[PATCH v6 3/7] mseal, system mappings: enable x86-64

[jeffxu]

From: Jeff Xu <jef...@chromium.org>

Provide support for CONFIG_MSEAL_SYSTEM_MAPPINGS on x86-64,
covering the vdso, vvar, vvar_vclock.

Production release testing passes on Android and Chrome OS.

Signed-off-by: Jeff Xu <jef...@chromium.org>
---
 arch/x86/Kconfig          |  1 +
 arch/x86/entry/vdso/vma.c | 16 ++++++++++------
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 87198d957e2f..8fa17032ca46 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -26,6 +26,7 @@ config X86_64
        depends on 64BIT
        # Options that are inherently 64-bit kernel only:
        select ARCH_HAS_GIGANTIC_PAGE
+       select ARCH_HAS_MSEAL_SYSTEM_MAPPINGS
        select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
        select ARCH_SUPPORTS_PER_VMA_LOCK
        select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 39e6efc1a9ca..54677964d0b5 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -247,6 +247,7 @@ static int map_vdso(const struct vdso_image *image, 
unsigned long addr)
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        unsigned long text_start;
+       unsigned long vm_flags;
        int ret = 0;
 
        if (mmap_write_lock_killable(mm))
@@ -264,11 +265,12 @@ static int map_vdso(const struct vdso_image *image, 
unsigned long addr)
        /*
         * MAYWRITE to allow gdb to COW and set breakpoints
         */
+       vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC;
+       vm_flags |= MSEAL_SYSTEM_MAPPINGS_VM_FLAG;
        vma = _install_special_mapping(mm,
                                       text_start,
                                       image->size,
-                                      VM_READ|VM_EXEC|
-                                      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+                                      vm_flags,
                                       &vdso_mapping);
 
        if (IS_ERR(vma)) {
@@ -276,11 +278,12 @@ static int map_vdso(const struct vdso_image *image, 
unsigned long addr)
                goto up_fail;
        }
 
+       vm_flags = VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|VM_PFNMAP;
+       vm_flags |= MSEAL_SYSTEM_MAPPINGS_VM_FLAG;
        vma = _install_special_mapping(mm,
                                       addr,
                                       (__VVAR_PAGES - VDSO_NR_VCLOCK_PAGES) * 
PAGE_SIZE,
-                                      VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
-                                      VM_PFNMAP,
+                                      vm_flags,
                                       &vvar_mapping);
 
        if (IS_ERR(vma)) {
@@ -289,11 +292,12 @@ static int map_vdso(const struct vdso_image *image, 
unsigned long addr)
                goto up_fail;
        }
 
+       vm_flags = VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|VM_PFNMAP;
+       vm_flags |= MSEAL_SYSTEM_MAPPINGS_VM_FLAG;
        vma = _install_special_mapping(mm,
                                       addr + (__VVAR_PAGES - 
VDSO_NR_VCLOCK_PAGES) * PAGE_SIZE,
                                       VDSO_NR_VCLOCK_PAGES * PAGE_SIZE,
-                                      VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
-                                      VM_PFNMAP,
+                                      vm_flags,
                                       &vvar_vclock_mapping);
 
        if (IS_ERR(vma)) {
-- 
2.48.1.601.g30ceb7b040-goog