4dc70e1aad
My original, naive, FPU support patch had the FPCSR register stored during both the *mode switch* and *context switch*. This is wasteful. Also, the original patches did not save the FPU state when handling signals during the system call fast path. We fix this by moving the FPCSR state to thread_struct in task_struct. We also introduce new helper functions save_fpu and restore_fpu which can be used to sync the FPU with thread_struct. These functions are now called when needed: - Setting up and restoring sigcontext when handling signals - Before and after __switch_to during context switches - When handling FPU exceptions - When reading and writing FPU register sets In the future we can further optimize this by doing lazy FPU save and restore. For example, FPU sync is not needed when switching to and from kernel threads (x86 does this). FPU save and restore does not need to be done two times if we have both rescheduling and signal work to do. However, since OpenRISC FPU state is a single register, I leave these optimizations for future consideration. Signed-off-by: Stafford Horne <shorne@gmail.com>
82 lines
2.3 KiB
C
82 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* OpenRISC Linux
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*
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* Linux architectural port borrowing liberally from similar works of
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* others. All original copyrights apply as per the original source
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* declaration.
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*
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* OpenRISC implementation:
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* Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
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* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
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* et al.
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*/
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#ifndef __ASM_OPENRISC_PROCESSOR_H
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#define __ASM_OPENRISC_PROCESSOR_H
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#include <asm/spr_defs.h>
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#include <asm/page.h>
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#include <asm/ptrace.h>
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#define STACK_TOP TASK_SIZE
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#define STACK_TOP_MAX STACK_TOP
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/* Kernel and user SR register setting */
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#define KERNEL_SR (SPR_SR_DME | SPR_SR_IME | SPR_SR_ICE \
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| SPR_SR_DCE | SPR_SR_SM)
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#define USER_SR (SPR_SR_DME | SPR_SR_IME | SPR_SR_ICE \
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| SPR_SR_DCE | SPR_SR_IEE | SPR_SR_TEE)
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/*
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* User space process size. This is hardcoded into a few places,
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* so don't change it unless you know what you are doing.
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*/
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#define TASK_SIZE (0x80000000UL)
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/* This decides where the kernel will search for a free chunk of vm
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* space during mmap's.
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*/
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#define TASK_UNMAPPED_BASE (TASK_SIZE / 8 * 3)
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#ifndef __ASSEMBLY__
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struct task_struct;
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struct thread_struct {
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long fpcsr; /* Floating point control status register. */
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};
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/*
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* At user->kernel entry, the pt_regs struct is stacked on the top of the
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* kernel-stack. This macro allows us to find those regs for a task.
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* Notice that subsequent pt_regs stackings, like recursive interrupts
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* occurring while we're in the kernel, won't affect this - only the first
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* user->kernel transition registers are reached by this (i.e. not regs
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* for running signal handler)
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*/
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#define user_regs(thread_info) (((struct pt_regs *)((unsigned long)(thread_info) + THREAD_SIZE - STACK_FRAME_OVERHEAD)) - 1)
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/*
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* Dito but for the currently running task
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*/
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#define task_pt_regs(task) user_regs(task_thread_info(task))
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#define INIT_SP (sizeof(init_stack) + (unsigned long) &init_stack)
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#define INIT_THREAD { }
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#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
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#define KSTK_ESP(tsk) (task_pt_regs(tsk)->sp)
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void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp);
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unsigned long __get_wchan(struct task_struct *p);
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void show_registers(struct pt_regs *regs);
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#define cpu_relax() barrier()
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_OPENRISC_PROCESSOR_H */
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