kernel/linux.git/arch/powerpc, branch v6.12.97

bpf, arm64, powerpc: Add bpf_jit_bypass_spec_v1/v4()

2026-07-24T14:11:52+00:00

[ Upstream commit 03c68a0f8c68936a0bb915b030693923784724cb ] JITs can set bpf_jit_bypass_spec_v1/v4() if they want the verifier to skip analysis/patching for the respective vulnerability. For v4, this will reduce the number of barriers the verifier inserts. For v1, it allows more programs to be accepted. The primary motivation for this is to not regress unpriv BPF's performance on ARM64 in a future commit where BPF_NOSPEC is also used against Spectre v1. This has the user-visible change that v1-induced rejections on non-vulnerable PowerPC CPUs are avoided. For now, this does not change the semantics of BPF_NOSPEC. It is still a v4-only barrier and must not be implemented if bypass_spec_v4 is always true for the arch. Changing it to a v1 AND v4-barrier is done in a future commit. As an alternative to bypass_spec_v1/v4, one could introduce NOSPEC_V1 AND NOSPEC_V4 instructions and allow backends to skip their lowering as suggested by commit f5e81d111750 ("bpf: Introduce BPF nospec instruction for mitigating Spectre v4"). Adding bpf_jit_bypass_spec_v1/v4() was found to be preferable for the following reason: * bypass_spec_v1/v4 benefits non-vulnerable CPUs: Always performing the same analysis (not taking into account whether the current CPU is vulnerable), needlessly restricts users of CPUs that are not vulnerable. The only use case for this would be portability-testing, but this can later be added easily when needed by allowing users to force bypass_spec_v1/v4 to false. * Portability is still acceptable: Directly disabling the analysis instead of skipping the lowering of BPF_NOSPEC(_V1/V4) might allow programs on non-vulnerable CPUs to be accepted while the program will be rejected on vulnerable CPUs. With the fallback to speculation barriers for Spectre v1 implemented in a future commit, this will only affect programs that do variable stack-accesses or are very complex. For PowerPC, the SEC_FTR checking in bpf_jit_bypass_spec_v4() is based on the check that was previously located in the BPF_NOSPEC case. For LoongArch, it would likely be safe to set both bpf_jit_bypass_spec_v1() and _v4() according to commit a6f6a95f2580 ("LoongArch, bpf: Fix jit to skip speculation barrier opcode"). This is omitted here as I am unable to do any testing for LoongArch. Hari's ack concerns the PowerPC part only. Signed-off-by: Luis Gerhorst Acked-by: Hari Bathini Cc: Henriette Herzog Cc: Maximilian Ott Cc: Milan Stephan Link: https://lore.kernel.org/r/20250603211318.337474-1-luis.gerhorst@fau.de Signed-off-by: Alexei Starovoitov Stable-dep-of: 2f884d371faf ("bpf: Allow LPM map access from sleepable BPF programs") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

powerpc/spufs: fix out-of-bounds access in spufs_mem_mmap_access()

2026-07-24T14:11:46+00:00

commit 47b87f469a35b5ffc81c16eee6b13a9b6c8d55c6 upstream. spufs_mem_mmap_access() computes the local store offset as address - vma->vm_start, but bounds-checks it against vma->vm_end instead of the local store size. On 64-bit, offset is always well below vma->vm_end, so the clamp never fires and len stays unbounded against the LS_SIZE buffer returned by ctx->ops->get_ls(). Reject offsets at or beyond LS_SIZE and clamp len to the remaining space, mirroring the guard already used by spufs_mem_mmap_fault() and spufs_ps_fault(). Fixes: a352894d0705 ("spufs: use new vm_ops->access to allow local state access from gdb") Reported-by: Yuhao Jiang Cc: stable@vger.kernel.org Signed-off-by: Junrui Luo Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/SYBPR01MB7881EE775E8B51C09F5A29E7AF152@SYBPR01MB7881.ausprd01.prod.outlook.com Signed-off-by: Greg Kroah-Hartman

powerpc/pseries: fix memory leak on krealloc failure in papr_init

2026-07-24T14:11:45+00:00

commit bd83c98b988d2c560531084e296dbfb530aff829 upstream. When krealloc() fails, free the original esi_buf before returning to avoid a memory leak. Fixes: 3c14b73454cf ("powerpc/pseries: Interface to represent PAPR firmware attributes") Cc: stable@vger.kernel.org Signed-off-by: Thorsten Blum Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260614142356.658212-2-thorsten.blum@linux.dev Signed-off-by: Greg Kroah-Hartman

powerpc/kexec: fix double get_cpu() imbalance in kexec_prepare_cpus

2026-07-24T14:11:03+00:00

[ Upstream commit 5c86f1c1f972761a04bf22f4c0618d1aa714185b ] kexec_prepare_cpus_wait() calls get_cpu() internally to obtain the current CPU id. kexec_prepare_cpus() calls kexec_prepare_cpus_wait() twice -- once for KEXEC_STATE_IRQS_OFF and once for KEXEC_STATE_REAL_MODE -- but only issues a single put_cpu() at the end, leaving preempt_count elevated by one extra nesting level. In practice the imbalance does not trigger a 'scheduling while atomic' splat because the kexec path is a one-way trip: IRQs are already disabled, no schedule() occurs after the leak, and default_machine_kexec() overwrites preempt_count with HARDIRQ_OFFSET before jumping into kexec_sequence() which never returns. However the bookkeeping is still wrong. kexec_prepare_cpus() calls local_irq_disable()/hard_irq_disable() before invoking kexec_prepare_cpus_wait(), so the CPU is already pinned and the get_cpu()/put_cpu() preempt_disable() bracketing is unnecessary. Only the current CPU id is needed, so replace get_cpu() with raw_smp_processor_id() and drop the now-unneeded put_cpu(). Fixes: 1fc711f7ffb0 ("powerpc/kexec: Fix race in kexec shutdown") Signed-off-by: Aboorva Devarajan Reviewed-by: Shrikanth Hegde Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260605082912.305100-4-aboorvad@linux.ibm.com Signed-off-by: Sasha Levin

powerpc/powernv: fix preempt count leak in pnv_kexec_wait_secondaries_down

2026-07-24T14:11:03+00:00

[ Upstream commit 0ecd26e93e698c8327521910fc6296f5b84a4b92 ] pnv_kexec_wait_secondaries_down() calls get_cpu() to obtain the current CPU id but never calls the matching put_cpu(), leaking one preempt_disable() nesting level on every invocation. In practice the imbalance does not trigger a visible splat because the kexec teardown path is a one-way trip: IRQs are already disabled, no schedule() occurs after the leak, and default_machine_kexec() overwrites preempt_count with HARDIRQ_OFFSET before jumping into kexec_sequence() which never returns. However the bookkeeping is still wrong. The function only needs the current CPU id, and this path runs with interrupts disabled and the CPU pinned, so the preempt_disable() side-effect of get_cpu() is unnecessary. Replace it with raw_smp_processor_id(). Fixes: 298b34d7d578 ("powerpc/powernv: Fix kexec races going back to OPAL") Signed-off-by: Aboorva Devarajan Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260605082912.305100-3-aboorvad@linux.ibm.com Signed-off-by: Sasha Levin

powerpc/perf: fix preempt count underflow in fsl_emb_pmu_del

2026-07-24T14:11:03+00:00

[ Upstream commit 81e3a86030462824a67d697739cf3f387f4ba350 ] fsl_emb_pmu_del() unconditionally calls put_cpu_var(cpu_hw_events) at the 'out:' label, but only calls the matching get_cpu_var() after the 'i < 0' early-return check. When event->hw.idx is negative the function jumps to 'out:' without having taken get_cpu_var(), and the trailing put_cpu_var() then issues an unmatched preempt_enable(), underflowing preempt_count. On a CONFIG_PREEMPT=y kernel preempt_count would underflow and eventually present as a 'scheduling while atomic' BUG. Move put_cpu_var() to pair with get_cpu_var() so the percpu access is correctly bracketed and the 'out:' label only handles perf_pmu_enable. Fixes: a11106544f33 ("powerpc/perf: e500 support") Reviewed-by: Shrikanth Hegde Signed-off-by: Aboorva Devarajan Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260605082912.305100-2-aboorvad@linux.ibm.com Signed-off-by: Sasha Levin

bpf: Restrict JIT predictor flush to cBPF

2026-07-24T14:10:39+00:00

commit 0bb99f2cfaae6822d734d69722de30af823efdf3 upstream. Currently predictor flush on memory reuse is done for all BPF JIT allocations, but only cBPF programs can be loaded by an unprivileged user. eBPF is privileged by default, and flushing predictors for all CPUs on every eBPF reuse penalizes the common case for no security benefit. eBPF allocations can be frequent on busy systems, only flush predictors for cBPF programs. Trampoline and dispatcher allocations also skip the flush as they are eBPF-only. [pawan: backport dropped "was_classic" hunk for arches that do not support pack allocator] Signed-off-by: Pawan Gupta Acked-by: Daniel Borkmann Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin

ring-buffer: Flush and stop persistent ring buffer on panic

2026-06-09T10:26:03+00:00

[ Upstream commit a494d3c8d5392bcdff83c2a593df0c160ff9f322 ] On real hardware, panic and machine reboot may not flush hardware cache to memory. This means the persistent ring buffer, which relies on a coherent state of memory, may not have its events written to the buffer and they may be lost. Moreover, there may be inconsistency with the counters which are used for validation of the integrity of the persistent ring buffer which may cause all data to be discarded. To avoid this issue, stop recording of the ring buffer on panic and flush the cache of the ring buffer's memory. Fixes: e645535a954a ("tracing: Add option to use memmapped memory for trace boot instance") Cc: stable@vger.kernel.org Cc: Will Deacon Cc: Mathieu Desnoyers Cc: Ian Rogers Link: https://patch.msgid.link/177751969602.2136606.12031934362587643488.stgit@mhiramat.tok.corp.google.com Signed-off-by: Masami Hiramatsu (Google) Acked-by: Catalin Marinas Acked-by: Geert Uytterhoeven Signed-off-by: Steven Rostedt Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()

2026-06-01T15:46:29+00:00

[ Upstream commit 31467b23823ffec1f6fff407f8e3ca9af8b7491a ] A kernel panic is observed when handling machine check exceptions from real mode. BUG: Unable to handle kernel data access on read at 0xc00000006be21300 Oops: Kernel access of bad area, sig: 11 [#1] MSR: 8000000000001003 CR: 88222248 XER: 00000005 CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0 NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70 LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150 Call Trace: [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150 [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0 The crash occurs because arch_irq_work_raise() calls preempt_disable() from machine check exception (MCE) handlers running in real mode. In this context, accessing the preempt_count can fault, leading to the panic. The preempt_disable()/preempt_enable() pair in arch_irq_work_raise() was originally added by commit 0fe1ac48bef0 ("powerpc/perf_event: Fix oops due to perf_event_do_pending call") to avoid races while raising irq work from exception context. Later, commit 471ba0e686cb ("irq_work: Do not raise an IPI when queueing work on the local CPU") added preemption protection in irq_work_queue() path, while commit 20b876918c06 ("irq_work: Use per cpu atomics instead of regular atomics") added equivalent protection in irq_work_queue_on() before reaching arch_irq_work_raise(): irq_work_queue() / irq_work_queue_on() -> preempt_disable() -> __irq_work_queue_local() -> irq_work_raise() -> arch_irq_work_raise() As a result, callers other than mce_irq_work_raise() already execute with preemption disabled, making the additional preempt_disable()/preempt_enable() pair in arch_irq_work_raise() redundant. The arch_irq_work_raise() function executes in NMI context when called from MCE handler. Hence we will not be preempted or scheduled out since we are in NMI context with MSR[EE]=0. Therefore, it is safe to remove the preempt_disable()/preempt_enable() calls from here. Remove it to avoid accessing preempt_count from real mode context. Fixes: cc15ff327569 ("powerpc/mce: Avoid using irq_work_queue() in realmode") Suggested-by: Mahesh Salgaonkar Acked-by: Shrikanth Hegde Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Sayali Patil [Maddy: Fixed the commit title] Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260513081413.222490-1-sayalip@linux.ibm.com Signed-off-by: Sasha Levin

powerpc: fix dead default for GUEST_STATE_BUFFER_TEST

2026-06-01T15:46:26+00:00

[ Upstream commit aef656a0e6c01796190bb5bd2bdba1c644ed7811 ] The GUEST_STATE_BUFFER_TEST config option should default to KUNIT_ALL_TESTS so that if all tests are enabled then it is included, but currently the 'default KUNIT_ALL_TESTS' statement is shadowed by 'def_tristate n', meaning that this second default statement is currently dead code. It looks to me like the commit 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers") intended to set the default to KUNIT_ALL_TESTS, but mistakenly missed the def_tristate. This dead code was found by kconfirm, a static analysis tool for Kconfig. Fixes: 6ccbbc33f06a ("KVM: PPC: Add helper library for Guest State Buffers") Signed-off-by: Julian Braha Tested-by: Gautam Menghani Reviewed-by: Amit Machhiwal Reviewed-by: Harsh Prateek Bora Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260405161545.161006-1-julianbraha@gmail.com Signed-off-by: Sasha Levin