forked from Minki/linux
f1c2bb8b99
Until now UML had no x86_64 vDSO. So glibc always used the vsyscall page for gettimeday() and friends. Calls to gettimeday() returned falsely the host time and confused some programs. This patch adds a vDSO which turns all __vdso_* calls into a system call so that UML can trap them. As glibc still uses the vsyscall page for static binaries this patch improves the situation only for dynamic binaries. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
75 lines
1.4 KiB
C
75 lines
1.4 KiB
C
/*
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* Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <asm/page.h>
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#include <linux/init.h>
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unsigned int __read_mostly vdso_enabled = 1;
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unsigned long um_vdso_addr;
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extern unsigned long task_size;
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extern char vdso_start[], vdso_end[];
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static struct page **vdsop;
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static int __init init_vdso(void)
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{
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struct page *um_vdso;
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BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
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um_vdso_addr = task_size - PAGE_SIZE;
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vdsop = kmalloc(GFP_KERNEL, sizeof(struct page *));
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if (!vdsop)
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goto oom;
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um_vdso = alloc_page(GFP_KERNEL);
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if (!um_vdso) {
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kfree(vdsop);
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goto oom;
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}
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copy_page(page_address(um_vdso), vdso_start);
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*vdsop = um_vdso;
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return 0;
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oom:
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printk(KERN_ERR "Cannot allocate vdso\n");
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vdso_enabled = 0;
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return -ENOMEM;
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}
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subsys_initcall(init_vdso);
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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int err;
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struct mm_struct *mm = current->mm;
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if (!vdso_enabled)
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return 0;
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down_write(&mm->mmap_sem);
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err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
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VM_ALWAYSDUMP,
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vdsop);
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up_write(&mm->mmap_sem);
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return err;
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}
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