4.18-stable review patch. If anyone has any objections, please let me know.
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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;