005f78cd88
If a task gets scheduled out and back in again and nothing has touched its FPSIMD state in the mean time, there is really no reason to reload it from memory. Similarly, repeated calls to kernel_neon_begin() and kernel_neon_end() will preserve and restore the FPSIMD state every time. This patch defers the FPSIMD state restore to the last possible moment, i.e., right before the task returns to userland. If a task does not return to userland at all (for any reason), the existing FPSIMD state is preserved and may be reused by the owning task if it gets scheduled in again on the same CPU. This patch adds two more functions to abstract away from straight FPSIMD register file saves and restores: - fpsimd_restore_current_state -> ensure current's FPSIMD state is loaded - fpsimd_flush_task_state -> invalidate live copies of a task's FPSIMD state Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
124 lines
3.7 KiB
C
124 lines
3.7 KiB
C
/*
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* Based on arch/arm/include/asm/thread_info.h
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*
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* Copyright (C) 2002 Russell King.
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ASM_THREAD_INFO_H
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#define __ASM_THREAD_INFO_H
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#ifdef __KERNEL__
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#include <linux/compiler.h>
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#ifndef CONFIG_ARM64_64K_PAGES
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#define THREAD_SIZE_ORDER 2
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#endif
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#define THREAD_SIZE 16384
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#define THREAD_START_SP (THREAD_SIZE - 16)
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#ifndef __ASSEMBLY__
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struct task_struct;
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struct exec_domain;
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#include <asm/types.h>
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typedef unsigned long mm_segment_t;
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/*
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* low level task data that entry.S needs immediate access to.
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* __switch_to() assumes cpu_context follows immediately after cpu_domain.
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*/
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struct thread_info {
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unsigned long flags; /* low level flags */
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mm_segment_t addr_limit; /* address limit */
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struct task_struct *task; /* main task structure */
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struct exec_domain *exec_domain; /* execution domain */
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struct restart_block restart_block;
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int preempt_count; /* 0 => preemptable, <0 => bug */
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int cpu; /* cpu */
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};
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#define INIT_THREAD_INFO(tsk) \
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{ \
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.task = &tsk, \
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.exec_domain = &default_exec_domain, \
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.flags = 0, \
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.preempt_count = INIT_PREEMPT_COUNT, \
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.addr_limit = KERNEL_DS, \
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.restart_block = { \
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.fn = do_no_restart_syscall, \
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}, \
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}
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#define init_thread_info (init_thread_union.thread_info)
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#define init_stack (init_thread_union.stack)
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/*
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* how to get the thread information struct from C
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*/
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static inline struct thread_info *current_thread_info(void) __attribute_const__;
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static inline struct thread_info *current_thread_info(void)
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{
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register unsigned long sp asm ("sp");
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return (struct thread_info *)(sp & ~(THREAD_SIZE - 1));
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}
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#define thread_saved_pc(tsk) \
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((unsigned long)(tsk->thread.cpu_context.pc))
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#define thread_saved_sp(tsk) \
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((unsigned long)(tsk->thread.cpu_context.sp))
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#define thread_saved_fp(tsk) \
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((unsigned long)(tsk->thread.cpu_context.fp))
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#endif
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/*
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* thread information flags:
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* TIF_SYSCALL_TRACE - syscall trace active
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* TIF_SIGPENDING - signal pending
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* TIF_NEED_RESCHED - rescheduling necessary
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* TIF_NOTIFY_RESUME - callback before returning to user
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* TIF_USEDFPU - FPU was used by this task this quantum (SMP)
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* TIF_POLLING_NRFLAG - true if poll_idle() is polling TIF_NEED_RESCHED
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*/
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#define TIF_SIGPENDING 0
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#define TIF_NEED_RESCHED 1
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#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
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#define TIF_FOREIGN_FPSTATE 3 /* CPU's FP state is not current's */
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#define TIF_SYSCALL_TRACE 8
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#define TIF_POLLING_NRFLAG 16
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#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
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#define TIF_FREEZE 19
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#define TIF_RESTORE_SIGMASK 20
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#define TIF_SINGLESTEP 21
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#define TIF_32BIT 22 /* 32bit process */
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#define TIF_SWITCH_MM 23 /* deferred switch_mm */
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#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
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#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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#define _TIF_FOREIGN_FPSTATE (1 << TIF_FOREIGN_FPSTATE)
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#define _TIF_32BIT (1 << TIF_32BIT)
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#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
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_TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE)
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#endif /* __KERNEL__ */
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#endif /* __ASM_THREAD_INFO_H */
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