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Diffstat (limited to 'arch/mips/include/asm/dsemul.h')
| -rw-r--r-- | arch/mips/include/asm/dsemul.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/arch/mips/include/asm/dsemul.h b/arch/mips/include/asm/dsemul.h new file mode 100644 index 0000000000..08bfe8fa3b --- /dev/null +++ b/arch/mips/include/asm/dsemul.h @@ -0,0 +1,115 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (C) 2016 Imagination Technologies + * Author: Paul Burton <paul.burton@mips.com> + */ + +#ifndef __MIPS_ASM_DSEMUL_H__ +#define __MIPS_ASM_DSEMUL_H__ + +#include <asm/break.h> +#include <asm/inst.h> + +/* Break instruction with special math emu break code set */ +#define BREAK_MATH(micromips) (((micromips) ? 0x7 : 0xd) | (BRK_MEMU << 16)) + +/* When used as a frame index, indicates the lack of a frame */ +#define BD_EMUFRAME_NONE ((int)BIT(31)) + +struct mm_struct; +struct pt_regs; +struct task_struct; + +/** + * mips_dsemul() - 'Emulate' an instruction from a branch delay slot + * @regs: User thread register context. + * @ir: The instruction to be 'emulated'. + * @branch_pc: The PC of the branch instruction. + * @cont_pc: The PC to continue at following 'emulation'. + * + * Emulate or execute an arbitrary MIPS instruction within the context of + * the current user thread. This is used primarily to handle instructions + * in the delay slots of emulated branch instructions, for example FP + * branch instructions on systems without an FPU. + * + * Return: Zero on success, negative if ir is a NOP, signal number on failure. + */ +extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir, + unsigned long branch_pc, unsigned long cont_pc); + +/** + * do_dsemulret() - Return from a delay slot 'emulation' frame + * @xcp: User thread register context. + * + * Call in response to the BRK_MEMU break instruction used to return to + * the kernel from branch delay slot 'emulation' frames following a call + * to mips_dsemul(). Restores the user thread PC to the value that was + * passed as the cpc parameter to mips_dsemul(). + * + * Return: True if an emulation frame was returned from, else false. + */ +#ifdef CONFIG_MIPS_FP_SUPPORT +extern bool do_dsemulret(struct pt_regs *xcp); +#else +static inline bool do_dsemulret(struct pt_regs *xcp) +{ + return false; +} +#endif + +/** + * dsemul_thread_cleanup() - Cleanup thread 'emulation' frame + * @tsk: The task structure associated with the thread + * + * If the thread @tsk has a branch delay slot 'emulation' frame + * allocated to it then free that frame. + * + * Return: True if a frame was freed, else false. + */ +#ifdef CONFIG_MIPS_FP_SUPPORT +extern bool dsemul_thread_cleanup(struct task_struct *tsk); +#else +static inline bool dsemul_thread_cleanup(struct task_struct *tsk) +{ + return false; +} +#endif +/** + * dsemul_thread_rollback() - Rollback from an 'emulation' frame + * @regs: User thread register context. + * + * If the current thread, whose register context is represented by @regs, + * is executing within a delay slot 'emulation' frame then exit that + * frame. The PC will be rolled back to the branch if the instruction + * that was being 'emulated' has not yet executed, or advanced to the + * continuation PC if it has. + * + * Return: True if a frame was exited, else false. + */ +#ifdef CONFIG_MIPS_FP_SUPPORT +extern bool dsemul_thread_rollback(struct pt_regs *regs); +#else +static inline bool dsemul_thread_rollback(struct pt_regs *regs) +{ + return false; +} +#endif + +/** + * dsemul_mm_cleanup() - Cleanup per-mm delay slot 'emulation' state + * @mm: The struct mm_struct to cleanup state for. + * + * Cleanup state for the given @mm, ensuring that any memory allocated + * for delay slot 'emulation' book-keeping is freed. This is to be called + * before @mm is freed in order to avoid memory leaks. + */ +#ifdef CONFIG_MIPS_FP_SUPPORT +extern void dsemul_mm_cleanup(struct mm_struct *mm); +#else +static inline void dsemul_mm_cleanup(struct mm_struct *mm) +{ + /* no-op */ +} +#endif + +#endif /* __MIPS_ASM_DSEMUL_H__ */ |