117 lines
3.7 KiB
C
117 lines
3.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* In-kernel FPU support functions
|
|
*
|
|
*
|
|
* Consider these guidelines before using in-kernel FPU functions:
|
|
*
|
|
* 1. Use kernel_fpu_begin() and kernel_fpu_end() to enclose all in-kernel
|
|
* use of floating-point or vector registers and instructions.
|
|
*
|
|
* 2. For kernel_fpu_begin(), specify the vector register range you want to
|
|
* use with the KERNEL_VXR_* constants. Consider these usage guidelines:
|
|
*
|
|
* a) If your function typically runs in process-context, use the lower
|
|
* half of the vector registers, for example, specify KERNEL_VXR_LOW.
|
|
* b) If your function typically runs in soft-irq or hard-irq context,
|
|
* prefer using the upper half of the vector registers, for example,
|
|
* specify KERNEL_VXR_HIGH.
|
|
*
|
|
* If you adhere to these guidelines, an interrupted process context
|
|
* does not require to save and restore vector registers because of
|
|
* disjoint register ranges.
|
|
*
|
|
* Also note that the __kernel_fpu_begin()/__kernel_fpu_end() functions
|
|
* includes logic to save and restore up to 16 vector registers at once.
|
|
*
|
|
* 3. You can nest kernel_fpu_begin()/kernel_fpu_end() by using different
|
|
* struct kernel_fpu states. Vector registers that are in use by outer
|
|
* levels are saved and restored. You can minimize the save and restore
|
|
* effort by choosing disjoint vector register ranges.
|
|
*
|
|
* 5. To use vector floating-point instructions, specify the KERNEL_FPC
|
|
* flag to save and restore floating-point controls in addition to any
|
|
* vector register range.
|
|
*
|
|
* 6. To use floating-point registers and instructions only, specify the
|
|
* KERNEL_FPR flag. This flag triggers a save and restore of vector
|
|
* registers V0 to V15 and floating-point controls.
|
|
*
|
|
* Copyright IBM Corp. 2015
|
|
* Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
|
|
*/
|
|
|
|
#ifndef _ASM_S390_FPU_API_H
|
|
#define _ASM_S390_FPU_API_H
|
|
|
|
#include <linux/preempt.h>
|
|
|
|
void save_fpu_regs(void);
|
|
|
|
static inline int test_fp_ctl(u32 fpc)
|
|
{
|
|
u32 orig_fpc;
|
|
int rc;
|
|
|
|
asm volatile(
|
|
" efpc %1\n"
|
|
" sfpc %2\n"
|
|
"0: sfpc %1\n"
|
|
" la %0,0\n"
|
|
"1:\n"
|
|
EX_TABLE(0b,1b)
|
|
: "=d" (rc), "=&d" (orig_fpc)
|
|
: "d" (fpc), "0" (-EINVAL));
|
|
return rc;
|
|
}
|
|
|
|
#define KERNEL_FPC 1
|
|
#define KERNEL_VXR_V0V7 2
|
|
#define KERNEL_VXR_V8V15 4
|
|
#define KERNEL_VXR_V16V23 8
|
|
#define KERNEL_VXR_V24V31 16
|
|
|
|
#define KERNEL_VXR_LOW (KERNEL_VXR_V0V7|KERNEL_VXR_V8V15)
|
|
#define KERNEL_VXR_MID (KERNEL_VXR_V8V15|KERNEL_VXR_V16V23)
|
|
#define KERNEL_VXR_HIGH (KERNEL_VXR_V16V23|KERNEL_VXR_V24V31)
|
|
|
|
#define KERNEL_VXR (KERNEL_VXR_LOW|KERNEL_VXR_HIGH)
|
|
#define KERNEL_FPR (KERNEL_FPC|KERNEL_VXR_V0V7)
|
|
|
|
struct kernel_fpu;
|
|
|
|
/*
|
|
* Note the functions below must be called with preemption disabled.
|
|
* Do not enable preemption before calling __kernel_fpu_end() to prevent
|
|
* an corruption of an existing kernel FPU state.
|
|
*
|
|
* Prefer using the kernel_fpu_begin()/kernel_fpu_end() pair of functions.
|
|
*/
|
|
void __kernel_fpu_begin(struct kernel_fpu *state, u32 flags);
|
|
void __kernel_fpu_end(struct kernel_fpu *state, u32 flags);
|
|
|
|
|
|
static inline void kernel_fpu_begin(struct kernel_fpu *state, u32 flags)
|
|
{
|
|
preempt_disable();
|
|
state->mask = S390_lowcore.fpu_flags;
|
|
if (!test_cpu_flag(CIF_FPU))
|
|
/* Save user space FPU state and register contents */
|
|
save_fpu_regs();
|
|
else if (state->mask & flags)
|
|
/* Save FPU/vector register in-use by the kernel */
|
|
__kernel_fpu_begin(state, flags);
|
|
S390_lowcore.fpu_flags |= flags;
|
|
}
|
|
|
|
static inline void kernel_fpu_end(struct kernel_fpu *state, u32 flags)
|
|
{
|
|
S390_lowcore.fpu_flags = state->mask;
|
|
if (state->mask & flags)
|
|
/* Restore FPU/vector register in-use by the kernel */
|
|
__kernel_fpu_end(state, flags);
|
|
preempt_enable();
|
|
}
|
|
|
|
#endif /* _ASM_S390_FPU_API_H */
|