linux-kernel - [PATCH 1/6] arch: x86: Don't use TIF flags for mm context

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Date:   Tue, 28 Jul 2020 16:22:24 -0400
From:   Gabriel Krisman Bertazi <krisman@...labora.com>
To:     luto@...nel.org, tglx@...utronix.de
Cc:     keescook@...omium.org, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Gabriel Krisman Bertazi <krisman@...labora.com>,
        kernel@...labora.com
Subject: [PATCH 1/6] arch: x86: Don't use TIF flags for mm context

TIF_IA32 and TIF_X32 are going away.  Create a dedicated enum for the
MM context.

Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>
---
 arch/x86/include/asm/mmu_context.h | 2 +-
 arch/x86/include/asm/thread_info.h | 6 ++++++
 arch/x86/kernel/process_64.c       | 4 ++--
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 47562147e70b..055ee5d66b41 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -178,7 +178,7 @@ static inline void arch_exit_mmap(struct mm_struct *mm)
 static inline bool is_64bit_mm(struct mm_struct *mm)
 {
 	return	!IS_ENABLED(CONFIG_IA32_EMULATION) ||
-		!(mm->context.ia32_compat == TIF_IA32);
+		!(mm->context.ia32_compat == PSABI_IA32);
 }
 #else
 static inline bool is_64bit_mm(struct mm_struct *mm)
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 267701ae3d86..934aa15b20f2 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -53,6 +53,12 @@ struct task_struct;
 #include <asm/cpufeature.h>
 #include <linux/atomic.h>
 
+enum {
+	PSABI_IA64 = 0,
+	PSABI_IA32 = 1,
+	PSABI_X32  = 2
+};
+
 struct thread_info {
 	unsigned long		flags;		/* low level flags */
 	u32			status;		/* thread synchronous flags */
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 9a97415b2139..4452a35402f9 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -557,7 +557,7 @@ static void __set_personality_x32(void)
 	clear_thread_flag(TIF_IA32);
 	set_thread_flag(TIF_X32);
 	if (current->mm)
-		current->mm->context.ia32_compat = TIF_X32;
+		current->mm->context.ia32_compat = PSABI_X32;
 	current->personality &= ~READ_IMPLIES_EXEC;
 	/*
 	 * in_32bit_syscall() uses the presence of the x32 syscall bit
@@ -578,7 +578,7 @@ static void __set_personality_ia32(void)
 	set_thread_flag(TIF_IA32);
 	clear_thread_flag(TIF_X32);
 	if (current->mm)
-		current->mm->context.ia32_compat = TIF_IA32;
+		current->mm->context.ia32_compat = PSABI_IA32;
 	current->personality |= force_personality32;
 	/* Prepare the first "return" to user space */
 	task_pt_regs(current)->orig_ax = __NR_ia32_execve;
-- 
2.27.0