i386: cleanup GDT Access From: Rusty Russell Now we have an explicit per-cpu GDT variable, we don't need to keep the descriptors around to use them to find the GDT: expose cpu_gdt directly. We could go further and make load_gdt() pack the descriptor for us, or even assume it means "load the current cpu's GDT" which is what it always does. Signed-off-by: Rusty Russell Signed-off-by: Andi Kleen Cc: Andi Kleen Signed-off-by: Andrew Morton --- arch/i386/kernel/cpu/common.c | 4 +--- arch/i386/kernel/efi.c | 16 ++++++++-------- arch/i386/kernel/entry.S | 3 +-- arch/i386/kernel/smpboot.c | 12 ++++++------ arch/i386/kernel/traps.c | 4 +--- include/asm-i386/desc.h | 7 ++----- 6 files changed, 19 insertions(+), 27 deletions(-) Index: linux/arch/i386/kernel/cpu/common.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/common.c +++ linux/arch/i386/kernel/cpu/common.c @@ -22,9 +22,6 @@ #include "cpu.h" -DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr); -EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr); - DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]) = { [GDT_ENTRY_KERNEL_CS] = { 0x0000ffff, 0x00cf9a00 }, [GDT_ENTRY_KERNEL_DS] = { 0x0000ffff, 0x00cf9200 }, @@ -52,6 +49,7 @@ 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); DEFINE_PER_CPU(struct i386_pda, _cpu_pda); EXPORT_PER_CPU_SYMBOL(_cpu_pda); Index: linux/arch/i386/kernel/efi.c =================================================================== --- linux.orig/arch/i386/kernel/efi.c +++ linux/arch/i386/kernel/efi.c @@ -69,13 +69,11 @@ static void efi_call_phys_prelog(void) _ { unsigned long cr4; unsigned long temp; - struct Xgt_desc_struct *cpu_gdt_descr; + struct Xgt_desc_struct gdt_descr; spin_lock(&efi_rt_lock); local_irq_save(efi_rt_eflags); - cpu_gdt_descr = &per_cpu(cpu_gdt_descr, 0); - /* * If I don't have PSE, I should just duplicate two entries in page * directory. If I have PSE, I just need to duplicate one entry in @@ -105,17 +103,19 @@ static void efi_call_phys_prelog(void) _ */ local_flush_tlb(); - cpu_gdt_descr->address = __pa(cpu_gdt_descr->address); - load_gdt(cpu_gdt_descr); + gdt_descr.address = __pa(get_cpu_gdt_table(0)); + gdt_descr.size = GDT_SIZE - 1; + load_gdt(&gdt_descr); } static void efi_call_phys_epilog(void) __releases(efi_rt_lock) { unsigned long cr4; - struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, 0); + struct Xgt_desc_struct gdt_descr; - cpu_gdt_descr->address = (unsigned long)__va(cpu_gdt_descr->address); - load_gdt(cpu_gdt_descr); + gdt_descr.address = (unsigned long)get_cpu_gdt_table(0); + gdt_descr.size = GDT_SIZE - 1; + load_gdt(&gdt_descr); cr4 = read_cr4(); Index: linux/arch/i386/kernel/entry.S =================================================================== --- linux.orig/arch/i386/kernel/entry.S +++ linux/arch/i386/kernel/entry.S @@ -561,8 +561,7 @@ 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_descr, %ebx); \ - movl GDS_address(%ebx), %ebx; \ + PER_CPU(cpu_gdt, %ebx); \ GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \ addl %esp, %eax; \ pushl $__KERNEL_DS; \ Index: linux/arch/i386/kernel/smpboot.c =================================================================== --- linux.orig/arch/i386/kernel/smpboot.c +++ linux/arch/i386/kernel/smpboot.c @@ -786,13 +786,9 @@ static inline struct task_struct * alloc secondary which will soon come up. */ static __cpuinit void init_gdt(int cpu, struct task_struct *idle) { - struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); - struct desc_struct *gdt = per_cpu(cpu_gdt, cpu); + struct desc_struct *gdt = get_cpu_gdt_table(cpu); struct i386_pda *pda = &per_cpu(_cpu_pda, cpu); - cpu_gdt_descr->address = (unsigned long)gdt; - cpu_gdt_descr->size = GDT_SIZE - 1; - pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a, (u32 *)&gdt[GDT_ENTRY_PDA].b, (unsigned long)pda, sizeof(*pda) - 1, @@ -1187,7 +1183,11 @@ void __init smp_prepare_cpus(unsigned in * it's on the real one. */ static inline void switch_to_new_gdt(void) { - load_gdt(&per_cpu(cpu_gdt_descr, smp_processor_id())); + struct Xgt_desc_struct gdt_descr; + + gdt_descr.address = (long)get_cpu_gdt_table(smp_processor_id()); + gdt_descr.size = GDT_SIZE - 1; + load_gdt(&gdt_descr); asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_PDA) : "memory"); } Index: linux/arch/i386/kernel/traps.c =================================================================== --- linux.orig/arch/i386/kernel/traps.c +++ linux/arch/i386/kernel/traps.c @@ -1098,9 +1098,7 @@ fastcall void do_spurious_interrupt_bug( fastcall unsigned long patch_espfix_desc(unsigned long uesp, unsigned long kesp) { - int cpu = smp_processor_id(); - struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); - struct desc_struct *gdt = (struct desc_struct *)cpu_gdt_descr->address; + struct desc_struct *gdt = __get_cpu_var(cpu_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 @@ -18,16 +18,13 @@ struct Xgt_desc_struct { unsigned short pad; } __attribute__ ((packed)); -extern struct Xgt_desc_struct idt_descr; -DECLARE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr); DECLARE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]); -extern struct Xgt_desc_struct early_gdt_descr; - static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu) { - return (struct desc_struct *)per_cpu(cpu_gdt_descr, cpu).address; + return per_cpu(cpu_gdt, cpu); } +extern struct Xgt_desc_struct idt_descr; extern struct desc_struct idt_table[]; extern void set_intr_gate(unsigned int irq, void * addr);