--- v7
+++ v5
@@ -1,94 +1,68 @@
From: Yu-cheng Yu <yu-cheng.yu@intel.com>
-New processors that support Shadow Stack regard Write=0,Dirty=1 PTEs as
-shadow stack pages.
-
-In normal cases, it can be helpful to create Write=1 PTEs as also Dirty=1
-if HW dirty tracking is not needed, because if the Dirty bit is not already
-set the CPU has to set Dirty=1 when the memory gets written to. This
-creates additional work for the CPU. So traditional wisdom was to simply
-set the Dirty bit whenever you didn't care about it. However, it was never
-really very helpful for read-only kernel memory.
-
-When CR4.CET=1 and IA32_S_CET.SH_STK_EN=1, some instructions can write to
-such supervisor memory. The kernel does not set IA32_S_CET.SH_STK_EN, so
-avoiding kernel Write=0,Dirty=1 memory is not strictly needed for any
-functional reason. But having Write=0,Dirty=1 kernel memory doesn't have
-any functional benefit either, so to reduce ambiguity between shadow stack
-and regular Write=0 pages, remove Dirty=1 from any kernel Write=0 PTEs.
+To prepare the introduction of _PAGE_COW, move pmd_write() and
+pud_write() up in the file, so that they can be used by other
+helpers below. No functional changes.
Tested-by: Pengfei Xu <pengfei.xu@intel.com>
Tested-by: John Allen <john.allen@amd.com>
-Tested-by: Kees Cook <keescook@chromium.org>
-Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
-Co-developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
+Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
-Cc: "H. Peter Anvin" <hpa@zytor.com>
-Cc: Kees Cook <keescook@chromium.org>
-Cc: Thomas Gleixner <tglx@linutronix.de>
-Cc: Dave Hansen <dave.hansen@linux.intel.com>
-Cc: Christoph Hellwig <hch@lst.de>
-Cc: Andy Lutomirski <luto@kernel.org>
-Cc: Ingo Molnar <mingo@redhat.com>
-Cc: Borislav Petkov <bp@alien8.de>
-Cc: Peter Zijlstra <peterz@infradead.org>
+---
+ arch/x86/include/asm/pgtable.h | 24 ++++++++++++------------
+ 1 file changed, 12 insertions(+), 12 deletions(-)
----
-v6:
- - Also remove dirty from newly added set_memory_rox()
-
-v5:
- - Spelling and grammar in commit log (Boris)
-
-v3:
- - Update commit log (Andrew Cooper, Peterz)
-
-v2:
- - Normalize PTE bit descriptions between patches
----
- arch/x86/include/asm/pgtable_types.h | 6 +++---
- arch/x86/mm/pat/set_memory.c | 4 ++--
- 2 files changed, 5 insertions(+), 5 deletions(-)
-
-diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
-index 447d4bee25c4..0646ad00178b 100644
---- a/arch/x86/include/asm/pgtable_types.h
-+++ b/arch/x86/include/asm/pgtable_types.h
-@@ -192,10 +192,10 @@ enum page_cache_mode {
- #define _KERNPG_TABLE (__PP|__RW| 0|___A| 0|___D| 0| 0| _ENC)
- #define _PAGE_TABLE_NOENC (__PP|__RW|_USR|___A| 0|___D| 0| 0)
- #define _PAGE_TABLE (__PP|__RW|_USR|___A| 0|___D| 0| 0| _ENC)
--#define __PAGE_KERNEL_RO (__PP| 0| 0|___A|__NX|___D| 0|___G)
--#define __PAGE_KERNEL_ROX (__PP| 0| 0|___A| 0|___D| 0|___G)
-+#define __PAGE_KERNEL_RO (__PP| 0| 0|___A|__NX| 0| 0|___G)
-+#define __PAGE_KERNEL_ROX (__PP| 0| 0|___A| 0| 0| 0|___G)
- #define __PAGE_KERNEL_NOCACHE (__PP|__RW| 0|___A|__NX|___D| 0|___G| __NC)
--#define __PAGE_KERNEL_VVAR (__PP| 0|_USR|___A|__NX|___D| 0|___G)
-+#define __PAGE_KERNEL_VVAR (__PP| 0|_USR|___A|__NX| 0| 0|___G)
- #define __PAGE_KERNEL_LARGE (__PP|__RW| 0|___A|__NX|___D|_PSE|___G)
- #define __PAGE_KERNEL_LARGE_EXEC (__PP|__RW| 0|___A| 0|___D|_PSE|___G)
- #define __PAGE_KERNEL_WP (__PP|__RW| 0|___A|__NX|___D| 0|___G| __WP)
-diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
-index 356758b7d4b4..1b5c0dc9f32b 100644
---- a/arch/x86/mm/pat/set_memory.c
-+++ b/arch/x86/mm/pat/set_memory.c
-@@ -2073,12 +2073,12 @@ int set_memory_nx(unsigned long addr, int numpages)
-
- int set_memory_ro(unsigned long addr, int numpages)
- {
-- return change_page_attr_clear(&addr, numpages, __pgprot(_PAGE_RW), 0);
-+ return change_page_attr_clear(&addr, numpages, __pgprot(_PAGE_RW | _PAGE_DIRTY), 0);
+diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
+index 0564edd24ffb..b39f16c0d507 100644
+--- a/arch/x86/include/asm/pgtable.h
++++ b/arch/x86/include/asm/pgtable.h
+@@ -160,6 +160,18 @@ static inline int pte_write(pte_t pte)
+ return pte_flags(pte) & _PAGE_RW;
}
- int set_memory_rox(unsigned long addr, int numpages)
++#define pmd_write pmd_write
++static inline int pmd_write(pmd_t pmd)
++{
++ return pmd_flags(pmd) & _PAGE_RW;
++}
++
++#define pud_write pud_write
++static inline int pud_write(pud_t pud)
++{
++ return pud_flags(pud) & _PAGE_RW;
++}
++
+ static inline int pte_huge(pte_t pte)
{
-- pgprot_t clr = __pgprot(_PAGE_RW);
-+ pgprot_t clr = __pgprot(_PAGE_RW | _PAGE_DIRTY);
+ return pte_flags(pte) & _PAGE_PSE;
+@@ -1120,12 +1132,6 @@ extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmdp);
- if (__supported_pte_mask & _PAGE_NX)
- clr.pgprot |= _PAGE_NX;
+
+-#define pmd_write pmd_write
+-static inline int pmd_write(pmd_t pmd)
+-{
+- return pmd_flags(pmd) & _PAGE_RW;
+-}
+-
+ #define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR
+ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, unsigned long addr,
+ pmd_t *pmdp)
+@@ -1155,12 +1161,6 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm,
+ clear_bit(_PAGE_BIT_RW, (unsigned long *)pmdp);
+ }
+
+-#define pud_write pud_write
+-static inline int pud_write(pud_t pud)
+-{
+- return pud_flags(pud) & _PAGE_RW;
+-}
+-
+ #ifndef pmdp_establish
+ #define pmdp_establish pmdp_establish
+ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
--
2.17.1