i386: Page-align the GDT From: Jeremy Fitzhardinge Xen wants a dedicated page for the GDT. I believe VMI likes it too. lguest, KVM and native don't care. Simple transformation to page-aligned "struct gdt_page". Signed-off-by: Rusty Russell Signed-off-by: Andi Kleen Acked-by: Jeremy Fitzhardinge --- arch/i386/kernel/cpu/common.c | 6 +++--- arch/i386/kernel/entry.S | 2 +- arch/i386/kernel/head.S | 2 +- arch/i386/kernel/traps.c | 2 +- include/asm-i386/desc.h | 9 +++++++-- 5 files changed, 13 insertions(+), 8 deletions(-) =================================================================== Index: linux/arch/i386/kernel/cpu/common.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/common.c +++ linux/arch/i386/kernel/cpu/common.c @@ -22,7 +22,7 @@ #include "cpu.h" -DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]) = { +DEFINE_PER_CPU(struct gdt_page, gdt_page) = { .gdt = { [GDT_ENTRY_KERNEL_CS] = { 0x0000ffff, 0x00cf9a00 }, [GDT_ENTRY_KERNEL_DS] = { 0x0000ffff, 0x00cf9200 }, [GDT_ENTRY_DEFAULT_USER_CS] = { 0x0000ffff, 0x00cffa00 }, @@ -48,8 +48,8 @@ DEFINE_PER_CPU(struct desc_struct, cpu_g [GDT_ENTRY_ESPFIX_SS] = { 0x00000000, 0x00c09200 }, [GDT_ENTRY_PDA] = { 0x00000000, 0x00c09200 }, /* set in setup_pda */ -}; -EXPORT_PER_CPU_SYMBOL_GPL(cpu_gdt); +} }; +EXPORT_PER_CPU_SYMBOL_GPL(gdt_page); DEFINE_PER_CPU(struct i386_pda, _cpu_pda); EXPORT_PER_CPU_SYMBOL(_cpu_pda); Index: linux/arch/i386/kernel/entry.S =================================================================== --- linux.orig/arch/i386/kernel/entry.S +++ linux/arch/i386/kernel/entry.S @@ -557,7 +557,7 @@ END(syscall_badsys) #define FIXUP_ESPFIX_STACK \ /* since we are on a wrong stack, we cant make it a C code :( */ \ movl %fs:PDA_cpu, %ebx; \ - PER_CPU(cpu_gdt, %ebx); \ + PER_CPU(gdt_page, %ebx); \ GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \ addl %esp, %eax; \ pushl $__KERNEL_DS; \ Index: linux/arch/i386/kernel/head.S =================================================================== --- linux.orig/arch/i386/kernel/head.S +++ linux/arch/i386/kernel/head.S @@ -598,7 +598,7 @@ idt_descr: .word 0 # 32 bit align gdt_desc.address ENTRY(early_gdt_descr) .word GDT_ENTRIES*8-1 - .long per_cpu__cpu_gdt /* Overwritten for secondary CPUs */ + .long per_cpu__gdt_page /* Overwritten for secondary CPUs */ /* * The boot_gdt must mirror the equivalent in setup.S and is Index: linux/arch/i386/kernel/traps.c =================================================================== --- linux.orig/arch/i386/kernel/traps.c +++ linux/arch/i386/kernel/traps.c @@ -1030,7 +1030,7 @@ fastcall void do_spurious_interrupt_bug( fastcall unsigned long patch_espfix_desc(unsigned long uesp, unsigned long kesp) { - struct desc_struct *gdt = __get_cpu_var(cpu_gdt); + struct desc_struct *gdt = __get_cpu_var(gdt_page).gdt; unsigned long base = (kesp - uesp) & -THREAD_SIZE; unsigned long new_kesp = kesp - base; unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT; Index: linux/include/asm-i386/desc.h =================================================================== --- linux.orig/include/asm-i386/desc.h +++ linux/include/asm-i386/desc.h @@ -18,10 +18,15 @@ struct Xgt_desc_struct { unsigned short pad; } __attribute__ ((packed)); -DECLARE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]); +struct gdt_page +{ + struct desc_struct gdt[GDT_ENTRIES]; +} __attribute__((aligned(PAGE_SIZE))); +DECLARE_PER_CPU(struct gdt_page, gdt_page); + static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu) { - return per_cpu(cpu_gdt, cpu); + return per_cpu(gdt_page, cpu).gdt; } extern struct Xgt_desc_struct idt_descr;