diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 27978f249016f80eb1dbe2c0037e9cc9022d2d4f..68f978beefac16a337f11fb684c5c6b15ae17483 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -596,6 +596,43 @@ void dup_userfaultfd_complete(struct list_head *fcs)
}
}
+void mremap_userfaultfd_prep(struct vm_area_struct *vma,
+ struct vm_userfaultfd_ctx *vm_ctx)
+{
+ struct userfaultfd_ctx *ctx;
+
+ ctx = vma->vm_userfaultfd_ctx.ctx;
+ if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) {
+ vm_ctx->ctx = ctx;
+ userfaultfd_ctx_get(ctx);
+ }
+}
+
+void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx vm_ctx,
+ unsigned long from, unsigned long to,
+ unsigned long len)
+{
+ struct userfaultfd_ctx *ctx = vm_ctx.ctx;
+ struct userfaultfd_wait_queue ewq;
+
+ if (!ctx)
+ return;
+
+ if (to & ~PAGE_MASK) {
+ userfaultfd_ctx_put(ctx);
+ return;
+ }
+
+ msg_init(&ewq.msg);
+
+ ewq.msg.event = UFFD_EVENT_REMAP;
+ ewq.msg.arg.remap.from = from;
+ ewq.msg.arg.remap.to = to;
+ ewq.msg.arg.remap.len = len;
+
+ userfaultfd_event_wait_completion(ctx, &ewq);
+}
+
static int userfaultfd_release(struct inode *inode, struct file *file)
{
struct userfaultfd_ctx *ctx = file->private_data;
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index 79002bca1f43650ab4fddd1f25a67ebeed7680ab..7f318a46044b0a88d88023efcee12841978524bd 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -55,6 +55,12 @@ static inline bool userfaultfd_armed(struct vm_area_struct *vma)
extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
extern void dup_userfaultfd_complete(struct list_head *);
+extern void mremap_userfaultfd_prep(struct vm_area_struct *,
+ struct vm_userfaultfd_ctx *);
+extern void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx,
+ unsigned long from, unsigned long to,
+ unsigned long len);
+
#else /* CONFIG_USERFAULTFD */
/* mm helpers */
@@ -89,6 +95,17 @@ static inline void dup_userfaultfd_complete(struct list_head *l)
{
}
+static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
+ struct vm_userfaultfd_ctx *ctx)
+{
+}
+
+static inline void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx ctx,
+ unsigned long from,
+ unsigned long to,
+ unsigned long len)
+{
+}
#endif /* CONFIG_USERFAULTFD */
#endif /* _LINUX_USERFAULTFD_K_H */
diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index c8953c84fdcc522b43a2315c8528ff08a6323830..79a85e5bd3880d47906dffb476e9a3dbf3019936 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -18,7 +18,8 @@
* means the userland is reading).
*/
#define UFFD_API ((__u64)0xAA)
-#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK)
+#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \
+ UFFD_FEATURE_EVENT_REMAP)
#define UFFD_API_IOCTLS \
((__u64)1 << _UFFDIO_REGISTER | \
(__u64)1 << _UFFDIO_UNREGISTER | \
@@ -76,6 +77,12 @@ struct uffd_msg {
__u32 ufd;
} fork;
+ struct {
+ __u64 from;
+ __u64 to;
+ __u64 len;
+ } remap;
+
struct {
/* unused reserved fields */
__u64 reserved1;
@@ -90,6 +97,7 @@ struct uffd_msg {
*/
#define UFFD_EVENT_PAGEFAULT 0x12
#define UFFD_EVENT_FORK 0x13
+#define UFFD_EVENT_REMAP 0x14
/* flags for UFFD_EVENT_PAGEFAULT */
#define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */
@@ -110,6 +118,7 @@ struct uffdio_api {
*/
#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
#define UFFD_FEATURE_EVENT_FORK (1<<1)
+#define UFFD_FEATURE_EVENT_REMAP (1<<2)
__u64 features;
__u64 ioctls;
diff --git a/mm/mremap.c b/mm/mremap.c
index 30d7d2482eea1d04cf72b03bcd54d1d293f666e4..504b560c013cb813ad1052757a9ff6183da7fc58 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -22,6 +22,7 @@
#include <linux/mmu_notifier.h>
#include <linux/uaccess.h>
#include <linux/mm-arch-hooks.h>
+#include <linux/userfaultfd_k.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
@@ -250,7 +251,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
static unsigned long move_vma(struct vm_area_struct *vma,
unsigned long old_addr, unsigned long old_len,
- unsigned long new_len, unsigned long new_addr, bool *locked)
+ unsigned long new_len, unsigned long new_addr,
+ bool *locked, struct vm_userfaultfd_ctx *uf)
{
struct mm_struct *mm = vma->vm_mm;
struct vm_area_struct *new_vma;
@@ -309,6 +311,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
old_addr = new_addr;
new_addr = err;
} else {
+ mremap_userfaultfd_prep(new_vma, uf);
arch_remap(mm, old_addr, old_addr + old_len,
new_addr, new_addr + new_len);
}
@@ -413,7 +416,8 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
}
static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
- unsigned long new_addr, unsigned long new_len, bool *locked)
+ unsigned long new_addr, unsigned long new_len, bool *locked,
+ struct vm_userfaultfd_ctx *uf)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
@@ -458,7 +462,7 @@ static unsigned long mremap_to(unsigned long addr, unsigned long old_len,
if (offset_in_page(ret))
goto out1;
- ret = move_vma(vma, addr, old_len, new_len, new_addr, locked);
+ ret = move_vma(vma, addr, old_len, new_len, new_addr, locked, uf);
if (!(offset_in_page(ret)))
goto out;
out1:
@@ -497,6 +501,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
unsigned long ret = -EINVAL;
unsigned long charged = 0;
bool locked = false;
+ struct vm_userfaultfd_ctx uf = NULL_VM_UFFD_CTX;
if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
return ret;
@@ -523,7 +528,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
if (flags & MREMAP_FIXED) {
ret = mremap_to(addr, old_len, new_addr, new_len,
- &locked);
+ &locked, &uf);
goto out;
}
@@ -592,7 +597,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
goto out;
}
- ret = move_vma(vma, addr, old_len, new_len, new_addr, &locked);
+ ret = move_vma(vma, addr, old_len, new_len, new_addr,
+ &locked, &uf);
}
out:
if (offset_in_page(ret)) {
@@ -602,5 +608,6 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
up_write(¤t->mm->mmap_sem);
if (locked && new_len > old_len)
mm_populate(new_addr + old_len, new_len - old_len);
+ mremap_userfaultfd_complete(uf, addr, new_addr, old_len);
return ret;
}