3963333fe6
Give the stubs a VMA. This allows the removal of a truly nasty kludge to make sure that mm->nr_ptes was correct in exit_mmap. The underlying problem was always that the stubs, which have ptes, and thus allocated a page table, weren't covered by a VMA. This patch fixes that by using install_special_mapping in arch_dup_mmap and activate_context to create the VMA. The stubs have to be moved, since shift_arg_pages seems to assume that the stack is the only VMA present at that point during exec, and uses vma_adjust to fiddle its VMA. However, that extends the stub VMA by the amount removed from the stack VMA. To avoid this problem, the stubs were moved to a different fixed location at the start of the address space. The init_stub_pte calls were moved from init_new_context to arch_dup_mmap because I was occasionally seeing arch_dup_mmap not being called, causing exit_mmap to die. Rather than figure out what was really happening, I decided it was cleaner to just move the calls so that there's no doubt that both the pte and VMA creation happen, no matter what. arch_exit_mmap is used to clear the stub ptes at exit time. The STUB_* constants in as-layout.h no longer depend on UM_TASK_SIZE, that that definition is removed, along with the comments complaining about gcc. Because the stubs are no longer at the top of the address space, some care is needed while flushing TLBs. update_pte_range checks for addresses in the stub range and skips them. flush_thread now issues two unmaps, one for the range before STUB_START and one for the range after STUB_END. Signed-off-by: Jeff Dike <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
61 lines
1.6 KiB
C
61 lines
1.6 KiB
C
/*
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* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.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 "um_mmu.h"
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extern void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm);
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extern void arch_exit_mmap(struct mm_struct *mm);
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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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__switch_mm(&new->context.id);
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arch_dup_mmap(old, new);
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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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__switch_mm(&next->context.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(struct task_struct *task, struct mm_struct *mm);
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extern void destroy_context(struct mm_struct *mm);
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#endif
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