x86/fpu: Provide struct fpstate
mainline inclusion from mainline-v5.16-rc1 commit 87d0e5be category: feature bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I590ZC CVE: NA Intel-SIG: commit 87d0e5be x86/fpu: Provide struct fpstate. -------------------------------- New xfeatures will not longer be automatically stored in the regular XSAVE buffer in thread_struct::fpu. The kernel will provide the default sized buffer for storing the regular features up to AVX512 in thread_struct::fpu and if a task requests to use one of the new features then the register storage has to be extended. The state will be accessed via a pointer in thread_struct::fpu which defaults to the builtin storage and can be switched when extended storage is required. To avoid conditionals all over the code, create a new container for the register storage which will gain other information, e.g. size, feature masks etc., later. For now it just contains the register storage, which gives it exactly the same layout as the exiting fpu::state. Stick fpu::state and the new fpu::__fpstate into an anonymous union and initialize the pointer. Add build time checks to validate that both are at the same place and have the same size. This allows step by step conversion of all users. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NBorislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211013145322.234458659@linutronix.deSigned-off-by: NLin Wang <lin.x.wang@intel.com> Signed-off-by: NAichun Shi <aichun.shi@intel.com>
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