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: Huang Ying

---
arch/x86/include/asm/kexec.h | 14 +++++++
arch/x86/kernel/machine_kexec_32.c | 69 +++++++++++++++++++++++++------------
include/linux/kexec.h | 4 ++
3 files changed, 65 insertions(+), 22 deletions(-)

--- a/arch/x86/kernel/machine_kexec_32.c
+++ b/arch/x86/kernel/machine_kexec_32.c
@@ -13,6 +13,7 @@
#include
#include
#include
+#include

#include
#include
@@ -25,15 +26,6 @@
#include
#include

-#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
{
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;
-#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.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(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;
page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) << PAGE_SHIFT);

/* The segment registers are funny things, they have both a
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -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
};


--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -170,6 +170,20 @@ relocate_kernel(unsigned long indirectio
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 */


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