x86/bugs: Expose /sys/../spec_store_bypass

commit c456442cd3a59eeb1d60293c26cbe2ff2c4e42cf upstream.

Add the sysfs file for the new vulerability. It does not do much except
show the words 'Vulnerable' for recent x86 cores.

Intel cores prior to family 6 are known not to be vulnerable, and so are
some Atoms and some Xeon Phi.

It assumes that older Cyrix, Centaur, etc. cores are immune.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16:
 - Renumber X86_BUG_SPEC_STORE_BYPASS
 - Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 49216c96236b557aa8a0198c9eaef3c5732c7efe..41bed89c8ee5d8a353dfc65403c3d674dfc400d6 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -229,6 +229,7 @@ What:               /sys/devices/system/cpu/vulnerabilities
                /sys/devices/system/cpu/vulnerabilities/meltdown
                /sys/devices/system/cpu/vulnerabilities/spectre_v1
                /sys/devices/system/cpu/vulnerabilities/spectre_v2
+               /sys/devices/system/cpu/vulnerabilities/spec_store_bypass
 Date:          January 2018
 Contact:       Linux kernel mailing list <linux-kernel@vger.kernel.org>
 Description:   Information about CPU vulnerabilities

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 8f45ed429ba0d73168fd2c2a4e8c0d9f8047a217..131892535e9a207af08e5e8018d884c474139365 100644 (file)
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -260,6 +260,7 @@
 #define X86_BUG_CPU_MELTDOWN   X86_BUG(5) /* CPU is affected by meltdown attack and needs kernel page table isolation */
 #define X86_BUG_SPECTRE_V1     X86_BUG(6) /* CPU is affected by Spectre variant 1 attack with conditional branches */
 #define X86_BUG_SPECTRE_V2     X86_BUG(7) /* CPU is affected by Spectre variant 2 attack with indirect branches */
+#define X86_BUG_SPEC_STORE_BYPASS X86_BUG(8) /* CPU is affected by speculative store bypass attack */
 
 #if defined(__KERNEL__) && !defined(__ASSEMBLY__)
 

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 7860ad8c6244a43b9d8b821d97f12a14ebafc9e2..f6b502709cd99ee4a9f5c438f898a2ef3bf6a6c3 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -442,4 +442,9 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, c
 {
        return cpu_show_common(dev, attr, buf, X86_BUG_SPECTRE_V2);
 }
+
+ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
+{
+       return cpu_show_common(dev, attr, buf, X86_BUG_SPEC_STORE_BYPASS);
+}
 #endif

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 4705958e02bdf7586a86e951ab48b253c1604a5e..4f12ac97a61bf830b83233a4dfa25c66ccff545d 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -803,10 +803,33 @@ static const __initconst struct x86_cpu_id cpu_no_meltdown[] = {
        {}
 };
 
+static const __initconst struct x86_cpu_id cpu_no_spec_store_bypass[] = {
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_PINEVIEW        },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_LINCROFT        },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_PENWELL         },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_CLOVERVIEW      },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_CEDARVIEW       },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_SILVERMONT1     },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_AIRMONT         },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_SILVERMONT2     },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_ATOM_MERRIFIELD      },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_CORE_YONAH           },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_XEON_PHI_KNL         },
+       { X86_VENDOR_INTEL,     6,      INTEL_FAM6_XEON_PHI_KNM         },
+       { X86_VENDOR_CENTAUR,   5,                                      },
+       { X86_VENDOR_INTEL,     5,                                      },
+       { X86_VENDOR_NSC,       5,                                      },
+       { X86_VENDOR_ANY,       4,                                      },
+       {}
+};
+
 static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 {
        u64 ia32_cap = 0;
 
+       if (!x86_match_cpu(cpu_no_spec_store_bypass))
+               setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS);
+
        if (x86_match_cpu(cpu_no_speculation))
                return;
 

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 9175c84161ec6bfceb0333aaef554a05ddb2450e..ba68d18ac4e9a7b967832959bb6133d80b29fcb6 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -438,14 +438,22 @@ ssize_t __weak cpu_show_spectre_v2(struct device *dev,
        return sprintf(buf, "Not affected\n");
 }
 
+ssize_t __weak cpu_show_spec_store_bypass(struct device *dev,
+                                         struct device_attribute *attr, char *buf)
+{
+       return sprintf(buf, "Not affected\n");
+}
+
 static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
 static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
 static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
+static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);
 
 static struct attribute *cpu_root_vulnerabilities_attrs[] = {
        &dev_attr_meltdown.attr,
        &dev_attr_spectre_v1.attr,
        &dev_attr_spectre_v2.attr,
+       &dev_attr_spec_store_bypass.attr,
        NULL
 };
 

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 0441fa7c20b1ca2d121ffb61377bc0328ec769cd..fabc2bb5d42583f347ab629bbb5a927ebfe9583c 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -45,6 +45,8 @@ extern ssize_t cpu_show_spectre_v1(struct device *dev,
                                   struct device_attribute *attr, char *buf);
 extern ssize_t cpu_show_spectre_v2(struct device *dev,
                                   struct device_attribute *attr, char *buf);
+extern ssize_t cpu_show_spec_store_bypass(struct device *dev,
+                                         struct device_attribute *attr, char *buf);
 
 #ifdef CONFIG_HOTPLUG_CPU
 extern void unregister_cpu(struct cpu *cpu);