[PATCH stable v4.4 32/52] powerpc64s: Show ori31 availability in spectre_v1 sysfs file not v2

[Michael Ellerman]

commit 6d44acae1937b81cf8115ada8958e04f601f3f2e 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: d6fbe1c55c55 ("powerpc/64s: Wire up cpu_show_spectre_v2()")
Cc: sta...@vger.kernel.org # v4.17+
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
 arch/powerpc/kernel/security.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 202083daebfb..e74057ba2e36 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -118,25 +118,35 @@ 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: ");
@@ -152,9 +162,6 @@ 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;
-- 
2.20.1