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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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d3ea9fa0a5
A number of small optimisations to FPU handling, in particular: - move the task USEDFPU flag from the thread_info flags field (which is accessed asynchronously to the thread) to a new status field, which is only accessed by the thread itself. This allows locking to be removed in most cases, or can be reduced to a preempt_lock(). This mimics the i386 behaviour. - move the modification of regs->sr and thread_info->status flags out of save_fpu() to __unlazy_fpu(). This gives the compiler a better chance to optimise things, as well as making save_fpu() symmetrical with restore_fpu() and init_fpu(). - implement prepare_to_copy(), so that when creating a thread, we can unlazy the FPU prior to copying the thread data structures. Also make sure that the FPU is disabled while in the kernel, in particular while booting, and for newly created kernel threads, In a very artificial benchmark, the execution time for 2500000 context switches was reduced from 50 to 45 seconds. Signed-off-by: Stuart Menefy <stuart.menefy@st.com> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
180 lines
5.3 KiB
C
180 lines
5.3 KiB
C
#ifndef __ASM_SH_THREAD_INFO_H
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#define __ASM_SH_THREAD_INFO_H
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/* SuperH version
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* Copyright (C) 2002 Niibe Yutaka
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*
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* The copyright of original i386 version is:
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*
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* Copyright (C) 2002 David Howells (dhowells@redhat.com)
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* - Incorporating suggestions made by Linus Torvalds and Dave Miller
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*/
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#ifdef __KERNEL__
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#include <asm/page.h>
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#ifndef __ASSEMBLY__
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#include <asm/processor.h>
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struct thread_info {
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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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unsigned long flags; /* low level flags */
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__u32 status; /* thread synchronous flags */
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__u32 cpu;
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int preempt_count; /* 0 => preemptable, <0 => BUG */
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mm_segment_t addr_limit; /* thread address space */
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struct restart_block restart_block;
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unsigned long previous_sp; /* sp of previous stack in case
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of nested IRQ stacks */
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__u8 supervisor_stack[0];
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};
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#endif
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#define PREEMPT_ACTIVE 0x10000000
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#if defined(CONFIG_4KSTACKS)
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#define THREAD_SHIFT 12
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#else
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#define THREAD_SHIFT 13
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#endif
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#define THREAD_SIZE (1 << THREAD_SHIFT)
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#define STACK_WARN (THREAD_SIZE >> 3)
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/*
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* macros/functions for gaining access to the thread information structure
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*/
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#ifndef __ASSEMBLY__
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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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.status = 0, \
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.cpu = 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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/* how to get the current stack pointer from C */
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register unsigned long current_stack_pointer asm("r15") __used;
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/* how to get the thread information struct from C */
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static inline struct thread_info *current_thread_info(void)
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{
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struct thread_info *ti;
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#if defined(CONFIG_SUPERH64)
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__asm__ __volatile__ ("getcon cr17, %0" : "=r" (ti));
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#elif defined(CONFIG_CPU_HAS_SR_RB)
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__asm__ __volatile__ ("stc r7_bank, %0" : "=r" (ti));
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#else
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unsigned long __dummy;
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__asm__ __volatile__ (
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"mov r15, %0\n\t"
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"and %1, %0\n\t"
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: "=&r" (ti), "=r" (__dummy)
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: "1" (~(THREAD_SIZE - 1))
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: "memory");
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#endif
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return ti;
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}
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/* thread information allocation */
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#if THREAD_SHIFT >= PAGE_SHIFT
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#define THREAD_SIZE_ORDER (THREAD_SHIFT - PAGE_SHIFT)
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#else /* THREAD_SHIFT < PAGE_SHIFT */
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#define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
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extern struct thread_info *alloc_thread_info(struct task_struct *tsk);
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extern void free_thread_info(struct thread_info *ti);
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#endif /* THREAD_SHIFT < PAGE_SHIFT */
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#endif /* __ASSEMBLY__ */
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/*
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* thread information flags
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* - these are process state flags that various assembly files may need to access
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* - pending work-to-be-done flags are in LSW
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* - other flags in MSW
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*/
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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#define TIF_SINGLESTEP 4 /* singlestepping active */
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#define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
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#define TIF_SECCOMP 6 /* secure computing */
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#define TIF_NOTIFY_RESUME 7 /* callback before returning to user */
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#define TIF_SYSCALL_TRACEPOINT 8 /* for ftrace syscall instrumentation */
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#define TIF_POLLING_NRFLAG 17 /* true if poll_idle() is polling TIF_NEED_RESCHED */
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#define TIF_MEMDIE 18
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#define TIF_FREEZE 19 /* Freezing for suspend */
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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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_SINGLESTEP (1 << TIF_SINGLESTEP)
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#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
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#define _TIF_SECCOMP (1 << TIF_SECCOMP)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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#define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
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#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
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#define _TIF_FREEZE (1 << TIF_FREEZE)
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/*
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* _TIF_ALLWORK_MASK and _TIF_WORK_MASK need to fit within 2 bytes, or we
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* blow the tst immediate size constraints and need to fix up
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* arch/sh/kernel/entry-common.S.
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*/
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/* work to do in syscall trace */
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#define _TIF_WORK_SYSCALL_MASK (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \
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_TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
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_TIF_SYSCALL_TRACEPOINT)
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/* work to do on any return to u-space */
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#define _TIF_ALLWORK_MASK (_TIF_SYSCALL_TRACE | _TIF_SIGPENDING | \
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_TIF_NEED_RESCHED | _TIF_SYSCALL_AUDIT | \
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_TIF_SINGLESTEP | _TIF_NOTIFY_RESUME | \
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_TIF_SYSCALL_TRACEPOINT)
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/* work to do on interrupt/exception return */
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#define _TIF_WORK_MASK (_TIF_ALLWORK_MASK & ~(_TIF_SYSCALL_TRACE | \
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_TIF_SYSCALL_AUDIT | _TIF_SINGLESTEP))
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/*
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* Thread-synchronous status.
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*
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* This is different from the flags in that nobody else
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* ever touches our thread-synchronous status, so we don't
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* have to worry about atomic accesses.
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*/
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#define TS_RESTORE_SIGMASK 0x0001 /* restore signal mask in do_signal() */
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#define TS_USEDFPU 0x0002 /* FPU used by this task this quantum */
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#ifndef __ASSEMBLY__
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#define HAVE_SET_RESTORE_SIGMASK 1
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static inline void set_restore_sigmask(void)
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{
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struct thread_info *ti = current_thread_info();
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ti->status |= TS_RESTORE_SIGMASK;
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set_bit(TIF_SIGPENDING, (unsigned long *)&ti->flags);
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}
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#endif /* !__ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* __ASM_SH_THREAD_INFO_H */
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