linux-dev/arch/s390/Makefile, branch master

s390: always build relocatable kernel

2022-11-08T18:32:32Z

Nathan Chancellor reported several link errors on s390 with CONFIG_RELOCATABLE disabled, after binutils commit 906f69cf65da ("IBM zSystems: Issue error for *DBL relocs on misaligned symbols"). The binutils commit reveals potential miscompiles that might have happened already before with linker script defined symbols at odd addresses. A similar bug was recently fixed in the kernel with commit c9305b6c1f52 ("s390: fix nospec table alignments"). See https://github.com/ClangBuiltLinux/linux/issues/1747 for an analysis from Ulich Weigand. Therefore always build a relocatable kernel to avoid this problem. There is hardly any use-case for non-relocatable kernels, so this shouldn't be controversial. Link: https://github.com/ClangBuiltLinux/linux/issues/1747 Signed-off-by: Heiko Carstens Reported-by: Nathan Chancellor Tested-by: Nathan Chancellor Link: https://lore.kernel.org/r/20221030182202.2062705-1-hca@linux.ibm.com Signed-off-by: Alexander Gordeev

kbuild: remove head-y syntax

2022-10-02T09:06:03Z

Kbuild puts the objects listed in head-y at the head of vmlinux. Conventionally, we do this for head*.S, which contains the kernel entry point. A counter approach is to control the section order by the linker script. Actually, the code marked as __HEAD goes into the ".head.text" section, which is placed before the normal ".text" section. I do not know if both of them are needed. From the build system perspective, head-y is not mandatory. If you can achieve the proper code placement by the linker script only, it would be cleaner. I collected the current head-y objects into head-object-list.txt. It is a whitelist. My hope is it will be reduced in the long run. Signed-off-by: Masahiro Yamada Tested-by: Nick Desaulniers Reviewed-by: Nicolas Schier

s390/nospec: remove unneeded header includes

2022-07-13T13:21:55Z

Commit 4efd417f298b ("s390: raise minimum supported machine generation to z10") removed the usage of alternatives and lowcore in expolines macros. Remove unneeded header includes as well. With that, expoline.S doesn't require asm-offsets.h and expoline_prepare target dependency could be removed. Tested-by: Joe Lawrence Link: https://lore.kernel.org/r/patch-2.thread-d13b6c.git-d13b6c96fb5f.your-ad-here.call-01656331067-ext-4899@work.hours Signed-off-by: Vasily Gorbik Signed-off-by: Alexander Gordeev

s390/nospec: build expoline.o for modules_prepare target

2022-07-13T13:21:55Z

When CONFIG_EXPOLINE_EXTERN is used expoline thunks are generated from arch/s390/lib/expoline.S and postlinked into every module. This is also true for external modules. Add expoline.o build to the modules_prepare target. Fixes: 1d2ad084800e ("s390/nospec: add an option to use thunk-extern") Reported-by: Joe Lawrence Tested-by: Sumanth Korikkar Acked-by: Sumanth Korikkar Tested-by: C. Erastus Toe Tested-by: Joe Lawrence Link: https://lore.kernel.org/r/patch-1.thread-d13b6c.git-a2387a74dc49.your-ad-here.call-01656331067-ext-4899@work.hours Signed-off-by: Vasily Gorbik Signed-off-by: Alexander Gordeev

gcc-12: disable '-Warray-bounds' universally for now

2022-06-09T17:11:12Z

In commit 8b202ee21839 ("s390: disable -Warray-bounds") the s390 people disabled the '-Warray-bounds' warning for gcc-12, because the new logic in gcc would cause warnings for their use of the S390_lowcore macro, which accesses absolute pointers. It turns out gcc-12 has many other issues in this area, so this takes that s390 warning disable logic, and turns it into a kernel build config entry instead. Part of the intent is that we can make this all much more targeted, and use this conflig flag to disable it in only particular configurations that cause problems, with the s390 case as an example: select GCC12_NO_ARRAY_BOUNDS and we could do that for other configuration cases that cause issues. Or we could possibly use the CONFIG_CC_NO_ARRAY_BOUNDS thing in a more targeted way, and disable the warning only for particular uses: again the s390 case as an example: KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_NO_ARRAY_BOUNDS),-Wno-array-bounds) but this ends up just doing it globally in the top-level Makefile, since the current issues are spread fairly widely all over: KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds We'll try to limit this later, since the gcc-12 problems are rare enough that *much* of the kernel can be built with it without disabling this warning. Cc: Kees Cook Cc: Nathan Chancellor Signed-off-by: Linus Torvalds

Merge tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2022-05-26T19:09:50Z

Pull Kbuild updates from Masahiro Yamada: - Add HOSTPKG_CONFIG env variable to allow users to override pkg-config - Support W=e as a shorthand for KCFLAGS=-Werror - Fix CONFIG_IKHEADERS build to support toybox cpio - Add scripts/dummy-tools/pahole to ease distro packagers' life - Suppress false-positive warnings from checksyscalls.sh for W=2 build - Factor out the common code of arch/*/boot/install.sh into scripts/install.sh - Support 'kernel-install' tool in scripts/prune-kernel - Refactor module-versioning to link the symbol versions at the final link of vmlinux and modules - Remove CONFIG_MODULE_REL_CRCS because module-versioning now works in an arch-agnostic way - Refactor modpost, Makefiles * tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (56 commits) genksyms: adjust the output format to modpost kbuild: stop merging *.symversions kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS modpost: extract symbol versions from *.cmd files modpost: add sym_find_with_module() helper modpost: change the license of EXPORT_SYMBOL to bool type modpost: remove left-over cross_compile declaration kbuild: record symbol versions in *.cmd files kbuild: generate a list of objects in vmlinux modpost: move *.mod.c generation to write_mod_c_files() modpost: merge add_{intree_flag,retpoline,staging_flag} to add_header scripts/prune-kernel: Use kernel-install if available kbuild: factor out the common installation code into scripts/install.sh modpost: split new_symbol() to symbol allocation and hash table addition modpost: make sym_add_exported() always allocate a new symbol modpost: make multiple export error modpost: dump Module.symvers in the same order of modules.order modpost: traverse the namespace_list in order modpost: use doubly linked list for dump_lists modpost: traverse unresolved symbols in order ...

Merge tag 's390-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2022-05-24T04:01:30Z

Pull s390 updates from Heiko Carstens: - Make use of the IBM z16 processor activity instrumentation facility to count cryptography operations: add a new PMU device driver so that perf can make use of this. - Add new IBM z16 extended counter set to cpumf support. - Add vdso randomization support. - Add missing KCSAN instrumentation to barriers and spinlocks, which should make s390's KCSAN support complete. - Add support for IPL-complete-control facility: notify the hypervisor that kexec finished work and the kernel starts. - Improve error logging for PCI. - Various small changes to workaround llvm's integrated assembler limitations, and one bug, to make it finally possible to compile the kernel with llvm's integrated assembler. This also requires to raise the minimum clang version to 14.0.0. - Various other small enhancements, bug fixes, and cleanups all over the place. * tag 's390-5.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (48 commits) s390/head: get rid of 31 bit leftovers scripts/min-tool-version.sh: raise minimum clang version to 14.0.0 for s390 s390/boot: do not emit debug info for assembly with llvm's IAS s390/boot: workaround llvm IAS bug s390/purgatory: workaround llvm's IAS limitations s390/entry: workaround llvm's IAS limitations s390/alternatives: remove padding generation code s390/alternatives: provide identical sized orginal/alternative sequences s390/cpumf: add new extended counter set for IBM z16 s390/preempt: disable __preempt_count_add() optimization for PROFILE_ALL_BRANCHES s390/stp: clock_delta should be signed s390/stp: fix todoff size s390/pai: add support for cryptography counters entry: Rename arch_check_user_regs() to arch_enter_from_user_mode() s390/compat: cleanup compat_linux.h header file s390/entry: remove broken and not needed code s390/boot: convert parmarea to C s390/boot: convert initial lowcore to C s390/ptrace: move short psw definitions to ptrace header file s390/head: initialize all new psws ...

s390/boot: do not emit debug info for assembly with llvm's IAS

2022-05-17T13:16:29Z

Commit ee6d777d3e93 ("s390/decompressor: support extra debug flags") added extra debug flags, in particular debug info is created, depending on config options. With llvm's IAS this causes this compile warning: arch/s390/boot/head.S:38:1: warning: DWARF2 only supports one section per compilation unit .section ".head.text","ax" ^ This is a known problem and was addressed with commit b8a9092330da ("Kbuild: do not emit debug info for assembly with LLVM_IAS=1"). Just do the same for s390 to get rid of this warning. Tested-by: Nathan Chancellor Tested-by: Nick Desaulniers Link: https://lore.kernel.org/r/20220511120532.2228616-8-hca@linux.ibm.com Signed-off-by: Heiko Carstens

kbuild: factor out the common installation code into scripts/install.sh

2022-05-11T12:45:53Z

Many architectures have similar install.sh scripts. The first half is really generic; it verifies that the kernel image and System.map exist, then executes ~/bin/${INSTALLKERNEL} or /sbin/${INSTALLKERNEL} if available. The second half is kind of arch-specific; it copies the kernel image and System.map to the destination, but the code is slightly different. Factor out the generic part into scripts/install.sh. Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier

s390: disable -Warray-bounds

2022-04-27T10:53:07Z

gcc-12 shows a lot of array bound warnings on s390. This is caused by the S390_lowcore macro which uses a hardcoded address of 0. Wrapping that with absolute_pointer() works, but gcc no longer knows that a 12 bit displacement is sufficient to access lowcore. So it emits instructions like 'lghi %r1,0; l %rx,xxx(%r1)' instead of a single load/store instruction. As s390 stores variables often read/written in lowcore, this is considered problematic. Therefore disable -Warray-bounds on s390 for gcc-12 for the time being, until there is a better solution. Signed-off-by: Sven Schnelle Link: https://lore.kernel.org/r/yt9dzgkelelc.fsf@linux.ibm.com Link: https://lore.kernel.org/r/20220422134308.1613610-1-svens@linux.ibm.com Link: https://lore.kernel.org/r/20220425121742.3222133-1-svens@linux.ibm.com Signed-off-by: Heiko Carstens