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powerpc/64s: Wire up cpu_show_spectre_v2()

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commit d6fbe1c55c upstream.

Add a definition for cpu_show_spectre_v2() to override the generic
version. This has several permuations, though in practice some may not
occur we cater for any combination.

The most verbose is:

  Mitigation: Indirect branch serialisation (kernel only), Indirect
  branch cache disabled, ori31 speculation barrier enabled

We don't treat the ori31 speculation barrier as a mitigation on its
own, because it has to be *used* by code in order to be a mitigation
and we don't know if userspace is doing that. So if that's all we see
we say:

  Vulnerable, ori31 speculation barrier enabled

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Ellerman
2018-05-26 14:27:44 +10:00
committed by Greg Kroah-Hartman
parent 6e77feadbf
commit 046e9adae4
1 changed files with 33 additions and 0 deletions
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33
arch/powerpc/kernel/security.c
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@@ -58,3 +58,36 @@ ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, c
return sprintf(buf, "Vulnerable\n");
}
ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
{
bool bcs, ccd, ori;
struct seq_buf s;
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: ");
if (bcs)
seq_buf_printf(&s, "Indirect branch serialisation (kernel only)");
if (bcs && ccd)
seq_buf_printf(&s, ", ");
if (ccd)
seq_buf_printf(&s, "Indirect branch cache disabled");
} else
seq_buf_printf(&s, "Vulnerable");
if (ori)
seq_buf_printf(&s, ", ori31 speculation barrier enabled");
seq_buf_printf(&s, "\n");
return s.len;
}