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Commit 24e4dd97 authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk Committed by Greg Kroah-Hartman
Browse files

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: 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>
Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cf21f58a

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

+1 −0
Original line number Diff line number Diff line
@@ -355,6 +355,7 @@ 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
@@ -335,5 +335,6 @@ 
#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
@@ -403,4 +403,9 @@ 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
@@ -879,10 +879,33 @@ 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
@@ -519,14 +519,22 @@ 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

};