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a62c34bd2a
Using arch_vma_name to give special mappings a name is awkward. x86 currently implements it by comparing the start address of the vma to the expected address of the vdso. This requires tracking the start address of special mappings and is probably buggy if a special vma is split or moved. Improve _install_special_mapping to just name the vma directly. Use it to give the x86 vvar area a name, which should make CRIU's life easier. As a side effect, the vvar area will show up in core dumps. This could be considered weird and is fixable. [hpa: I say we accept this as-is but be prepared to deal with knocking out the vvars from core dumps if this becomes a problem.] Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/276b39b6b645fb11e345457b503f17b83c2c6fd0.1400538962.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
137 lines
2.7 KiB
C
137 lines
2.7 KiB
C
/*
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* (C) Copyright 2002 Linus Torvalds
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* Portions based on the vdso-randomization code from exec-shield:
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* Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
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*
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* This file contains the needed initializations to support sysenter.
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*/
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/kernel.h>
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#include <linux/mm_types.h>
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#include <asm/cpufeature.h>
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#include <asm/processor.h>
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#include <asm/vdso.h>
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#ifdef CONFIG_COMPAT_VDSO
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#define VDSO_DEFAULT 0
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#else
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#define VDSO_DEFAULT 1
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#endif
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/*
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* Should the kernel map a VDSO page into processes and pass its
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* address down to glibc upon exec()?
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*/
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unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT;
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static int __init vdso32_setup(char *s)
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{
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vdso32_enabled = simple_strtoul(s, NULL, 0);
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if (vdso32_enabled > 1)
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pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
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return 1;
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}
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/*
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* For consistency, the argument vdso32=[012] affects the 32-bit vDSO
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* behavior on both 64-bit and 32-bit kernels.
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* On 32-bit kernels, vdso=[012] means the same thing.
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*/
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__setup("vdso32=", vdso32_setup);
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#ifdef CONFIG_X86_32
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__setup_param("vdso=", vdso_setup, vdso32_setup, 0);
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#endif
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#ifdef CONFIG_X86_64
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#define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SYSENTER32))
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#define vdso32_syscall() (boot_cpu_has(X86_FEATURE_SYSCALL32))
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#else /* CONFIG_X86_32 */
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#define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP))
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#define vdso32_syscall() (0)
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#endif /* CONFIG_X86_64 */
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#if defined(CONFIG_X86_32) || defined(CONFIG_COMPAT)
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const struct vdso_image *selected_vdso32;
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#endif
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int __init sysenter_setup(void)
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{
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#ifdef CONFIG_COMPAT
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if (vdso32_syscall())
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selected_vdso32 = &vdso_image_32_syscall;
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else
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#endif
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if (vdso32_sysenter())
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selected_vdso32 = &vdso_image_32_sysenter;
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else
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selected_vdso32 = &vdso_image_32_int80;
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init_vdso_image(selected_vdso32);
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return 0;
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}
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#ifdef CONFIG_X86_64
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subsys_initcall(sysenter_setup);
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#ifdef CONFIG_SYSCTL
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/* Register vsyscall32 into the ABI table */
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#include <linux/sysctl.h>
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static struct ctl_table abi_table2[] = {
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{
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.procname = "vsyscall32",
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.data = &vdso32_enabled,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = proc_dointvec
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},
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{}
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};
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static struct ctl_table abi_root_table2[] = {
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{
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.procname = "abi",
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.mode = 0555,
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.child = abi_table2
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},
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{}
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};
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static __init int ia32_binfmt_init(void)
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{
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register_sysctl_table(abi_root_table2);
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return 0;
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}
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__initcall(ia32_binfmt_init);
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#endif
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#else /* CONFIG_X86_32 */
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struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
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{
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return NULL;
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}
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int in_gate_area(struct mm_struct *mm, unsigned long addr)
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{
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return 0;
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}
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int in_gate_area_no_mm(unsigned long addr)
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{
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return 0;
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}
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#endif /* CONFIG_X86_64 */
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