linux-kernel - [PATCH v3 5/7] x86/cpu: Move X86_BUG_ESPFIX initialization to generic

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Message-Id: <0949337f13660461edca08ab67d1a841441289c9.1460075211.git.luto@kernel.org>
Date:	Thu,  7 Apr 2016 17:31:48 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	Borislav Petkov <bp@...en8.de>, security@...nel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Rudolf Marek <r.marek@...embler.cz>,
	Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v3 5/7] x86/cpu: Move X86_BUG_ESPFIX initialization to generic_identify

It was in detect_nopl, which was either a mistake by me or some kind
of mis-merge.

Fixes: ff236456f072 ("x86/cpu: Move X86_BUG_ESPFIX initialization to generic_identify")
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/kernel/cpu/common.c | 50 ++++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index ceef584ae8b0..9ede8aa41f18 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -862,31 +862,6 @@ static void detect_nopl(struct cpuinfo_x86 *c)
 #else
 	set_cpu_cap(c, X86_FEATURE_NOPL);
 #endif
-
-	/*
-	 * ESPFIX is a strange bug.  All real CPUs have it.  Paravirt
-	 * systems that run Linux at CPL > 0 may or may not have the
-	 * issue, but, even if they have the issue, there's absolutely
-	 * nothing we can do about it because we can't use the real IRET
-	 * instruction.
-	 *
-	 * NB: For the time being, only 32-bit kernels support
-	 * X86_BUG_ESPFIX as such.  64-bit kernels directly choose
-	 * whether to apply espfix using paravirt hooks.  If any
-	 * non-paravirt system ever shows up that does *not* have the
-	 * ESPFIX issue, we can change this.
-	 */
-#ifdef CONFIG_X86_32
-#ifdef CONFIG_PARAVIRT
-	do {
-		extern void native_iret(void);
-		if (pv_cpu_ops.iret == native_iret)
-			set_cpu_bug(c, X86_BUG_ESPFIX);
-	} while (0);
-#else
-	set_cpu_bug(c, X86_BUG_ESPFIX);
-#endif
-#endif
 }
 
 static void detect_null_seg_behavior(struct cpuinfo_x86 *c)
@@ -952,6 +927,31 @@ static void generic_identify(struct cpuinfo_x86 *c)
 	detect_nopl(c);
 
 	detect_null_seg_behavior(c);
+
+	/*
+	 * ESPFIX is a strange bug.  All real CPUs have it.  Paravirt
+	 * systems that run Linux at CPL > 0 may or may not have the
+	 * issue, but, even if they have the issue, there's absolutely
+	 * nothing we can do about it because we can't use the real IRET
+	 * instruction.
+	 *
+	 * NB: For the time being, only 32-bit kernels support
+	 * X86_BUG_ESPFIX as such.  64-bit kernels directly choose
+	 * whether to apply espfix using paravirt hooks.  If any
+	 * non-paravirt system ever shows up that does *not* have the
+	 * ESPFIX issue, we can change this.
+	 */
+#ifdef CONFIG_X86_32
+#ifdef CONFIG_PARAVIRT
+	do {
+		extern void native_iret(void);
+		if (pv_cpu_ops.iret == native_iret)
+			set_cpu_bug(c, X86_BUG_ESPFIX);
+	} while (0);
+#else
+	set_cpu_bug(c, X86_BUG_ESPFIX);
+#endif
+#endif
 }
 
 static void x86_init_cache_qos(struct cpuinfo_x86 *c)
-- 
2.5.5