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e08e6c5213
On SN2, MMIO writes which are issued from separate processors are not guaranteed to arrive in any particular order at the IO hardware. When performing such writes from the kernel this is not a problem, as a kernel thread will not migrate to another CPU during execution, and mmiowb() calls can guarantee write ordering when control of the IO resource is allowed to move between threads. However, when MMIO writes can be performed from user space (e.g. DRM) there are no such guarantees and mechanisms, as the process may context-switch at any time, and may migrate to a different CPU as part of the switch. For such programs/hardware to operate correctly, it is required that the MMIO writes from the old CPU be accepted by the IO hardware before subsequent writes from the new CPU can be issued. The following patch implements this behavior on SN2 by waiting for a Shub register to indicate that these writes have been accepted. This is placed in the context switch-in path, and only performs the wait when the newly scheduled task changes CPUs. Signed-off-by: Prarit Bhargava <prarit@sgi.com> Signed-off-by: Brent Casavant <bcasavan@sgi.com>
116 lines
4.2 KiB
C
116 lines
4.2 KiB
C
/*
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* Copyright (C) 2002-2003 Hewlett-Packard Co
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* David Mosberger-Tang <davidm@hpl.hp.com>
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*/
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#ifndef _ASM_IA64_THREAD_INFO_H
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#define _ASM_IA64_THREAD_INFO_H
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#ifndef ASM_OFFSETS_C
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#include <asm/asm-offsets.h>
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#endif
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#include <asm/processor.h>
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#include <asm/ptrace.h>
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#define PREEMPT_ACTIVE_BIT 30
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#define PREEMPT_ACTIVE (1 << PREEMPT_ACTIVE_BIT)
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#ifndef __ASSEMBLY__
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/*
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* On IA-64, we want to keep the task structure and kernel stack together, so they can be
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* mapped by a single TLB entry and so they can be addressed by the "current" pointer
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* without having to do pointer masking.
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*/
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struct thread_info {
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struct task_struct *task; /* XXX not really needed, except for dup_task_struct() */
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struct exec_domain *exec_domain;/* execution domain */
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__u32 flags; /* thread_info flags (see TIF_*) */
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__u32 cpu; /* current CPU */
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__u32 last_cpu; /* Last CPU thread ran on */
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mm_segment_t addr_limit; /* user-level address space limit */
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int preempt_count; /* 0=premptable, <0=BUG; will also serve as bh-counter */
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struct restart_block restart_block;
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struct {
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int signo;
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int code;
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void __user *addr;
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unsigned long start_time;
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pid_t pid;
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} sigdelayed; /* Saved information for TIF_SIGDELAYED */
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};
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#define THREAD_SIZE KERNEL_STACK_SIZE
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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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.cpu = 0, \
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.addr_limit = KERNEL_DS, \
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.preempt_count = 0, \
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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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#ifndef ASM_OFFSETS_C
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/* how to get the thread information struct from C */
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#define current_thread_info() ((struct thread_info *) ((char *) current + IA64_TASK_SIZE))
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#define alloc_thread_info(tsk) ((struct thread_info *) ((char *) (tsk) + IA64_TASK_SIZE))
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#define task_thread_info(tsk) ((struct thread_info *) ((char *) (tsk) + IA64_TASK_SIZE))
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#else
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#define current_thread_info() ((struct thread_info *) 0)
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#define alloc_thread_info(tsk) ((struct thread_info *) 0)
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#define task_thread_info(tsk) ((struct thread_info *) 0)
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#endif
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#define free_thread_info(ti) /* nothing */
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#define task_stack_page(tsk) ((void *)(tsk))
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#define __HAVE_THREAD_FUNCTIONS
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#define setup_thread_stack(p, org) \
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*task_thread_info(p) = *task_thread_info(org); \
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task_thread_info(p)->task = (p);
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#define end_of_stack(p) (unsigned long *)((void *)(p) + IA64_RBS_OFFSET)
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#define __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
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#define alloc_task_struct() ((task_t *)__get_free_pages(GFP_KERNEL, KERNEL_STACK_SIZE_ORDER))
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#define free_task_struct(tsk) free_pages((unsigned long) (tsk), KERNEL_STACK_SIZE_ORDER)
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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 least-significant 16 bits, other flags
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* in top 16 bits
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*/
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#define TIF_NOTIFY_RESUME 0 /* resumption notification requested */
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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_SYSCALL_TRACE 3 /* syscall trace active */
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#define TIF_SYSCALL_AUDIT 4 /* syscall auditing active */
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#define TIF_SIGDELAYED 5 /* signal delayed from MCA/INIT/NMI/PMI context */
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#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
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#define TIF_MEMDIE 17
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#define TIF_MCA_INIT 18 /* this task is processing MCA or INIT */
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#define TIF_DB_DISABLED 19 /* debug trap disabled for fsyscall */
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#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
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#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
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#define _TIF_SYSCALL_TRACEAUDIT (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
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#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
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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_SIGDELAYED (1 << TIF_SIGDELAYED)
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#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
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#define _TIF_MCA_INIT (1 << TIF_MCA_INIT)
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#define _TIF_DB_DISABLED (1 << TIF_DB_DISABLED)
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/* "work to do on user-return" bits */
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#define TIF_ALLWORK_MASK (_TIF_NOTIFY_RESUME|_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SIGDELAYED)
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/* like TIF_ALLWORK_BITS but sans TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT */
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#define TIF_WORK_MASK (TIF_ALLWORK_MASK&~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT))
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#endif /* _ASM_IA64_THREAD_INFO_H */
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