Commit c44c9ec0 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge
Browse files

x86: split NX setup into separate file to limit unstack-protected code 



Move the NX setup into a separate file so that it can be compiled
without stack-protection while leaving the rest of the mm/init code
protected.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
parent b75fe4e5

arch/x86/include/asm/pgtable_types.h

+1 −0
Original line number Diff line number Diff line
@@ -277,6 +277,7 @@ static inline pteval_t pte_flags(pte_t pte) 
typedef struct page *pgtable_t;



extern pteval_t __supported_pte_mask;

extern void set_nx(void);

extern int nx_enabled;



#define pgprot_writecombine	pgprot_writecombine

arch/x86/mm/Makefile

+2 −2
Original line number Diff line number Diff line 
obj-y	:=  init.o init_$(BITS).o fault.o ioremap.o extable.o pageattr.o mmap.o \

	    pat.o pgtable.o physaddr.o gup.o

	    pat.o pgtable.o physaddr.o gup.o setup_nx.o



# Make sure __phys_addr has no stackprotector

nostackp := $(call cc-option, -fno-stack-protector)

CFLAGS_physaddr.o		:= $(nostackp)

CFLAGS_init.o			:= $(nostackp)

CFLAGS_setup_nx.o		:= $(nostackp)



obj-$(CONFIG_SMP)		+= tlb.o

arch/x86/mm/init.c

+0 −63
Original line number Diff line number Diff line
@@ -28,69 +28,6 @@ int direct_gbpages 
#endif

;



int nx_enabled;



#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)

static int disable_nx __cpuinitdata;



/*

 * noexec = on|off

 *

 * Control non-executable mappings for processes.

 *

 * on      Enable

 * off     Disable

 */

static int __init noexec_setup(char *str)

{

	if (!str)

		return -EINVAL;

	if (!strncmp(str, "on", 2)) {

		__supported_pte_mask |= _PAGE_NX;

		disable_nx = 0;

	} else if (!strncmp(str, "off", 3)) {

		disable_nx = 1;

		__supported_pte_mask &= ~_PAGE_NX;

	}

	return 0;

}

early_param("noexec", noexec_setup);

#endif



#ifdef CONFIG_X86_PAE

static void __init set_nx(void)

{

	unsigned int v[4], l, h;



	if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {

		cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);



		if ((v[3] & (1 << 20)) && !disable_nx) {

			rdmsr(MSR_EFER, l, h);

			l |= EFER_NX;

			wrmsr(MSR_EFER, l, h);

			nx_enabled = 1;

			__supported_pte_mask |= _PAGE_NX;

		}

	}

}

#else

static inline void set_nx(void)

{

}

#endif



#ifdef CONFIG_X86_64

void __cpuinit check_efer(void)

{

	unsigned long efer;



	rdmsrl(MSR_EFER, efer);

	if (!(efer & EFER_NX) || disable_nx)

		__supported_pte_mask &= ~_PAGE_NX;

}

#endif



static void __init find_early_table_space(unsigned long end, int use_pse,

					  int use_gbpages)

{

arch/x86/mm/setup_nx.c

0 → 100644
+69 −0
Original line number Diff line number Diff line 
#include <linux/spinlock.h>

#include <linux/errno.h>

#include <linux/init.h>



#include <asm/pgtable.h>



int nx_enabled;



#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)

static int disable_nx __cpuinitdata;



/*

 * noexec = on|off

 *

 * Control non-executable mappings for processes.

 *

 * on      Enable

 * off     Disable

 */

static int __init noexec_setup(char *str)

{

	if (!str)

		return -EINVAL;

	if (!strncmp(str, "on", 2)) {

		__supported_pte_mask |= _PAGE_NX;

		disable_nx = 0;

	} else if (!strncmp(str, "off", 3)) {

		disable_nx = 1;

		__supported_pte_mask &= ~_PAGE_NX;

	}

	return 0;

}

early_param("noexec", noexec_setup);

#endif



#ifdef CONFIG_X86_PAE

void __init set_nx(void)

{

	unsigned int v[4], l, h;



	if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {

		cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);



		if ((v[3] & (1 << 20)) && !disable_nx) {

			rdmsr(MSR_EFER, l, h);

			l |= EFER_NX;

			wrmsr(MSR_EFER, l, h);

			nx_enabled = 1;

			__supported_pte_mask |= _PAGE_NX;

		}

	}

}

#else

void set_nx(void)

{

}

#endif



#ifdef CONFIG_X86_64

void __cpuinit check_efer(void)

{

	unsigned long efer;



	rdmsrl(MSR_EFER, efer);

	if (!(efer & EFER_NX) || disable_nx)

		__supported_pte_mask &= ~_PAGE_NX;

}

#endif

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