_xstate represents the "extended state" of the FPU (e.g., for AVX, AVX-512 registers). _vstate appears to be a legacy or specific component for managing bound registers with MPX.
When a Linux process receives an asynchronous signal, the kernel temporarily interrupts normal execution to invoke a signal handler. Before jumping to user space code, the kernel builds a on the user's stack. fpstate vso
The FPState VSO mechanism allows for the efficient saving and restoration of the floating-point state of VMs. This is particularly important during context switches, where the VM's current state must be saved, and the state of another VM must be restored. By optimizing this process, FPState VSO helps to minimize overhead and improve the performance of VMs. _xstate represents the "extended state" of the FPU (e
While "fpstate" and "vso" appear in various technical and organizational contexts, they do not belong to a single unified project or product. Instead, they refer to specific components in programming, volunteering, or linguistics depending on the field. Before jumping to user space code, the kernel
The original FPU lazy restore vulnerability (CVE-2018-3665) allowed a malicious process to read FPU state from another process (including cryptographic keys in FPU registers). VSO is a mitigation enabler but not a silver bullet.
FPSTATE VSO offers several key features that make it an attractive solution for FPU management:
An ARM Linux kernel developer might be working on context-switching code for the FPU. A key variable is vfp_current_hw_state , a per-CPU pointer to the vfpstate (the ARM equivalent of fpstate ) of the thread currently using the FPU hardware on that core.