296 lines
8.2 KiB
C
296 lines
8.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* In-kernel FPU support functions
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*
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*
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* Consider these guidelines before using in-kernel FPU functions:
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*
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* 1. Use kernel_fpu_begin() and kernel_fpu_end() to enclose all in-kernel
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* use of floating-point or vector registers and instructions.
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*
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* 2. For kernel_fpu_begin(), specify the vector register range you want to
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* use with the KERNEL_VXR_* constants. Consider these usage guidelines:
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*
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* a) If your function typically runs in process-context, use the lower
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* half of the vector registers, for example, specify KERNEL_VXR_LOW.
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* b) If your function typically runs in soft-irq or hard-irq context,
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* prefer using the upper half of the vector registers, for example,
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* specify KERNEL_VXR_HIGH.
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*
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* If you adhere to these guidelines, an interrupted process context
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* does not require to save and restore vector registers because of
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* disjoint register ranges.
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*
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* Also note that the __kernel_fpu_begin()/__kernel_fpu_end() functions
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* includes logic to save and restore up to 16 vector registers at once.
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*
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* 3. You can nest kernel_fpu_begin()/kernel_fpu_end() by using different
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* struct kernel_fpu states. Vector registers that are in use by outer
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* levels are saved and restored. You can minimize the save and restore
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* effort by choosing disjoint vector register ranges.
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*
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* 5. To use vector floating-point instructions, specify the KERNEL_FPC
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* flag to save and restore floating-point controls in addition to any
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* vector register range.
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*
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* 6. To use floating-point registers and instructions only, specify the
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* KERNEL_FPR flag. This flag triggers a save and restore of vector
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* registers V0 to V15 and floating-point controls.
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*
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* Copyright IBM Corp. 2015
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* Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
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*/
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#ifndef _ASM_S390_FPU_H
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#define _ASM_S390_FPU_H
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#include <linux/processor.h>
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#include <linux/preempt.h>
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#include <linux/string.h>
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#include <linux/sched.h>
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#include <asm/sigcontext.h>
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#include <asm/fpu-types.h>
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#include <asm/fpu-insn.h>
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#include <asm/facility.h>
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static inline bool cpu_has_vx(void)
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{
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return likely(test_facility(129));
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}
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enum {
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KERNEL_FPC_BIT = 0,
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KERNEL_VXR_V0V7_BIT,
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KERNEL_VXR_V8V15_BIT,
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KERNEL_VXR_V16V23_BIT,
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KERNEL_VXR_V24V31_BIT,
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};
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#define KERNEL_FPC BIT(KERNEL_FPC_BIT)
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#define KERNEL_VXR_V0V7 BIT(KERNEL_VXR_V0V7_BIT)
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#define KERNEL_VXR_V8V15 BIT(KERNEL_VXR_V8V15_BIT)
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#define KERNEL_VXR_V16V23 BIT(KERNEL_VXR_V16V23_BIT)
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#define KERNEL_VXR_V24V31 BIT(KERNEL_VXR_V24V31_BIT)
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#define KERNEL_VXR_LOW (KERNEL_VXR_V0V7 | KERNEL_VXR_V8V15)
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#define KERNEL_VXR_MID (KERNEL_VXR_V8V15 | KERNEL_VXR_V16V23)
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#define KERNEL_VXR_HIGH (KERNEL_VXR_V16V23 | KERNEL_VXR_V24V31)
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#define KERNEL_VXR (KERNEL_VXR_LOW | KERNEL_VXR_HIGH)
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#define KERNEL_FPR (KERNEL_FPC | KERNEL_VXR_LOW)
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void load_fpu_state(struct fpu *state, int flags);
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void save_fpu_state(struct fpu *state, int flags);
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void __kernel_fpu_begin(struct kernel_fpu *state, int flags);
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void __kernel_fpu_end(struct kernel_fpu *state, int flags);
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static __always_inline void save_vx_regs(__vector128 *vxrs)
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{
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fpu_vstm(0, 15, &vxrs[0]);
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fpu_vstm(16, 31, &vxrs[16]);
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}
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static __always_inline void load_vx_regs(__vector128 *vxrs)
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{
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fpu_vlm(0, 15, &vxrs[0]);
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fpu_vlm(16, 31, &vxrs[16]);
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}
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static __always_inline void __save_fp_regs(freg_t *fprs, unsigned int offset)
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{
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fpu_std(0, &fprs[0 * offset]);
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fpu_std(1, &fprs[1 * offset]);
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fpu_std(2, &fprs[2 * offset]);
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fpu_std(3, &fprs[3 * offset]);
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fpu_std(4, &fprs[4 * offset]);
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fpu_std(5, &fprs[5 * offset]);
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fpu_std(6, &fprs[6 * offset]);
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fpu_std(7, &fprs[7 * offset]);
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fpu_std(8, &fprs[8 * offset]);
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fpu_std(9, &fprs[9 * offset]);
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fpu_std(10, &fprs[10 * offset]);
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fpu_std(11, &fprs[11 * offset]);
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fpu_std(12, &fprs[12 * offset]);
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fpu_std(13, &fprs[13 * offset]);
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fpu_std(14, &fprs[14 * offset]);
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fpu_std(15, &fprs[15 * offset]);
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}
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static __always_inline void __load_fp_regs(freg_t *fprs, unsigned int offset)
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{
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fpu_ld(0, &fprs[0 * offset]);
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fpu_ld(1, &fprs[1 * offset]);
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fpu_ld(2, &fprs[2 * offset]);
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fpu_ld(3, &fprs[3 * offset]);
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fpu_ld(4, &fprs[4 * offset]);
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fpu_ld(5, &fprs[5 * offset]);
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fpu_ld(6, &fprs[6 * offset]);
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fpu_ld(7, &fprs[7 * offset]);
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fpu_ld(8, &fprs[8 * offset]);
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fpu_ld(9, &fprs[9 * offset]);
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fpu_ld(10, &fprs[10 * offset]);
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fpu_ld(11, &fprs[11 * offset]);
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fpu_ld(12, &fprs[12 * offset]);
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fpu_ld(13, &fprs[13 * offset]);
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fpu_ld(14, &fprs[14 * offset]);
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fpu_ld(15, &fprs[15 * offset]);
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}
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static __always_inline void save_fp_regs(freg_t *fprs)
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{
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__save_fp_regs(fprs, sizeof(freg_t) / sizeof(freg_t));
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}
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static __always_inline void load_fp_regs(freg_t *fprs)
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{
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__load_fp_regs(fprs, sizeof(freg_t) / sizeof(freg_t));
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}
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static __always_inline void save_fp_regs_vx(__vector128 *vxrs)
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{
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freg_t *fprs = (freg_t *)&vxrs[0].high;
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__save_fp_regs(fprs, sizeof(__vector128) / sizeof(freg_t));
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}
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static __always_inline void load_fp_regs_vx(__vector128 *vxrs)
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{
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freg_t *fprs = (freg_t *)&vxrs[0].high;
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__load_fp_regs(fprs, sizeof(__vector128) / sizeof(freg_t));
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}
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static inline void load_user_fpu_regs(void)
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{
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struct thread_struct *thread = ¤t->thread;
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if (!thread->ufpu_flags)
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return;
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load_fpu_state(&thread->ufpu, thread->ufpu_flags);
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thread->ufpu_flags = 0;
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}
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static __always_inline void __save_user_fpu_regs(struct thread_struct *thread, int flags)
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{
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save_fpu_state(&thread->ufpu, flags);
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__atomic_or(flags, &thread->ufpu_flags);
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}
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static inline void save_user_fpu_regs(void)
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{
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struct thread_struct *thread = ¤t->thread;
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int mask, flags;
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mask = __atomic_or(KERNEL_FPC | KERNEL_VXR, &thread->kfpu_flags);
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flags = ~READ_ONCE(thread->ufpu_flags) & (KERNEL_FPC | KERNEL_VXR);
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if (flags)
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__save_user_fpu_regs(thread, flags);
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barrier();
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WRITE_ONCE(thread->kfpu_flags, mask);
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}
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static __always_inline void _kernel_fpu_begin(struct kernel_fpu *state, int flags)
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{
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struct thread_struct *thread = ¤t->thread;
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int mask, uflags;
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mask = __atomic_or(flags, &thread->kfpu_flags);
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state->hdr.mask = mask;
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uflags = READ_ONCE(thread->ufpu_flags);
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if ((uflags & flags) != flags)
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__save_user_fpu_regs(thread, ~uflags & flags);
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if (mask & flags)
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__kernel_fpu_begin(state, flags);
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}
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static __always_inline void _kernel_fpu_end(struct kernel_fpu *state, int flags)
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{
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int mask = state->hdr.mask;
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if (mask & flags)
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__kernel_fpu_end(state, flags);
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barrier();
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WRITE_ONCE(current->thread.kfpu_flags, mask);
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}
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void __kernel_fpu_invalid_size(void);
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static __always_inline void kernel_fpu_check_size(int flags, unsigned int size)
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{
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unsigned int cnt = 0;
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if (flags & KERNEL_VXR_V0V7)
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cnt += 8;
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if (flags & KERNEL_VXR_V8V15)
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cnt += 8;
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if (flags & KERNEL_VXR_V16V23)
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cnt += 8;
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if (flags & KERNEL_VXR_V24V31)
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cnt += 8;
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if (cnt != size)
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__kernel_fpu_invalid_size();
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}
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#define kernel_fpu_begin(state, flags) \
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{ \
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typeof(state) s = (state); \
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int _flags = (flags); \
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\
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kernel_fpu_check_size(_flags, ARRAY_SIZE(s->vxrs)); \
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_kernel_fpu_begin((struct kernel_fpu *)s, _flags); \
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}
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#define kernel_fpu_end(state, flags) \
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{ \
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typeof(state) s = (state); \
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int _flags = (flags); \
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\
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kernel_fpu_check_size(_flags, ARRAY_SIZE(s->vxrs)); \
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_kernel_fpu_end((struct kernel_fpu *)s, _flags); \
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}
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static inline void save_kernel_fpu_regs(struct thread_struct *thread)
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{
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if (!thread->kfpu_flags)
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return;
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save_fpu_state(&thread->kfpu, thread->kfpu_flags);
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}
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static inline void restore_kernel_fpu_regs(struct thread_struct *thread)
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{
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if (!thread->kfpu_flags)
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return;
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load_fpu_state(&thread->kfpu, thread->kfpu_flags);
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}
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static inline void convert_vx_to_fp(freg_t *fprs, __vector128 *vxrs)
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{
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int i;
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for (i = 0; i < __NUM_FPRS; i++)
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fprs[i].ui = vxrs[i].high;
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}
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static inline void convert_fp_to_vx(__vector128 *vxrs, freg_t *fprs)
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{
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int i;
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for (i = 0; i < __NUM_FPRS; i++)
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vxrs[i].high = fprs[i].ui;
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}
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static inline void fpregs_store(_s390_fp_regs *fpregs, struct fpu *fpu)
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{
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fpregs->pad = 0;
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fpregs->fpc = fpu->fpc;
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convert_vx_to_fp((freg_t *)&fpregs->fprs, fpu->vxrs);
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}
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static inline void fpregs_load(_s390_fp_regs *fpregs, struct fpu *fpu)
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{
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fpu->fpc = fpregs->fpc;
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convert_fp_to_vx(fpu->vxrs, (freg_t *)&fpregs->fprs);
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}
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#endif /* _ASM_S390_FPU_H */
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