linux-kernel - [PATCH 2/7] x86/entry: Move PTI_USER_* to arch/x86/include/asm/processor-flags.h

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Message-Id: <20220511072747.3960-3-jiangshanlai@gmail.com>
Date:   Wed, 11 May 2022 15:27:42 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        Lai Jiangshan <jiangshan.ljs@...group.com>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Pasha Tatashin <pasha.tatashin@...een.com>
Subject: [PATCH 2/7] x86/entry: Move PTI_USER_* to arch/x86/include/asm/processor-flags.h

From: Lai Jiangshan <jiangshan.ljs@...group.com>

These constants will be also used in C file.

Move them to arch/x86/include/asm/processor-flags.h which already has
a kin X86_CR3_PTI_PCID_USER_BIT defined in it.

Remove PTI_PGTABLE_SWITCH_BIT and replace it with PTI_USER_PGTABLE_BIT
since they are the same in meaning and value.

Remove kernel_to_user_p4dp() and user_to_kernel_p4dp() since they
are using the removed PTI_PGTABLE_SWITCH_BIT and they have no caller.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
---
 arch/x86/entry/calling.h               | 10 ----------
 arch/x86/include/asm/pgtable.h         | 23 +++--------------------
 arch/x86/include/asm/processor-flags.h | 15 +++++++++++++++
 3 files changed, 18 insertions(+), 30 deletions(-)

diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h
index a97cc78ecb92..f0f60810aee7 100644
--- a/arch/x86/entry/calling.h
+++ b/arch/x86/entry/calling.h
@@ -142,16 +142,6 @@ For 32-bit we have the following conventions - kernel is built with
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 
-/*
- * PAGE_TABLE_ISOLATION PGDs are 8k.  Flip bit 12 to switch between the two
- * halves:
- */
-#define PTI_USER_PGTABLE_BIT		PAGE_SHIFT
-#define PTI_USER_PGTABLE_MASK		(1 << PTI_USER_PGTABLE_BIT)
-#define PTI_USER_PCID_BIT		X86_CR3_PTI_PCID_USER_BIT
-#define PTI_USER_PCID_MASK		(1 << PTI_USER_PCID_BIT)
-#define PTI_USER_PGTABLE_AND_PCID_MASK  (PTI_USER_PCID_MASK | PTI_USER_PGTABLE_MASK)
-
 .macro SET_NOFLUSH_BIT	reg:req
 	bts	$X86_CR3_PCID_NOFLUSH_BIT, \reg
 .endm
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 62ab07e24aef..19095f7a0840 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -5,6 +5,7 @@
 #include <linux/mem_encrypt.h>
 #include <asm/page.h>
 #include <asm/pgtable_types.h>
+#include <asm/processor-flags.h>
 
 /*
  * Macro to mark a page protection value as UC-
@@ -1191,14 +1192,6 @@ static inline bool pgdp_maps_userspace(void *__ptr)
 static inline int pgd_large(pgd_t pgd) { return 0; }
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
-/*
- * All top-level PAGE_TABLE_ISOLATION page tables are order-1 pages
- * (8k-aligned and 8k in size).  The kernel one is at the beginning 4k and
- * the user one is in the last 4k.  To switch between them, you
- * just need to flip the 12th bit in their addresses.
- */
-#define PTI_PGTABLE_SWITCH_BIT	PAGE_SHIFT
-
 /*
  * This generates better code than the inline assembly in
  * __set_bit().
@@ -1220,22 +1213,12 @@ static inline void *ptr_clear_bit(void *ptr, int bit)
 
 static inline pgd_t *kernel_to_user_pgdp(pgd_t *pgdp)
 {
-	return ptr_set_bit(pgdp, PTI_PGTABLE_SWITCH_BIT);
+	return ptr_set_bit(pgdp, PTI_USER_PGTABLE_BIT);
 }
 
 static inline pgd_t *user_to_kernel_pgdp(pgd_t *pgdp)
 {
-	return ptr_clear_bit(pgdp, PTI_PGTABLE_SWITCH_BIT);
-}
-
-static inline p4d_t *kernel_to_user_p4dp(p4d_t *p4dp)
-{
-	return ptr_set_bit(p4dp, PTI_PGTABLE_SWITCH_BIT);
-}
-
-static inline p4d_t *user_to_kernel_p4dp(p4d_t *p4dp)
-{
-	return ptr_clear_bit(p4dp, PTI_PGTABLE_SWITCH_BIT);
+	return ptr_clear_bit(pgdp, PTI_USER_PGTABLE_BIT);
 }
 #endif /* CONFIG_PAGE_TABLE_ISOLATION */
 
diff --git a/arch/x86/include/asm/processor-flags.h b/arch/x86/include/asm/processor-flags.h
index 02c2cbda4a74..4dd2fbbc861a 100644
--- a/arch/x86/include/asm/processor-flags.h
+++ b/arch/x86/include/asm/processor-flags.h
@@ -4,6 +4,7 @@
 
 #include <uapi/asm/processor-flags.h>
 #include <linux/mem_encrypt.h>
+#include <asm/page_types.h>
 
 #ifdef CONFIG_VM86
 #define X86_VM_MASK	X86_EFLAGS_VM
@@ -50,7 +51,21 @@
 #endif
 
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
+
 # define X86_CR3_PTI_PCID_USER_BIT	11
+
+#ifdef CONFIG_X86_64
+/*
+ * PAGE_TABLE_ISOLATION PGDs are 8k.  Flip bit 12 to switch between the two
+ * halves:
+ */
+#define PTI_USER_PGTABLE_BIT		PAGE_SHIFT
+#define PTI_USER_PGTABLE_MASK		(1 << PTI_USER_PGTABLE_BIT)
+#define PTI_USER_PCID_BIT		X86_CR3_PTI_PCID_USER_BIT
+#define PTI_USER_PCID_MASK		(1 << PTI_USER_PCID_BIT)
+#define PTI_USER_PGTABLE_AND_PCID_MASK  (PTI_USER_PCID_MASK | PTI_USER_PGTABLE_MASK)
+#endif
+
 #endif
 
 #endif /* _ASM_X86_PROCESSOR_FLAGS_H */
-- 
2.19.1.6.gb485710b