4.16-stable review patch. If anyone has any objections, please let me know.
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From: Michael Ellerman mpe@ellerman.id.au
commit d6fbe1c55c55c6937cbea3531af7da84ab7473c3 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 --- arch/powerpc/kernel/security.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+)
--- a/arch/powerpc/kernel/security.c +++ b/arch/powerpc/kernel/security.c @@ -58,3 +58,36 @@ ssize_t cpu_show_spectre_v1(struct devic
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; +}