linux.git - Linux kernel

Age	Commit message (Collapse)	Author
2016-08-29	s390/fpu: improve kernel_fpu_[begin\|end]	Martin Schwidefsky
	In case of nested user of the FPU or vector registers in the kernel the current code uses the mask of the FPU/vector registers of the previous contexts to decide which registers to save and restore. E.g. if the previous context used KERNEL_VXR_V0V7 and the next context wants to use KERNEL_VXR_V24V31 the first 8 vector registers are stored to the FPU state structure. But this is not necessary as the next context does not use these registers. Rework the FPU/vector register save and restore code. The new code does a few things differently: 1) A lowcore field is used instead of a per-cpu variable. 2) The kernel_fpu_end function now has two parameters just like kernel_fpu_begin. The register flags are required by both functions to save / restore the minimal register set. 3) The inline functions kernel_fpu_begin/kernel_fpu_end now do the update of the register masks. If the user space FPU registers have already been stored neither save_fpu_regs nor the __kernel_fpu_begin/__kernel_fpu_end functions have to be called for the first context. In this case kernel_fpu_begin adds 7 instructions and kernel_fpu_end adds 4 instructions. 3) The inline assemblies in __kernel_fpu_begin / __kernel_fpu_end to save / restore the vector registers are simplified a bit. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-06-14	s390/vx: add support functions for in-kernel FPU use	Hendrik Brueckner
	Introduce the kernel_fpu_begin() and kernel_fpu_end() function to enclose any in-kernel use of FPU instructions and registers. In enclosed sections, you can perform floating-point or vector (SIMD) computations. The functions take care of saving and restoring FPU register contents and controls. For usage details, see the guidelines in arch/s390/include/asm/fpu/api.h Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>