summaryrefslogtreecommitdiff
AgeCommit message (Collapse)Author
2020-06-03kbuild: refactor KBUILD_VMLINUX_{OBJS,LIBS} calculationMasahiro Yamada
Do not overwrite core-y or drivers-y. Remove libs-y1 and libs-y2. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-01kbuild: merge net-y and virt-y into drivers-yMasahiro Yamada
This will slightly change the link order; drivers-y from arch Makefile will be linked after virt/built-in.a, but I guess this is not a big deal. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-01kbuild: merge init-y into core-yMasahiro Yamada
No arch Makefile specifies init-y. Merge init-y into core-y. This does not change the link order. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-01kbuild: refactor tagets caluculation for KBUILD_{BUILTIN,KBUILD_MODULES}Masahiro Yamada
Remove lib-target, builtin-target, modorder-target, and modtargets. Instead, add targets-for-builtin and targets-for-modules. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-01kbuild: refactor subdir-ym calculationMasahiro Yamada
Remove the unneeded variables, __subdir-y and __subdir-m. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-01kbuild: merge two 'ifdef CONFIG_TRIM_UNUSED_KSYMS' blocksMasahiro Yamada
This hunk has two 'ifdef CONFIG_TRIM_UNUSED_KSYMS ... endif' blocks with no other code interleaved. Merge them. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-06-01kbuild: force to build vmlinux if CONFIG_MODVERSION=yMasahiro Yamada
This code does not work as stated in the comment. $(CONFIG_MODVERSIONS) is always empty because it is expanded before include/config/auto.conf is included. Hence, 'make modules' with CONFIG_MODVERSION=y cannot record the version CRCs. This has been broken since 2003, commit ("kbuild: Enable modules to be build using the "make dir/" syntax"). [1] [1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=15c6240cdc44bbeef3c4797ec860f9765ef4f1a7 Cc: linux-stable <stable@vger.kernel.org> # v2.5.71+ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-29Makefile: support compressed debug infoNick Desaulniers
As debug information gets larger and larger, it helps significantly save the size of vmlinux images to compress the information in the debug information sections. Note: this debug info is typically split off from the final compressed kernel image, which is why vmlinux is what's used in conjunction with GDB. Minimizing the debug info size should have no impact on boot times, or final compressed kernel image size. All of the debug sections will have a `C` flag set. $ readelf -S <object file> $ bloaty vmlinux.gcc75.compressed.dwarf4 -- \ vmlinux.gcc75.uncompressed.dwarf4 FILE SIZE VM SIZE -------------- -------------- +0.0% +18 [ = ] 0 [Unmapped] -73.3% -114Ki [ = ] 0 .debug_aranges -76.2% -2.01Mi [ = ] 0 .debug_frame -73.6% -2.89Mi [ = ] 0 .debug_str -80.7% -4.66Mi [ = ] 0 .debug_abbrev -82.9% -4.88Mi [ = ] 0 .debug_ranges -70.5% -9.04Mi [ = ] 0 .debug_line -79.3% -10.9Mi [ = ] 0 .debug_loc -39.5% -88.6Mi [ = ] 0 .debug_info -18.2% -123Mi [ = ] 0 TOTAL $ bloaty vmlinux.clang11.compressed.dwarf4 -- \ vmlinux.clang11.uncompressed.dwarf4 FILE SIZE VM SIZE -------------- -------------- +0.0% +23 [ = ] 0 [Unmapped] -65.6% -871 [ = ] 0 .debug_aranges -77.4% -1.84Mi [ = ] 0 .debug_frame -82.9% -2.33Mi [ = ] 0 .debug_abbrev -73.1% -2.43Mi [ = ] 0 .debug_str -84.8% -3.07Mi [ = ] 0 .debug_ranges -65.9% -8.62Mi [ = ] 0 .debug_line -86.2% -40.0Mi [ = ] 0 .debug_loc -42.0% -64.1Mi [ = ] 0 .debug_info -22.1% -122Mi [ = ] 0 TOTAL For x86_64 defconfig + LLVM=1 (before): Elapsed (wall clock) time (h:mm:ss or m:ss): 3:22.03 Maximum resident set size (kbytes): 43856 For x86_64 defconfig + LLVM=1 (after): Elapsed (wall clock) time (h:mm:ss or m:ss): 3:32.52 Maximum resident set size (kbytes): 1566776 Thanks to: Nick Clifton helped us to provide the minimal binutils version. Sedat Dilek found an increase in size of debug .deb package. Cc: Nick Clifton <nickc@redhat.com> Suggested-by: David Blaikie <blaikie@google.com> Reviewed-by: Fangrui Song <maskray@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-29modpost: refactor sech_name()Masahiro Yamada
Use sym_get_data_by_offset() helper to get access to the .shstrtab section data. No functional change is intended because elf->sechdrs[elf->secindex_strings].sh_addr is 0 for both ET_REL and ET_EXEC object types. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-29modpost: fix potential segmentation fault for addend_i386_rel()Masahiro Yamada
This may not be a practical problem, but the second pass of ARCH=i386 modpost causes segmentation fault if the -s option is not passed. MODPOST 12 modules Segmentation fault (core dumped) make[2]: *** [scripts/Makefile.modpost:94: __modpost] Error 139 make[1]: *** [Makefile:1339: modules] Error 2 make[1]: *** Waiting for unfinished jobs.... The segmentation fault occurs when section_rel() is called for vmlinux, which is untested in regular builds. The cause of the problem is reloc_location() returning a wrong pointer for ET_EXEC object type. In this case, you need to subtract sechdr->sh_addr, otherwise it would get access beyond the mmap'ed memory. Add sym_get_data_by_offset() helper to avoid code duplication. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-29kbuild: disallow multi-word in M= or KBUILD_EXTMODMasahiro Yamada
$(firstword ...) in scripts/Makefile.modpost was added by commit 3f3fd3c05585 ("[PATCH] kbuild: allow multi-word $M in Makefile.modpost") to build multiple external module directories. It was a solution to resolve symbol dependencies when an external module depends on another external module. Commit 0d96fb20b7ed ("kbuild: Add new Kbuild variable KBUILD_EXTRA_SYMBOLS") introduced another solution by passing symbol info via KBUILD_EXTRA_SYMBOLS, then broke the multi-word M= support. include $(if $(wildcard $(KBUILD_EXTMOD)/Kbuild), \ $(KBUILD_EXTMOD)/Kbuild, $(KBUILD_EXTMOD)/Makefile) ... does not work if KBUILD_EXTMOD contains multiple words. This feature has been broken for more than a decade. Remove the bitrotten code, and stop parsing if M or KBUILD_EXTMOD contains multiple words. As Documentation/kbuild/modules.rst explains, if your module depends on another one, there are two solutions: - add a common top-level Kbuild file - use KBUILD_EXTRA_SYMBOLS Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: make modules.order rule consistent with built-in.aMasahiro Yamada
built-in.a contains the built-in object paths from the current and sub directories. module.order collects the module paths from the current and sub directories. Make their build rules look more symmetrical. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: rename subdir-obj-y to subdir-builtinMasahiro Yamada
I think subdir-builtin is clearer. While I was here, I made its build rule explicit. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: move subdir-obj-y to scripts/Makefile.buildMasahiro Yamada
Save $(addprefix ...) for subdir-obj-y. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: clear KBUILD_MODULES in top Makefile if CONFIG_MODULES=nMasahiro Yamada
Do not try to build any module-related artifacts when CONFIG_MODULES is disabled. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: remove ifdef builtin-target / lib-targetMasahiro Yamada
I do not see a good reason to add ifdef here. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: doc: remove documentation about copying Module.symvers aroundMasahiro Yamada
This is a left-over of commit 39808e451fdf ("kbuild: do not read $(KBUILD_EXTMOD)/Module.symvers"). Kbuild no longer supports this way. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: make module name conflict fatal errorMasahiro Yamada
I think all the warnings have been fixed by now. Make it a fatal error. Check it before modpost because we need to stop building *.ko files. Also, pass modules.order via a script parameter. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: error out if targets prefixed with '__' are directly runMasahiro Yamada
Some targets are internal-use only. It is tedious to care about "what if __build_one_by_one is contained in $(MAKECMDGOALS)?" etc. Prefix internal targets with double underscores. Stop parsing Makefile if they are directly run. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: add this-makefile as a shorthand for $(lastword $(MAKEFILE_LIST))Masahiro Yamada
Make it clearer, and self-documenting. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26gcc-plugins: remove always-false $(if ...) in MakefileMasahiro Yamada
This is the remnant of commit c17d6179ad5a ("gcc-plugins: remove unused GCC_PLUGIN_SUBDIR"). The conditional $(if $(findstring /,$(p)),...) is always false because none of plugins contains '/' in the file name. Clean up the code. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org>
2020-05-26bpfilter: document build requirements for bpfilter_umhValdis Kl ē tnieks
It's not intuitively obvious that bpfilter_umh is a statically linked binary. Mention the toolchain requirement in the Kconfig help, so people have an easier time figuring out what's needed. Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26scripts/checkstack.pl: fix arm sp regexManinder Singh
if objdump has below entries; c01ed608 <X>: c01ed614: e24ddff7 sub sp, sp, #120 ; 0x78 c01f0d50 <Y>: c01f0d50: e24dd094 sub sp, sp, #140 ; 0x8c scripts fails to read stack usage. so making regex $re for ARM similar to aarch64 Co-developed-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26scripts/checkstack.pl: add arm push handling for stack usageManinder Singh
To count stack usage of push {*, fp, ip, lr, pc} instruction in ARM, if FRAME POINTER is enabled. e.g. c01f0d48: e92ddff0 push {r4, r5, r6, r7, r8, r9, sl, fp, ip, lr, pc} c01f0d50 <Y>: c01f0d44: e1a0c00d mov ip, sp c01f0d48: e92ddff0 push {r4, r5, r6, r7, r8, r9, sl, fp, ip, lr, pc} c01f0d4c: e24cb004 sub fp, ip, #4 c01f0d50: e24dd094 sub sp, sp, #448 ; 0x1C0 $ cat dump | scripts/checkstack.pl arm 0xc01f0d50 Y []: 448 added subroutine frame work for this. After change: 0xc01f0d500 Y []: 492 Co-developed-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26scripts/checkstack.pl: Add argument to print stacks greather than value.Maninder Singh
Add arguments support to print stacks which are greater than argument value only. Co-developed-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26scripts/checkstack.pl: don't display $dre as different entityManinder Singh
currently script prints stack usage for functions in two ways:($re and $dre) dre breaks sorting mechanism. 0xffffa00011f26f88 sunxi_mux_clk_setup.isra.0 [vmlinux]:Dynamic (0x140) .. 0xffffa00011f27210 sunxi_divs_clk_setup [vmlinux]: Dynamic (0x1d0) so we can print it in decimal only. Also address before function name is changed to function start address rather than stack consumption address. Because in next patch, arm has two ways to use stack which can be clubbed and printed in one function only. All symbols whose stack by adding(re and dre) is greater than 100, will be printed. 0xffffa00011f2720c0 sunxi_divs_clk_setup [vmlinux]: 464 ... 0xffffa00011f26f840 sunxi_mux_clk_setup.isra.0 [vmlinux]:320 Co-developed-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Vaneet Narang <v.narang@samsung.com> Signed-off-by: Maninder Singh <maninder1.s@samsung.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26modpost,fixdep: Replace zero-length array with flexible-arrayGustavo A. R. Silva
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26scripts: headers_install: Exit with error on config leakSiddharth Gupta
Misuse of CONFIG_* in UAPI headers should result in an error. These config options can be set in userspace by the user application which includes these headers to control the APIs and structures being used in a kernel which supports multiple targets. Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: remove {CLEAN,MRPROPER,DISTCLEAN}_DIRSMasahiro Yamada
Merge {CLEAN,MRPROPER,DISTCLEAN}_DIRS into {CLEAN,MRPROPER,DISTCLEAN}_FILES because the difference is just the -r option passed to the 'rm' command. Do likewise as commit 1634f2bfdb84 ("kbuild: remove clean-dirs syntax"). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: remove misleading stale FIXME commentMasahiro Yamada
This comment was added by commit ("kbuild: Restore build nr, improve vmlinux link") [1]. It was talking about if_changed_rule at that time. Now, it is unclear what to fix. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=ea52ca1b3e3882b499cc6c043f384958b88b62ff Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-26kbuild: invoke syncconfig if autoconf.h is missingMasahiro Yamada
If include/generated/autoconf.h is accidentally lost somehow, there is no clear way to fix it. Make it self-healing. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-17samples: watchdog: use 'userprogs' syntaxMasahiro Yamada
Kbuild now supports the 'userprogs' syntax to compile userspace programs for the same architecture as the kernel. Add the entry to samples/Makefile to put this into the build bot coverage. I also added the CONFIG option guarded by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: timers: use 'userprogs' syntaxMasahiro Yamada
Kbuild now supports the 'userprogs' syntax to compile userspace programs for the same architecture as the kernel. Add the entry to samples/Makefile to put this into the build bot coverage. I also added the CONFIG option guarded by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: auxdisplay: use 'userprogs' syntaxMasahiro Yamada
Kbuild now supports the 'userprogs' syntax to compile userspace programs for the same architecture as the kernel. Add the entry to samples/Makefile to put this into the build bot coverage. I also added the CONFIG option guarded by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: mei: build sample program for target architectureMasahiro Yamada
This userspace program includes UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample program should be built for the target as well. Kbuild now supports 'userprogs' for that. I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: pidfd: build sample program for target architectureMasahiro Yamada
This userspace program includes UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample program should be built for the target as well. Kbuild now supports 'userprogs' for that. I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: vfs: build sample programs for target architectureMasahiro Yamada
These userspace programs include UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample programs should be built for the target as well. Kbuild now supports 'userprogs' for that. I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: connector: build sample program for target architectureMasahiro Yamada
This userspace program includes UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample program should be built for the target as well. Kbuild now supports 'userprogs' for that. $(CC) can always compile cn_text.o since it is the kenrel-space code, but building ucon requires libc. I guarded it by: always-$(CONFIG_CC_CAN_LINK) := $(userprogs) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: hidraw: build sample program for target architectureMasahiro Yamada
This userspace program includes UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample program should be built for the target as well. Kbuild now supports 'userprogs' for that. I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: uhid: build sample program for target architectureMasahiro Yamada
This userspace program includes UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample program should be built for the target as well. Kbuild now supports 'userprogs' for that. Add the entry to samples/Makefile to put this into the build bot coverage. I also added the CONFIG option guarded by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: uhid: fix warnings in uhid-exampleSam Ravnborg
Fix warnings seen when building for 32-bit architecture. Use "%xd" for arguments of type size_t to fix the warnings. Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-17kbuild: doc: document the new syntax 'userprogs'Masahiro Yamada
Kbuild now supports the syntax 'userprogs' to compile userspace programs for the same architecture as the kernel. Insert the section '5 Userspace Program support' to explain it. I copy-pasted '4 Host Program support' and fixed it up. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17samples: seccomp: build sample programs for target architectureMasahiro Yamada
These userspace programs include UAPI headers exported to usr/include/. 'make headers' always works for the target architecture (i.e. the same architecture as the kernel), so the sample programs should be built for the target as well. Kbuild now supports 'userprogs' for that. I also guarded the CONFIG option by 'depends on CC_CAN_LINK' because $(CC) may not provide libc. The 'ifndef CROSS_COMPILE' is no longer needed. BTW, the -m31 for s390 is left-over code. Commit 5a79859ae0f3 ("s390: remove 31 bit support") killed it. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17bpfilter: use 'userprogs' syntax to build bpfilter_umhMasahiro Yamada
The user mode helper should be compiled for the same architecture as the kernel. This Makefile reused the 'hostprogs' syntax by overriding HOSTCC with CC. Use the new syntax 'userprogs' to fix the Makefile mess. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17kbuild: add infrastructure to build userspace programsMasahiro Yamada
Kbuild supports the infrastructure to build host programs, but there was no support to build userspace programs for the target architecture (i.e. the same architecture as the kernel). Sam Ravnborg worked on this in 2014 (https://lkml.org/lkml/2014/7/13/154), but it was not merged. One problem at that time was, there was no good way to know whether $(CC) can link standalone programs. In fact, pre-built kernel.org toolchains [1] are often used for building the kernel, but they do not provide libc. Now, we can handle this cleanly because the compiler capability is evaluated at the Kconfig time. If $(CC) cannot link standalone programs, the relevant options are hidden by 'depends on CC_CAN_LINK'. The implementation just mimics scripts/Makefile.host The userspace programs are compiled with the same flags as the host programs. In addition, it uses -m32 or -m64 if it is found in $(KBUILD_CFLAGS). This new syntax has two usecases. - Sample programs Several userspace programs under samples/ include UAPI headers installed in usr/include. Most of them were previously built for the host architecture just to use the 'hostprogs' syntax. However, 'make headers' always works for the target architecture. This caused the arch mismatch in cross-compiling. To fix this distortion, sample code should be built for the target architecture. - Bpfilter net/bpfilter/Makefile compiles bpfilter_umh as the user mode helper, and embeds it into the kernel. Currently, it overrides HOSTCC with CC to use the 'hostprogs' syntax. This hack should go away. [1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/ Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Sam Ravnborg <sam@ravnborg.org>
2020-05-17bpfilter: check if $(CC) can link static libc in KconfigMasahiro Yamada
On Fedora, linking static glibc requires the glibc-static RPM package, which is not part of the glibc-devel package. CONFIG_CC_CAN_LINK does not check the capability of static linking, so you can enable CONFIG_BPFILTER_UMH, then fail to build: HOSTLD net/bpfilter/bpfilter_umh /usr/bin/ld: cannot find -lc collect2: error: ld returned 1 exit status Add CONFIG_CC_CAN_LINK_STATIC, and make CONFIG_BPFILTER_UMH depend on it. Reported-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Acked-by: Alexei Starovoitov <ast@kernel.org>
2020-05-17bpfilter: match bit size of bpfilter_umh to that of the kernelMasahiro Yamada
bpfilter_umh is built for the default machine bit of the compiler, which may not match to the bit size of the kernel. This happens in the scenario below: You can use biarch GCC that defaults to 64-bit for building the 32-bit kernel. In this case, Kbuild passes -m32 to teach the compiler to produce 32-bit kernel space objects. However, it is missing when building bpfilter_umh. It is built as a 64-bit ELF, and then embedded into the 32-bit kernel. The 32-bit kernel and 64-bit umh is a bad combination. In theory, we can have 32-bit umh running on 64-bit kernel, but we do not have a good reason to support such a usecase. The best is to match the bit size between them. Pass -m32 or -m64 to the umh build command if it is found in $(KBUILD_CFLAGS). Evaluate CC_CAN_LINK against the kernel bit-size. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-17kbuild: warn if always, hostprogs-y, or hostprogs-m is usedMasahiro Yamada
always, hostprogs-y, and hostprogs-m are deprecated. There is no user in upstream code, but I will keep them for external modules. I want to remove them entirely someday. Prompt downstream users for the migration. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-12kbuild: determine the output format of DTC by the target suffixMasahiro Yamada
cmd_dtc takes the additional parameter $(2) to select the target format, dtb or yaml. This makes things complicated when it is used with cmd_and_fixdep and if_changed_rule. I actually stumbled on this. See commit 3d4b2238684a ("kbuild: fix DT binding schema rule again to avoid needless rebuilds"). Extract the suffix part of the target instead of passing the parameter. Fortunately, this works for both $(obj)/%.dtb and $(obj)/%.dt.yaml . Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-05-12kbuild: remove unused AS assignmentMasahiro Yamada
$(AS) is not used anywhere in the kernel build, hence commit aa824e0c962b ("kbuild: remove AS variable") killed it. Remove the left-over code in arch/{arm,arm64}/Makefile. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Acked-by: Will Deacon <will@kernel.org>