riscv: hwprobe: Fix stale vDSO data for late-initialized keys at boot

2025-10-29T13:10:21Z

commit 5d15d2ad36b0f7afab83ca9fc8a2a6e60cbe54c4 upstream. The hwprobe vDSO data for some keys, like MISALIGNED_VECTOR_PERF, is determined by an asynchronous kthread. This can create a race condition where the kthread finishes after the vDSO data has already been populated, causing userspace to read stale values. To fix this race, a new 'ready' flag is added to the vDSO data, initialized to 'false' during arch_initcall_sync. This flag is checked by both the vDSO's user-space code and the riscv_hwprobe syscall. The syscall serves as a one-time gate, using a completion to wait for any pending probes before populating the data and setting the flag to 'true', thus ensuring userspace reads fresh values on its first request. Reported-by: Tsukasa OI Closes: https://lore.kernel.org/linux-riscv/760d637b-b13b-4518-b6bf-883d55d44e7f@irq.a4lg.com/ Fixes: e7c9d66e313b ("RISC-V: Report vector unaligned access speed hwprobe") Cc: Palmer Dabbelt Cc: Alexandre Ghiti Cc: Olof Johansson Cc: stable@vger.kernel.org Reviewed-by: Alexandre Ghiti Co-developed-by: Palmer Dabbelt Signed-off-by: Palmer Dabbelt Signed-off-by: Jingwei Wang Link: https://lore.kernel.org/r/20250811142035.105820-1-wangjingwei@iscas.ac.cn [pjw@kernel.org: fix checkpatch issues] Signed-off-by: Paul Walmsley Signed-off-by: Greg Kroah-Hartman

riscv: vdso: Switch to generic storage implementation

2025-02-21T08:54:02Z

The generic storage implementation provides the same features as the custom one. However it can be shared between architectures, making maintenance easier. Co-developed-by: Nam Cao Signed-off-by: Nam Cao Signed-off-by: Thomas Weißschuh Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20250204-vdso-store-rng-v3-9-13a4669dfc8c@linutronix.de

kernel/arch/riscv/include/asm/vdso/arch_data.h, branch linux-rolling-stable

riscv: hwprobe: Fix stale vDSO data for late-initialized keys at boot

riscv: vdso: Switch to generic storage implementation