linux-dev/arch/s390/Kconfig, 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

Merge tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random

2022-08-03T00:31:35Z

Pull random number generator updates from Jason Donenfeld: "Though there's been a decent amount of RNG-related development during this last cycle, not all of it is coming through this tree, as this cycle saw a shift toward tackling early boot time seeding issues, which took place in other trees as well. Here's a summary of the various patches: - The CONFIG_ARCH_RANDOM .config option and the "nordrand" boot option have been removed, as they overlapped with the more widely supported and more sensible options, CONFIG_RANDOM_TRUST_CPU and "random.trust_cpu". This change allowed simplifying a bit of arch code. - x86's RDRAND boot time test has been made a bit more robust, with RDRAND disabled if it's clearly producing bogus results. This would be a tip.git commit, technically, but I took it through random.git to avoid a large merge conflict. - The RNG has long since mixed in a timestamp very early in boot, on the premise that a computer that does the same things, but does so starting at different points in wall time, could be made to still produce a different RNG state. Unfortunately, the clock isn't set early in boot on all systems, so now we mix in that timestamp when the time is actually set. - User Mode Linux now uses the host OS's getrandom() syscall to generate a bootloader RNG seed and later on treats getrandom() as the platform's RDRAND-like faculty. - The arch_get_random_{seed_,}_long() family of functions is now arch_get_random_{seed_,}_longs(), which enables certain platforms, such as s390, to exploit considerable performance advantages from requesting multiple CPU random numbers at once, while at the same time compiling down to the same code as before on platforms like x86. - A small cleanup changing a cmpxchg() into a try_cmpxchg(), from Uros. - A comment spelling fix" More info about other random number changes that come in through various architecture trees in the full commentary in the pull request: https://lore.kernel.org/all/20220731232428.2219258-1-Jason@zx2c4.com/ * tag 'random-6.0-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: random: correct spelling of "overwrites" random: handle archrandom with multiple longs um: seed rng using host OS rng random: use try_cmpxchg in _credit_init_bits timekeeping: contribute wall clock to rng on time change x86/rdrand: Remove "nordrand" flag in favor of "random.trust_cpu" random: remove CONFIG_ARCH_RANDOM

mmu_gather: Remove per arch tlb_{start,end}_vma()

2022-07-21T17:50:13Z

Scattered across the archs are 3 basic forms of tlb_{start,end}_vma(). Provide two new MMU_GATHER_knobs to enumerate them and remove the per arch tlb_{start,end}_vma() implementations. - MMU_GATHER_NO_FLUSH_CACHE indicates the arch has flush_cache_range() but does *NOT* want to call it for each VMA. - MMU_GATHER_MERGE_VMAS indicates the arch wants to merge the invalidate across multiple VMAs if possible. With these it is possible to capture the three forms: 1) empty stubs; select MMU_GATHER_NO_FLUSH_CACHE and MMU_GATHER_MERGE_VMAS 2) start: flush_cache_range(), end: empty; select MMU_GATHER_MERGE_VMAS 3) start: flush_cache_range(), end: flush_tlb_range(); default Obviously, if the architecture does not have flush_cache_range() then it also doesn't need to select MMU_GATHER_NO_FLUSH_CACHE. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Will Deacon Cc: David Miller Signed-off-by: Linus Torvalds

random: remove CONFIG_ARCH_RANDOM

2022-07-18T13:03:37Z

When RDRAND was introduced, there was much discussion on whether it should be trusted and how the kernel should handle that. Initially, two mechanisms cropped up, CONFIG_ARCH_RANDOM, a compile time switch, and "nordrand", a boot-time switch. Later the thinking evolved. With a properly designed RNG, using RDRAND values alone won't harm anything, even if the outputs are malicious. Rather, the issue is whether those values are being *trusted* to be good or not. And so a new set of options were introduced as the real ones that people use -- CONFIG_RANDOM_TRUST_CPU and "random.trust_cpu". With these options, RDRAND is used, but it's not always credited. So in the worst case, it does nothing, and in the best case, maybe it helps. Along the way, CONFIG_ARCH_RANDOM's meaning got sort of pulled into the center and became something certain platforms force-select. The old options don't really help with much, and it's a bit odd to have special handling for these instructions when the kernel can deal fine with the existence or untrusted existence or broken existence or non-existence of that CPU capability. Simplify the situation by removing CONFIG_ARCH_RANDOM and using the ordinary asm-generic fallback pattern instead, keeping the two options that are actually used. For now it leaves "nordrand" for now, as the removal of that will take a different route. Acked-by: Michael Ellerman Acked-by: Catalin Marinas Acked-by: Borislav Petkov Acked-by: Heiko Carstens Acked-by: Greg Kroah-Hartman Signed-off-by: Jason A. Donenfeld

s390: remove unneeded 'select BUILD_BIN2C'

2022-06-30T12:18:15Z

Since commit 4c0f032d4963 ("s390/purgatory: Omit use of bin2c"), s390 builds the purgatory without using bin2c. Remove 'select BUILD_BIN2C' to avoid the unneeded build of bin2c. Fixes: 4c0f032d4963 ("s390/purgatory: Omit use of bin2c") Signed-off-by: Masahiro Yamada Link: https://lore.kernel.org/r/20220613170902.1775211-1-masahiroy@kernel.org Signed-off-by: Alexander Gordeev

Merge tag 'for-linus-5.19a-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2022-06-10T16:57:11Z

Pull xen updates from Juergen Gross: - a small cleanup removing "export" of an __init function - a small series adding a new infrastructure for platform flags - a series adding generic virtio support for Xen guests (frontend side) * tag 'for-linus-5.19a-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen: unexport __init-annotated xen_xlate_map_ballooned_pages() arm/xen: Assign xen-grant DMA ops for xen-grant DMA devices xen/grant-dma-ops: Retrieve the ID of backend's domain for DT devices xen/grant-dma-iommu: Introduce stub IOMMU driver dt-bindings: Add xen,grant-dma IOMMU description for xen-grant DMA ops xen/virtio: Enable restricted memory access using Xen grant mappings xen/grant-dma-ops: Add option to restrict memory access under Xen xen/grants: support allocating consecutive grants arm/xen: Introduce xen_setup_dma_ops() virtio: replace arch_has_restricted_virtio_memory_access() kernel: add platform_has() infrastructure

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

virtio: replace arch_has_restricted_virtio_memory_access()

2022-06-06T06:22:01Z

Instead of using arch_has_restricted_virtio_memory_access() together with CONFIG_ARCH_HAS_RESTRICTED_VIRTIO_MEMORY_ACCESS, replace those with platform_has() and a new platform feature PLATFORM_VIRTIO_RESTRICTED_MEM_ACCESS. Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Tested-by: Oleksandr Tyshchenko # Arm64 only Reviewed-by: Christoph Hellwig Acked-by: Borislav Petkov

Merge tag 's390-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2022-06-03T20:57:50Z

Pull more s390 updates from Heiko Carstens: "Just a couple of small improvements, bug fixes and cleanups: - Add Eric Farman as maintainer for s390 virtio drivers. - Improve machine check handling, and avoid incorrectly injecting a machine check into a kvm guest. - Add cond_resched() call to gmap page table walker in order to avoid possible huge latencies. Also use non-quiesing sske instruction to speed up storage key handling. - Add __GFP_NORETRY to KEXEC_CONTROL_MEMORY_GFP so s390 behaves similar like common code. - Get sie control block address from correct stack slot in perf event code. This fixes potential random memory accesses. - Change uaccess code so that the exception handler sets the result of get_user() and __get_kernel_nofault() to zero in case of a fault. Until now this was done via input parameters for inline assemblies. Doing it via fault handling is what most or even all other architectures are doing. - Couple of other small cleanups and fixes" * tag 's390-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390/stack: add union to reflect kvm stack slot usages s390/stack: merge empty stack frame slots s390/uaccess: whitespace cleanup s390/uaccess: use __noreturn instead of __attribute__((noreturn)) s390/uaccess: use exception handler to zero result on get_user() failure s390/uaccess: use symbolic names for inline assembler operands s390/mcck: isolate SIE instruction when setting CIF_MCCK_GUEST flag s390/mm: use non-quiescing sske for KVM switch to keyed guest s390/gmap: voluntarily schedule during key setting MAINTAINERS: Update s390 virtio-ccw s390/kexec: add __GFP_NORETRY to KEXEC_CONTROL_MEMORY_GFP s390/Kconfig.debug: fix indentation s390/Kconfig: fix indentation s390/perf: obtain sie_block from the right address s390: generate register offsets into pt_regs automatically s390: simplify early program check handler s390/crypto: fix scatterwalk_unmap() callers in AES-GCM

s390/Kconfig: fix indentation

2022-06-01T10:03:15Z

The convention for indentation seems to be a single tab. Help text is further indented by an additional two whitespaces. Fix the lines that violate these rules. Signed-off-by: Juerg Haefliger Link: https://lore.kernel.org/r/20220525120140.39534-1-juerg.haefliger@canonical.com Signed-off-by: Heiko Carstens