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Commit c456442c authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk Committed by Thomas Gleixner
Browse files

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



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: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5cf68754

Documentation/ABI/testing/sysfs-devices-system-cpu

+1 −0
Original line number Diff line number Diff line
@@ -478,6 +478,7 @@ 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

arch/x86/include/asm/cpufeatures.h

+1 −0
Original line number Diff line number Diff line
@@ -363,5 +363,6 @@ 
#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 */

arch/x86/kernel/cpu/bugs.c

+5 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/kernel/cpu/common.c

+23 −0
Original line number Diff line number Diff line
@@ -927,10 +927,33 @@ 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;

drivers/base/cpu.c

+8 −0
Original line number Diff line number Diff line
@@ -534,14 +534,22 @@ 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

};