[RFC][PATCH 11/24] x86/mm: Add kernel shadow stack permission macros

[Dave Hansen]

Add PAGE_KERNEL* macros for kernel-permission shadow stacks. These allow
shadow stack mappings to be established in a visually similar way to
existing PAGE_KERNEL* users.

---

 b/arch/x86/include/asm/pgtable_types.h |    2 ++
 1 file changed, 2 insertions(+)

diff -puN arch/x86/include/asm/pgtable_types.h~PAGE_KERNEL_SHSTK arch/x86/include/asm/pgtable_types.h
--- a/arch/x86/include/asm/pgtable_types.h~PAGE_KERNEL_SHSTK	2026-10-21 12:36:37.794880805 -0700
+++ b/arch/x86/include/asm/pgtable_types.h	2026-10-21 12:36:37.797880811 -0700
@@ -224,6 +224,7 @@ enum page_cache_mode {
 #define __PAGE_KERNEL_ROX	 (__PP|   0|   0|___A|   0|   0|   0|___G)
 #define __PAGE_KERNEL		 (__PP|__RW|   0|___A|__NX|___D|   0|___G)
 #define __PAGE_KERNEL_EXEC	 (__PP|__RW|   0|___A|   0|___D|   0|___G)
+#define __PAGE_KERNEL_SHSTK	 (__PP|   0|   0|___A|__NX|___D|   0|___G)
 #define __PAGE_KERNEL_NOCACHE	 (__PP|__RW|   0|___A|__NX|___D|   0|___G| __NC)
 #define __PAGE_KERNEL_VVAR	 (__PP|   0|_USR|___A|__NX|   0|   0|___G)
 #define __PAGE_KERNEL_LARGE	 (__PP|__RW|   0|___A|__NX|___D|_PSE|___G)
@@ -249,6 +250,7 @@ enum page_cache_mode {
 #define PAGE_KERNEL_RO		__pgprot_mask(__PAGE_KERNEL_RO         | _ENC)
 #define PAGE_KERNEL_EXEC	__pgprot_mask(__PAGE_KERNEL_EXEC       | _ENC)
 #define PAGE_KERNEL_EXEC_NOENC	__pgprot_mask(__PAGE_KERNEL_EXEC       |    0)
+#define PAGE_KERNEL_SHSTK	__pgprot_mask(__PAGE_KERNEL_SHSTK      | _ENC)
 #define PAGE_KERNEL_ROX		__pgprot_mask(__PAGE_KERNEL_ROX        | _ENC)
 #define PAGE_KERNEL_NOCACHE	__pgprot_mask(__PAGE_KERNEL_NOCACHE    | _ENC)
 #define PAGE_KERNEL_LARGE	__pgprot_mask(__PAGE_KERNEL_LARGE      | _ENC)
_