cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

dsemul.h (3595B)

      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__ */