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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 | ||
23 | struct mm_struct; | |
24 | struct pt_regs; | |
25 | struct 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 | */ | |
41 | extern 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 | */ | |
55 | extern 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 | */ | |
66 | extern 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 | */ | |
80 | extern 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 | */ | |
90 | extern void dsemul_mm_cleanup(struct mm_struct *mm); | |
91 | ||
92 | #endif /* __MIPS_ASM_DSEMUL_H__ */ |