链接地址学习笔记

链接地址

启动过程

 

 

示例代码如下：

 

start.S文件

.globl_start

_start:

/*硬件相关设置*/

ldrr0,=0x70000000

orrr0,r0,#0x13

mcrp15,0,r0,c15,c2,4

/*关看门狗*/

 

bltest/*位置无关*/

ldrpc,=test/*位置相关*/

 

ldrr0,=0x7E00400

movr1,#0

strr1,[r0]

 

/*设置栈*/

ldrsp,=8*1024

blmain

halt:

bhalt

test:

movpc,lr

 

 

 

 

Led.c文件

voiddelay(){

volatileinti=0x1000;

while(i--);

}

 

volatileinti=0;

volatileintj=0x12345678;

volatileintk=0;

volatileintg;

 

intmain(){

volatileunsignedlong*gpkcon=(volatileunsignedlong*)0x7F008800;

volatileunsignedlong*gpkdat=(volatileunsignedlong*)0x7F008808;

*gpkcon=0x1111;

while(1){

*gpkdat=i;

i++;

if(i==16)

i=0;

delay();

}

return0;

}

 

 

Leds.lds文件

SECTIONS

{

.=0x50000000;

.text:{

start.o

*(.text)

}

 

.data:{

*(.data)

}

 

bss_start=.;

.bss:{

*(.bss)

}

bss_end=.;

}

 

Makefile文件

led.bin:start.oled.o

arm-linux-ld-Tleds.lds-oled.elfstart.oled.o

arm-linux-objcopy-Obinaryled.elfled.bin

arm-linux-objdump-Dled.elf>led.dis

 

start.o:start.S

arm-linux-gcc-ostart.ostart.S-c

led.o:led.c

arm-linux-gcc-oled.oled.c-c

 

clean:

rm*.oled.elfled.binled.dis

 

 

Led.dis文件

 

led.elf:fileformatelf32-littlearm

 

 

 

首地址为0x50000000;

 

Disassemblyofsection.text:

 

50000000<_start>:

50000000: e3a00207 mov r0,#1879048192 ;0x70000000

50000004: e3800013 orr r0,r0,#19

50000008: ee0f0f92 mcr 15,0,r0,cr15,cr2,{4}

5000000c: e59f0014 ldr r0,[pc,#20] ;50000028<test+0x4>

50000010: e3a01000 mov r1,#0

50000014: e5801000 str r1,[r0]

50000018: e3a0da02 mov sp,#8192 ;0x2000

5000001c: eb00001e bl 5000009c<main>

 

50000020<halt>:

50000020: eafffffe b 50000020<halt>

 

50000024<test>:

50000024: e1a0f00e mov pc,lr

50000028: 07e00400 strbeq r0,[r0,r0,lsl#8]!

5000002c: 00002541 andeq r2,r0,r1,asr#10

50000030: 61656100 cmnvs r5,r0,lsl#2

50000034: 01006962 tsteq r0,r2,ror#18

50000038: 0000001b andeq r0,r0,fp,lslr0

5000003c: 4d524105 ldfmie f4,[r2,#-20] ;0xffffffec

50000040: 36373131 undefinedinstruction0x36373131

50000044: 2d465a4a vstrcs s11,[r6,#-296] ;0xfffffed8

50000048: 09060053 stmdbeq r6,{r0,r1,r4,r6}

5000004c: 01090108 tsteq r9,r8,lsl#2

50000050: 0000020a andeq r0,r0,sl,lsl#4

 

50000054<delay>:

50000054: e52db004 push {fp} ;(strfp,[sp,#-4]!)

50000058: e28db000 add fp,sp,#0

5000005c: e24dd00c sub sp,sp,#12

50000060: e3a03a01 mov r3,#4096 ;0x1000

50000064: e50b3008 str r3,[fp,#-8]

50000068: e1a00000 nop ;(movr0,r0)

5000006c: e51b3008 ldr r3,[fp,#-8]

50000070: e3530000 cmp r3,#0

50000074: 03a02000 moveq r2,#0

50000078: 13a02001 movne r2,#1

5000007c: e6ef2072 uxtb r2,r2

50000080: e2433001 sub r3,r3,#1

50000084: e50b3008 str r3,[fp,#-8]

50000088: e3520000 cmp r2,#0

5000008c: 1afffff6 bne 5000006c<delay+0x18>

50000090: e28bd000 add sp,fp,#0

50000094: e8bd0800 pop {fp}

50000098: e12fff1e bx lr

 

5000009c<main>:

5000009c: e92d4800 push {fp,lr}

500000a0: e28db004 add fp,sp,#4

500000a4: e24dd008 sub sp,sp,#8

500000a8: e59f3060 ldr r3,[pc,#96] ;50000110<main+0x74>

500000ac: e50b3008 str r3,[fp,#-8]

500000b0: e59f305c ldr r3,[pc,#92] ;50000114<main+0x78>

500000b4: e50b300c str r3,[fp,#-12]

500000b8: e51b3008 ldr r3,[fp,#-8]

500000bc: e59f2054 ldr r2,[pc,#84] ;50000118<main+0x7c>

500000c0: e5832000 str r2,[r3]

500000c4: e59f3050 ldr r3,[pc,#80] ;5000011c<main+0x80>

500000c8: e5933000 ldr r3,[r3]

500000cc: e1a02003 mov r2,r3

500000d0: e51b300c ldr r3,[fp,#-12]

500000d4: e5832000 str r2,[r3]

500000d8: e59f303c ldr r3,[pc,#60] ;5000011c<main+0x80>

500000dc: e5933000 ldr r3,[r3]

500000e0: e2832001 add r2,r3,#1

500000e4: e59f3030 ldr r3,[pc,#48] ;5000011c<main+0x80>

500000e8: e5832000 str r2,[r3]

500000ec: e59f3028 ldr r3,[pc,#40] ;5000011c<main+0x80>

500000f0: e5933000 ldr r3,[r3]

500000f4: e3530010 cmp r3,#16

500000f8: 1a000002 bne 50000108<main+0x6c>

500000fc: e59f3018 ldr r3,[pc,#24] ;5000011c<main+0x80>

50000100: e3a02000 mov r2,#0

50000104: e5832000 str r2,[r3]

50000108: ebffffd1 bl 50000054<delay>

5000010c: eaffffec b 500000c4<main+0x28>

50000110: 7f008800 svcvc 0x00008800

50000114: 7f008808 svcvc 0x00008808

50000118: 00001111 andeq r1,r0,r1,lslr1

5000011c: 50000124 andpl r0,r0,r4,lsr#2

 

Disassemblyofsection.data:

 

50000120<j>:

50000120: 12345678 eorsne r5,r4,#125829120 ;0x7800000

 

Disassemblyofsection.bss:

 

50000124<i>:

50000124: 00000000 andeq r0,r0,r0

 

50000128<k>:

50000128: 00000000 andeq r0,r0,r0

 

5000012c<g>:

5000012c: 00000000 andeq r0,r0,r0

 

Disassemblyofsection.comment:

 

00000000<.comment>:

0: 3a434347 bcc 10d0d24<_start-0x4ef2f2dc>

4: 74632820 strbtvc r2,[r3],#-2080 ;0x820

8: 312d676e teqcc sp,lr,ror#14

c: 312e382e teqcc lr,lr,lsr#16

10: 2941462d stmdbcs r1,{r0,r2,r3,r5,r9,sl,lr}^

14: 352e3420 strcc r3,[lr,#-1056]! ;0x420

18: Address0x00000018isoutofbounds.

 

 

首地址为0

Disassemblyofsection.ARM.attributes:

 

00000000<.ARM.attributes>:

0: 00003341 andeq r3,r0,r1,asr#6

4: 61656100 cmnvs r5,r0,lsl#2

8: 01006962 tsteq r0,r2,ror#18

c: 00000029 andeq r0,r0,r9,lsr#32

10: 4d524105 ldfmie f4,[r2,#-20] ;0xffffffec

14: 36373131 undefinedinstruction0x36373131

18: 2d465a4a vstrcs s11,[r6,#-296] ;0xfffffed8

1c: 09060053 stmdbeq r6,{r0,r1,r4,r6}

20: 01090108 tsteq r9,r8,lsl#2

24: 0412020a ldreq r0,[r2],#-522 ;0x20a

28: 01150114 tsteq r5,r4,lslr1

2c: 01180317 tsteq r8,r7,lslr3

30: 031b021a tsteq fp,#-1610612735 ;0xa0000001

 

 

 

led.elf:fileformatelf32-littlearm

 

 

Disassemblyofsection.text:

 

00000000<_start>:

0:e3a00207movr0,#1879048192;0x70000000

4:e3800013orrr0,r0,#19

8:ee0f0f92mcr15,0,r0,cr15,cr2,{4}

/*

Bltest的机器码eb00,0006

1110,1011,000000000000000000000110

--------------------------------------------------------------

1确定b/bl

剩余为偏移量

Branchinstructioncontainsasigned2'scomplement24bitoffset.Thisisshiftedlefttwobits,signextendedto32

bits,andaddedtothePC.

偏移量offset6<<2=6*2*2=24

Pc=pc+24

=（当前指令+8）+24

=（c+8）+24=(12+8)+24=44=0x2c

*/

 

 

c:eb000006Bltestldrpc,=test

10:e59ff018ldrpc,[pc,#24];30<test+0x4>

14:e59f0018ldrr0,[pc,#24];34<test+0x8>

18:e3a01000movr1,#0

1c:e5801000strr1,[r0]

20:e3a0da02movsp,#8192;0x2000

24:eb00001fbla8<main>

 

00000020<halt>:

20: eafffffe b 20<halt>

 

/*跳转到此位置*/

0000002c<test>:

2c:e1a0f00emovpc,lr

30:0000002candeqr0,r0,ip,lsr#32

34:07e00400strbeqr0,[r0,r0,lsl#8]!

38:00002541andeqr2,r0,r1,asr#10

3c:61656100cmnvsr5,r0,lsl#2

40:01006962tsteqr0,r2,ror#18

44:0000001bandeqr0,r0,fp,lslr0

48:4d524105ldfmief4,[r2,#-20];0xffffffec

4c:36373131undefinedinstruction0x36373131

50:2d465a4avstrcss11,[r6,#-296];0xfffffed8

54:09060053stmdbeqr6,{r0,r1,r4,r6}

58:01090108tsteqr9,r8,lsl#2

5c:0000020aandeqr0,r0,sl,lsl#4

 

00000054<delay>:

54: e52db004 push {fp} ;(strfp,[sp,#-4]!)

58: e28db000 add fp,sp,#0

5c: e24dd00c sub sp,sp,#12

60: e3a03a01 mov r3,#4096 ;0x1000

64: e50b3008 str r3,[fp,#-8]

68: e1a00000 nop ;(movr0,r0)

6c: e51b3008 ldr r3,[fp,#-8]

70: e3530000 cmp r3,#0

74: 03a02000 moveq r2,#0

78: 13a02001 movne r2,#1

7c: e6ef2072 uxtb r2,r2

80: e2433001 sub r3,r3,#1

84: e50b3008 str r3,[fp,#-8]

88: e3520000 cmp r2,#0

8c: 1afffff6 bne 6c<delay+0x18>

90: e28bd000 add sp,fp,#0

94: e8bd0800 pop {fp}

98: e12fff1e bx lr

 

0000009c<main>:

9c: e92d4800 push {fp,lr}

a0: e28db004 add fp,sp,#4

a4: e24dd008 sub sp,sp,#8

a8: e59f3060 ldr r3,[pc,#96] ;110<main+0x74>

ac: e50b3008 str r3,[fp,#-8]

b0: e59f305c ldr r3,[pc,#92] ;114<main+0x78>

b4: e50b300c str r3,[fp,#-12]

b8: e51b3008 ldr r3,[fp,#-8]

bc: e59f2054 ldr r2,[pc,#84] ;118<main+0x7c>

c0: e5832000 str r2,[r3]

c4: e59f3050 ldr r3,[pc,#80] ;11c<main+0x80>

c8: e5933000 ldr r3,[r3]

cc: e1a02003 mov r2,r3

d0: e51b300c ldr r3,[fp,#-12]

d4: e5832000 str r2,[r3]

d8: e59f303c ldr r3,[pc,#60] ;11c<main+0x80>

dc: e5933000 ldr r3,[r3]

e0: e2832001 add r2,r3,#1

e4: e59f3030 ldr r3,[pc,#48] ;11c<main+0x80>

e8: e5832000 str r2,[r3]

ec: e59f3028 ldr r3,[pc,#40] ;11c<main+0x80>

f0: e5933000 ldr r3,[r3]

f4: e3530010 cmp r3,#16

f8: 1a000002 bne 108<main+0x6c>

fc: e59f3018 ldr r3,[pc,#24] ;11c<main+0x80>

100: e3a02000 mov r2,#0

104: e5832000 str r2,[r3]

108: ebffffd1 bl 54<delay>

10c: eaffffec b c4<main+0x28>

110: 7f008800 svcvc 0x00008800

114: 7f008808 svcvc 0x00008808

118: 00001111 andeq r1,r0,r1,lslr1

11c: 00000124andeq r0,r0,r4,lsr#2

 

Disassemblyofsection.data:

 

00000120<j>:

120: 12345678 eorsne r5,r4,#125829120 ;0x7800000

 

Disassemblyofsection.bss:

 

00000124<i>:

124: 00000000 andeq r0,r0,r0

 

00000128<k>:

128: 00000000 andeq r0,r0,r0

 

0000012c<g>:

12c: 00000000 andeq r0,r0,r0

 

Disassemblyofsection.comment:

 

00000000<.comment>:

0: 3a434347 bcc 10d0d24<bss_end+0x10d0bf4>

4: 74632820 strbtvc r2,[r3],#-2080 ;0x820

8: 312d676e teqcc sp,lr,ror#14

c: 312e382e teqcc lr,lr,lsr#16

10: 2941462d stmdbcs r1,{r0,r2,r3,r5,r9,sl,lr}^

14: 352e3420 strcc r3,[lr,#-1056]! ;0x420

18: Address0x00000018isoutofbounds.

 

 

Disassemblyofsection.ARM.attributes:

 

00000000<.ARM.attributes>:

0: 00003341 andeq r3,r0,r1,asr#6

4: 61656100 cmnvs r5,r0,lsl#2

8: 01006962 tsteq r0,r2,ror#18

c: 00000029 andeq r0,r0,r9,lsr#32

10: 4d524105 ldfmie f4,[r2,#-20] ;0xffffffec

14: 36373131 undefinedinstruction0x36373131

18: 2d465a4a vstrcs s11,[r6,#-296] ;0xfffffed8

1c: 09060053 stmdbeq r6,{r0,r1,r4,r6}

20: 01090108 tsteq r9,r8,lsl#2

24: 0412020a ldreq r0,[r2],#-522 ;0x20a

28: 01150114 tsteq r5,r4,lslr1

2c: 01180317 tsteq r8,r7,lslr3

30: 031b021a tsteq fp,#-1610612735 ;0xa0000001