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    Subject[PATCH 06/17] x86-64: Move current task from PDA to per-cpu and consolidate with 32-bit.
    Date
    Signed-off-by: Brian Gerst <brgerst@gmail.com>
    ---
    arch/x86/include/asm/current.h | 24 +++---------------------
    arch/x86/include/asm/pda.h | 4 ++--
    arch/x86/include/asm/system.h | 4 ++--
    arch/x86/kernel/asm-offsets_64.c | 1 -
    arch/x86/kernel/cpu/common.c | 5 +----
    arch/x86/kernel/dumpstack_64.c | 2 +-
    arch/x86/kernel/process_64.c | 5 ++++-
    arch/x86/kernel/smpboot.c | 3 +--
    arch/x86/xen/smp.c | 3 +--
    9 files changed, 15 insertions(+), 36 deletions(-)

    diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h
    index 0728480..c68c361 100644
    --- a/arch/x86/include/asm/current.h
    +++ b/arch/x86/include/asm/current.h
    @@ -1,39 +1,21 @@
    #ifndef _ASM_X86_CURRENT_H
    #define _ASM_X86_CURRENT_H

    -#ifdef CONFIG_X86_32
    #include <linux/compiler.h>
    #include <asm/percpu.h>

    +#ifndef __ASSEMBLY__
    struct task_struct;

    DECLARE_PER_CPU(struct task_struct *, current_task);
    -static __always_inline struct task_struct *get_current(void)
    -{
    - return percpu_read(current_task);
    -}
    -
    -#else /* X86_32 */
    -
    -#ifndef __ASSEMBLY__
    -#include <asm/pda.h>
    -
    -struct task_struct;

    static __always_inline struct task_struct *get_current(void)
    {
    - return read_pda(pcurrent);
    + return percpu_read(current_task);
    }

    -#else /* __ASSEMBLY__ */
    -
    -#include <asm/asm-offsets.h>
    -#define GET_CURRENT(reg) movq %gs:(pda_pcurrent),reg
    +#define current get_current()

    #endif /* __ASSEMBLY__ */

    -#endif /* X86_32 */
    -
    -#define current get_current()
    -
    #endif /* _ASM_X86_CURRENT_H */
    diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h
    index 668d5a5..7209302 100644
    --- a/arch/x86/include/asm/pda.h
    +++ b/arch/x86/include/asm/pda.h
    @@ -11,8 +11,8 @@

    /* Per processor datastructure. %gs points to it while the kernel runs */
    struct x8664_pda {
    - struct task_struct *pcurrent; /* 0 Current process */
    - unsigned long dummy;
    + unsigned long unused1;
    + unsigned long unused2;
    unsigned long kernelstack; /* 16 top of kernel stack for current */
    unsigned long oldrsp; /* 24 user rsp for system call */
    int irqcount; /* 32 Irq nesting counter. Starts -1 */
    diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
    index 8e626ea..4399aac 100644
    --- a/arch/x86/include/asm/system.h
    +++ b/arch/x86/include/asm/system.h
    @@ -94,7 +94,7 @@ do { \
    "call __switch_to\n\t" \
    ".globl thread_return\n" \
    "thread_return:\n\t" \
    - "movq %%gs:%P[pda_pcurrent],%%rsi\n\t" \
    + "movq "__percpu_seg_str"%P[current_task],%%rsi\n\t" \
    "movq %P[thread_info](%%rsi),%%r8\n\t" \
    LOCK_PREFIX "btr %[tif_fork],%P[ti_flags](%%r8)\n\t" \
    "movq %%rax,%%rdi\n\t" \
    @@ -106,7 +106,7 @@ do { \
    [ti_flags] "i" (offsetof(struct thread_info, flags)), \
    [tif_fork] "i" (TIF_FORK), \
    [thread_info] "i" (offsetof(struct task_struct, stack)), \
    - [pda_pcurrent] "i" (offsetof(struct x8664_pda, pcurrent)) \
    + [current_task] "m" (per_cpu_var(current_task)) \
    : "memory", "cc" __EXTRA_CLOBBER)
    #endif

    diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c
    index cae6697..4f7a210 100644
    --- a/arch/x86/kernel/asm-offsets_64.c
    +++ b/arch/x86/kernel/asm-offsets_64.c
    @@ -51,7 +51,6 @@ int main(void)
    #define ENTRY(entry) DEFINE(pda_ ## entry, offsetof(struct x8664_pda, entry))
    ENTRY(kernelstack);
    ENTRY(oldrsp);
    - ENTRY(pcurrent);
    ENTRY(irqcount);
    DEFINE(pda_size, sizeof(struct x8664_pda));
    BLANK();
    diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
    index 1cf466f..fbc8468 100644
    --- a/arch/x86/kernel/cpu/common.c
    +++ b/arch/x86/kernel/cpu/common.c
    @@ -898,10 +898,7 @@ void __cpuinit pda_init(int cpu)
    pda->kernelstack = (unsigned long)stack_thread_info() -
    PDA_STACKOFFSET + THREAD_SIZE;

    - if (cpu == 0) {
    - /* others are initialized in smpboot.c */
    - pda->pcurrent = &init_task;
    - } else {
    + if (cpu != 0) {
    if (pda->nodenumber == 0 && cpu_to_node(cpu) != NUMA_NO_NODE)
    pda->nodenumber = cpu_to_node(cpu);
    }
    diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
    index 46c6bf0..0c01ad2 100644
    --- a/arch/x86/kernel/dumpstack_64.c
    +++ b/arch/x86/kernel/dumpstack_64.c
    @@ -241,7 +241,7 @@ void show_registers(struct pt_regs *regs)
    int i;
    unsigned long sp;
    const int cpu = smp_processor_id();
    - struct task_struct *cur = cpu_pda(cpu)->pcurrent;
    + struct task_struct *cur = current;

    sp = regs->sp;
    printk("CPU %d ", cpu);
    diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
    index 416fb92..e00c31a 100644
    --- a/arch/x86/kernel/process_64.c
    +++ b/arch/x86/kernel/process_64.c
    @@ -57,6 +57,9 @@

    asmlinkage extern void ret_from_fork(void);

    +DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
    +EXPORT_PER_CPU_SYMBOL(current_task);
    +
    unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;

    static ATOMIC_NOTIFIER_HEAD(idle_notifier);
    @@ -615,7 +618,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
    */
    prev->usersp = read_pda(oldrsp);
    write_pda(oldrsp, next->usersp);
    - write_pda(pcurrent, next_p);
    + percpu_write(current_task, next_p);

    write_pda(kernelstack,
    (unsigned long)task_stack_page(next_p) +
    diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
    index a33da98..ecc2fc5 100644
    --- a/arch/x86/kernel/smpboot.c
    +++ b/arch/x86/kernel/smpboot.c
    @@ -792,13 +792,12 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)

    set_idle_for_cpu(cpu, c_idle.idle);
    do_rest:
    -#ifdef CONFIG_X86_32
    per_cpu(current_task, cpu) = c_idle.idle;
    +#ifdef CONFIG_X86_32
    init_gdt(cpu);
    /* Stack for startup_32 can be just as for start_secondary onwards */
    irq_ctx_init(cpu);
    #else
    - cpu_pda(cpu)->pcurrent = c_idle.idle;
    clear_tsk_thread_flag(c_idle.idle, TIF_FORK);
    initial_gs = per_cpu_offset(cpu);
    #endif
    diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
    index 9ff3b09..72c2eb9 100644
    --- a/arch/x86/xen/smp.c
    +++ b/arch/x86/xen/smp.c
    @@ -279,12 +279,11 @@ static int __cpuinit xen_cpu_up(unsigned int cpu)
    struct task_struct *idle = idle_task(cpu);
    int rc;

    + per_cpu(current_task, cpu) = idle;
    #ifdef CONFIG_X86_32
    init_gdt(cpu);
    - per_cpu(current_task, cpu) = idle;
    irq_ctx_init(cpu);
    #else
    - cpu_pda(cpu)->pcurrent = idle;
    clear_tsk_thread_flag(idle, TIF_FORK);
    #endif
    xen_setup_timer(cpu);
    --
    1.6.1.rc1


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