[RFC PATCH v2 1/6] x86/mm: add a pti_disable entry in mm_context_t

[Willy Tarreau]

This will be set/cleared using arch_prctl() to allow the tasks using
this mm to disable the PTI protection.

Signed-off-by: Willy Tarreau <w@xxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
---
 arch/x86/include/asm/mmu.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 5ff3e8a..c7c2ca1 100644
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -36,6 +36,10 @@
 	/* True if mm supports a task running in 32 bit compatibility mode. */
 	unsigned short ia32_compat;
 #endif
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+	/* True if mm is forced to run with page table isolation disabled */
+	char pti_disable;
+#endif
 
 	struct mutex lock;
 	void __user *vdso;			/* vdso base address */
-- 
1.7.12.1