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Commit 5765040e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-smep-for-linus' of... 

Merge branch 'x86-smep-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-smep-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, cpu: Enable/disable Supervisor Mode Execution Protection
  x86, cpu: Add SMEP CPU feature in CR4
  x86, cpufeature: Add cpufeature flag for SMEP
parents 08839ff8 de5397ad

Documentation/kernel-parameters.txt

+4 −0
Original line number Diff line number Diff line
@@ -1664,6 +1664,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			noexec=on: enable non-executable mappings (default)

			noexec=off: disable non-executable mappings



	nosmep		[X86]

			Disable SMEP (Supervisor Mode Execution Protection)

			even if it is supported by processor.



	noexec32	[X86-64]

			This affects only 32-bit executables.

			noexec32=on: enable non-executable mappings (default)

arch/x86/include/asm/cpufeature.h

+1 −0
Original line number Diff line number Diff line
@@ -195,6 +195,7 @@ 


/* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 9 */

#define X86_FEATURE_FSGSBASE	(9*32+ 0) /* {RD/WR}{FS/GS}BASE instructions*/

#define X86_FEATURE_SMEP	(9*32+ 7) /* Supervisor Mode Execution Protection */

#define X86_FEATURE_ERMS	(9*32+ 9) /* Enhanced REP MOVSB/STOSB */



#if defined(__KERNEL__) && !defined(__ASSEMBLY__)

arch/x86/include/asm/processor-flags.h

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ 
#define X86_CR4_OSXMMEXCPT 0x00000400 /* enable unmasked SSE exceptions */

#define X86_CR4_VMXE	0x00002000 /* enable VMX virtualization */

#define X86_CR4_OSXSAVE 0x00040000 /* enable xsave and xrestore */

#define X86_CR4_SMEP	0x00100000 /* enable SMEP support */



/*

 * x86-64 Task Priority Register, CR8

arch/x86/kernel/cpu/common.c

+23 −0
Original line number Diff line number Diff line
@@ -254,6 +254,25 @@ static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c) 
}

#endif



static int disable_smep __initdata;

static __init int setup_disable_smep(char *arg)

{

	disable_smep = 1;

	return 1;

}

__setup("nosmep", setup_disable_smep);



static __init void setup_smep(struct cpuinfo_x86 *c)

{

	if (cpu_has(c, X86_FEATURE_SMEP)) {

		if (unlikely(disable_smep)) {

			setup_clear_cpu_cap(X86_FEATURE_SMEP);

			clear_in_cr4(X86_CR4_SMEP);

		} else

			set_in_cr4(X86_CR4_SMEP);

	}

}



/*

 * Some CPU features depend on higher CPUID levels, which may not always

 * be available due to CPUID level capping or broken virtualization
@@ -667,6 +686,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) 
	c->cpu_index = 0;

#endif

	filter_cpuid_features(c, false);



	setup_smep(c);

}



void __init early_cpu_init(void)
@@ -752,6 +773,8 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c) 
#endif

	}



	setup_smep(c);



	get_model_name(c); /* Default name */



	detect_nopl(c);