问题描述
$ sudo docker container ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d207fd2d9dd8 my_qt_cross_win:qttools "/bin/sh -c 'qmake /…" 11 minutes ago Exited (2) 10 minutes ago musing_chebyshev
和启动代码 startup.s :
/* write for machine virt */
ENTRY(_Reset)
MEMORY
{
rm(rx) : ORIGIN = 0x00000000,LENGTH = 0x80000
ram (rwx) : ORIGIN = 0x40000000,LENGTH = 0x40000000
}
SECTIONS
{
. = 0x10000;
.startup . : { startup.o(.startup) }
.text : { *(.text) }
.data : { *(.data) }
.bss : { *(.bss COMMON) }
. = ALIGN(8);
. = . + 0x1000; /* 4kB of stack memory */
stack_top = .;
}
和 test.c 用于打印：
.section .startup
.global _Reset
_Reset:
ldr x5,stack_top
msr sp_el0,x5
bl c_entry
b .
这就是我编译和链接程序的方式。
volatile unsigned int * const UART0DR = (unsigned int *)0x09000000;
void print_uart0(const char *s) {
while(*s != '\0') { /* Loop until end of string */
*UART0DR = (unsigned int)(*s); /* Transmit char */
s++; /* Next char */
}
}
void c_entry() {
print_uart0("Hello World!\n");
}
当我对 aarch64-elf-as startup.s -o startup.o
aarch64-elf-gcc -c -g test.c -o test.o
aarch64-elf-ld -T test.ld test.o startup.o -o test.elf
aarch64-elf-objcopy -O binary test.elf test.bin
的最终结果做 objdump 时，我看到这个结果：
aarch64-none-elf-objdump -D test.elf我不知道为什么 _Reset 正确地位于 0x10000，但 print_uart0 和 c_entry 函数位于 0x00000000。根据链接描述文件，.text 部分不应该紧跟在 .startup 部分之后吗？
解决方法
_Reset 位于 0x10000，因为您的脚本使用 . = 0x10000; 语句显式请求它。
并且您可能应该告诉链接器 .startup 应该与所有 .text 相关的内容放在一起，并且在开始时：
/* write for machine virt */
ENTRY(_Reset)
MEMORY
{
rm(rx) : ORIGIN = 0x00000000,LENGTH = 0x80000
ram (rwx) : ORIGIN = 0x40000000,LENGTH = 0x40000000
}
SECTIONS
{
.text : {
*(.startup)
*(.text)
}
.data : { *(.data) }
.bss : { *(.bss COMMON) }
. = ALIGN(8);
. = . + 0x1000; /* 4kB of stack memory */
stack_top = .;
}
结果将是：
test.elf: file format elf64-littleaarch64
Disassembly of section .text:
0000000000000000 <_Reset>:
0: 58008485 ldr x5,1090 <stack_top>
4: d5184105 msr sp_el0,x5
8: 94000014 bl 58 <c_entry>
c: 14000000 b c <_Reset+0xc>
0000000000000010 <print_uart0>:
10: d10043ff sub sp,sp,#0x10
14: f90007e0 str x0,[sp,#8]
18: 14000008 b 38 <print_uart0+0x28>
1c: f94007e0 ldr x0,#8]
20: 39400001 ldrb w1,[x0]
24: d2a12000 mov x0,#0x9000000 // #150994944
28: b9000001 str w1,[x0]
2c: f94007e0 ldr x0,#8]
30: 91000400 add x0,x0,#0x1
34: f90007e0 str x0,#8]
38: f94007e0 ldr x0,#8]
3c: 39400000 ldrb w0,[x0]
40: 7100001f cmp w0,#0x0
44: 54fffec1 b.ne 1c <print_uart0+0xc> // b.any
48: d503201f nop
4c: d503201f nop
50: 910043ff add sp,#0x10
54: d65f03c0 ret
0000000000000058 <c_entry>:
58: a9bf7bfd stp x29,x30,#-16]!
5c: 910003fd mov x29,sp
60: 90000000 adrp x0,0 <_Reset>
64: 91020000 add x0,#0x80
68: 97ffffea bl 10 <print_uart0>
6c: d503201f nop
70: a8c17bfd ldp x29,[sp],#16
74: d65f03c0 ret
Disassembly of section .rodata:
0000000000000078 <UART0DR>:
78: 09000000 .inst 0x09000000 ; undefined
7c: 00000000 udf #0
80: 6c6c6548 ldnp d8,d25,[x10,#-320]
84: 6f77206f umlal2 v15.4s,v3.8h,v7.h[3]
88: 21646c72 .inst 0x21646c72 ; undefined
8c: Address 0x000000000000008c is out of bounds.
请注意，如果您希望您的代码从 0x40000000 开始，您必须通过在 > ram 部分的定义中添加 .text（同样的事情.data 部分）：
/* write for machine virt */
ENTRY(_Reset)
MEMORY
{
rm(rx) : ORIGIN = 0x00000000,LENGTH = 0x40000000
}
SECTIONS
{
.text : {
*(.startup)
*(.text)
} > ram
.data : {
*(.data)
} > ram
.bss : { *(.bss COMMON) }
. = ALIGN(8);
. = . + 0x1000; /* 4kB of stack memory */
stack_top = .;
}
结果将是：
test.elf: file format elf64-littleaarch64
Disassembly of section .text:
0000000040000000 <_Reset>:
40000000: 58008485 ldr x5,40001090 <stack_top>
40000004: d5184105 msr sp_el0,x5
40000008: 94000014 bl 40000058 <c_entry>
4000000c: 14000000 b 4000000c <_Reset+0xc>
0000000040000010 <print_uart0>:
40000010: d10043ff sub sp,#0x10
40000014: f90007e0 str x0,#8]
40000018: 14000008 b 40000038 <print_uart0+0x28>
4000001c: f94007e0 ldr x0,#8]
40000020: 39400001 ldrb w1,[x0]
40000024: d2a12000 mov x0,#0x9000000 // #150994944
40000028: b9000001 str w1,[x0]
4000002c: f94007e0 ldr x0,#8]
40000030: 91000400 add x0,#0x1
40000034: f90007e0 str x0,#8]
40000038: f94007e0 ldr x0,#8]
4000003c: 39400000 ldrb w0,[x0]
40000040: 7100001f cmp w0,#0x0
40000044: 54fffec1 b.ne 4000001c <print_uart0+0xc> // b.any
40000048: d503201f nop
4000004c: d503201f nop
40000050: 910043ff add sp,#0x10
40000054: d65f03c0 ret
0000000040000058 <c_entry>:
40000058: a9bf7bfd stp x29,#-16]!
4000005c: 910003fd mov x29,sp
40000060: 90000000 adrp x0,40000000 <_Reset>
40000064: 91020000 add x0,#0x80
40000068: 97ffffea bl 40000010 <print_uart0>
4000006c: d503201f nop
40000070: a8c17bfd ldp x29,#16
40000074: d65f03c0 ret
Disassembly of section .rodata:
0000000040000078 <UART0DR>:
40000078: 09000000 .inst 0x09000000 ; undefined
4000007c: 00000000 udf #0
40000080: 6c6c6548 ldnp d8,#-320]
40000084: 6f77206f umlal2 v15.4s,v7.h[3]
40000088: 21646c72 .inst 0x21646c72 ; undefined
4000008c: Address 0x000000004000008c is out of bounds.