linux-kernel - [PATCH 3.16 49/76] x86/cpu/bugs: Make retpoline module warning conditional

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Date:   Mon, 12 Mar 2018 03:06:12 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Andi Kleen" <ak@...ux.intel.com>,
        "Borislav Petkov" <bp@...en8.de>,
        "David Woodhouse" <dwmw2@...radead.org>,
        "Thomas Gleixner" <tglx@...utronix.de>
Subject: [PATCH 3.16 49/76] x86/cpu/bugs: Make retpoline module warning
 conditional

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

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

From: Thomas Gleixner <tglx@...utronix.de>

commit e383095c7fe8d218e00ec0f83e4b95ed4e627b02 upstream.

If sysfs is disabled and RETPOLINE not defined:

arch/x86/kernel/cpu/bugs.c:97:13: warning: ‘spectre_v2_bad_module’ defined but not used
[-Wunused-variable]
 static bool spectre_v2_bad_module;

Hide it.

Fixes: caf7501a1b4e ("module/retpoline: Warn about missing retpoline in module")
Reported-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: David Woodhouse <dwmw2@...radead.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/kernel/cpu/bugs.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -156,9 +156,10 @@ static const char *spectre_v2_strings[]
 #define pr_fmt(fmt)     "Spectre V2 : " fmt
 
 static enum spectre_v2_mitigation spectre_v2_enabled = SPECTRE_V2_NONE;
-static bool spectre_v2_bad_module;
 
 #ifdef RETPOLINE
+static bool spectre_v2_bad_module;
+
 bool retpoline_module_ok(bool has_retpoline)
 {
 	if (spectre_v2_enabled == SPECTRE_V2_NONE || has_retpoline)
@@ -168,6 +169,13 @@ bool retpoline_module_ok(bool has_retpol
 	spectre_v2_bad_module = true;
 	return false;
 }
+
+static inline const char *spectre_v2_module_string(void)
+{
+	return spectre_v2_bad_module ? " - vulnerable module loaded" : "";
+}
+#else
+static inline const char *spectre_v2_module_string(void) { return ""; }
 #endif
 
 static void __init spec2_print_if_insecure(const char *reason)
@@ -355,6 +363,6 @@ ssize_t cpu_show_spectre_v2(struct devic
 		return sprintf(buf, "Not affected\n");
 
 	return sprintf(buf, "%s%s\n", spectre_v2_strings[spectre_v2_enabled],
-		       spectre_v2_bad_module ? " - vulnerable module loaded" : "");
+		       spectre_v2_module_string());
 }
 #endif