x86/speculation: Move STIPB/IBPB string conditionals out of cpu_show_common()

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>
Link: https://lkml.kernel.org/r/20181125185003.874479208@linutronix.de
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 7b47cdf..64e5f64 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -850,6 +850,22 @@ 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)
 {
@@ -868,9 +884,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
 
        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());