937e12556 upstream. Add rules to kbuild in order to generate LLVM assembly files with the .ll extension when using clang. # from c code make CC=clang kernel/pid.ll Signed-off-by: Vinícius Tinti Signed-off-by: Behan Webster Signed-off-by: Matthias Kaehlcke Signed-off-by: Masahiro Yamada Signed-off-by: Nick Desaulniers Signed-off-by: Greg Kroah-Hartman

objtool: Fix gcov check for older versions of GCC

2018-06-13T14:16:44Z

commit 867ac9d737094e46a6c33213f16dd1ec9e8bd5d5 upstream. Objtool tries to silence 'unreachable instruction' warnings when it detects gcov is enabled, because gcov produces a lot of unreachable instructions and they don't really matter. However, the 0-day bot is still reporting some unreachable instruction warnings with CONFIG_GCOV_KERNEL=y on GCC 4.6.4. As it turns out, objtool's gcov detection doesn't work with older versions of GCC because they don't create a bunch of symbols with the 'gcov.' prefix like newer versions of GCC do. Move the gcov check out of objtool and instead just create a new '--no-unreachable' flag which can be passed in by the kernel Makefile when CONFIG_GCOV_KERNEL is defined. Also rename the 'nofp' variable to 'no_fp' for consistency with the new 'no_unreachable' variable. Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 9cfffb116887 ("objtool: Skip all "unreachable instruction" warnings for gcov kernels") Link: http://lkml.kernel.org/r/c243dc78eb2ffdabb6e927844dea39b6033cd395.1500939244.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar [just Makefile.build as the other parts of this patch already applied - gregkh] Signed-off-by: Greg Kroah-Hartman

kbuild: be more careful about matching preprocessed asm ___EXPORT_SYMBOL

2016-11-09T21:29:53Z

The CRC code for asm exports grabs the preprocessed asm, finds the ___EXPORT_SYMBOL and turns those into EXPORT_SYMBOL in a C program that can be preprocessed and parsed to create the CRC signatures from the type. The existing regex matching and replacement is too strict, and doesn't deal well with whitespace among other things. The line " EXPORT_SYMBOL(sym)" in a .S file would not match due to initial whitespace, for example, which resulted in x86's ___preempt_schedule failing to get CRCs. Reported-by: Philip Müller Signed-off-by: Nicholas Piggin Signed-off-by: Michal Marek

kbuild: modversions for EXPORT_SYMBOL() for asm

2016-11-01T15:20:17Z

Allow architectures to create asm/asm-prototypes.h file that provides C prototypes for exported asm functions, which enables proper CRC versions to be generated for them. Signed-off-by: Nicholas Piggin Signed-off-by: Michal Marek

kbuild: prevent lib-ksyms.o rebuilds

2016-10-22T19:49:30Z

Signed-off-by: Nicholas Piggin Reported-by: Russell King Tested-by: Russell King Signed-off-by: Michal Marek

kbuild: allow architectures to use thin archives instead of ld -r

2016-09-09T08:31:19Z

ld -r is an incremental link used to create built-in.o files in build subdirectories. It produces relocatable object files containing all its input files, and these are are then pulled together and relocated in the final link. Aside from the bloat, this constrains the final link relocations, which has bitten large powerpc builds with unresolvable relocations in the final link. Alan Modra has recommended the kernel use thin archives for linking. This is an alternative and means that the linker has more information available to it when it links the kernel. This patch enables a config option architectures can select, which causes all built-in.o files to be built as thin archives. built-in.o files in subdirectories do not get symbol table or index attached, which improves speed and size. The final link pass creates a built-in.o archive in the root output directory which includes the symbol table and index. The linker then uses takes this file to link. The --whole-archive linker option is required, because the linker now has visibility to every individual object file, and it will otherwise just completely avoid including those without external references (consider a file with EXPORT_SYMBOL or initcall or hardware exceptions as its only entry points). The traditional built works "by luck" as built-in.o files are large enough that they're going to get external references. However this optimisation is unpredictable for the kernel (due to above external references), ineffective at culling unused, and costly because the .o files have to be searched for references. Superior alternatives for link-time culling should be used instead. Build characteristics for inclink vs thinarc, on a small powerpc64le pseries VM with a modest .config: inclink thinarc sizes vmlinux 15 618 680 15 625 028 sum of all built-in.o 56 091 808 1 054 334 sum excluding root built-in.o 151 430 find -name built-in.o | xargs rm ; time make vmlinux real 22.772s 21.143s user 13.280s 13.430s sys 4.310s 2.750s - Final kernel pulled in only about 6K more, which shows how ineffective the object file culling is. - Build performance looks improved due to less pagecache activity. On IO constrained systems it could be a bigger win. - Build size saving is significant. Side note, the toochain understands archives, so there's some tricks, $ ar t built-in.o # list all files you linked with $ size built-in.o # and their sizes $ objdump -d built-in.o # disassembly (unrelocated) with filenames Implementation by sfr, minor tweaks by npiggin. Signed-off-by: Stephen Rothwell Signed-off-by: Nicholas Piggin Signed-off-by: Michal Marek

[kbuild] handle exports in lib-y objects reliably

2016-08-08T03:46:30Z

Collect the symbols exported by anything that goes into lib.a and add an empty object (lib-exports.o) with explicit undefs for each of those to obj-y. That allows to relax the rules regarding the use of exports in lib-* objects - right now an object with export can be in lib-* only if we are guaranteed that there always will be users in built-in parts of the tree, otherwise it needs to be in obj-*. As the result, we have an unholy mix of lib- and obj- in lib/Makefile and (especially) in arch/*/lib/Makefile. Moreover, a change in generic part of the kernel can lead to mysteriously missing exports on some configs. With this change we don't have to worry about that anymore. One side effect is that built-in.o now pulls everything with exports from the corresponding lib.a (if such exists). That's exactly what we want for linking vmlinux and fortunately it's almost the only thing built-in.o is used in. arch/ia64/hp/sim/boot/bootloader is the only exception and it's easy to get rid of now - just turn everything in arch/ia64/lib into lib-* and don't bother with arch/ia64/lib/built-in.o anymore. [AV: stylistic fix from Michal folded in] Acked-by: Michal Marek Signed-off-by: Al Viro

Shared library support

2016-06-07T20:57:10Z

Infrastructure for building independent shared library targets. Based on work created by the PaX Team. Signed-off-by: Emese Revfy Acked-by: Kees Cook Signed-off-by: Michal Marek

kbuild: rename cmd_as_s_S to cmd_cpp_s_S

2016-04-20T08:49:09Z

This command just preprocesses .S files into .s files, so cmd_cpp_s_S seems more suitable. Signed-off-by: Masahiro Yamada Signed-off-by: Michal Marek

kbuild: rename cmd_cc_i_c to cmd_cpp_i_c

2016-04-20T08:48:19Z

This command just preprocesses .c files into .i files, so cmd_cpp_i_c seems more suitable. Signed-off-by: Masahiro Yamada Acked-by: Arnaldo Carvalho de Melo Signed-off-by: Michal Marek