[PATCH v7 20/41] x86/mm: Teach pte_mkwrite() about stack memory
From: Rick Edgecombe <rick.p.edgecombe@intel.com>
Date: 2023-02-27 22:33:33
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
If a VMA has the VM_SHADOW_STACK flag, it is shadow stack memory. So when it is made writable with pte_mkwrite(), it should create shadow stack memory, not conventionally writable memory. Now that pte_mkwrite() takes a VMA, and places where shadow stack memory might be created pass one, pte_mkwrite() can know when it should do this. So make pte_mkwrite() create shadow stack memory when the VMA has the VM_SHADOW_STACK flag. Do the same thing for pmd_mkwrite(). This requires referencing VM_SHADOW_STACK in these functions, which are currently defined in pgtable.h, however mm.h (where VM_SHADOW_STACK is located) can't be pulled in without causing problems for files that reference pgtable.h. So also move pte/pmd_mkwrite() into pgtable.c, where they can safely reference VM_SHADOW_STACK. Tested-by: Pengfei Xu <redacted> Tested-by: John Allen <john.allen@amd.com> Tested-by: Kees Cook <redacted> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Reviewed-by: Kees Cook <redacted> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> --- v6: - New patch --- arch/x86/include/asm/pgtable.h | 20 ++------------------ arch/x86/mm/pgtable.c | 26 ++++++++++++++++++++++++++ 2 files changed, 28 insertions(+), 18 deletions(-)
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 05dfdbdf96b4..d81e7ec27507 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h@@ -456,15 +456,7 @@ static inline pte_t pte_mkwrite_kernel(pte_t pte) struct vm_area_struct; -static inline pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma) -{ - pte = pte_mkwrite_kernel(pte); - - if (pte_dirty(pte)) - pte = pte_clear_saveddirty(pte); - - return pte; -} +pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma); static inline pte_t pte_mkhuge(pte_t pte) {
@@ -601,15 +593,7 @@ static inline pmd_t pmd_mkyoung(pmd_t pmd) return pmd_set_flags(pmd, _PAGE_ACCESSED); } -static inline pmd_t pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) -{ - pmd = pmd_set_flags(pmd, _PAGE_RW); - - if (pmd_dirty(pmd)) - pmd = pmd_clear_saveddirty(pmd); - - return pmd; -} +pmd_t pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma); static inline pud_t pud_set_flags(pud_t pud, pudval_t set) {
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index e4f499eb0f29..98856bcc8102 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c@@ -880,3 +880,29 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) #endif /* CONFIG_X86_64 */ #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */ + +pte_t pte_mkwrite(pte_t pte, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHADOW_STACK) + return pte_mkwrite_shstk(pte); + + pte = pte_mkwrite_kernel(pte); + + if (pte_dirty(pte)) + pte = pte_clear_saveddirty(pte); + + return pte; +} + +pmd_t pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) +{ + if (vma->vm_flags & VM_SHADOW_STACK) + return pmd_mkwrite_shstk(pmd); + + pmd = pmd_set_flags(pmd, _PAGE_RW); + + if (pmd_dirty(pmd)) + pmd = pmd_clear_saveddirty(pmd); + + return pmd; +}
--
2.17.1