116 lines
3.5 KiB
C
116 lines
3.5 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2016 Imagination Technologies
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* Author: Paul Burton <paul.burton@mips.com>
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*/
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#ifndef __MIPS_ASM_DSEMUL_H__
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#define __MIPS_ASM_DSEMUL_H__
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#include <asm/break.h>
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#include <asm/inst.h>
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/* Break instruction with special math emu break code set */
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#define BREAK_MATH(micromips) (((micromips) ? 0x7 : 0xd) | (BRK_MEMU << 16))
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/* When used as a frame index, indicates the lack of a frame */
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#define BD_EMUFRAME_NONE ((int)BIT(31))
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struct mm_struct;
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struct pt_regs;
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struct task_struct;
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/**
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* mips_dsemul() - 'Emulate' an instruction from a branch delay slot
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* @regs: User thread register context.
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* @ir: The instruction to be 'emulated'.
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* @branch_pc: The PC of the branch instruction.
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* @cont_pc: The PC to continue at following 'emulation'.
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*
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* Emulate or execute an arbitrary MIPS instruction within the context of
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* the current user thread. This is used primarily to handle instructions
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* in the delay slots of emulated branch instructions, for example FP
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* branch instructions on systems without an FPU.
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*
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* Return: Zero on success, negative if ir is a NOP, signal number on failure.
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*/
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extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir,
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unsigned long branch_pc, unsigned long cont_pc);
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/**
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* do_dsemulret() - Return from a delay slot 'emulation' frame
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* @xcp: User thread register context.
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*
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* Call in response to the BRK_MEMU break instruction used to return to
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* the kernel from branch delay slot 'emulation' frames following a call
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* to mips_dsemul(). Restores the user thread PC to the value that was
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* passed as the cpc parameter to mips_dsemul().
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*
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* Return: True if an emulation frame was returned from, else false.
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*/
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#ifdef CONFIG_MIPS_FP_SUPPORT
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extern bool do_dsemulret(struct pt_regs *xcp);
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#else
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static inline bool do_dsemulret(struct pt_regs *xcp)
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{
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return false;
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}
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#endif
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/**
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* dsemul_thread_cleanup() - Cleanup thread 'emulation' frame
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* @tsk: The task structure associated with the thread
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*
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* If the thread @tsk has a branch delay slot 'emulation' frame
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* allocated to it then free that frame.
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*
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* Return: True if a frame was freed, else false.
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*/
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#ifdef CONFIG_MIPS_FP_SUPPORT
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extern bool dsemul_thread_cleanup(struct task_struct *tsk);
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#else
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static inline bool dsemul_thread_cleanup(struct task_struct *tsk)
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{
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return false;
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}
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#endif
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/**
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* dsemul_thread_rollback() - Rollback from an 'emulation' frame
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* @regs: User thread register context.
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*
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* If the current thread, whose register context is represented by @regs,
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* is executing within a delay slot 'emulation' frame then exit that
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* frame. The PC will be rolled back to the branch if the instruction
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* that was being 'emulated' has not yet executed, or advanced to the
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* continuation PC if it has.
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*
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* Return: True if a frame was exited, else false.
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*/
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#ifdef CONFIG_MIPS_FP_SUPPORT
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extern bool dsemul_thread_rollback(struct pt_regs *regs);
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#else
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static inline bool dsemul_thread_rollback(struct pt_regs *regs)
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{
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return false;
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}
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#endif
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/**
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* dsemul_mm_cleanup() - Cleanup per-mm delay slot 'emulation' state
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* @mm: The struct mm_struct to cleanup state for.
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*
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* Cleanup state for the given @mm, ensuring that any memory allocated
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* for delay slot 'emulation' book-keeping is freed. This is to be called
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* before @mm is freed in order to avoid memory leaks.
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*/
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#ifdef CONFIG_MIPS_FP_SUPPORT
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extern void dsemul_mm_cleanup(struct mm_struct *mm);
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#else
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static inline void dsemul_mm_cleanup(struct mm_struct *mm)
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{
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/* no-op */
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}
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#endif
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#endif /* __MIPS_ASM_DSEMUL_H__ */
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