1makefile 的规则
命令必须使用tab 按键， 而不能使用 空格按键。
1. TARGET=start
2. TARGETC=main
3. all:
4. arm-none-linux-gnueabi-gcc -O0 -g -c -o $(TARGETC).o $(TARGETC).c
5. arm-none-linux-gnueabi-gcc -O0 -g -c -o $(TARGET).o $(TARGET).s
6. #arm-none-linux-gnueabi-gcc -O0 -g -S -o $(TARGETC).s $(TARGETC).c
7. arm-none-linux-gnueabi-ld $(TARGETC).o $(TARGET).o -Ttext 0x40008000 -o $(TARGET).elf
8. arm-none-linux-gnueabi-objcopy -O binary -S $(TARGET).elf $(TARGET).bin
9. clean:
10. rm -rf *.o *.elf *.dis *.bin
这里的 -O0 代表的是优化的标准， -ｇ，表示增加调试信息， -c , -o 就不用说了。
-Ttext 代表的是，程序的运行地址。 -O binary 代表的是 生成二进制文件。 -S带表的是 去掉不要重定位信息和符号信息，缩小了文件尺寸。
2 然后是连接脚本的分析。
OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
/*OUTPUT_FORMAT("elf32-arm", "elf32-arm", "elf32-arm")*/
OUTPUT_ARCH(arm)
ENTRY(_start)
SECTIONS
{
. = 0x40008000;
. = ALIGN(4);
.text :
{
.start.o(.text)
*(.text)
}
. = ALIGN(4);
.rodata :
{ *(.rodata) }
. = ALIGN(4);
.data :
{ *(.data) }
. = ALIGN(4);
.bss :
{ *(.bss) }
}
我觉得 这个链接脚本没什么需要讲的，
最主要的是 搞清楚 如何在程序中定义自己的段。
网上的资料
另一个例子
这里的
#define func_init(func) myown_call _fn_##func _init = func
最终展开就是
#define func_init(func) myown_call fn##func attribute((unused, section(".myown"))) = func
这里的 func 单词都是可以替换成具体的函数指针的。
这里也就是 定义了一个函数指针，并且附上了值。
3 然后是 uboot ，以及内核的连接脚本的举例。
OUTPUT_FORMAT("elf64-littleaarch64", "elf64-littleaarch64", "elf64-littleaarch64")
OUTPUT_ARCH(aarch64)
ENTRY(_start)
SECTIONS
{
. = 0x00000000;
. = ALIGN(8);
.text :
{
*(.__image_copy_start)
arch/arm/cpu/armv8/start.o (.text*)
*(.text*)
}
. = ALIGN(8);
.rodata : { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }
. = ALIGN(8);
.data : {
*(.data*)
}
. = ALIGN(8);
. = .;
. = ALIGN(8);
.u_boot_list : {
KEEP(*(SORT(.u_boot_list*)));
}
. = ALIGN(8);
.efi_runtime : {
__efi_runtime_start = .;
*(efi_runtime_text)
*(efi_runtime_data)
__efi_runtime_stop = .;
}
.efi_runtime_rel : {
__efi_runtime_rel_start = .;
*(.relaefi_runtime_text)
*(.relaefi_runtime_data)
__efi_runtime_rel_stop = .;
}
. = ALIGN(8);
.image_copy_end :
{
*(.__image_copy_end)
}
. = ALIGN(8);
.rel_dyn_start :
{
*(.__rel_dyn_start)
}
.rela.dyn : {
*(.rela*)
}
.rel_dyn_end :
{
*(.__rel_dyn_end)
}
_end = .;
. = ALIGN(8);
.bss_start : {
KEEP(*(.__bss_start));
}
.bss : {
*(.bss*)
. = ALIGN(8);
}
.bss_end : {
KEEP(*(.__bss_end));
}
/DISCARD/ : { *(.dynsym) }
/DISCARD/ : { *(.dynstr*) }
/DISCARD/ : { *(.dynamic*) }
/DISCARD/ : { *(.plt*) }
/DISCARD/ : { *(.interp*) }
/DISCARD/ : { *(.gnu*) }
这个链接脚本整体上还是 比较规范的，没有什么幺蛾子。
入口点就是 _start , 就在 start.o里面。
就是这里。
但是内核的 lds 文件就比较恶心了。
OUTPUT_ARCH(aarch64)
ENTRY(_text)
jiffies = jiffies_64;
PECOFF_FILE_ALIGNMENT = 0x200;
SECTIONS
{
/DISCARD/ : {
*(.exitcall.exit)
*(.discard)
*(.discard.*)
*(.interp .dynamic)
*(.dynsym .dynstr .hash .gnu.hash)
*(.eh_frame)
}
. = ((((((0xffffffffffffffff)) - (((1)) << (39)) + 1) + (0)) + (0x08000000))) + 0x00080000;
.head.text : {
_text = .;
KEEP(*(.head.text))
}
.text : {
_stext = .;
__exception_text_start = .;
*(.exception.text)
__exception_text_end = .;
. = ALIGN(8); __irqentry_text_start = .; *(.irqentry.text) __irqentry_text_end = .;
. = ALIGN(8); __softirqentry_text_start = .; *(.softirqentry.text) __softirqentry_text_end = .;
. = ALIGN(8); __entry_text_start = .; *(.entry.text) __entry_text_end = .;
. = ALIGN(8); *(.text.hot .text.hot.*) *(.text .text.fixup) *(.text.unlikely .text.unlikely.*) *(.text.unknown .text.unknown.*) *(.text.cfi) . = ALIGN(8); __noinstr_text_start = .; *(.noinstr.text) __noinstr_text_end = .; *(.text..refcount) *(.text..ftrace) *(.ref.text) *(.text.asan.* .text.tsan.*)
. = ALIGN(8); __sched_text_start = .; *(.sched.text) __sched_text_end = .;
. = ALIGN(8); __cpuidle_text_start = .; *(.cpuidle.text) __cpuidle_text_end = .;
. = ALIGN(8); __lock_text_start = .; *(.spinlock.text) __lock_text_end = .;
. = ALIGN(8); __kprobes_text_start = .; *(.kprobes.text) __kprobes_text_end = .;
. = ALIGN(0x00001000); __hyp_idmap_text_start = .; *(.hyp.idmap.text) __hyp_idmap_text_end = .; __hyp_text_start = .; *(.hyp.text) . = ALIGN(0x00000008); __start___kvm_ex_table = .; *(__kvm_ex_table) __stop___kvm_ex_table = .; __hyp_text_end = .;
. = ALIGN(0x00001000); __idmap_text_start = .; *(.idmap.text) __idmap_text_end = .;
. = ALIGN((1 << 12)); __entry_tramp_text_start = .; *(.entry.tramp.text) . = ALIGN((1 << 12)); __entry_tramp_text_end = .;
*(.fixup)
*(.gnu.warning)
. = ALIGN(16);
*(.got)
}
. = ALIGN(0x00010000);
_etext = .;
. = ALIGN(((1 << 12))); .rodata : AT(ADDR(.rodata) - 0) { __start_rodata = .; *(.rodata) *(.rodata.*) . = ALIGN(8); __start_ro_after_init = .; *(.data..ro_after_init) __end_ro_after_init = .; KEEP(*(__vermagic)) . = ALIGN(8); __start___tracepoints_ptrs = .; KEEP(*(__tracepoints_ptrs)) __stop___tracepoints_ptrs = .; *(__tracepoints_strings) } .rodata1 : AT(ADDR(.rodata1) - 0) { *(.rodata1) } .pci_fixup : AT(ADDR(.pci_fixup) - 0) { __start_pci_fixups_early = .; KEEP(*(.pci_fixup_early)) __end_pci_fixups_early = .; __start_pci_fixups_header = .; KEEP(*(.pci_fixup_header)) __end_pci_fixups_header = .; __start_pci_fixups_final = .; KEEP(*(.pci_fixup_final)) __end_pci_fixups_final = .; __start_pci_fixups_enable = .; KEEP(*(.pci_fixup_enable)) __end_pci_fixups_enable = .; __start_pci_fixups_resume = .; KEEP(*(.pci_fixup_resume)) __end_pci_fixups_resume = .; __start_pci_fixups_resume_early = .; KEEP(*(.pci_fixup_resume_early)) __end_pci_fixups_resume_early = .; __start_pci_fixups_suspend = .; KEEP(*(.pci_fixup_suspend)) __end_pci_fixups_suspend = .; __start_pci_fixups_suspend_late = .; KEEP(*(.pci_fixup_suspend_late)) __end_pci_fixups_suspend_late = .; } .builtin_fw : AT(ADDR(.builtin_fw) - 0) ALIGN(8) { __start_builtin_fw = .; KEEP(*(.builtin_fw)) __end_builtin_fw = .; } __ksymtab : AT(ADDR(__ksymtab) - 0) { __start___ksymtab = .; KEEP(*(SORT(___ksymtab+*))) __stop___ksymtab = .; } __ksymtab_gpl : AT(ADDR(__ksymtab_gpl) - 0) { __start___ksymtab_gpl = .; KEEP(*(SORT(___ksymtab_gpl+*))) __stop___ksymtab_gpl = .; } __ksymtab_unused : AT(ADDR(__ksymtab_unused) - 0) { __start___ksymtab_unused = .; KEEP(*(SORT(___ksymtab_unused+*))) __stop___ksymtab_unused = .; } __ksymtab_unused_gpl : AT(ADDR(__ksymtab_unused_gpl) - 0) { __start___ksymtab_unused_gpl = .; KEEP(*(SORT(___ksymtab_unused_gpl+*))) __stop___ksymtab_unused_gpl = .; } __ksymtab_gpl_future : AT(ADDR(__ksymtab_gpl_future) - 0) { __start___ksymtab_gpl_future = .; KEEP(*(SORT(___ksymtab_gpl_future+*))) __stop___ksymtab_gpl_future = .; } __kcrctab : AT(ADDR(__kcrctab) - 0) { __start___kcrctab = .; KEEP(*(SORT(___kcrctab+*))) __stop___kcrctab = .; } __kcrctab_gpl : AT(ADDR(__kcrctab_gpl) - 0) { __start___kcrctab_gpl = .; KEEP(*(SORT(___kcrctab_gpl+*))) __stop___kcrctab_gpl = .; } __kcrctab_unused : AT(ADDR(__kcrctab_unused) - 0) { __start___kcrctab_unused = .; KEEP(*(SORT(___kcrctab_unused+*))) __stop___kcrctab_unused = .; } __kcrctab_unused_gpl : AT(ADDR(__kcrctab_unused_gpl) - 0) { __start___kcrctab_unused_gpl = .; KEEP(*(SORT(___kcrctab_unused_gpl+*))) __stop___kcrctab_unused_gpl = .; } __kcrctab_gpl_future : AT(ADDR(__kcrctab_gpl_future) - 0) { __start___kcrctab_gpl_future = .; KEEP(*(SORT(___kcrctab_gpl_future+*))) __stop___kcrctab_gpl_future = .; } __ksymtab_strings : AT(ADDR(__ksymtab_strings) - 0) { *(__ksymtab_strings) } __init_rodata : AT(ADDR(__init_rodata) - 0) { *(.ref.rodata) } __param : AT(ADDR(__param) - 0) { __start___param = .; KEEP(*(__param)) __stop___param = .; } __modver : AT(ADDR(__modver) - 0) { __start___modver = .; KEEP(*(__modver)) __stop___modver = .; . = ALIGN(((1 << 12))); __end_rodata = .; } . = ALIGN(((1 << 12)));
. = ALIGN(8); __ex_table : AT(ADDR(__ex_table) - 0) { __start___ex_table = .; KEEP(*(__ex_table)) __stop___ex_table = .; }
.notes : AT(ADDR(.notes) - 0) { __start_notes = .; KEEP(*(.note.*)) __stop_notes = .; }
. = ALIGN(0x00010000);
__init_begin = .;
__inittext_begin = .;
. = ALIGN(8); .init.text : AT(ADDR(.init.text) - 0) { _sinittext = .; *(.init.text .init.text.*) *(.text.startup) *(.meminit.text*) _einittext = .; }
.exit.text : {
*(.exit.text) *(.text.exit) *(.memexit.text)
}
. = ALIGN(4);
.altinstructions : {
__alt_instructions = .;
*(.altinstructions)
__alt_instructions_end = .;
}
.altinstr_replacement : {
*(.altinstr_replacement)
}
. = ALIGN((1 << 12));
__inittext_end = .;
__initdata_begin = .;
.init.data : {
KEEP(*(SORT(___kentry+*))) *(.init.data init.data.*) *(.meminit.data*) . = ALIGN(8); __start_mcount_loc = .; KEEP(*(__mcount_loc)) __stop_mcount_loc = .; *(.init.rodata .init.rodata.*) . = ALIGN(8); __start_ftrace_events = .; KEEP(*(_ftrace_events)) __stop_ftrace_events = .; __start_ftrace_eval_maps = .; KEEP(*(_ftrace_eval_map)) __stop_ftrace_eval_maps = .; *(.meminit.rodata) . = ALIGN(8); __clk_of_table = .; KEEP(*(__clk_of_table)) KEEP(*(__clk_of_table_end)) . = ALIGN(8); __reservedmem_of_table = .; KEEP(*(__reservedmem_of_table)) KEEP(*(__reservedmem_of_table_end)) . = ALIGN(8); __timer_of_table = .; KEEP(*(__timer_of_table)) KEEP(*(__timer_of_table_end)) . = ALIGN(8); __cpu_method_of_table = .; KEEP(*(__cpu_method_of_table)) KEEP(*(__cpu_method_of_table_end)) . = ALIGN(8); __cpuidle_method_of_table = .; KEEP(*(__cpuidle_method_of_table)) KEEP(*(__cpuidle_method_of_table_end)) . = ALIGN(32); __dtb_start = .; KEEP(*(.dtb.init.rodata)) __dtb_end = .; . = ALIGN(8); __irqchip_of_table = .; KEEP(*(__irqchip_of_table)) KEEP(*(__irqchip_of_table_end)) . = ALIGN(8); __earlycon_table = .; KEEP(*(__earlycon_table)) __earlycon_table_end = .;
. = ALIGN(16); __setup_start = .; KEEP(*(.init.setup)) __setup_end = .;
__initcall_start = .; KEEP(*(.initcallearly.init)) __initcall0_start = .; KEEP(*(.initcall0.init)) __initcall0s_start = .; KEEP(*(.initcall0s.init)) __initcall1_start = .; KEEP(*(.initcall1.init)) __initcall1s_start = .; KEEP(*(.initcall1s.init)) __initcall2_start = .; KEEP(*(.initcall2.init)) __initcall2s_start = .; KEEP(*(.initcall2s.init)) __initcall3_start = .; KEEP(*(.initcall3.init)) __initcall3s_start = .; KEEP(*(.initcall3s.init)) __initcall4_start = .; KEEP(*(.initcall4.init)) __initcall4s_start = .; KEEP(*(.initcall4s.init)) __initcall5_start = .; KEEP(*(.initcall5.init)) __initcall5s_start = .; KEEP(*(.initcall5s.init)) __initcallrootfs_start = .; KEEP(*(.initcallrootfs.init)) __initcallrootfss_start = .; KEEP(*(.initcallrootfss.init)) __initcall6_start = .; KEEP(*(.initcall6.init)) __initcall6s_start = .; KEEP(*(.initcall6s.init)) __initcall7_start = .; KEEP(*(.initcall7.init)) __initcall7s_start = .; KEEP(*(.initcall7s.init)) __initcall_end = .;
__con_initcall_start = .; KEEP(*(.con_initcall.init)) __con_initcall_end = .;
__security_initcall_start = .; KEEP(*(.security_initcall.init)) __security_initcall_end = .;
. = ALIGN(4); __initramfs_start = .; KEEP(*(.init.ramfs)) . = ALIGN(8); KEEP(*(.init.ramfs.info))
*(.init.rodata.* .init.bss)
}
.exit.data : {
*(.exit.data .exit.data.*) *(.fini_array .fini_array.*) *(.dtors .dtors.*) *(.memexit.data*) *(.memexit.rodata*)
}
. = ALIGN((1 << 12)); .data..percpu : AT(ADDR(.data..percpu) - 0) { __per_cpu_load = .; __per_cpu_start = .; *(.data..percpu..first) . = ALIGN((1 << 12)); *(.data..percpu..page_aligned) . = ALIGN((1 << (6))); *(.data..percpu..read_mostly) . = ALIGN((1 << (6))); *(.data..percpu) *(.data..percpu..shared_aligned) __per_cpu_end = .; }
.rela.dyn : ALIGN(8) {
*(.rela .rela*)
}
__rela_offset = ABSOLUTE(ADDR(.rela.dyn) - ((((((0xffffffffffffffff)) - (((1)) << (39)) + 1) + (0)) + (0x08000000))));
__rela_size = SIZEOF(.rela.dyn);
. = ALIGN(0x00010000);
__initdata_end = .;
__init_end = .;
_data = .;
_sdata = .;
. = ALIGN((1 << 12)); .data : AT(ADDR(.data) - 0) { . = ALIGN((2 * (((1)) << (14 + 0)))); __start_init_task = .; init_thread_union = .; init_stack = .; KEEP(*(.data..init_task)) KEEP(*(.data..init_thread_info)) . = __start_init_task + (((1)) << (14 + 0)); __end_init_task = .; . = ALIGN((1 << 12)); __nosave_begin = .; *(.data..nosave) . = ALIGN((1 << 12)); __nosave_end = .; . = ALIGN((1 << 12)); *(.data..page_aligned) . = ALIGN((1 << 12)); . = ALIGN((1 << (6))); *(.data..cacheline_aligned) . = ALIGN((1 << (6))); *(.data..read_mostly) . = ALIGN((1 << (6))); *(.xiptext) *(.data) *(.ref.data) *(.data..shared_aligned) *(.data.unlikely) __start_once = .; *(.data.once) __end_once = .; . = ALIGN(32); *(__tracepoints) . = ALIGN(8); __start___jump_table = .; KEEP(*(__jump_table)) __stop___jump_table = .; . = ALIGN(8); __start___verbose = .; KEEP(*(__verbose)) __stop___verbose = .; __start___trace_bprintk_fmt = .; KEEP(*(__trace_printk_fmt)) __stop___trace_bprintk_fmt = .; . = ALIGN(32); __start__bpf_raw_tp = .; KEEP(*(__bpf_raw_tp_map)) __stop__bpf_raw_tp = .; __start___tracepoint_str = .; KEEP(*(__tracepoint_str)) __stop___tracepoint_str = .; CONSTRUCTORS } . = ALIGN(8); __bug_table : AT(ADDR(__bug_table) - 0) { __start___bug_table = .; KEEP(*(__bug_table)) __stop___bug_table = .; }
.mmuoff.data.write : ALIGN(0x00000800) {
__mmuoff_data_start = .;
*(.mmuoff.data.write)
}
. = ALIGN(0x00000800);
.mmuoff.data.read : {
*(.mmuoff.data.read)
__mmuoff_data_end = .;
}
__pecoff_data_rawsize = ABSOLUTE(. - __initdata_begin);
_edata = .;
. = ALIGN(0); __bss_start = .; . = ALIGN(0); .sbss : AT(ADDR(.sbss) - 0) { *(.dynsbss) *(.sbss) *(.scommon) } . = ALIGN(0); .bss : AT(ADDR(.bss) - 0) { . = ALIGN((1 << 12)); *(.bss..page_aligned) . = ALIGN((1 << 12)); *(.dynbss) *(.bss) *(COMMON) } . = ALIGN(0); __bss_stop = .;
. = ALIGN((1 << 12));
idmap_pg_dir = .;
. += ((((((48)) - 4) / (12 - 3)) - 1) * (1 << 12));
tramp_pg_dir = .;
. += (1 << 12);
swapper_pg_dir = .;
. += ((1 << 12) * ( 1 + ((((((_end)) - 1) >> (((12 - 3) * (4 - (4 - 3)) + 3))) - (((((((((0xffffffffffffffff)) - (((1)) << (39)) + 1) + (0)) + (0x08000000))) + 0x00080000)) >> (((12 - 3) * (4 - (4 - 3)) + 3))) + 1 + (0))) + (0) + (0)));
swapper_pg_end = .;
__pecoff_data_size = ABSOLUTE(. - __initdata_begin);
_end = .;
.stab 0 : { *(.stab) } .stabstr 0 : { *(.stabstr) } .stab.excl 0 : { *(.stab.excl) } .stab.exclstr 0 : { *(.stab.exclstr) } .stab.index 0 : { *(.stab.index) } .stab.indexstr 0 : { *(.stab.indexstr) } .comment 0 : { *(.comment) }
_kernel_size_le_lo32 = (((_end - _text) & 0xffffffff) & 0xffffffff); _kernel_size_le_hi32 = (((_end - _text) >> 32) & 0xffffffff); _kernel_offset_le_lo32 = (((0x00080000) & 0xffffffff) & 0xffffffff); _kernel_offset_le_hi32 = (((0x00080000) >> 32) & 0xffffffff); _kernel_flags_le_lo32 = (((((0 << 0) | (((12 - 10) / 2) << 1) | (1 << 3))) & 0xffffffff) & 0xffffffff); _kernel_flags_le_hi32 = (((((0 << 0) | (((12 - 10) / 2) << 1) | (1 << 3))) >> 32) & 0xffffffff);
}
ASSERT(__hyp_idmap_text_end - (__hyp_idmap_text_start & ~(0x00001000 - 1)) <= 0x00001000,
"HYP init code too big or misaligned")
ASSERT(__idmap_text_end - (__idmap_text_start & ~(0x00001000 - 1)) <= 0x00001000,
"ID map text too big or misaligned")
ASSERT((__entry_tramp_text_end - __entry_tramp_text_start) == (1 << 12),
"Entry trampoline text too big")
ASSERT(_text == (((((((0xffffffffffffffff)) - (((1)) << (39)) + 1) + (0)) + (0x08000000))) + 0x00080000), "HEAD is misaligned")
设置 我连 入口 都很难找。
它说入口是 _text
但是 _text 是一个 .
那这里 是不是 说如果就是 .head.text 段的第一条指令呢。
网上找到 入口的文件是 arch/arm64/kernel/head.S
我估计 这里的entry 相当于 标号的意思吧。