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Commit 2eefd878 authored by Dmitry Safonov's avatar Dmitry Safonov Committed by Thomas Gleixner
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x86/arch_prctl/vdso: Add ARCH_MAP_VDSO_* 



Add API to change vdso blob type with arch_prctl.
As this is usefull only by needs of CRIU, expose
this interface under CONFIG_CHECKPOINT_RESTORE.

Signed-off-by: default avatarDmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: 0x7f454c46@gmail.com
Cc: oleg@redhat.com
Cc: linux-mm@kvack.org
Cc: gorcunov@openvz.org
Cc: xemul@virtuozzo.com
Link: http://lkml.kernel.org/r/20160905133308.28234-4-dsafonov@virtuozzo.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 576ebfef

arch/x86/entry/vdso/vma.c

+35 −10
Original line number Diff line number Diff line
@@ -176,6 +176,16 @@ static int vvar_fault(const struct vm_special_mapping *sm, 
	return VM_FAULT_SIGBUS;

}



static const struct vm_special_mapping vdso_mapping = {

	.name = "[vdso]",

	.fault = vdso_fault,

	.mremap = vdso_mremap,

};

static const struct vm_special_mapping vvar_mapping = {

	.name = "[vvar]",

	.fault = vvar_fault,

};



/*

 * Add vdso and vvar mappings to current process.

 * @image          - blob to map
@@ -188,16 +198,6 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr) 
	unsigned long text_start;

	int ret = 0;



	static const struct vm_special_mapping vdso_mapping = {

		.name = "[vdso]",

		.fault = vdso_fault,

		.mremap = vdso_mremap,

	};

	static const struct vm_special_mapping vvar_mapping = {

		.name = "[vvar]",

		.fault = vvar_fault,

	};



	if (down_write_killable(&mm->mmap_sem))

		return -EINTR;
@@ -256,6 +256,31 @@ static int map_vdso_randomized(const struct vdso_image *image) 
	return map_vdso(image, addr);

}



int map_vdso_once(const struct vdso_image *image, unsigned long addr)

{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;



	down_write(&mm->mmap_sem);

	/*

	 * Check if we have already mapped vdso blob - fail to prevent

	 * abusing from userspace install_speciall_mapping, which may

	 * not do accounting and rlimit right.

	 * We could search vma near context.vdso, but it's a slowpath,

	 * so let's explicitely check all VMAs to be completely sure.

	 */

	for (vma = mm->mmap; vma; vma = vma->vm_next) {

		if (vma_is_special_mapping(vma, &vdso_mapping) ||

				vma_is_special_mapping(vma, &vvar_mapping)) {

			up_write(&mm->mmap_sem);

			return -EEXIST;

		}

	}

	up_write(&mm->mmap_sem);



	return map_vdso(image, addr);

}



#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)

static int load_vdso32(void)

{

arch/x86/include/asm/vdso.h

+2 −0
Original line number Diff line number Diff line
@@ -41,6 +41,8 @@ extern const struct vdso_image vdso_image_32; 


extern void __init init_vdso_image(const struct vdso_image *image);



extern int map_vdso_once(const struct vdso_image *image, unsigned long addr);



#endif /* __ASSEMBLER__ */



#endif /* _ASM_X86_VDSO_H */

arch/x86/include/uapi/asm/prctl.h

+6 −0
Original line number Diff line number Diff line
@@ -6,4 +6,10 @@ 
#define ARCH_GET_FS 0x1003

#define ARCH_GET_GS 0x1004



#ifdef CONFIG_CHECKPOINT_RESTORE

# define ARCH_MAP_VDSO_X32	0x2001

# define ARCH_MAP_VDSO_32	0x2002

# define ARCH_MAP_VDSO_64	0x2003

#endif



#endif /* _ASM_X86_PRCTL_H */

arch/x86/kernel/process_64.c

+25 −0
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ 
#include <asm/debugreg.h>

#include <asm/switch_to.h>

#include <asm/xen/hypervisor.h>

#include <asm/vdso.h>



asmlinkage extern void ret_from_fork(void);
@@ -524,6 +525,17 @@ void set_personality_ia32(bool x32) 
}

EXPORT_SYMBOL_GPL(set_personality_ia32);



static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr)

{

	int ret;



	ret = map_vdso_once(image, addr);

	if (ret)

		return ret;



	return (long)image->size;

}



long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)

{

	int ret = 0;
@@ -577,6 +589,19 @@ long do_arch_prctl(struct task_struct *task, int code, unsigned long addr) 
		break;

	}



#ifdef CONFIG_CHECKPOINT_RESTORE

#ifdef CONFIG_X86_X32

	case ARCH_MAP_VDSO_X32:

		return prctl_map_vdso(&vdso_image_x32, addr);

#endif

#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION

	case ARCH_MAP_VDSO_32:

		return prctl_map_vdso(&vdso_image_32, addr);

#endif

	case ARCH_MAP_VDSO_64:

		return prctl_map_vdso(&vdso_image_64, addr);

#endif



	default:

		ret = -EINVAL;

		break;

include/linux/mm.h

+2 −0
Original line number Diff line number Diff line
@@ -2019,6 +2019,8 @@ extern struct file *get_task_exe_file(struct task_struct *task); 
extern bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);

extern void vm_stat_account(struct mm_struct *, vm_flags_t, long npages);



extern bool vma_is_special_mapping(const struct vm_area_struct *vma,

				   const struct vm_special_mapping *sm);

extern struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,

				   unsigned long addr, unsigned long len,

				   unsigned long flags,