1e40cd383c
Normally, activate_mm() is called from exec(), and thus it used to be a no-op because we use a completely new "MM context" on the host (for instance, a new process), and so we didn't need to flush any "TLB entries" (which for us are the set of memory mappings for the host process from the virtual "RAM" file). Kernel threads, instead, are usually handled in a different way. So, when for AIO we call use_mm(), things used to break and so Benjamin implemented activate_mm(). However, that is only needed for AIO, and could slow down exec() inside UML, so be smart: detect being called for AIO (via PF_BORROWED_MM) and do the full flush only in that situation. Comment also the caller so that people won't go breaking UML without noticing. I also rely on the caller's locks for testing current->flags. Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> CC: Benjamin LaHaise <bcrl@kvack.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
88 lines
2.3 KiB
C
88 lines
2.3 KiB
C
/*
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* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
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* Licensed under the GPL
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*/
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#ifndef __UM_MMU_CONTEXT_H
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#define __UM_MMU_CONTEXT_H
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#include "linux/sched.h"
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#include "linux/config.h"
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#include "choose-mode.h"
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#include "um_mmu.h"
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#define get_mmu_context(task) do ; while(0)
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#define activate_context(tsk) do ; while(0)
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#define deactivate_mm(tsk,mm) do { } while (0)
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extern void force_flush_all(void);
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static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
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{
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/*
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* This is called by fs/exec.c and fs/aio.c. In the first case, for an
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* exec, we don't need to do anything as we're called from userspace
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* and thus going to use a new host PID. In the second, we're called
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* from a kernel thread, and thus need to go doing the mmap's on the
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* host. Since they're very expensive, we want to avoid that as far as
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* possible.
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*/
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if (old != new && (current->flags & PF_BORROWED_MM))
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force_flush_all();
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}
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static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
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struct task_struct *tsk)
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{
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unsigned cpu = smp_processor_id();
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if(prev != next){
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cpu_clear(cpu, prev->cpu_vm_mask);
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cpu_set(cpu, next->cpu_vm_mask);
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if(next != &init_mm)
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CHOOSE_MODE((void) 0,
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switch_mm_skas(&next->context.skas.id));
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}
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}
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static inline void enter_lazy_tlb(struct mm_struct *mm,
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struct task_struct *tsk)
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{
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}
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extern int init_new_context_skas(struct task_struct *task,
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struct mm_struct *mm);
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static inline int init_new_context_tt(struct task_struct *task,
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struct mm_struct *mm)
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{
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return(0);
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}
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static inline int init_new_context(struct task_struct *task,
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struct mm_struct *mm)
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{
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return(CHOOSE_MODE_PROC(init_new_context_tt, init_new_context_skas,
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task, mm));
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}
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extern void destroy_context_skas(struct mm_struct *mm);
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static inline void destroy_context(struct mm_struct *mm)
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{
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CHOOSE_MODE((void) 0, destroy_context_skas(mm));
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}
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#endif
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/*
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* Overrides for Emacs so that we follow Linus's tabbing style.
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* Emacs will notice this stuff at the end of the file and automatically
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* adjust the settings for this buffer only. This must remain at the end
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* of the file.
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* ---------------------------------------------------------------------------
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* Local variables:
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* c-file-style: "linux"
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* End:
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*/
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