The following commit has been merged into the timers/core branch of tip:
Commit-ID: 6f74acfde20af1eb2178d0bd846bfd8f50b3be32
Gitweb: https://git.kernel.org/tip/6f74acfde20af1eb2178d0bd846bfd8f50b3be32
Author: Dmitry Safonov <dima@xxxxxxxxxx>
AuthorDate: Tue, 12 Nov 2019 01:27:08
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 14 Jan 2020 12:20:56 +01:00
x86/vdso: Restrict splitting VVAR VMA
Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the
amount of corner-cases to consider while working further on VDSO time
namespace support.
As the offset from timens to VVAR page is computed compile-time, the pages
in VVAR should stay together and not being partically mremap()'ed.
Co-developed-by: Andrei Vagin <avagin@xxxxxxxxxx>
Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191112012724.250792-20-dima@xxxxxxxxxx
---
arch/x86/entry/vdso/vma.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index f593774..76cbe54 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -84,6 +84,18 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
return 0;
}
+static int vvar_mremap(const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ const struct vdso_image *image = new_vma->vm_mm->context.vdso_image;
+ unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+
+ if (new_size != -image->sym_vvar_start)
+ return -EINVAL;
+
+ return 0;
+}
+
static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
struct vm_area_struct *vma, struct vm_fault *vmf)
{
@@ -136,6 +148,7 @@ static const struct vm_special_mapping vdso_mapping = {
static const struct vm_special_mapping vvar_mapping = {
.name = "[vvar]",
.fault = vvar_fault,
+ .mremap = vvar_mremap,
};
/*
|