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

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

s390: allow to compile with z16 optimizations

2022-04-06T11:08:50Z

Add config and compile options which allow to compile with z16 optimizations if the compiler supports it. Signed-off-by: Heiko Carstens

s390: raise minimum supported machine generation to z10

2022-03-10T14:58:17Z

Machine generations up to z9 (released in May 2006) have been officially out of service for several years now (z9 end of service - January 31, 2019). No distributions build kernels supporting those old machine generations anymore, except Debian, which seems to pick the oldest supported generation. The team supporting Debian on s390 has been notified about the change. Raising minimum supported machine generation to z10 helps to reduce maintenance cost and effectively remove code, which is not getting enough testing coverage due to lack of older hardware and distributions support. Besides that this unblocks some optimization opportunities and allows to use wider instruction set in asm files for future features implementation. Due to this change spectre mitigation and usercopy implementations could be drastically simplified and many newer instructions could be converted from ".insn" encoding to instruction names. Acked-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/nospec: add an option to use thunk-extern

2022-03-10T14:58:17Z

Currently with -mindirect-branch=thunk and -mfunction-return=thunk compiler options expoline thunks are put into individual COMDAT group sections. s390 is the only architecture which has group sections and it has implications for kpatch and objtool tools support. Using -mindirect-branch=thunk-extern and -mfunction-return=thunk-extern is an alternative, which comes with a need to generate all required expoline thunks manually. Unfortunately modules area is too far away from the kernel image, and expolines from the kernel image cannon be used. But since all new distributions (except Debian) build kernels for machine generations newer than z10, where "exrl" instruction is available, that leaves only 16 expolines thunks possible. Provide an option to build the kernel with -mindirect-branch=thunk-extern and -mfunction-return=thunk-extern for z10 or newer. This also requires to postlink expoline thunks into all modules explicitly. Currently modules already contain most expolines anyhow. Unfortunately -mindirect-branch=thunk-extern and -mfunction-return=thunk-extern options support is broken in gcc <= 11.2. Additional compile test is required to verify proper gcc support. Acked-by: Ilya Leoshkevich Co-developed-by: Sumanth Korikkar Signed-off-by: Sumanth Korikkar Signed-off-by: Vasily Gorbik

s390: always use the packed stack layout

2022-03-01T20:05:09Z

-mpacked-stack option has been supported by both minimum gcc and clang versions for a while. With commit e2bc3e91d91e ("scripts/min-tool-version.sh: Raise minimum clang version to 13.0.0 for s390") minimum clang version now also supports a combination of flags -mpacked-stack -mbackchain -pg -mfentry and fulfills all requirements to always enable the packed stack layout. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik