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Subject[PATCH -mm 1/2] kexec/i386: kexec page table code clean up - add arch_kimage
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This patch add an architecture specific struct arch_kimage into struct
kimage. Three pointers to page table pages used by kexec are added to
struct arch_kimage. 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: Huang Ying <ying.huang@intel.com>

---
arch/x86/kernel/machine_kexec_32.c | 68 +++++++++++++++++++++++++------------
include/asm-x86/kexec_32.h | 12 ++++++
include/linux/kexec.h | 4 ++
3 files changed, 63 insertions(+), 21 deletions(-)

--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -11,6 +11,7 @@
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/numa.h>
+#include <linux/gfp.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
@@ -21,15 +22,6 @@
#include <asm/desc.h>
#include <asm/system.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 Xgt_desc_struct curidt;
@@ -72,6 +64,28 @@ static void load_segments(void)
#undef __STR
}

+static void alloc_page_tables(struct kimage *image)
+{
+ image->arch_kimage.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL);
+#ifdef CONFIG_X86_PAE
+ image->arch_kimage.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
+ image->arch_kimage.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);
+#endif
+ image->arch_kimage.pte0 = (pte_t *)get_zeroed_page(GFP_KERNEL);
+ image->arch_kimage.pte1 = (pte_t *)get_zeroed_page(GFP_KERNEL);
+}
+
+static void free_page_tables(struct kimage *image)
+{
+ free_page((unsigned long)image->arch_kimage.pgd);
+#ifdef CONFIG_X86_PAE
+ free_page((unsigned long)image->arch_kimage.pmd0);
+ free_page((unsigned long)image->arch_kimage.pmd1);
+#endif
+ free_page((unsigned long)image->arch_kimage.pte0);
+ free_page((unsigned long)image->arch_kimage.pte1);
+}
+
/*
* A architecture hook called to validate the
* proposed image and prepare the control pages
@@ -83,10 +97,21 @@ static void load_segments(void)
* reboot code buffer to allow us to avoid allocations
* later.
*
- * Currently nothing.
+ * - Allocate page tables
*/
int machine_kexec_prepare(struct kimage *image)
{
+ alloc_page_tables(image);
+ if (!image->arch_kimage.pgd ||
+#ifdef CONFIG_X86_PAE
+ !image->arch_kimage.pmd0 ||
+ !image->arch_kimage.pmd1 ||
+#endif
+ !image->arch_kimage.pte0 ||
+ !image->arch_kimage.pte1) {
+ free_page_tables(image);
+ return -ENOMEM;
+ }
return 0;
}

@@ -96,6 +121,7 @@ int machine_kexec_prepare(struct kimage
*/
void machine_kexec_cleanup(struct kimage *image)
{
+ free_page_tables(image);
}

/*
@@ -115,18 +141,18 @@ NORET_TYPE void machine_kexec(struct kim

page_list[PA_CONTROL_PAGE] = __pa(control_page);
page_list[VA_CONTROL_PAGE] = (unsigned long)relocate_kernel;
- page_list[PA_PGD] = __pa(kexec_pgd);
- page_list[VA_PGD] = (unsigned long)kexec_pgd;
+ page_list[PA_PGD] = __pa(image->arch_kimage.pgd);
+ page_list[VA_PGD] = (unsigned long)image->arch_kimage.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;
-#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_PMD_0] = __pa(image->arch_kimage.pmd0);
+ page_list[VA_PMD_0] = (unsigned long)image->arch_kimage.pmd0;
+ page_list[PA_PMD_1] = __pa(image->arch_kimage.pmd1);
+ page_list[VA_PMD_1] = (unsigned long)image->arch_kimage.pmd1;
+#endif
+ page_list[PA_PTE_0] = __pa(image->arch_kimage.pte0);
+ page_list[VA_PTE_0] = (unsigned long)image->arch_kimage.pte0;
+ page_list[PA_PTE_1] = __pa(image->arch_kimage.pte1);
+ page_list[VA_PTE_1] = (unsigned long)image->arch_kimage.pte1;

/* The segment registers are funny things, they have both a
* visible and an invisible part. Whenever the visible part is
--- a/include/asm-x86/kexec_32.h
+++ b/include/asm-x86/kexec_32.h
@@ -94,6 +94,18 @@ relocate_kernel(unsigned long indirectio
unsigned long start_address,
unsigned int has_pae) ATTRIB_NORET;

+#define ARCH_HAS_ARCH_KIMAGE
+
+struct arch_kimage {
+ pgd_t *pgd;
+#ifdef CONFIG_X86_PAE
+ pmd_t *pmd0;
+ pmd_t *pmd1;
+#endif
+ pte_t *pte0;
+ pte_t *pte1;
+};
+
#endif /* __ASSEMBLY__ */

#endif /* _I386_KEXEC_H */
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -98,6 +98,10 @@ struct kimage {
unsigned int type : 1;
#define KEXEC_TYPE_DEFAULT 0
#define KEXEC_TYPE_CRASH 1
+
+#ifdef ARCH_HAS_ARCH_KIMAGE
+ struct arch_kimage arch_kimage;
+#endif
};




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