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
 19struct mm_struct;
 20struct pt_regs;
 21struct 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 */
 37extern 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
 52extern bool do_dsemulret(struct pt_regs *xcp);
 53#else
 54static 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
 70extern bool dsemul_thread_cleanup(struct task_struct *tsk);
 71#else
 72static 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
 90extern bool dsemul_thread_rollback(struct pt_regs *regs);
 91#else
 92static 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
107extern void dsemul_mm_cleanup(struct mm_struct *mm);
108#else
109static inline void dsemul_mm_cleanup(struct mm_struct *mm)
110{
111	/* no-op */
112}
113#endif
114
115#endif /* __MIPS_ASM_DSEMUL_H__ */

 
 1/*
 2 * Copyright (C) 2016 Imagination Technologies
 3 * Author: Paul Burton <paul.burton@imgtec.com>
 4 *
 5 * This program is free software; you can redistribute it and/or modify it
 6 * under the terms of the GNU General Public License as published by the
 7 * Free Software Foundation;  either version 2 of the  License, or (at your
 8 * option) any later version.
 9 */
10
11#ifndef __MIPS_ASM_DSEMUL_H__
12#define __MIPS_ASM_DSEMUL_H__
13
14#include <asm/break.h>
15#include <asm/inst.h>
16
17/* Break instruction with special math emu break code set */
18#define BREAK_MATH(micromips)	(((micromips) ? 0x7 : 0xd) | (BRK_MEMU << 16))
19
20/* When used as a frame index, indicates the lack of a frame */
21#define BD_EMUFRAME_NONE	((int)BIT(31))
22
23struct mm_struct;
24struct pt_regs;
25struct task_struct;
26
27/**
28 * mips_dsemul() - 'Emulate' an instruction from a branch delay slot
29 * @regs:	User thread register context.
30 * @ir:		The instruction to be 'emulated'.
31 * @branch_pc:	The PC of the branch instruction.
32 * @cont_pc:	The PC to continue at following 'emulation'.
33 *
34 * Emulate or execute an arbitrary MIPS instruction within the context of
35 * the current user thread. This is used primarily to handle instructions
36 * in the delay slots of emulated branch instructions, for example FP
37 * branch instructions on systems without an FPU.
38 *
39 * Return: Zero on success, negative if ir is a NOP, signal number on failure.
40 */
41extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir,
42		       unsigned long branch_pc, unsigned long cont_pc);
43
44/**
45 * do_dsemulret() - Return from a delay slot 'emulation' frame
46 * @xcp:	User thread register context.
47 *
48 * Call in response to the BRK_MEMU break instruction used to return to
49 * the kernel from branch delay slot 'emulation' frames following a call
50 * to mips_dsemul(). Restores the user thread PC to the value that was
51 * passed as the cpc parameter to mips_dsemul().
52 *
53 * Return: True if an emulation frame was returned from, else false.
54 */
 
55extern bool do_dsemulret(struct pt_regs *xcp);
 
 
 
 
 
 
56
57/**
58 * dsemul_thread_cleanup() - Cleanup thread 'emulation' frame
59 * @tsk: The task structure associated with the thread
60 *
61 * If the thread @tsk has a branch delay slot 'emulation' frame
62 * allocated to it then free that frame.
63 *
64 * Return: True if a frame was freed, else false.
65 */
 
66extern bool dsemul_thread_cleanup(struct task_struct *tsk);
67
 
 
 
 
 
68/**
69 * dsemul_thread_rollback() - Rollback from an 'emulation' frame
70 * @regs:	User thread register context.
71 *
72 * If the current thread, whose register context is represented by @regs,
73 * is executing within a delay slot 'emulation' frame then exit that
74 * frame. The PC will be rolled back to the branch if the instruction
75 * that was being 'emulated' has not yet executed, or advanced to the
76 * continuation PC if it has.
77 *
78 * Return: True if a frame was exited, else false.
79 */
 
80extern bool dsemul_thread_rollback(struct pt_regs *regs);
 
 
 
 
 
 
81
82/**
83 * dsemul_mm_cleanup() - Cleanup per-mm delay slot 'emulation' state
84 * @mm:		The struct mm_struct to cleanup state for.
85 *
86 * Cleanup state for the given @mm, ensuring that any memory allocated
87 * for delay slot 'emulation' book-keeping is freed. This is to be called
88 * before @mm is freed in order to avoid memory leaks.
89 */
 
90extern void dsemul_mm_cleanup(struct mm_struct *mm);
 
 
 
 
 
 
91
92#endif /* __MIPS_ASM_DSEMUL_H__ */