linux/arch/x86/entry, branch master

x86/entry/vdso32: Work around libgcc unwinder bug

2026-03-04T16:06:08Z

The unwinder code in libgcc has a long standing bug which causes it to fail to pick up the signal frame CFI flag. This is a generic bug across all platforms. It affects the __kernel_sigreturn and __kernel_rt_sigreturn vdso entry points on i386. The x86-64 kernel doesn't provide a sigreturn stub, and so there is no kernel-provided code that is affected on x86-64. libgcc does have a legacy fallback path which happens to work as long as the bytes immediately before each of the sigreturn functions fall outside any function. This patch adds a nop before the ALIGN to each of the sigreturn stubs to ensure that this is, indeed, the case. The rest of the patch is just a comment which documents the invariants that need to be maintained for this legacy path to work correctly. This is a manifest bug: in the current vdso, __kernel_vsyscall is a multiple of 16 bytes long and thus __kernel_sigreturn does not have any padding in front of it. Closes: https://lore.kernel.org/lkml/f3412cc3e8f66d1853cc9d572c0f2fab076872b1.camel@xry111.site Fixes: 884961618ee5 ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S") Reported-by: Xi Ruoyao Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Peter Zijlstra (Intel) Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124050 Link: https://patch.msgid.link/20260227010308.310342-1-hpa@zytor.com

x86/fred: Correct speculative safety in fred_extint()

2026-02-23T10:19:11Z

array_index_nospec() is no use if the result gets spilled to the stack, as it makes the believed safe-under-speculation value subject to memory predictions. For all practical purposes, this means array_index_nospec() must be used in the expression that accesses the array. As the code currently stands, it's the wrong side of irqentry_enter(), and 'index' is put into %ebp across the function call. Remove the index variable and reposition array_index_nospec(), so it's calculated immediately before the array access. Fixes: 14619d912b65 ("x86/fred: FRED entry/exit and dispatch code") Signed-off-by: Andrew Cooper Signed-off-by: Peter Zijlstra (Intel) Link: https://patch.msgid.link/20260106131504.679932-1-andrew.cooper3@citrix.com

x86: keep legacy generated vdso files around in .gitignore file

2026-02-11T04:03:30Z

Commit 93d73005bff4 ("x86/entry/vdso: Rename vdso_image_* to vdso*_image") updated the vdso .gitignore file with the new filenames, which is certainly not incorrect. However, while adding new generated names is obviously the right thing to do, you should *not* immediately remove the old filenames from the .gitignore file when things move around or get renamed, because people still have those old generated files in their build trees - and they haven't suddenly become valid files to commit to the repository just because they were moved or renamed. While it's mostly just a slight visual nuisance for 'git status' that can be fixed up with a clean build tree, it can become more serious than that: see for example commit 04a3389b3535 ("Remove stale generated 'genheaders' file"). That commit removed up a stale generated file that had been carelessly committed by a kernel developer because it wasn't properly ignored any more and thus showed up as a new file in their tree. Fixes: 93d73005bff4 ("x86/entry/vdso: Rename vdso_image_* to vdso*_image") Cc: Peter Anvin Cc: Dave Hansen Signed-off-by: Linus Torvalds

Merge tag 'x86_entry_for_7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-02-11T03:34:26Z

Pull x86 entry code updates from Dave Hansen: "This is entirely composed of a set of long overdue VDSO cleanups. They makes the VDSO build much more logical and zap quite a bit of old cruft. It also results in a coveted net-code-removal diffstat" * tag 'x86_entry_for_7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/entry/vdso: Add vdso2c to .gitignore x86/entry/vdso32: Omit '.cfi_offset eflags' for LLVM < 16 MAINTAINERS: Adjust vdso file entry in INTEL SGX x86/entry/vdso/selftest: Update location of vgetrandom-chacha.S x86/entry/vdso: Fix filtering of vdso compiler flags x86/entry/vdso: Update the object paths for "make vdso_install" x86/entry/vdso32: When using int $0x80, use it directly x86/cpufeature: Replace X86_FEATURE_SYSENTER32 with X86_FEATURE_SYSFAST32 x86/vdso: Abstract out vdso system call internals x86/entry/vdso: Include GNU_PROPERTY and GNU_STACK PHDRs x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S x86/entry/vdso32: Remove SYSCALL_ENTER_KERNEL macro in sigreturn.S x86/entry/vdso32: Don't rely on int80_landing_pad for adjusting ip x86/entry/vdso: Refactor the vdso build x86/entry/vdso: Move vdso2c to arch/x86/tools x86/entry/vdso: Rename vdso_image_* to vdso*_image

Merge tag 'x86_paravirt_for_v7.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-02-11T03:01:45Z

Pull x86 paravirt updates from Borislav Petkov: - A nice cleanup to the paravirt code containing a unification of the paravirt clock interface, taming the include hell by splitting the pv_ops structure and removing of a bunch of obsolete code (Juergen Gross) * tag 'x86_paravirt_for_v7.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits) x86/paravirt: Use XOR r32,r32 to clear register in pv_vcpu_is_preempted() x86/paravirt: Remove trailing semicolons from alternative asm templates x86/pvlocks: Move paravirt spinlock functions into own header x86/paravirt: Specify pv_ops array in paravirt macros x86/paravirt: Allow pv-calls outside paravirt.h objtool: Allow multiple pv_ops arrays x86/xen: Drop xen_mmu_ops x86/xen: Drop xen_cpu_ops x86/xen: Drop xen_irq_ops x86/paravirt: Move pv_native_*() prototypes to paravirt.c x86/paravirt: Introduce new paravirt-base.h header x86/paravirt: Move paravirt_sched_clock() related code into tsc.c x86/paravirt: Use common code for paravirt_steal_clock() riscv/paravirt: Use common code for paravirt_steal_clock() loongarch/paravirt: Use common code for paravirt_steal_clock() arm64/paravirt: Use common code for paravirt_steal_clock() arm/paravirt: Use common code for paravirt_steal_clock() sched: Move clock related paravirt code to kernel/sched paravirt: Remove asm/paravirt_api_clock.h x86/paravirt: Move thunk macros to paravirt_types.h ...

Merge tag 'timers-vdso-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-02-11T01:02:23Z

Pull VDSO updates from Thomas Gleixner: - Provide the missing 64-bit variant of clock_getres() This allows the extension of CONFIG_COMPAT_32BIT_TIME to the vDSO and finally the removal of 32-bit time types from the kernel and UAPI. - Remove the useless and broken getcpu_cache from the VDSO The intention was to provide a trivial way to retrieve the CPU number from the VDSO, but as the VDSO data is per process there is no way to make it work. - Switch get/put_unaligned() from packed struct to memcpy() The packed struct violates strict aliasing rules which requires to pass -fno-strict-aliasing to the compiler. As this are scalar values __builtin_memcpy() turns them into simple loads and stores - Use __typeof_unqual__() for __unqual_scalar_typeof() The get/put_unaligned() changes triggered a new sparse warning when __beNN types are used with get/put_unaligned() as sparse builds add a special 'bitwise' attribute to them which prevents sparse to evaluate the Generic in __unqual_scalar_typeof(). Newer sparse versions support __typeof_unqual__() which avoids the problem, but requires a recent sparse install. So this adds a sanity check to sparse builds, which validates that sparse is available and capable of handling it. - Force inline __cvdso_clock_getres_common() Compilers sometimes un-inline agressively, which results in function call overhead and problems with automatic stack variable initialization. Interestingly enough the force inlining results in smaller code than the un-inlined variant produced by GCC when optimizing for size. * tag 'timers-vdso-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: vdso/gettimeofday: Force inlining of __cvdso_clock_getres_common() x86/percpu: Make CONFIG_USE_X86_SEG_SUPPORT work with sparse compiler: Use __typeof_unqual__() for __unqual_scalar_typeof() powerpc/vdso: Provide clock_getres_time64() tools headers: Remove unneeded ignoring of warnings in unaligned.h tools headers: Update the linux/unaligned.h copy with the kernel sources vdso: Switch get/put_unaligned() from packed struct to memcpy() parisc: Inline a type punning version of get_unaligned_le32() vdso: Remove struct getcpu_cache MIPS: vdso: Provide getres_time64() for 32-bit ABIs arm64: vdso32: Provide clock_getres_time64() ARM: VDSO: Provide clock_getres_time64() ARM: VDSO: Patch out __vdso_clock_getres() if unavailable x86/vdso: Provide clock_getres_time64() for x86-32 selftests: vDSO: vdso_test_abi: Add test for clock_getres_time64() selftests: vDSO: vdso_test_abi: Use UAPI system call numbers selftests: vDSO: vdso_config: Add configurations for clock_getres_time64() vdso: Add prototype for __vdso_clock_getres_time64()

Merge tag 'sched-core-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-02-10T20:50:10Z

Pull scheduler updates from Ingo Molnar: "Scheduler Kconfig space updates: - Further consolidate configurable preemption modes (Peter Zijlstra) Reduce the number of architectures that are allowed to offer PREEMPT_NONE and PREEMPT_VOLUNTARY, reducing the number of preemption models from four to just two: 'full' and 'lazy' on up-to-date architectures (arm64, loongarch, powerpc, riscv, s390, x86). None and voluntary are only available as legacy features on platforms that don't implement lazy preemption yet, or which don't even support preemption. The goal is to eventually remove cond_resched() and voluntary preemption altogether. RSEQ based 'scheduler time slice extension' support (Thomas Gleixner and Peter Zijlstra): This allows a thread to request a time slice extension when it enters a critical section to avoid contention on a resource when the thread is scheduled out inside of the critical section. - Add fields and constants for time slice extension - Provide static branch for time slice extensions - Add statistics for time slice extensions - Add prctl() to enable time slice extensions - Implement sys_rseq_slice_yield() - Implement syscall entry work for time slice extensions - Implement time slice extension enforcement timer - Reset slice extension when scheduled - Implement rseq_grant_slice_extension() - entry: Hook up rseq time slice extension - selftests: Implement time slice extension test - Allow registering RSEQ with slice extension - Move slice_ext_nsec to debugfs - Lower default slice extension - selftests/rseq: Add rseq slice histogram script Scheduler performance/scalability improvements: - Update rq->avg_idle when a task is moved to an idle CPU, which improves the scalability of various workloads (Shubhang Kaushik) - Reorder fields in 'struct rq' for better caching (Blake Jones) - Fair scheduler SMP NOHZ balancing code speedups (Shrikanth Hegde): - Move checking for nohz cpus after time check - Change likelyhood of nohz.nr_cpus - Remove nohz.nr_cpus and use weight of cpumask instead - Avoid false sharing for sched_clock_irqtime (Wangyang Guo) - Cleanups (Yury Norov): - Drop useless cpumask_empty() in find_energy_efficient_cpu() - Simplify task_numa_find_cpu() - Use cpumask_weight_and() in sched_balance_find_dst_group() DL scheduler updates: - Add a deadline server for sched_ext tasks (by Andrea Righi and Joel Fernandes, with fixes by Peter Zijlstra) RT scheduler updates: - Skip currently executing CPU in rto_next_cpu() (Chen Jinghuang) Entry code updates and performance improvements (Jinjie Ruan) This is part of the scheduler tree in this cycle due to inter- dependencies with the RSEQ based time slice extension work: - Remove unused syscall argument from syscall_trace_enter() - Rework syscall_exit_to_user_mode_work() for architecture reuse - Add arch_ptrace_report_syscall_entry/exit() - Inline syscall_exit_work() and syscall_trace_enter() Scheduler core updates (Peter Zijlstra): - Rework sched_class::wakeup_preempt() and rq_modified_*() - Avoid rq->lock bouncing in sched_balance_newidle() - Rename rcu_dereference_check_sched_domain() => rcu_dereference_sched_domain() - : Add the __signed_scalar_typeof() helper Fair scheduler updates/refactoring (Peter Zijlstra and Ingo Molnar): - Fold the sched_avg update - Change rcu_dereference_check_sched_domain() to rcu-sched - Switch to rcu_dereference_all() - Remove superfluous rcu_read_lock() - Limit hrtick work - Join two #ifdef CONFIG_FAIR_GROUP_SCHED blocks - Clean up comments in 'struct cfs_rq' - Separate se->vlag from se->vprot - Rename cfs_rq::avg_load to cfs_rq::sum_weight - Rename cfs_rq::avg_vruntime to ::sum_w_vruntime & helper functions - Introduce and use the vruntime_cmp() and vruntime_op() wrappers for wrapped-signed aritmetics - Sort out 'blocked_load*' namespace noise Scheduler debugging code updates: - Export hidden tracepoints to modules (Gabriele Monaco) - Convert copy_from_user() + kstrtouint() to kstrtouint_from_user() (Fushuai Wang) - Add assertions to QUEUE_CLASS (Peter Zijlstra) - hrtimer: Fix tracing oddity (Thomas Gleixner) Misc fixes and cleanups: - Re-evaluate scheduling when migrating queued tasks out of throttled cgroups (Zicheng Qu) - Remove task_struct->faults_disabled_mapping (Christoph Hellwig) - Fix math notation errors in avg_vruntime comment (Zhan Xusheng) - sched/cpufreq: Use %pe format for PTR_ERR() printing (zenghongling)" * tag 'sched-core-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits) sched: Re-evaluate scheduling when migrating queued tasks out of throttled cgroups sched/cpufreq: Use %pe format for PTR_ERR() printing sched/rt: Skip currently executing CPU in rto_next_cpu() sched/clock: Avoid false sharing for sched_clock_irqtime selftests/sched_ext: Add test for DL server total_bw consistency selftests/sched_ext: Add test for sched_ext dl_server sched/debug: Fix dl_server (re)start conditions sched/debug: Add support to change sched_ext server params sched_ext: Add a DL server for sched_ext tasks sched/debug: Stop and start server based on if it was active sched/debug: Fix updating of ppos on server write ops sched/deadline: Clear the defer params entry: Inline syscall_exit_work() and syscall_trace_enter() entry: Add arch_ptrace_report_syscall_entry/exit() entry: Rework syscall_exit_to_user_mode_work() for architecture reuse entry: Remove unused syscall argument from syscall_trace_enter() sched: remove task_struct->faults_disabled_mapping sched: Update rq->avg_idle when a task is moved to an idle CPU selftests/rseq: Add rseq slice histogram script hrtimer: Fix trace oddity ...

x86/entry/vdso32: Omit '.cfi_offset eflags' for LLVM < 16

2026-01-24T09:18:28Z

After commit: 884961618ee5 ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S") building arch/x86/entry/vdso/vdso32/sigreturn.S with LLVM 15 fails with: :18:20: error: invalid register name .cfi_offset eflags, 64 ^ arch/x86/entry/vdso/vdso32/sigreturn.S:33:2: note: while in macro instantiation STARTPROC_SIGNAL_FRAME 8 ^ Support for eflags as an argument to .cfi_offset was added in the LLVM 16 development cycle: https://github.com/llvm/llvm-project/commit/67bd3c58c0c7389e39c5a2f4d3b1a30459ccf5b7 [1] Only add this .cfi_offset directive if it is supported by the assembler to clear up the error. [ mingo: Tidied up the changelog and the comment a bit ] Fixes: 884961618ee5 ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S") Signed-off-by: Nathan Chancellor Signed-off-by: Ingo Molnar Acked-by: H. Peter Anvin (Intel) Link: https://patch.msgid.link/20260123-x86-vdso32-wa-llvm-15-cfi-offset-eflags-v1-1-0f412e3516a4@kernel.org

rseq: Implement sys_rseq_slice_yield()

2026-01-22T10:11:17Z

Provide a new syscall which has the only purpose to yield the CPU after the kernel granted a time slice extension. sched_yield() is not suitable for that because it unconditionally schedules, but the end of the time slice extension is not required to schedule when the task was already preempted. This also allows to have a strict check for termination to catch user space invoking random syscalls including sched_yield() from a time slice extension region. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Mathieu Desnoyers Acked-by: Arnd Bergmann Link: https://patch.msgid.link/20251215155708.929634896@linutronix.de

x86/entry/vdso: Fix filtering of vdso compiler flags

2026-01-16T21:25:33Z

This fixes several typos in the filtering of compiler flags for vdso, discovered by Chris Mason using an AI script: 1. "-fno-PIE" was written as "fno-PIE". 2. "CC_PLUGINS_FLAGS" was written as "CC_PLUGIN_FLAGS" To the best of my knowledge, none of these actually had any real impact on the build at this time but they are genuine bugs which could break things at any point in the future. Chris's script also found that "CONFIG_X86_USER_SHADOW_STACK" was missing "CONFIG_", but it needs a different fix. [ dhansen: remove CONFIG_X86_USER_SHADOW_STACK munging, add mention in changelog. ] Closes: https://lore.kernel.org/20260116035807.2307742-1-clm@meta.com Fixes: 693c819fedcd ("x86/entry/vdso: Refactor the vdso build") Reported-by: Chris Mason Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Dave Hansen Link: https://patch.msgid.link/20260116204057.386268-3-hpa@zytor.com