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    Subject[PATCH 5/8] Cleanup GDT access
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    Date
    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. Also remove the
    cpu_pda() accessor: it's just a per-cpu variable.

    Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

    diff -r e9d5b8e6f5ee arch/i386/kernel/cpu/common.c
    --- a/arch/i386/kernel/cpu/common.c Tue Mar 06 16:20:48 2007 +1100
    +++ b/arch/i386/kernel/cpu/common.c Tue Mar 06 17:04:37 2007 +1100
    @@ -22,11 +22,8 @@

    #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]);
    -
    +EXPORT_PER_CPU_SYMBOL_GPL(cpu_gdt);
    DEFINE_PER_CPU(struct i386_pda, _cpu_pda);
    EXPORT_PER_CPU_SYMBOL(_cpu_pda);

    @@ -631,14 +628,11 @@ static inline void set_kernel_fs(void)
    will soon come up. */
    __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 i386_pda *pda = &per_cpu(_cpu_pda, cpu);

    + /* Based on boot_gdt_table: set PDA so it can be used immediately */
    memcpy(gdt, boot_gdt_table, GDT_SIZE);
    - 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,
    @@ -653,9 +647,12 @@ __cpuinit void init_gdt(int cpu, struct
    /* Move this CPU from boot_gdt_table & boot_pda to this cpu's proper one. */
    void __cpuinit cpu_set_gdt(int cpu)
    {
    - struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu);
    -
    - load_gdt(cpu_gdt_descr);
    + struct Xgt_desc_struct gdt_descr;
    +
    + gdt_descr.address = (unsigned long)per_cpu(cpu_gdt, cpu);
    + gdt_descr.size = GDT_SIZE - 1;
    +
    + load_gdt(&gdt_descr);
    set_kernel_fs();
    }

    diff -r e9d5b8e6f5ee arch/i386/kernel/efi.c
    --- a/arch/i386/kernel/efi.c Tue Mar 06 16:20:48 2007 +1100
    +++ b/arch/i386/kernel/efi.c Tue Mar 06 17:05:41 2007 +1100
    @@ -69,12 +69,10 @@ 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
    @@ -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);
    -
    - cpu_gdt_descr->address = (unsigned long)__va(cpu_gdt_descr->address);
    - load_gdt(cpu_gdt_descr);
    + struct Xgt_desc_struct 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();

    diff -r e9d5b8e6f5ee arch/i386/kernel/entry.S
    --- a/arch/i386/kernel/entry.S Tue Mar 06 16:20:48 2007 +1100
    +++ b/arch/i386/kernel/entry.S Tue Mar 06 17:04:37 2007 +1100
    @@ -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; \
    diff -r e9d5b8e6f5ee arch/i386/kernel/traps.c
    --- a/arch/i386/kernel/traps.c Tue Mar 06 16:20:48 2007 +1100
    +++ b/arch/i386/kernel/traps.c Tue Mar 06 17:04:37 2007 +1100
    @@ -1018,9 +1018,7 @@ fastcall unsigned long patch_espfix_desc
    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;
    diff -r e9d5b8e6f5ee include/asm-i386/desc.h
    --- a/include/asm-i386/desc.h Tue Mar 06 16:20:48 2007 +1100
    +++ b/include/asm-i386/desc.h Tue Mar 06 17:04:37 2007 +1100
    @@ -13,6 +13,7 @@
    #include <asm/mmu.h>

    extern struct desc_struct boot_gdt_table[GDT_ENTRIES];
    +DECLARE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]);

    struct Xgt_desc_struct {
    unsigned short size;
    @@ -21,13 +22,9 @@ struct Xgt_desc_struct {
    } __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 desc_struct idt_table[];
    @@ -102,13 +99,12 @@ static inline fastcall void native_set_l
    if (likely(entries == 0))
    __asm__ __volatile__("lldt %w0"::"q" (0));
    else {
    - unsigned cpu = smp_processor_id();
    __u32 a, b;

    pack_descriptor(&a, &b, (unsigned long)addr,
    entries * sizeof(struct desc_struct) - 1,
    DESCTYPE_LDT, 0);
    - write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_LDT, a, b);
    + write_gdt_entry(__get_cpu_var(cpu_gdt), GDT_ENTRY_LDT, a, b);
    __asm__ __volatile__("lldt %w0"::"q" (GDT_ENTRY_LDT*8));
    }
    }
    diff -r e9d5b8e6f5ee include/asm-i386/pda.h
    --- a/include/asm-i386/pda.h Tue Mar 06 16:20:48 2007 +1100
    +++ b/include/asm-i386/pda.h Tue Mar 06 17:04:26 2007 +1100
    @@ -20,8 +20,6 @@ struct i386_pda
    };

    DECLARE_PER_CPU(struct i386_pda, _cpu_pda);
    -
    -#define cpu_pda(i) (&per_cpu(_cpu_pda, (i)))

    #define pda_offset(field) offsetof(struct i386_pda, field)


    -
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