proc_info_list

内核中每种处理器架构抽象为一个proc_info_list结构体，在arch/arm/include/asm/procinfo.h中定义，

struct proc_info_list {
    unsigned int        cpu_val;
    unsigned int        cpu_mask;
    unsigned long        __cpu_mm_mmu_flags;    /* used by head.S */
    unsigned long        __cpu_io_mmu_flags;    /* used by head.S */
    unsigned long        __cpu_flush;        /* used by head.S */
    const char        *arch_name;
    const char        *elf_name;
    unsigned int        elf_hwcap;
    const char        *cpu_name;
    struct processor    *proc;
    struct cpu_tlb_fns    *tlb;
    struct cpu_user_fns    *user;
    struct cpu_cache_fns    *cache;
};

proc_info_list结构体的实现与处理器架构相关，这里以arch/arm/mm/proc-v6.S为例,

    /*
     * Match any ARMv6 processor core.
     */
    .type    __v6_proc_info, #object
__v6_proc_info:
    .long    0x0007b000 /*unsigned int        cpu_val*/
    .long    0x0007f000 /*unsigned int        cpu_mask*/
    /*unsigned long        __cpu_mm_mmu_flags;    used by head.S */
    .long   PMD_TYPE_SECT | PMD_SECT_BUFFERABLE | PMD_SECT_CACHEABLE | PMD_SECT_AP_WRITE |     PMD_SECT_AP_READ
    /*unsigned long        __cpu_io_mmu_flags;     used by head.S */
    .long   PMD_TYPE_SECT | PMD_SECT_XN | PMD_SECT_AP_WRITE | PMD_SECT_AP_READ
    /*unsigned long        __cpu_flush;         used by head.S */
    b    __v6_setup
    .long    cpu_arch_name /*const char        *arch_name;*/
    .long    cpu_elf_name /*const char        *elf_name;*/
    /*unsigned int        elf_hwcap;*/
    .long    HWCAP_SWP|HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_EDSP|HWCAP_JAVA
    .long    cpu_v6_name /*const char        *cpu_name;*/
    .long    v6_processor_functions /*struct processor    *proc*/
    .long    v6wbi_tlb_fns /*struct cpu_tlb_fns    *tlb*/
    .long    v6_user_fns /*struct cpu_user_fns    *user*/
    .long    v6_cache_fns /*struct cpu_cache_fns    *cache*/
    .size    __v6_proc_info, . - __v6_proc_info

1. cpu_val,cpu_mask

用于匹配下面的协处理指令读出的cupID。

MRC p15,,<Rd>,c0,c0, ;Read Main ID Register

2.__cpu_flush,arch/arm/mm/proc-v6.S

/*
 *    __v6_setup
 *
 *    Initialise TLB, Caches, and MMU state ready to switch the MMU
 *    on.  Return in r0 the new CP15 C1 control register setting.
 *
 *    We automatically detect if we have a Harvard cache, and use the
 *    Harvard cache control instructions insead of the unified cache
 *    control instructions.
 *
 *    This should be able to cover all ARMv6 cores.
 *
 *    It is assumed that:
 *    - cache type register is implemented
 */
__v6_setup:
#ifdef CONFIG_SMP
    mrc    p15, , r0, c1, c0,         @ Enable SMP/nAMP mode
    orr    r0, r0, #0x20
    mcr    p15, , r0, c1, c0,
#endif

    mov    r0, #
    mcr    p15, , r0, c7, c14,         @ clean+invalidate D cache
    mcr    p15, , r0, c7, c5,         @ invalidate I cache
    mcr    p15, , r0, c7, c15,         @ clean+invalidate cache
    mcr    p15, , r0, c7, c10,         @ drain write buffer
#ifdef CONFIG_MMU
    mcr    p15, , r0, c8, c7,         @ invalidate I + D TLBs
    mcr    p15, , r0, c2, c0,         @ TTB control register
    orr    r4, r4, #TTB_FLAGS
    mcr    p15, , r4, c2, c0,         @ load TTB1
#endif /* CONFIG_MMU */
    adr    r5, v6_crval
    ldmia    r5, {r5, r6}
    mrc    p15, , r0, c1, c0,         @ read control register
    bic    r0, r0, r5            @ clear bits them
    orr    r0, r0, r6            @ set them
    mov    pc, lr                @ return to head.S:__ret

3. arch_name

    .type    cpu_arch_name, #object
cpu_arch_name:
    .asciz    "armv6"
    .size    cpu_arch_name, . - cpu_arch_name

4.elf_name

    .type    cpu_elf_name, #object
cpu_elf_name:
    .asciz    "v6"
    .size    cpu_elf_name, . - cpu_elf_name
    .align

5.cpu_name

cpu_v6_name:
    .asciz    "ARMv6-compatible processor"
    .align

6.struct processor *proc

该结构体在在arch/arm/include/asm/procinfo.h中声明，

struct processor;

在include/asm-arm/cpu-multi32.h中定义，是一系列函数指针的结构体。

/*
 * Don't change this structure - ASM code
 * relies on it.
 */
extern struct processor {
    /* MISC
     * get data abort address/flags
     */
    void (*_data_abort)(unsigned long pc);
    /*
     * Retrieve prefetch fault address
     */
    unsigned long (*_prefetch_abort)(unsigned long lr);
    /*
     * Set up any processor specifics
     */
    void (*_proc_init)(void);
    /*
     * Disable any processor specifics
     */
    void (*_proc_fin)(void);
    /*
     * Special stuff for a reset
     */
    void (*reset)(unsigned long addr) __attribute__((noreturn));
    /*
     * Idle the processor
     */
    int (*_do_idle)(void);
    /*
     * Processor architecture specific
     */
    /*
     * clean a virtual address range from the
     * D-cache without flushing the cache.
     */
    void (*dcache_clean_area)(void *addr, int size);

    /*
     * Set the page table
     */
    void (*switch_mm)(unsigned long pgd_phys, struct mm_struct *mm);
    /*
     * Set a possibly extended PTE.  Non-extended PTEs should
     * ignore 'ext'.
     */
    void (*set_pte_ext)(pte_t *ptep, pte_t pte, unsigned int ext);
} processor;

这些函数指针在arch/arm/mm/proc-v6.S中指定，

    .type    v6_processor_functions, #object
ENTRY(v6_processor_functions)
    .word    v6_early_abort
    .word    pabort_noifar
    .word    cpu_v6_proc_init
    .word    cpu_v6_proc_fin
    .word    cpu_v6_reset
    .word    cpu_v6_do_idle
    .word    cpu_v6_dcache_clean_area
    .word    cpu_v6_switch_mm
    .word    cpu_v6_set_pte_ext
    .size    v6_processor_functions, . - v6_processor_functions

7.struct cpu_tlb_fns *tlb

该结构体在在arch/arm/include/asm/procinfo.h中声明

struct cpu_tlb_fns;

在arch/arm/include/asm/tlbflush.h中定义，

struct cpu_tlb_fns {
    void (*flush_user_range)(unsigned long, unsigned long, struct vm_area_struct *);
    void (*flush_kern_range)(unsigned long, unsigned long);
    unsigned long tlb_flags;
};

具体函数实现在arm/arm/mm/tlb-v6.S

    .type    v6wbi_tlb_fns, #object
ENTRY(v6wbi_tlb_fns)
    .long    v6wbi_flush_user_tlb_range
    .long    v6wbi_flush_kern_tlb_range
    .long    v6wbi_tlb_flags
    .size    v6wbi_tlb_fns, . - v6wbi_tlb_fns

8.struct cpu_user_fns *user

该结构体在在arch/arm/include/asm/procinfo.h中声明

struct cpu_user_fns;

在arch/arm/include/asm/page.h中定义

struct cpu_user_fns {
    void (*cpu_clear_user_highpage)(struct page *page, unsigned long vaddr);
    void (*cpu_copy_user_highpage)(struct page *to, struct page *from,
            unsigned long vaddr);
};

具体函数实现在arm/arm/mm/copypage-v6.S

struct cpu_user_fns v6_user_fns __initdata = {
    .cpu_clear_user_highpage = v6_clear_user_highpage_nonaliasing,
    .cpu_copy_user_highpage    = v6_copy_user_highpage_nonaliasing,
};

9.struct cpu_cache_fns *cache

该结构体在在arch/arm/include/asm/procinfo.h中声明

struct cpu_cache_fns;

在arch/arm/include/asm/cacheflush.h中定义，是包含一系列函数指针的结构体

struct cpu_cache_fns {
    void (*flush_kern_all)(void);
    void (*flush_user_all)(void);
    void (*flush_user_range)(unsigned long, unsigned long, unsigned int);

    void (*coherent_kern_range)(unsigned long, unsigned long);
    void (*coherent_user_range)(unsigned long, unsigned long);
    void (*flush_kern_dcache_page)(void *);

    void (*dma_inv_range)(const void *, const void *);
    void (*dma_clean_range)(const void *, const void *);
    void (*dma_flush_range)(const void *, const void *);
};

具体函数实现在arm/arm/mm/cache-v6.S

    .type    v6_cache_fns, #object
ENTRY(v6_cache_fns)
    .long    v6_flush_kern_cache_all
    .long    v6_flush_user_cache_all
    .long    v6_flush_user_cache_range
    .long    v6_coherent_kern_range
    .long    v6_coherent_user_range
    .long    v6_flush_kern_dcache_page
    .long    v6_dma_inv_range
    .long    v6_dma_clean_range
    .long    v6_dma_flush_range
    .size    v6_cache_fns, . - v6_cache_fns