[PATCH 4.18 07/22] powerpc64s: Show ori31 availability in spectre_v1 sysfs file not v2

Greg Kroah-Hartman
2018-08-23T09:11:44Z

From: Michael Ellerman <mpe@ellerman.id.au>

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: stable@vger.kernel.org # v4.17+
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/powerpc/kernel/security.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)

--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -117,25 +117,35 @@ ssize_t cpu_show_meltdown(struct device

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 (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");

- if (barrier_nospec_enabled)
- return sprintf(buf, "Mitigation: __user pointer sanitization\n");
+ if (security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31))
+ seq_buf_printf(&s, ", ori31 speculation barrier enabled");

- return sprintf(buf, "Vulnerable\n");
+ 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: ");
@@ -151,9 +161,6 @@ ssize_t cpu_show_spectre_v2(struct devic
} else
seq_buf_printf(&s, "Vulnerable");

- if (ori)
- seq_buf_printf(&s, ", ori31 speculation barrier enabled");
-
seq_buf_printf(&s, "\n");

return s.len;