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>
67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
/*
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* Copyright (C) 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 __START_H__
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#define __START_H__
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#include "uml-config.h"
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#include "kern_constants.h"
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/*
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* Stolen from linux/const.h, which can't be directly included since
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* this is used in userspace code, which has no access to the kernel
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* headers. Changed to be suitable for adding casts to the start,
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* rather than "UL" to the end.
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*/
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/* Some constant macros are used in both assembler and
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* C code. Therefore we cannot annotate them always with
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* 'UL' and other type specifiers unilaterally. We
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* use the following macros to deal with this.
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*/
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#ifdef __ASSEMBLY__
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#define _AC(X, Y) (Y)
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#else
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#define __AC(X, Y) (X (Y))
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#define _AC(X, Y) __AC(X, Y)
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#endif
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#define STUB_START _AC(, 0x100000)
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#define STUB_CODE _AC((unsigned long), STUB_START)
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#define STUB_DATA _AC((unsigned long), STUB_CODE + UM_KERN_PAGE_SIZE)
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#define STUB_END _AC((unsigned long), STUB_DATA + UM_KERN_PAGE_SIZE)
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#ifndef __ASSEMBLY__
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#include "sysdep/ptrace.h"
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struct cpu_task {
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int pid;
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void *task;
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};
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extern struct cpu_task cpu_tasks[];
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extern unsigned long low_physmem;
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extern unsigned long high_physmem;
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extern unsigned long uml_physmem;
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extern unsigned long uml_reserved;
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extern unsigned long end_vm;
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extern unsigned long start_vm;
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extern unsigned long long highmem;
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extern unsigned long _stext, _etext, _sdata, _edata, __bss_start, _end;
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extern unsigned long _unprotected_end;
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extern unsigned long brk_start;
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extern int linux_main(int argc, char **argv);
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extern void (*sig_info[])(int, struct uml_pt_regs *);
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#endif
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#endif
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