x86: kexec: Use one page table in x86_64 machine_kexec
Impact: reduce kernel BSS size by 7 pages, improve code readability
Two page tables are used in current x86_64 kexec implementation. One
is used to jump from kernel virtual address to identity map address,
the other is used to map all physical memory. In fact, on x86_64,
there is no conflict between kernel virtual address space and physical
memory space, so just one page table is sufficient. The page table
pages used to map control page are dynamically allocated to save
memory if kexec image is not loaded. ASM code used to map control page
is replaced by C code too.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index c61d8b2..0ceb6d1 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -9,23 +9,8 @@
# define PAGES_NR 4
#else
# define PA_CONTROL_PAGE 0
-# define VA_CONTROL_PAGE 1
-# define PA_PGD 2
-# define VA_PGD 3
-# define PA_PUD_0 4
-# define VA_PUD_0 5
-# define PA_PMD_0 6
-# define VA_PMD_0 7
-# define PA_PTE_0 8
-# define VA_PTE_0 9
-# define PA_PUD_1 10
-# define VA_PUD_1 11
-# define PA_PMD_1 12
-# define VA_PMD_1 13
-# define PA_PTE_1 14
-# define VA_PTE_1 15
-# define PA_TABLE_PAGE 16
-# define PAGES_NR 17
+# define PA_TABLE_PAGE 1
+# define PAGES_NR 2
#endif
#ifdef CONFIG_X86_32
@@ -157,9 +142,9 @@
unsigned long start_address) ATTRIB_NORET;
#endif
-#ifdef CONFIG_X86_32
#define ARCH_HAS_KIMAGE_ARCH
+#ifdef CONFIG_X86_32
struct kimage_arch {
pgd_t *pgd;
#ifdef CONFIG_X86_PAE
@@ -169,6 +154,12 @@
pte_t *pte0;
pte_t *pte1;
};
+#else
+struct kimage_arch {
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+};
#endif
#endif /* __ASSEMBLY__ */