Hendrik Brueckner | b075390 | 2015-10-06 12:25:59 +0200 | [diff] [blame] | 1 | /* |
| 2 | * In-kernel FPU support functions |
| 3 | * |
Hendrik Brueckner | 0486480 | 2015-02-18 14:46:00 +0100 | [diff] [blame] | 4 | * |
| 5 | * Consider these guidelines before using in-kernel FPU functions: |
| 6 | * |
| 7 | * 1. Use kernel_fpu_begin() and kernel_fpu_end() to enclose all in-kernel |
| 8 | * use of floating-point or vector registers and instructions. |
| 9 | * |
| 10 | * 2. For kernel_fpu_begin(), specify the vector register range you want to |
| 11 | * use with the KERNEL_VXR_* constants. Consider these usage guidelines: |
| 12 | * |
| 13 | * a) If your function typically runs in process-context, use the lower |
| 14 | * half of the vector registers, for example, specify KERNEL_VXR_LOW. |
| 15 | * b) If your function typically runs in soft-irq or hard-irq context, |
| 16 | * prefer using the upper half of the vector registers, for example, |
| 17 | * specify KERNEL_VXR_HIGH. |
| 18 | * |
| 19 | * If you adhere to these guidelines, an interrupted process context |
| 20 | * does not require to save and restore vector registers because of |
| 21 | * disjoint register ranges. |
| 22 | * |
| 23 | * Also note that the __kernel_fpu_begin()/__kernel_fpu_end() functions |
| 24 | * includes logic to save and restore up to 16 vector registers at once. |
| 25 | * |
| 26 | * 3. You can nest kernel_fpu_begin()/kernel_fpu_end() by using different |
| 27 | * struct kernel_fpu states. Vector registers that are in use by outer |
| 28 | * levels are saved and restored. You can minimize the save and restore |
| 29 | * effort by choosing disjoint vector register ranges. |
| 30 | * |
| 31 | * 5. To use vector floating-point instructions, specify the KERNEL_FPC |
| 32 | * flag to save and restore floating-point controls in addition to any |
| 33 | * vector register range. |
| 34 | * |
| 35 | * 6. To use floating-point registers and instructions only, specify the |
| 36 | * KERNEL_FPR flag. This flag triggers a save and restore of vector |
| 37 | * registers V0 to V15 and floating-point controls. |
| 38 | * |
Hendrik Brueckner | b075390 | 2015-10-06 12:25:59 +0200 | [diff] [blame] | 39 | * Copyright IBM Corp. 2015 |
| 40 | * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com> |
| 41 | */ |
| 42 | |
| 43 | #ifndef _ASM_S390_FPU_API_H |
| 44 | #define _ASM_S390_FPU_API_H |
| 45 | |
Hendrik Brueckner | 0486480 | 2015-02-18 14:46:00 +0100 | [diff] [blame] | 46 | #include <linux/preempt.h> |
| 47 | |
Hendrik Brueckner | b075390 | 2015-10-06 12:25:59 +0200 | [diff] [blame] | 48 | void save_fpu_regs(void); |
| 49 | |
| 50 | static inline int test_fp_ctl(u32 fpc) |
| 51 | { |
| 52 | u32 orig_fpc; |
| 53 | int rc; |
| 54 | |
| 55 | asm volatile( |
| 56 | " efpc %1\n" |
| 57 | " sfpc %2\n" |
| 58 | "0: sfpc %1\n" |
| 59 | " la %0,0\n" |
| 60 | "1:\n" |
| 61 | EX_TABLE(0b,1b) |
Martin Schwidefsky | bcf4dd5 | 2016-06-27 17:06:45 +0200 | [diff] [blame] | 62 | : "=d" (rc), "=&d" (orig_fpc) |
Hendrik Brueckner | b075390 | 2015-10-06 12:25:59 +0200 | [diff] [blame] | 63 | : "d" (fpc), "0" (-EINVAL)); |
| 64 | return rc; |
| 65 | } |
| 66 | |
Hendrik Brueckner | 0486480 | 2015-02-18 14:46:00 +0100 | [diff] [blame] | 67 | #define KERNEL_VXR_V0V7 1 |
| 68 | #define KERNEL_VXR_V8V15 2 |
| 69 | #define KERNEL_VXR_V16V23 4 |
| 70 | #define KERNEL_VXR_V24V31 8 |
| 71 | #define KERNEL_FPR 16 |
| 72 | #define KERNEL_FPC 256 |
| 73 | |
| 74 | #define KERNEL_VXR_LOW (KERNEL_VXR_V0V7|KERNEL_VXR_V8V15) |
| 75 | #define KERNEL_VXR_MID (KERNEL_VXR_V8V15|KERNEL_VXR_V16V23) |
| 76 | #define KERNEL_VXR_HIGH (KERNEL_VXR_V16V23|KERNEL_VXR_V24V31) |
| 77 | |
| 78 | #define KERNEL_FPU_MASK (KERNEL_VXR_LOW|KERNEL_VXR_HIGH|KERNEL_FPR) |
| 79 | |
| 80 | struct kernel_fpu; |
| 81 | |
| 82 | /* |
| 83 | * Note the functions below must be called with preemption disabled. |
| 84 | * Do not enable preemption before calling __kernel_fpu_end() to prevent |
| 85 | * an corruption of an existing kernel FPU state. |
| 86 | * |
| 87 | * Prefer using the kernel_fpu_begin()/kernel_fpu_end() pair of functions. |
| 88 | */ |
| 89 | void __kernel_fpu_begin(struct kernel_fpu *state, u32 flags); |
| 90 | void __kernel_fpu_end(struct kernel_fpu *state); |
| 91 | |
| 92 | |
| 93 | static inline void kernel_fpu_begin(struct kernel_fpu *state, u32 flags) |
| 94 | { |
| 95 | preempt_disable(); |
| 96 | __kernel_fpu_begin(state, flags); |
| 97 | } |
| 98 | |
| 99 | static inline void kernel_fpu_end(struct kernel_fpu *state) |
| 100 | { |
| 101 | __kernel_fpu_end(state); |
| 102 | preempt_enable(); |
| 103 | } |
| 104 | |
Hendrik Brueckner | b075390 | 2015-10-06 12:25:59 +0200 | [diff] [blame] | 105 | #endif /* _ASM_S390_FPU_API_H */ |