kernel.git/arch/s390/kernel, branch linux-6.19.y

kbuild: Split .modinfo out from ELF_DETAILS

2026-03-12T11:09:39Z

commit 8678591b47469fe16357234efef9b260317b8be4 upstream. Commit 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped") added .modinfo to ELF_DETAILS while removing it from COMMON_DISCARDS, as it was needed in vmlinux.unstripped and ELF_DETAILS was present in all architecture specific vmlinux linker scripts. While this shuffle is fine for vmlinux, ELF_DETAILS and COMMON_DISCARDS may be used by other linker scripts, such as the s390 and x86 compressed boot images, which may not expect to have a .modinfo section. In certain circumstances, this could result in a bootloader failing to load the compressed kernel [1]. Commit ddc6cbef3ef1 ("s390/boot/vmlinux.lds.S: Ensure bzImage ends with SecureBoot trailer") recently addressed this for the s390 bzImage but the same bug remains for arm, parisc, and x86. The presence of .modinfo in the x86 bzImage was the root cause of the issue worked around with commit d50f21091358 ("kbuild: align modinfo section for Secureboot Authenticode EDK2 compat"). misc.c in arch/x86/boot/compressed includes lib/decompress_unzstd.c, which in turn includes lib/xxhash.c and its MODULE_LICENSE / MODULE_DESCRIPTION macros due to the STATIC definition. Split .modinfo out from ELF_DETAILS into its own macro and handle it in all vmlinux linker scripts. Discard .modinfo in the places where it was previously being discarded from being in COMMON_DISCARDS, as it has never been necessary in those uses. Cc: stable@vger.kernel.org Fixes: 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped") Reported-by: Ed W Closes: https://lore.kernel.org/587f25e0-a80e-46a5-9f01-87cb40cfa377@wildgooses.com/ [1] Tested-by: Ed W # x86_64 Link: https://patch.msgid.link/20260225-separate-modinfo-from-elf-details-v1-1-387ced6baf4b@kernel.org Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman

s390/kexec: Disable stack protector in s390_reset_system()

2026-03-12T11:09:20Z

[ Upstream commit 1623a554c68f352c17d0a358bc62580dc187f06b ] s390_reset_system() calls set_prefix(0), which switches back to the absolute lowcore. At that point the stack protector canary no longer matches the canary from the lowcore the function was entered with, so the stack check fails. Mark s390_reset_system() __no_stack_protector. This is safe here since its callers (__do_machine_kdump() and __do_machine_kexec()) are effectively no-return and fall back to disabled_wait() on failure. Fixes: f5730d44e05e ("s390: Add stackprotector support") Reported-by: Nikita Dubrovskii Reviewed-by: Heiko Carstens Acked-by: Alexander Gordeev Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/vtime: Fix virtual timer forwarding

2026-03-12T11:09:19Z

[ Upstream commit dbc0fb35679ed5d0adecf7d02137ac2c77244b3b ] Since delayed accounting of system time [1] the virtual timer is forwarded by do_account_vtime() but also vtime_account_kernel(), vtime_account_softirq(), and vtime_account_hardirq(). This leads to double accounting of system, guest, softirq, and hardirq time. Remove accounting from the vtime_account*() family to restore old behavior. There is only one user of the vtimer interface, which might explain why nobody noticed this so far. Fixes: b7394a5f4ce9 ("sched/cputime, s390: Implement delayed accounting of system time") [1] Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/idle: Fix cpu idle exit cpu time accounting

2026-03-12T11:09:19Z

[ Upstream commit 0d785e2c324c90662baa4fe07a0d02233ff92824 ] With the conversion to generic entry [1] cpu idle exit cpu time accounting was converted from assembly to C. This introduced an reversed order of cpu time accounting. On cpu idle exit the current accounting happens with the following call chain: -> do_io_irq()/do_ext_irq() -> irq_enter_rcu() -> account_hardirq_enter() -> vtime_account_irq() -> vtime_account_kernel() vtime_account_kernel() accounts the passed cpu time since last_update_timer as system time, and updates last_update_timer to the current cpu timer value. However the subsequent call of -> account_idle_time_irq() will incorrectly subtract passed cpu time from timer_idle_enter to the updated last_update_timer value from system_timer. Then last_update_timer is updated to a sys_enter_timer, which means that last_update_timer goes back in time. Subsequently account_hardirq_exit() will account too much cpu time as hardirq time. The sum of all accounted cpu times is still correct, however some cpu time which was previously accounted as system time is now accounted as hardirq time, plus there is the oddity that last_update_timer goes back in time. Restore previous behavior by extracting cpu time accounting code from account_idle_time_irq() into a new update_timer_idle() function and call it before irq_enter_rcu(). Fixes: 56e62a737028 ("s390: convert to generic entry") [1] Reviewed-by: Sven Schnelle Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin

s390/perf: Disable register readout on sampling events

2026-03-04T12:19:40Z

[ Upstream commit b2c04fc1239062b39ddfdd8731ee1a10810dfb74 ] Running commands # ./perf record -IR0,R1 -a sleep 1 extracts and displays register value of general purpose register r1 and r0. However the value displayed of any register is random and does not reflect the register value recorded at the time of the sample interrupt. The sampling device driver on s390 creates a very large buffer for the hardware to store the samples. Only when that large buffer gets full an interrupt is generated and many hundreds of sample entries are processed and copied to the kernel ring buffer and eventually get copied to the perf tool. It is during the copy to the kernel ring buffer that each sample is processed (on s390) and at that time the register values are extracted. This is not the original goal, the register values should be read when the samples are created not when the samples are copied to the kernel ring buffer. Prevent this event from being installed in the first place and return -EOPNOTSUPP. This is already the case for PERF_SAMPLE_REGS_USER. Signed-off-by: Thomas Richter Reviewed-by: Jan Polensky Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin

s390/vdso: Disable kstack erase

2026-01-17T14:51:28Z

For some reason gcc 8, 9, 10, and 11 generate a dynamic relocation in vdso.so.dbg if CONFIG_KSTACK_ERASE is enabled: >> arch/s390/kernel/vdso/vdso.so.dbg: dynamic relocations are not supported make[3]: *** [arch/s390/kernel/vdso/Makefile:54: arch/s390/kernel/vdso/vdso.so.dbg] Error 1 $ readelf -rW arch/s390/kernel/vdso/vdso.so.dbg Relocation section '.rela.dyn' at offset 0x15c0 contains 1 entry: Offset Info Type Symbol's Value Symbol's Name + Addend 00000000000015f0 000000010000000b R_390_JMP_SLOT 0000000000000000 __sanitizer_cov_stack_depth + 0 Add $(DISABLE_KSTACK_ERASE) to vdso compile flags to fix this. Reported-by: kernel test robot Closes: https://lore.kernel.org/r/202601070505.xQcLr5KV-lkp@intel.com/ Signed-off-by: Heiko Carstens

s390/stacktrace: Do not fallback to RA register

2025-12-14T10:03:58Z

The logic to fallback to the return address (RA) register value in the topmost frame when stack tracing using back chain is broken in multiple ways: When assuming the RA register 14 has not been saved yet one must assume that a new user stack frame has not been allocated either. Therefore the back chain would not contain the stack pointer (SP) at entry, but the caller's SP at its entry instead. Therefore when falling back to the RA register 14 value it would also be necessary to fallback to the SP register 15 value. Otherwise an invalid combination of RA register 14 and caller's SP at its entry (from the back chain) is used. In the topmost frame the back chain contains either the caller's SP at its entry (before having allocated a new stack frame in the prologue), the SP at entry (after having allocated a new stack frame), or an uninitialized value (during static/dynamic stack allocation). In both cases where the back chain is valid either the caller or prologue must have saved its respective RA to the respective frame. Therefore, if the RA obtained from the frame pointed to by the back chain is invalid, this does not indicate that the IP in the topmost frame is still early in the prologue and the RA has not been saved. Reviewed-by: Heiko Carstens Signed-off-by: Jens Remus Signed-off-by: Heiko Carstens

s390/ipl: Clear SBP flag when bootprog is set

2025-12-14T10:03:57Z

With z16 a new flag 'search boot program' was introduced for list-directed IPL (SCSI, NVMe, ECKD DASD). If this flag is set, e.g. via selecting the "Automatic" value for the "Boot program selector" control on an HMC load panel, it is copied to the reipl structure from the initial ipl structure. When a user now sets a boot prog via sysfs, the flag is not cleared and the bootloader will again automatically select the boot program, ignoring user configuration. To avoid that, clear the SBP flag when a bootprog sysfs file is written. Cc: stable@vger.kernel.org Reviewed-by: Peter Oberparleiter Reviewed-by: Heiko Carstens Signed-off-by: Sven Schnelle Signed-off-by: Heiko Carstens

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2025-12-06T01:01:20Z

Pull KVM updates from Paolo Bonzini: "ARM: - Support for userspace handling of synchronous external aborts (SEAs), allowing the VMM to potentially handle the abort in a non-fatal manner - Large rework of the VGIC's list register handling with the goal of supporting more active/pending IRQs than available list registers in hardware. In addition, the VGIC now supports EOImode==1 style deactivations for IRQs which may occur on a separate vCPU than the one that acked the IRQ - Support for FEAT_XNX (user / privileged execute permissions) and FEAT_HAF (hardware update to the Access Flag) in the software page table walkers and shadow MMU - Allow page table destruction to reschedule, fixing long need_resched latencies observed when destroying a large VM - Minor fixes to KVM and selftests Loongarch: - Get VM PMU capability from HW GCFG register - Add AVEC basic support - Use 64-bit register definition for EIOINTC - Add KVM timer test cases for tools/selftests RISC/V: - SBI message passing (MPXY) support for KVM guest - Give a new, more specific error subcode for the case when in-kernel AIA virtualization fails to allocate IMSIC VS-file - Support KVM_DIRTY_LOG_INITIALLY_SET, enabling dirty log gradually in small chunks - Fix guest page fault within HLV* instructions - Flush VS-stage TLB after VCPU migration for Andes cores s390: - Always allocate ESCA (Extended System Control Area), instead of starting with the basic SCA and converting to ESCA with the addition of the 65th vCPU. The price is increased number of exits (and worse performance) on z10 and earlier processor; ESCA was introduced by z114/z196 in 2010 - VIRT_XFER_TO_GUEST_WORK support - Operation exception forwarding support - Cleanups x86: - Skip the costly "zap all SPTEs" on an MMIO generation wrap if MMIO SPTE caching is disabled, as there can't be any relevant SPTEs to zap - Relocate a misplaced export - Fix an async #PF bug where KVM would clear the completion queue when the guest transitioned in and out of paging mode, e.g. when handling an SMI and then returning to paged mode via RSM - Leave KVM's user-return notifier registered even when disabling virtualization, as long as kvm.ko is loaded. On reboot/shutdown, keeping the notifier registered is ok; the kernel does not use the MSRs and the callback will run cleanly and restore host MSRs if the CPU manages to return to userspace before the system goes down - Use the checked version of {get,put}_user() - Fix a long-lurking bug where KVM's lack of catch-up logic for periodic APIC timers can result in a hard lockup in the host - Revert the periodic kvmclock sync logic now that KVM doesn't use a clocksource that's subject to NTP corrections - Clean up KVM's handling of MMIO Stale Data and L1TF, and bury the latter behind CONFIG_CPU_MITIGATIONS - Context switch XCR0, XSS, and PKRU outside of the entry/exit fast path; the only reason they were handled in the fast path was to paper of a bug in the core #MC code, and that has long since been fixed - Add emulator support for AVX MOV instructions, to play nice with emulated devices whose guest drivers like to access PCI BARs with large multi-byte instructions x86 (AMD): - Fix a few missing "VMCB dirty" bugs - Fix the worst of KVM's lack of EFER.LMSLE emulation - Add AVIC support for addressing 4k vCPUs in x2AVIC mode - Fix incorrect handling of selective CR0 writes when checking intercepts during emulation of L2 instructions - Fix a currently-benign bug where KVM would clobber SPEC_CTRL[63:32] on VMRUN and #VMEXIT - Fix a bug where KVM corrupt the guest code stream when re-injecting a soft interrupt if the guest patched the underlying code after the VM-Exit, e.g. when Linux patches code with a temporary INT3 - Add KVM_X86_SNP_POLICY_BITS to advertise supported SNP policy bits to userspace, and extend KVM "support" to all policy bits that don't require any actual support from KVM x86 (Intel): - Use the root role from kvm_mmu_page to construct EPTPs instead of the current vCPU state, partly as worthwhile cleanup, but mostly to pave the way for tracking per-root TLB flushes, and elide EPT flushes on pCPU migration if the root is clean from a previous flush - Add a few missing nested consistency checks - Rip out support for doing "early" consistency checks via hardware as the functionality hasn't been used in years and is no longer useful in general; replace it with an off-by-default module param to WARN if hardware fails a check that KVM does not perform - Fix a currently-benign bug where KVM would drop the guest's SPEC_CTRL[63:32] on VM-Enter - Misc cleanups - Overhaul the TDX code to address systemic races where KVM (acting on behalf of userspace) could inadvertantly trigger lock contention in the TDX-Module; KVM was either working around these in weird, ugly ways, or was simply oblivious to them (though even Yan's devilish selftests could only break individual VMs, not the host kernel) - Fix a bug where KVM could corrupt a vCPU's cpu_list when freeing a TDX vCPU, if creating said vCPU failed partway through - Fix a few sparse warnings (bad annotation, 0 != NULL) - Use struct_size() to simplify copying TDX capabilities to userspace - Fix a bug where TDX would effectively corrupt user-return MSR values if the TDX Module rejects VP.ENTER and thus doesn't clobber host MSRs as expected Selftests: - Fix a math goof in mmu_stress_test when running on a single-CPU system/VM - Forcefully override ARCH from x86_64 to x86 to play nice with specifying ARCH=x86_64 on the command line - Extend a bunch of nested VMX to validate nested SVM as well - Add support for LA57 in the core VM_MODE_xxx macro, and add a test to verify KVM can save/restore nested VMX state when L1 is using 5-level paging, but L2 is not - Clean up the guest paging code in anticipation of sharing the core logic for nested EPT and nested NPT guest_memfd: - Add NUMA mempolicy support for guest_memfd, and clean up a variety of rough edges in guest_memfd along the way - Define a CLASS to automatically handle get+put when grabbing a guest_memfd from a memslot to make it harder to leak references - Enhance KVM selftests to make it easer to develop and debug selftests like those added for guest_memfd NUMA support, e.g. where test and/or KVM bugs often result in hard-to-debug SIGBUS errors - Misc cleanups Generic: - Use the recently-added WQ_PERCPU when creating the per-CPU workqueue for irqfd cleanup - Fix a goof in the dirty ring documentation - Fix choice of target for directed yield across different calls to kvm_vcpu_on_spin(); the function was always starting from the first vCPU instead of continuing the round-robin search" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (260 commits) KVM: arm64: at: Update AF on software walk only if VM has FEAT_HAFDBS KVM: arm64: at: Use correct HA bit in TCR_EL2 when regime is EL2 KVM: arm64: Document KVM_PGTABLE_PROT_{UX,PX} KVM: arm64: Fix spelling mistake "Unexpeced" -> "Unexpected" KVM: arm64: Add break to default case in kvm_pgtable_stage2_pte_prot() KVM: arm64: Add endian casting to kvm_swap_s[12]_desc() KVM: arm64: Fix compilation when CONFIG_ARM64_USE_LSE_ATOMICS=n KVM: arm64: selftests: Add test for AT emulation KVM: arm64: nv: Expose hardware access flag management to NV guests KVM: arm64: nv: Implement HW access flag management in stage-2 SW PTW KVM: arm64: Implement HW access flag management in stage-1 SW PTW KVM: arm64: Propagate PTW errors up to AT emulation KVM: arm64: Add helper for swapping guest descriptor KVM: arm64: nv: Use pgtable definitions in stage-2 walk KVM: arm64: Handle endianness in read helper for emulated PTW KVM: arm64: nv: Stop passing vCPU through void ptr in S2 PTW KVM: arm64: Call helper for reading descriptors directly KVM: arm64: nv: Advertise support for FEAT_XNX KVM: arm64: Teach ptdump about FEAT_XNX permissions KVM: s390: Use generic VIRT_XFER_TO_GUEST_WORK functions ...

Merge tag 's390-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2025-12-03T00:37:00Z

Pull s390 updates from Heiko Carstens: - Provide a new interface for dynamic configuration and deconfiguration of hotplug memory, allowing with and without memmap_on_memory support. This makes the way memory hotplug is handled on s390 much more similar to other architectures - Remove compat support. There shouldn't be any compat user space around anymore, therefore get rid of a lot of code which also doesn't need to be tested anymore - Add stackprotector support. GCC 16 will get new compiler options, which allow to generate code required for kernel stackprotector support - Merge pai_crypto and pai_ext PMU drivers into a new driver. This removes a lot of duplicated code. The new driver is also extendable and allows to support new PMUs - Add driver override support for AP queues - Rework and extend zcrypt and AP trace events to allow for tracing of crypto requests - Support block sizes larger than 65535 bytes for CCW tape devices - Since the rework of the virtual kernel address space the module area and the kernel image are within the same 4GB area. This eliminates the need of weak per cpu variables. Get rid of ARCH_MODULE_NEEDS_WEAK_PER_CPU - Various other small improvements and fixes * tag 's390-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (92 commits) watchdog: diag288_wdt: Remove KMSG_COMPONENT macro s390/entry: Use lay instead of aghik s390/vdso: Get rid of -m64 flag handling s390/vdso: Rename vdso64 to vdso s390: Rename head64.S to head.S s390/vdso: Use common STABS_DEBUG and DWARF_DEBUG macros s390: Add stackprotector support s390/modules: Simplify module_finalize() slightly s390: Remove KMSG_COMPONENT macro s390/percpu: Get rid of ARCH_MODULE_NEEDS_WEAK_PER_CPU s390/ap: Restrict driver_override versus apmask and aqmask use s390/ap: Rename mutex ap_perms_mutex to ap_attr_mutex s390/ap: Support driver_override for AP queue devices s390/ap: Use all-bits-one apmask/aqmask for vfio in_use() checks s390/debug: Update description of resize operation s390/syscalls: Switch to generic system call table generation s390/syscalls: Remove system call table pointer from thread_struct s390/uapi: Remove 31 bit support from uapi header files s390: Remove compat support tools: Remove s390 compat support ...