powerpc64s: Show ori31 availability in spectre_v1 sysfs file not v2

BugLink: https://bugs.launchpad.net/bugs/1830176

commit 6d44acae upstream.

When I added the spectre_v2 information in sysfs, I included the
availability of the ori31 speculation barrier.

Although the ori31 barrier can be used to mitigate v2, it's primarily
intended as a spectre v1 mitigation. Spectre v2 is mitigated by
hardware changes.

So rework the sysfs files to show the ori31 information in the
spectre_v1 file, rather than v2.

Currently we display eg:

  $ grep . spectre_v*
  spectre_v1:Mitigation: __user pointer sanitization
  spectre_v2:Mitigation: Indirect branch cache disabled, ori31 speculation barrier enabled

After:

  $ grep . spectre_v*
  spectre_v1:Mitigation: __user pointer sanitization, ori31 speculation barrier enabled
  spectre_v2:Mitigation: Indirect branch cache disabled

Fixes: d6fbe1c5 ("powerpc/64s: Wire up cpu_show_spectre_v2()")
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/kernel/security.c

@@ -119,25 +119,35 @@ ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, cha
 
 ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	if (!security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR))
-		return sprintf(buf, "Not affected\n");
+	struct seq_buf s;
+
+	seq_buf_init(&s, buf, PAGE_SIZE - 1);
 
-	if (barrier_nospec_enabled)
-		return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+	if (security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR)) {
+		if (barrier_nospec_enabled)
+			seq_buf_printf(&s, "Mitigation: __user pointer sanitization");
+		else
+			seq_buf_printf(&s, "Vulnerable");
 
-	return sprintf(buf, "Vulnerable\n");
+		if (security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31))
+			seq_buf_printf(&s, ", ori31 speculation barrier enabled");
+
+		seq_buf_printf(&s, "\n");
+	} else
+		seq_buf_printf(&s, "Not affected\n");
+
+	return s.len;
 }
 
 ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
 {
-	bool bcs, ccd, ori;
 	struct seq_buf s;
+	bool bcs, ccd;
 
 	seq_buf_init(&s, buf, PAGE_SIZE - 1);
 
 	bcs = security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED);
 	ccd = security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED);
-	ori = security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31);
 
 	if (bcs || ccd) {
 		seq_buf_printf(&s, "Mitigation: ");
@@ -153,9 +163,6 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c
 	} else
 		seq_buf_printf(&s, "Vulnerable");
 
-	if (ori)
-		seq_buf_printf(&s, ", ori31 speculation barrier enabled");
-
 	seq_buf_printf(&s, "\n");
 
 	return s.len;