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Commit 92be3d6b authored by Huang Ying's avatar Huang Ying Committed by Ingo Molnar
Browse files

kexec/i386: allocate page table pages dynamically 



Impact: save .text size when kexec is built in but not loaded

This patch adds an architecture specific struct kimage_arch into
struct kimage. The pointers to page table pages used by kexec are
added to struct kimage_arch. The page tables pages are dynamically
allocated in machine_kexec_prepare instead of statically from BSS
segment. This will save up to 20k memory when kexec image is not
loaded.

Signed-off-by: default avatarHuang Ying <ying.huang@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 31498a01

arch/x86/include/asm/kexec.h

+14 −0
Original line number Diff line number Diff line
@@ -170,6 +170,20 @@ relocate_kernel(unsigned long indirection_page, 
		unsigned long start_address) ATTRIB_NORET;

#endif



#ifdef CONFIG_X86_32

#define ARCH_HAS_KIMAGE_ARCH



struct kimage_arch {

	pgd_t *pgd;

#ifdef CONFIG_X86_PAE

	pmd_t *pmd0;

	pmd_t *pmd1;

#endif

	pte_t *pte0;

	pte_t *pte1;

};

#endif



#endif /* __ASSEMBLY__ */



#endif /* _ASM_X86_KEXEC_H */

arch/x86/kernel/machine_kexec_32.c

+46 −21
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/numa.h>

#include <linux/ftrace.h>

#include <linux/suspend.h>

#include <linux/gfp.h>



#include <asm/pgtable.h>

#include <asm/pgalloc.h>
@@ -25,15 +26,6 @@ 
#include <asm/system.h>

#include <asm/cacheflush.h>



#define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))

static u32 kexec_pgd[1024] PAGE_ALIGNED;

#ifdef CONFIG_X86_PAE

static u32 kexec_pmd0[1024] PAGE_ALIGNED;

static u32 kexec_pmd1[1024] PAGE_ALIGNED;

#endif

static u32 kexec_pte0[1024] PAGE_ALIGNED;

static u32 kexec_pte1[1024] PAGE_ALIGNED;



static void set_idt(void *newidt, __u16 limit)

{

	struct desc_ptr curidt;
@@ -76,6 +68,37 @@ static void load_segments(void) 
#undef __STR

}



static void machine_kexec_free_page_tables(struct kimage *image)

{

	free_page((unsigned long)image->arch.pgd);

#ifdef CONFIG_X86_PAE

	free_page((unsigned long)image->arch.pmd0);

	free_page((unsigned long)image->arch.pmd1);

#endif

	free_page((unsigned long)image->arch.pte0);

	free_page((unsigned long)image->arch.pte1);

}



static int machine_kexec_alloc_page_tables(struct kimage *image)

{

	image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);

#ifdef CONFIG_X86_PAE

	image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);

	image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);

#endif

	image->arch.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);

	image->arch.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);

	if (!image->arch.pgd ||

#ifdef CONFIG_X86_PAE

	    !image->arch.pmd0 || !image->arch.pmd1 ||

#endif

	    !image->arch.pte0 || !image->arch.pte1) {

		machine_kexec_free_page_tables(image);

		return -ENOMEM;

	}

	return 0;

}



/*

 * A architecture hook called to validate the

 * proposed image and prepare the control pages
@@ -87,13 +110,14 @@ static void load_segments(void) 
 * reboot code buffer to allow us to avoid allocations

 * later.

 *

 * Make control page executable.

 * - Make control page executable.

 * - Allocate page tables

 */

int machine_kexec_prepare(struct kimage *image)

{

	if (nx_enabled)

		set_pages_x(image->control_code_page, 1);

	return 0;

	return machine_kexec_alloc_page_tables(image);

}



/*
@@ -104,6 +128,7 @@ void machine_kexec_cleanup(struct kimage *image) 
{

	if (nx_enabled)

		set_pages_nx(image->control_code_page, 1);

	machine_kexec_free_page_tables(image);

}



/*
@@ -150,18 +175,18 @@ void machine_kexec(struct kimage *image) 
	relocate_kernel_ptr = control_page;

	page_list[PA_CONTROL_PAGE] = __pa(control_page);

	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;

	page_list[PA_PGD] = __pa(kexec_pgd);

	page_list[VA_PGD] = (unsigned long)kexec_pgd;

	page_list[PA_PGD] = __pa(image->arch.pgd);

	page_list[VA_PGD] = (unsigned long)image->arch.pgd;

#ifdef CONFIG_X86_PAE

	page_list[PA_PMD_0] = __pa(kexec_pmd0);

	page_list[VA_PMD_0] = (unsigned long)kexec_pmd0;

	page_list[PA_PMD_1] = __pa(kexec_pmd1);

	page_list[VA_PMD_1] = (unsigned long)kexec_pmd1;

	page_list[PA_PMD_0] = __pa(image->arch.pmd0);

	page_list[VA_PMD_0] = (unsigned long)image->arch.pmd0;

	page_list[PA_PMD_1] = __pa(image->arch.pmd1);

	page_list[VA_PMD_1] = (unsigned long)image->arch.pmd1;

#endif

	page_list[PA_PTE_0] = __pa(kexec_pte0);

	page_list[VA_PTE_0] = (unsigned long)kexec_pte0;

	page_list[PA_PTE_1] = __pa(kexec_pte1);

	page_list[VA_PTE_1] = (unsigned long)kexec_pte1;

	page_list[PA_PTE_0] = __pa(image->arch.pte0);

	page_list[VA_PTE_0] = (unsigned long)image->arch.pte0;

	page_list[PA_PTE_1] = __pa(image->arch.pte1);

	page_list[VA_PTE_1] = (unsigned long)image->arch.pte1;



	if (image->type == KEXEC_TYPE_DEFAULT)

		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)

include/linux/kexec.h

+4 −0
Original line number Diff line number Diff line
@@ -100,6 +100,10 @@ struct kimage { 
#define KEXEC_TYPE_DEFAULT 0

#define KEXEC_TYPE_CRASH   1

	unsigned int preserve_context : 1;



#ifdef ARCH_HAS_KIMAGE_ARCH

	struct kimage_arch arch;

#endif

};