LK call_constructors

最新推荐文章于 2023-07-20 20:05:09 发布

原创最新推荐文章于 2023-07-20 20:05:09 发布 · 736 阅读

0 ·

CC 4.0 BY-SA版权

LK 源码研究专栏收录该内容

26 篇文章

订阅专栏

本文详细解析了Arm64架构下启动加载的过程及链接脚本配置，介绍了构造函数和析构函数的调用机制，以及不同内存段的分配与初始化过程。

lk/top/main.c

call_constructors:

static void call_constructors(void)
{
    void **ctor;
    ctor = &__ctor_list;
    while (ctor != &__ctor_end) {
        void (*func)(void);
        func = (void ( *)(void))*ctor;
        func();
        ctor++;
    }
}
 
lk/arch/arm64/system-onesegment.ld :
OUTPUT_FORMAT("elf64-littleaarch64", "elf64-bigaarch64", "elf64-littleaarch64")
OUTPUT_ARCH(aarch64)
ENTRY(_start)
SECTIONS
{
    . = %KERNEL_BASE% + %KERNEL_LOAD_OFFSET%;
    /* text/read-only data */
    /* set the load address to physical MEMBASE */
    .text : AT(%MEMBASE% + %KERNEL_LOAD_OFFSET%) {
        __code_start = .;
        KEEP(*(.text.boot))
        KEEP(*(.text.boot.vectab))
        *(.text* .sram.text.glue_7* .gnu.linkonce.t.*)
    }
    .interp : { *(.interp) }
    .hash : { *(.hash) }
    .dynsym : { *(.dynsym) }
    .dynstr : { *(.dynstr) }
    .rel.text : { *(.rel.text) *(.rel.gnu.linkonce.t*) }
    .rela.text : { *(.rela.text) *(.rela.gnu.linkonce.t*) }
    .rel.data : { *(.rel.data) *(.rel.gnu.linkonce.d*) }
    .rela.data : { *(.rela.data) *(.rela.gnu.linkonce.d*) }
    .rel.rodata : { *(.rel.rodata) *(.rel.gnu.linkonce.r*) }
    .rela.rodata : { *(.rela.rodata) *(.rela.gnu.linkonce.r*) }
    .rel.got : { *(.rel.got) }
    .rela.got : { *(.rela.got) }
    .rel.ctors : { *(.rel.ctors) }
    .rela.ctors : { *(.rela.ctors) }
    .rel.dtors : { *(.rel.dtors) }
    .rela.dtors : { *(.rela.dtors) }
    .rel.init : { *(.rel.init) }
    .rela.init : { *(.rela.init) }
    .rel.fini : { *(.rel.fini) }
    .rela.fini : { *(.rela.fini) }
    .rel.bss : { *(.rel.bss) }
    .rela.bss : { *(.rela.bss) }
    .rel.plt : { *(.rel.plt) }
    .rela.plt : { *(.rela.plt) }
    .init : { *(.init) } =0x9090
    .plt : { *(.plt) }
    /* .ARM.exidx is sorted, so has to go in its own output section.  */
    __exidx_start = .;
    .ARM.exidx : { *(.ARM.exidx* .gnu.linkonce.armexidx.*) }
    __exidx_end = .;
    .dummy_post_text : {
     __code_end = .;
    }
    .rodata : ALIGN(4096) {
        __rodata_start = .;
        __fault_handler_table_start = .;
        KEEP(*(.rodata.fault_handler_table))
        __fault_handler_table_end = .;
        *(.rodata .rodata.* .gnu.linkonce.r.*)
    }
    /*
     * extra linker scripts tend to insert sections just after .rodata,
     * so we want to make sure this symbol comes after anything inserted above,
     * but not aligned to the next section necessarily.
     */
    .dummy_post_rodata : {
        __rodata_end = .;
    }
    .data : ALIGN(4096) {
        /* writable data  */
        __data_start_rom = .;
        /* in one segment binaries, the rom data address is on top of the ram data address */
        __data_start = .;
        *(.data .data.* .gnu.linkonce.d.*)
    }
    .ctors : ALIGN(8) {
        __ctor_list = .;
        KEEP(*(.ctors .init_array))
        __ctor_end = .;
    }
    .dtors : ALIGN(8) {
        __dtor_list = .;
        KEEP(*(.dtors .fini_array))
        __dtor_end = .;
    }
    .got : { *(.got.plt) *(.got) }
    .dynamic : { *(.dynamic) }
    /*
     * extra linker scripts tend to insert sections just after .data,
     * so we want to make sure this symbol comes after anything inserted above,
     * but not aligned to the next section necessarily.
     */
    .dummy_post_data : {
        __data_end = .;
    }
    /* unintialized data (in same segment as writable data) */
    .bss : ALIGN(4096) {
        __bss_start = .;
        KEEP(*(.bss.prebss.*))
        . = ALIGN(8);
        __post_prebss_bss_start = .;
        *(.bss .bss.*)
        *(.gnu.linkonce.b.*)
        *(COMMON)
        . = ALIGN(8);
        __bss_end = .;
    }
    /* Align the end to ensure anything after the kernel ends up on its own pages */
    . = ALIGN(4096);
    _end = .;
    . = %KERNEL_BASE% + %MEMSIZE%;
    _end_of_ram = .;
    /* Strip unnecessary stuff */
    /DISCARD/ : { *(.comment .note .eh_frame) }
}