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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 258902db14bf1872c35faf2d6919e2020909d26c..8355e79350b79cf8789719d20e48f34497fee93b 100644 (file)
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -378,6 +378,7 @@ 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/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 23a65439c37c22fb4a46c143546bf149f7d874da..a70e9d438042093db1a3512a91245c28aa8ab8f0 100644 (file)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -360,5 +360,6 @@
 #define X86_BUG_CPU_MELTDOWN           X86_BUG(14) /* CPU is affected by meltdown attack and needs kernel page table isolation */
 #define X86_BUG_SPECTRE_V1             X86_BUG(15) /* CPU is affected by Spectre variant 1 attack with conditional branches */
 #define X86_BUG_SPECTRE_V2             X86_BUG(16) /* CPU is affected by Spectre variant 2 attack with indirect branches */
+#define X86_BUG_SPEC_STORE_BYPASS      X86_BUG(17) /* CPU is affected by speculative store bypass attack */
 
 #endif /* _ASM_X86_CPUFEATURES_H */

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 38a8626c894c63deb6494cb1bccf0ecce0e3b63e..59a9f3aa9f7adeb889a7b0979ddcb95e067f9890 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -404,4 +404,9 @@ 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 d5fea0f57c8fd4adaa85eb8793382ba580f73f5b..0a78d38c66ec8e6c768af51ff200fc8d83640e56 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -894,10 +894,33 @@ 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 825964efda1dc3c78aebd37e55dc7e7edad73288..433f14bcab15bc0447f96a3afe954b05e441205c 100644 (file)
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -521,14 +521,22 @@ 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 c816e6f2730cd6e58e4dd98970c418c8a4c8eaec..9546bf2fe31058ba57b7f95e0a990784aff4506b 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -53,6 +53,8 @@ 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);
 
 extern __printf(4, 5)
 struct device *cpu_device_create(struct device *parent, void *drvdata,