linux-kernel - [PATCH 03/13] x86/cpufeatures, x86/fault: Mark SMAP as disabled when configured out

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Message-Id: <fe93332eded3d702f0b0b4cf83928d6830739ba3.1542667307.git.luto@kernel.org>
Date:   Mon, 19 Nov 2018 14:45:27 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     x86@...nel.org
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 03/13] x86/cpufeatures, x86/fault: Mark SMAP as disabled when configured out

Add X86_FEATURE_SMAP to the disabled features mask as appropriate
and use cpu_feature_enabled() in the fault code.  This lets us get
rid of a redundant IS_ENABLED(CONFIG_X86_SMAP).

Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/include/asm/disabled-features.h | 8 +++++++-
 arch/x86/mm/fault.c                      | 5 +----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index 33833d1909af..a5ea841cc6d2 100644
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -16,6 +16,12 @@
 # define DISABLE_MPX	(1<<(X86_FEATURE_MPX & 31))
 #endif
 
+#ifdef CONFIG_X86_SMAP
+# define DISABLE_SMAP	0
+#else
+# define DISABLE_SMAP	(1<<(X86_FEATURE_SMAP & 31))
+#endif
+
 #ifdef CONFIG_X86_INTEL_UMIP
 # define DISABLE_UMIP	0
 #else
@@ -68,7 +74,7 @@
 #define DISABLED_MASK6	0
 #define DISABLED_MASK7	(DISABLE_PTI)
 #define DISABLED_MASK8	0
-#define DISABLED_MASK9	(DISABLE_MPX)
+#define DISABLED_MASK9	(DISABLE_MPX|DISABLE_SMAP)
 #define DISABLED_MASK10	0
 #define DISABLED_MASK11	0
 #define DISABLED_MASK12	0
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index eae7ee3ce89b..0597342d4a55 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1150,10 +1150,7 @@ static int fault_in_kernel_space(unsigned long address)
 
 static inline bool smap_violation(int error_code, struct pt_regs *regs)
 {
-	if (!IS_ENABLED(CONFIG_X86_SMAP))
-		return false;
-
-	if (!static_cpu_has(X86_FEATURE_SMAP))
+	if (!cpu_feature_enabled(X86_FEATURE_SMAP))
 		return false;
 
 	if (error_code & X86_PF_USER)
-- 
2.17.2