Commit 2eefd878 authored by Dmitry Safonov's avatar Dmitry Safonov Committed by Thomas Gleixner

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.comSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 576ebfef
......@@ -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)
{
......
......@@ -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 */
......@@ -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 */
......@@ -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;
......
......@@ -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,
......
......@@ -3063,6 +3063,14 @@ static struct vm_area_struct *__install_special_mapping(
return ERR_PTR(ret);
}
bool vma_is_special_mapping(const struct vm_area_struct *vma,
const struct vm_special_mapping *sm)
{
return vma->vm_private_data == sm &&
(vma->vm_ops == &special_mapping_vmops ||
vma->vm_ops == &legacy_special_mapping_vmops);
}
/*
* Called with mm->mmap_sem held for writing.
* Insert a new vma covering the given region, with the given flags.
......
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