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        Kees Cook <keescook@chromium.org>
Subject: [PATCH 4.19 036/139] x86/speculation: Move STIPB/IBPB string conditionals out of cpu_show_common()
Date: Tue,  4 Dec 2018 11:48:37 +0100
Message-Id: <20181204103651.471509429@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

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

From: Tim Chen tim.c.chen@linux.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@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Casey Schaufler <casey.schaufler@intel.com>
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Jon Masters <jcm@redhat.com>
Cc: Waiman Long <longman9394@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Dave Stewart <david.c.stewart@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181125185003.874479208@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 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
@@ -842,6 +842,22 @@ static ssize_t l1tf_show_state(char *buf
 }
 #endif
 
+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)
 {
@@ -863,9 +879,9 @@ 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());