1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Copyright (C) 2016 Imagination Technologies 4 * Author: Paul Burton <paul.burton@mips.com> 5 */ 6 7 #ifndef __MIPS_ASM_DSEMUL_H__ 8 #define __MIPS_ASM_DSEMUL_H__ 9 10 #include <asm/break.h> 11 #include <asm/inst.h> 12 13 /* Break instruction with special math emu break code set */ 14 #define BREAK_MATH(micromips) (((micromips) ? 0x7 : 0xd) | (BRK_MEMU << 16)) 15 16 /* When used as a frame index, indicates the lack of a frame */ 17 #define BD_EMUFRAME_NONE ((int)BIT(31)) 18 19 struct mm_struct; 20 struct pt_regs; 21 struct task_struct; 22 23 /** 24 * mips_dsemul() - 'Emulate' an instruction from a branch delay slot 25 * @regs: User thread register context. 26 * @ir: The instruction to be 'emulated'. 27 * @branch_pc: The PC of the branch instruction. 28 * @cont_pc: The PC to continue at following 'emulation'. 29 * 30 * Emulate or execute an arbitrary MIPS instruction within the context of 31 * the current user thread. This is used primarily to handle instructions 32 * in the delay slots of emulated branch instructions, for example FP 33 * branch instructions on systems without an FPU. 34 * 35 * Return: Zero on success, negative if ir is a NOP, signal number on failure. 36 */ 37 extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir, 38 unsigned long branch_pc, unsigned long cont_pc); 39 40 /** 41 * do_dsemulret() - Return from a delay slot 'emulation' frame 42 * @xcp: User thread register context. 43 * 44 * Call in response to the BRK_MEMU break instruction used to return to 45 * the kernel from branch delay slot 'emulation' frames following a call 46 * to mips_dsemul(). Restores the user thread PC to the value that was 47 * passed as the cpc parameter to mips_dsemul(). 48 * 49 * Return: True if an emulation frame was returned from, else false. 50 */ 51 #ifdef CONFIG_MIPS_FP_SUPPORT 52 extern bool do_dsemulret(struct pt_regs *xcp); 53 #else 54 static inline bool do_dsemulret(struct pt_regs *xcp) 55 { 56 return false; 57 } 58 #endif 59 60 /** 61 * dsemul_thread_cleanup() - Cleanup thread 'emulation' frame 62 * @tsk: The task structure associated with the thread 63 * 64 * If the thread @tsk has a branch delay slot 'emulation' frame 65 * allocated to it then free that frame. 66 * 67 * Return: True if a frame was freed, else false. 68 */ 69 #ifdef CONFIG_MIPS_FP_SUPPORT 70 extern bool dsemul_thread_cleanup(struct task_struct *tsk); 71 #else 72 static inline bool dsemul_thread_cleanup(struct task_struct *tsk) 73 { 74 return false; 75 } 76 #endif 77 /** 78 * dsemul_thread_rollback() - Rollback from an 'emulation' frame 79 * @regs: User thread register context. 80 * 81 * If the current thread, whose register context is represented by @regs, 82 * is executing within a delay slot 'emulation' frame then exit that 83 * frame. The PC will be rolled back to the branch if the instruction 84 * that was being 'emulated' has not yet executed, or advanced to the 85 * continuation PC if it has. 86 * 87 * Return: True if a frame was exited, else false. 88 */ 89 #ifdef CONFIG_MIPS_FP_SUPPORT 90 extern bool dsemul_thread_rollback(struct pt_regs *regs); 91 #else 92 static inline bool dsemul_thread_rollback(struct pt_regs *regs) 93 { 94 return false; 95 } 96 #endif 97 98 /** 99 * dsemul_mm_cleanup() - Cleanup per-mm delay slot 'emulation' state 100 * @mm: The struct mm_struct to cleanup state for. 101 * 102 * Cleanup state for the given @mm, ensuring that any memory allocated 103 * for delay slot 'emulation' book-keeping is freed. This is to be called 104 * before @mm is freed in order to avoid memory leaks. 105 */ 106 #ifdef CONFIG_MIPS_FP_SUPPORT 107 extern void dsemul_mm_cleanup(struct mm_struct *mm); 108 #else 109 static inline void dsemul_mm_cleanup(struct mm_struct *mm) 110 { 111 /* no-op */ 112 } 113 #endif 114 115 #endif /* __MIPS_ASM_DSEMUL_H__ */ 116