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Date:   Thu, 16 May 2019 16:55:33 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Jiri Kosina" <jkosina@...e.cz>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "David Woodhouse" <dwmw@...zon.co.uk>,
        "Asit Mallick" <asit.k.mallick@...el.com>,
        "Kees Cook" <keescook@...omium.org>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...nel.org>,
        "Andi Kleen" <ak@...ux.intel.com>,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Arjan van de Ven" <arjan@...ux.intel.com>,
        "Andrea Arcangeli" <aarcange@...hat.com>,
        "Tim Chen" <tim.c.chen@...ux.intel.com>,
        "Andy Lutomirski" <luto@...nel.org>,
        "Casey Schaufler" <casey.schaufler@...el.com>,
        "Waiman Long" <longman9394@...il.com>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Jon Masters" <jcm@...hat.com>,
        "Dave Stewart" <david.c.stewart@...el.com>,
        "Josh Poimboeuf" <jpoimboe@...hat.com>,
        "Greg KH" <gregkh@...uxfoundation.org>,
        "Tom Lendacky" <thomas.lendacky@....com>
Subject: [PATCH 3.16 37/86] x86/speculation: Move STIPB/IBPB string
 conditionals out of cpu_show_common()

3.16.68-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Tim Chen <tim.c.chen@...ux.intel.com>

commit a8f76ae41cd633ac00be1b3019b1eb4741be3828 upstream.

The Spectre V2 printout in cpu_show_common() handles conditionals for the
various mitigation methods directly in the sprintf() argument list. That's
hard to read and will become unreadable if more complex decisions need to
be made for a particular method.

Move the conditionals for STIBP and IBPB string selection into helper
functions, so they can be extended later on.

Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: David Woodhouse <dwmw@...zon.co.uk>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Casey Schaufler <casey.schaufler@...el.com>
Cc: Asit Mallick <asit.k.mallick@...el.com>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Jon Masters <jcm@...hat.com>
Cc: Waiman Long <longman9394@...il.com>
Cc: Greg KH <gregkh@...uxfoundation.org>
Cc: Dave Stewart <david.c.stewart@...el.com>
Cc: Kees Cook <keescook@...omium.org>
Link: https://lkml.kernel.org/r/20181125185003.874479208@linutronix.de
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kernel/cpu/bugs.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -821,6 +821,22 @@ static void __init l1tf_select_mitigatio
 
 #ifdef CONFIG_SYSFS
 
+static char *stibp_state(void)
+{
+	if (x86_spec_ctrl_base & SPEC_CTRL_STIBP)
+		return ", STIBP";
+	else
+		return "";
+}
+
+static char *ibpb_state(void)
+{
+	if (boot_cpu_has(X86_FEATURE_USE_IBPB))
+		return ", IBPB";
+	else
+		return "";
+}
+
 static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
 			       char *buf, unsigned int bug)
 {
@@ -839,9 +855,9 @@ static ssize_t cpu_show_common(struct de
 
 	case X86_BUG_SPECTRE_V2:
 		return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled],
-			       boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "",
+			       ibpb_state(),
 			       boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "",
-			       (x86_spec_ctrl_base & SPEC_CTRL_STIBP) ? ", STIBP" : "",
+			       stibp_state(),
 			       boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "",
 			       spectre_v2_module_string());
 

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