[U-Boot-Users] Question About how the CPU find the right string address in U-boot binary file ?

wang baohua wbh7602 at gmail.com
Wed Jun 4 06:04:47 CEST 2008 

Dear all,
 I study the U-boot.bin file using the objdump command, I don't know how the
CPU can find the right string address when puts() string.
 For example, In my binary file, the string "Call backtrace: " in func
"print_backtrace()" address is :0x0002b280, the func address is
 0xfff03564, How the CPU can find the 0x0002b280 when call  puts ("Call
backtrace: "); ?  I find the SMC serial driver
 "serial_putc()" but cannot know how to find the char address in binary
file.

Below is the objdump result, can anyone explain to me ? thanks!

(PowerPC platform)
void print_backtrace(unsigned long *sp)
{
int cnt = 0;
unsigned long i;

puts ("Call backtrace: ");
while (sp) {
if ((uint)sp > END_OF_MEM)
break;

i = sp[1];
if (cnt++ % 7 == 0)
putc ('\n');
printf("%08lX ", i);
if (cnt > 32) break;
sp = (unsigned long *)*sp;
}
putc ('\n');
}

void show_regs(struct pt_regs * regs)
{
int i;

printf("NIP: %08lX XER: %08lX LR: %08lX REGS: %p TRAP: %04lx DAR: %08lX\n",
regs->nip, regs->xer, regs->link, regs, regs->trap, regs->dar);
printf("MSR: %08lx EE: %01x PR: %01x FP: %01x ME: %01x IR/DR: %01x%01x\n",
regs->msr, regs->msr&MSR_EE ? 1 : 0, regs->msr&MSR_PR ? 1 : 0,
regs->msr & MSR_FP ? 1 : 0,regs->msr&MSR_ME ? 1 : 0,
regs->msr&MSR_IR ? 1 : 0,
regs->msr&MSR_DR ? 1 : 0);

putc ('\n');
for (i = 0; i < 32; i++) {
if ((i % 8) == 0) {
printf("GPR%02d: ", i);
}

printf("%08lX ", regs->gpr[i]);
if ((i % 8) == 7) {
putc ('\n');
}
}
}

void puts (const char *s)
{
DECLARE_GLOBAL_DATA_PTR;

#ifdef CONFIG_SILENT_CONSOLE
if (gd->flags & GD_FLG_SILENT)
return;
#endif

if (gd->flags & GD_FLG_DEVINIT) {
/* Send to the standard output */
fputs (stdout, s);
} else {
/* Send directly to the handler */
serial_puts (s);
}
}

void serial_putc(const char c)
{
volatile cbd_t *tbdf;
volatile char *buf;
volatile smc_uart_t *up;
volatile immap_t *im = (immap_t *)CFG_IMMR;

if (c == '\n')
serial_putc ('\r');

up = (smc_uart_t *)&(im->im_dprambase[PROFF_SMC]);

tbdf = (cbd_t *)&im->im_dprambase[up->smc_tbase];

/* Wait for last character to go.
*/
buf = (char *)tbdf->cbd_bufaddr;
while (tbdf->cbd_sc & BD_SC_READY)
;

*buf = c;
tbdf->cbd_datlen = 1;
tbdf->cbd_sc |= BD_SC_READY;
}

------------------------------------------------------------------------------------
hex code in u-boot.bin
string:
0002b280h: 43 61 6C 6C 20 62 61 63 6B 74 72 61 63 65 3A 20 ; Call backtrace:

0002b290h: 00 00 00 00 25 30 38 6C 58 20 00 00 4E 49 50 3A ; ....%08lX
..NIP:
0002b2a0h: 20 25 30 38 6C 58 20 58 45 52 3A 20 25 30 38 6C ; %08lX XER: %08l
0002b2b0h: 58 20 4C 52 3A 20 25 30 38 6C 58 20 52 45 47 53 ; X LR: %08lX
REGS
0002b2c0h: 3A 20 25 70 20 54 52 41 50 3A 20 25 30 34 6C 78 ; : %p TRAP:
%04lx
0002b2d0h: 20 44 41 52 3A 20 25 30 38 6C 58 0A 00 00 00 00 ; DAR: %08lX.....
0002b2e0h: 4D 53 52 3A 20 25 30 38 6C 78 20 45 45 3A 20 25 ; MSR: %08lx EE:
%
0002b2f0h: 30 31 78 20 50 52 3A 20 25 30 31 78 20 46 50 3A ; 01x PR: %01x
FP:
0002b300h: 20 25 30 31 78 20 4D 45 3A 20 25 30 31 78 20 49 ; %01x ME: %01x I
0002b310h: 52 2F 44 52 3A 20 25 30 31 78 25 30 31 78 0A 00 ; R/DR:
%01x%01x..
0002b320h: 47 50 52 25 30 32 64 3A ; GPR%02d:


hex code in u-boot.bin
func:
print_backtrace()
00003584h: 94 21 FF D8 7C 08 02 A6 42 9F 00 05 BF 61 00 14 ;
?&#63733;Ø|..¦B?.¿a..
00003594h: 7F C8 02 A6 90 01 00 2C 80 1E FF F0 7C 7C 1B 78 ;
?¦..,&#8364;.&#63733;ð||.x
000035a4h: 3B E0 00 00 7F C0 F2 14 80 7E 80 00 48 01 1B AD ;
;?.Àò.&#8364;~&#8364;.H..?
000035b4h: 2C 1C 00 00 41 82 00 70 3C 00 02 00 7C 1C 00 40 ; ,...A?p<...|..@
000035c4h: 3D 20 92 49 61 29 24 93 7F EB FE 70 38 60 00 0A ; = 'Ia)$?ëþp8`..
000035d4h: 41 81 00 54 7C 1F 48 96 83 7C 00 04 7C 00 FA 14 ; A?T|.H–ƒ|..|.?
000035e4h: 7C 00 16 70 7C 0B 00 50 1C 00 00 07 7C 00 F8 50 ;
|..p|..P....|.øP
000035f4h: 2C 00 00 00 3B FF 00 01 40 A2 00 08 48 01 1B 21 ;
,...;&#63733;..@?.H..!
00003604h: 80 7E 80 04 7F 64 DB 78 4C C6 31 82 48 01 1B 89 ;
&#8364;~&#8364;.dÛxL?‚H..?
00003614h: 2C 1F 00 20 41 81 00 10 83 9C 00 00 2C 1C 00 00 ; ,.. A?.ƒœ..,...
00003624h: 40 82 FF 98 38 60 00 0A 48 01 1A F5 BB 61 00 14 ; @??`..H..õ»a..
00003634h: 80 01 00 2C 38 21 00 28 7C 08 03 A6 4E 80 00 20 ;
&#8364;..,8!.(|..¦N&#8364;.
00003644h: 00 03 89 F0 ; ..‰ð

show_regs()
00003648h: 94 21 FF E8 7C 08 02 A6 42 9F 00 05 BF 81 00 08 ;
?&#63733;è|..¦B?.¿..
00003658h: 7F C8 02 A6 90 01 00 1C 80 1E FF F0 7C 7F 1B 78 ;
?¦...&#8364;.&#63733;ð|.x
00003668h: 80 9F 00 80 7F E7 FB 78 7F C0 F2 14 80 BF 00 94 ;
&#8364;?&#8364;çûxÀò.&#8364;??
00003678h: 80 7E 80 08 3B 80 00 00 80 DF 00 90 81 1F 00 A0 ;
&#8364;~&#8364;.;&#8364;..&#8364;?..?
00003688h: 81 3F 00 A4 4C C6 31 82 48 01 1B 09 80 9F 00 84 ;
?.¤L?‚H...&#8364;??
00003698h: 80 7E 80 0C 54 85 8F FE 54 86 97 FE 54 87 9F FE ;
&#8364;~&#8364;.T…&#59417;†—&#59417;‡Ÿ?
000036a8h: 54 88 A7 FE 54 89 DF FE 54 8A E7 FE 4C C6 31 82 ;
Tˆ§&#59417;‰ß&#59417;ŠçþL??
000036b8h: 48 01 1A E1 38 60 00 0A 48 01 1A 61 73 80 00 07 ;
H..?`..H..as&#8364;..
000036c8h: 7F 84 E3 78 40 A2 00 10 80 7E 80 10 4C C6 31 82 ; „ãx@
?.&#8364;~&#8364;.L??
000036d8h: 48 01 1A C1 57 80 10 3A 80 7E 80 04 7C 9F 00 2E ;
H..ÁW&#8364;.:&#8364;~&#8364;.|?.
000036e8h: 4C C6 31 82 48 01 1A AD 38 60 00 0A 7F 80 1E 70 ;
L?‚H..?`..&#8364;.p
000036f8h: 7C 00 01 94 54 00 18 38 7C 00 E0 50 2C 00 00 07 ;
|.."T..8|.àP,...
00003708h: 3B 9C 00 01 40 A2 00 08 48 01 1A 11 2C 1C 00 1F ; ;?.@?.H...,...
00003718h: 40 81 FF AC 80 01 00 1C BB 81 00 08 38 21 00 18 ; @?¬€...»..8!..
00003728h: 7C 08 03 A6 4E 80 00 20 00 03 89 04 ; |..¦N&#8364;. ..?

puts()
0001515ch: 94 21 FF E8 7C 08 02 A6 90 01 00 1C 7C 64 1B 78 ;
?&#63733;è|..¦...|d.x
0001516ch: 80 1D 00 04 70 09 00 02 41 82 00 10 38 60 00 01 ;
&#8364;...p...A?.8`..
0001517ch: 4B FF FE 4D 48 00 00 08 48 00 FE 89 80 01 00 1C ;
K&#63733;þMH...H.&#59469;&#8364;...
0001518ch: 38 21 00 18 7C 08 03 A6 4E 80 00 20 ; 8!..|..¦N&#8364;.

serial_putc()
00024f9ch: 2C 03 00 0A 94 21 FF E8 7C 08 02 A6 93 E1 00 10 ;
,...?&#63733;è|..¦"?.
00024fach: 90 01 00 1C 7C 7F 1B 78 40 A2 00 0C 38 60 00 0D ; ?..|.x@?.8`..
00024fbch: 4B FF FF E1 3D 20 F0 00 A1 29 00 02 3D 29 F0 00 ;
K&#63733;&#63733;? ??..=)?
00024fcch: 81 69 00 04 A8 09 00 00 2C 00 00 00 41 80 FF F8 ;
i..?..,...A&#8364;&#63733;?
00024fdch: 38 00 00 01 9B EB 00 00 B0 09 00 02 A0 09 00 00 ; 8...ݑ..?..?..
00024fech: 83 E1 00 10 64 00 FF FF 60 00 80 00 B0 09 00 00 ;
ć..d.&#63733;&#63733;`.&#8364;.?..
00024ffch: 80 01 00 1C 38 21 00 18 7C 08 03 A6 4E 80 00 20 ;
&#8364;...8!..|..¦N&#8364;.

-------------------------------------------------------------------------------------
assemble code
fff03564 <print_backtrace>: ---> length: C0,  u-boot.bin  address
0x00003584,offset address: 0xFFEFFFE0
fff03564: 94 21 ff d8 stwu r1,-40(r1)
fff03568: 7c 08 02 a6 mflr r0
fff0356c: 42 9f 00 05 bcl- 20,4*cr7+so,fff03570 <print_backtrace+0xc>
fff03570: bf 61 00 14 stmw r27,20(r1)
fff03574: 7f c8 02 a6 mflr r30
fff03578: 90 01 00 2c stw r0,44(r1)
fff0357c: 80 1e ff f0 lwz r0,-16(r30)
fff03580: 7c 7c 1b 78 mr r28,r3
fff03584: 3b e0 00 00 li r31,0
fff03588: 7f c0 f2 14 add r30,r0,r30
fff0358c: 80 7e 80 00 lwz r3,-32768(r30)
fff03590: 48 01 1b ad bl fff1513c <puts>
fff03594: 2c 1c 00 00 cmpwi r28,0
fff03598: 41 82 00 70 beq- fff03608 <print_backtrace+0xa4>
fff0359c: 3c 00 02 00 lis r0,512
fff035a0: 7c 1c 00 40 cmplw r28,r0
fff035a4: 3d 20 92 49 lis r9,-28087
fff035a8: 61 29 24 93 ori r9,r9,9363
fff035ac: 7f eb fe 70 srawi r11,r31,31
fff035b0: 38 60 00 0a li r3,10
fff035b4: 41 81 00 54 bgt- fff03608 <print_backtrace+0xa4>
fff035b8: 7c 1f 48 96 mulhw r0,r31,r9
fff035bc: 83 7c 00 04 lwz r27,4(r28)
fff035c0: 7c 00 fa 14 add r0,r0,r31
fff035c4: 7c 00 16 70 srawi r0,r0,2
fff035c8: 7c 0b 00 50 subf r0,r11,r0
fff035cc: 1c 00 00 07 mulli r0,r0,7
fff035d0: 7c 00 f8 50 subf r0,r0,r31
fff035d4: 2c 00 00 00 cmpwi r0,0
fff035d8: 3b ff 00 01 addi r31,r31,1
fff035dc: 40 a2 00 08 bne+ fff035e4 <print_backtrace+0x80>
fff035e0: 48 01 1b 21 bl fff15100 <putc>
fff035e4: 80 7e 80 04 lwz r3,-32764(r30)
fff035e8: 7f 64 db 78 mr r4,r27
fff035ec: 4c c6 31 82 crclr 4*cr1+eq
fff035f0: 48 01 1b 89 bl fff15178 <printf>
fff035f4: 2c 1f 00 20 cmpwi r31,32
fff035f8: 41 81 00 10 bgt- fff03608 <print_backtrace+0xa4>
fff035fc: 83 9c 00 00 lwz r28,0(r28)
fff03600: 2c 1c 00 00 cmpwi r28,0
fff03604: 40 82 ff 98 bne+ fff0359c <print_backtrace+0x38>
fff03608: 38 60 00 0a li r3,10
fff0360c: 48 01 1a f5 bl fff15100 <putc>
fff03610: bb 61 00 14 lmw r27,20(r1)
fff03614: 80 01 00 2c lwz r0,44(r1)
fff03618: 38 21 00 28 addi r1,r1,40
fff0361c: 7c 08 03 a6 mtlr r0
fff03620: 4e 80 00 20 blr
fff03624: 00 03 89 f0 .long 0x389f0

fff03628 <show_regs>: --->length 0xE8,  u-boot.bin  address
0x00003648,offset address: 0xFFEFFFE0
fff03628: 94 21 ff e8 stwu r1,-24(r1)
fff0362c: 7c 08 02 a6 mflr r0
fff03630: 42 9f 00 05 bcl- 20,4*cr7+so,fff03634 <show_regs+0xc>
fff03634: bf 81 00 08 stmw r28,8(r1)
fff03638: 7f c8 02 a6 mflr r30
fff0363c: 90 01 00 1c stw r0,28(r1)
fff03640: 80 1e ff f0 lwz r0,-16(r30)
fff03644: 7c 7f 1b 78 mr r31,r3
fff03648: 80 9f 00 80 lwz r4,128(r31)
fff0364c: 7f e7 fb 78 mr r7,r31
fff03650: 7f c0 f2 14 add r30,r0,r30
fff03654: 80 bf 00 94 lwz r5,148(r31)
fff03658: 80 7e 80 08 lwz r3,-32760(r30)
fff0365c: 3b 80 00 00 li r28,0
fff03660: 80 df 00 90 lwz r6,144(r31)
fff03664: 81 1f 00 a0 lwz r8,160(r31)
fff03668: 81 3f 00 a4 lwz r9,164(r31)
fff0366c: 4c c6 31 82 crclr 4*cr1+eq
fff03670: 48 01 1b 09 bl fff15178 <printf>
fff03674: 80 9f 00 84 lwz r4,132(r31)
fff03678: 80 7e 80 0c lwz r3,-32756(r30)
fff0367c: 54 85 8f fe rlwinm r5,r4,17,31,31
fff03680: 54 86 97 fe rlwinm r6,r4,18,31,31
fff03684: 54 87 9f fe rlwinm r7,r4,19,31,31
fff03688: 54 88 a7 fe rlwinm r8,r4,20,31,31
fff0368c: 54 89 df fe rlwinm r9,r4,27,31,31
fff03690: 54 8a e7 fe rlwinm r10,r4,28,31,31
fff03694: 4c c6 31 82 crclr 4*cr1+eq
fff03698: 48 01 1a e1 bl fff15178 <printf>
fff0369c: 38 60 00 0a li r3,10
fff036a0: 48 01 1a 61 bl fff15100 <putc>
fff036a4: 73 80 00 07 andi. r0,r28,7
fff036a8: 7f 84 e3 78 mr r4,r28
fff036ac: 40 a2 00 10 bne+ fff036bc <show_regs+0x94>
fff036b0: 80 7e 80 10 lwz r3,-32752(r30)
fff036b4: 4c c6 31 82 crclr 4*cr1+eq
fff036b8: 48 01 1a c1 bl fff15178 <printf>
fff036bc: 57 80 10 3a rlwinm r0,r28,2,0,29
fff036c0: 80 7e 80 04 lwz r3,-32764(r30)
fff036c4: 7c 9f 00 2e lwzx r4,r31,r0
fff036c8: 4c c6 31 82 crclr 4*cr1+eq
fff036cc: 48 01 1a ad bl fff15178 <printf>
fff036d0: 38 60 00 0a li r3,10
fff036d4: 7f 80 1e 70 srawi r0,r28,3
fff036d8: 7c 00 01 94 addze r0,r0
fff036dc: 54 00 18 38 rlwinm r0,r0,3,0,28
fff036e0: 7c 00 e0 50 subf r0,r0,r28
fff036e4: 2c 00 00 07 cmpwi r0,7
fff036e8: 3b 9c 00 01 addi r28,r28,1
fff036ec: 40 a2 00 08 bne+ fff036f4 <show_regs+0xcc>
fff036f0: 48 01 1a 11 bl fff15100 <putc>
fff036f4: 2c 1c 00 1f cmpwi r28,31
fff036f8: 40 81 ff ac ble+ fff036a4 <show_regs+0x7c>
fff036fc: 80 01 00 1c lwz r0,28(r1)
fff03700: bb 81 00 08 lmw r28,8(r1)
fff03704: 38 21 00 18 addi r1,r1,24
fff03708: 7c 08 03 a6 mtlr r0
fff0370c: 4e 80 00 20 blr
fff03710: 00 03 89 04 .long 0x38904


fff1513c <puts>: ---> Length 0x38,  u-boot.bin  0x0001515c,  Offset address:
0xFFEFFFE0
fff1513c: 94 21 ff e8 stwu r1,-24(r1)
fff15140: 7c 08 02 a6 mflr r0
fff15144: 90 01 00 1c stw r0,28(r1)
fff15148: 7c 64 1b 78 mr r4,r3
fff1514c: 80 1d 00 04 lwz r0,4(r29)
fff15150: 70 09 00 02 andi. r9,r0,2
fff15154: 41 82 00 10 beq- fff15164 <puts+0x28>
fff15158: 38 60 00 01 li r3,1
fff1515c: 4b ff fe 4d bl fff14fa8 <fputs>
fff15160: 48 00 00 08 b fff15168 <puts+0x2c>
fff15164: 48 00 fe 89 bl fff24fec <serial_puts>
fff15168: 80 01 00 1c lwz r0,28(r1)
fff1516c: 38 21 00 18 addi r1,r1,24
fff15170: 7c 08 03 a6 mtlr r0
fff15174: 4e 80 00 20 blr


fff24f7c <serial_putc>: Length 0x6C
fff24f7c: 2c 03 00 0a cmpwi r3,10
fff24f80: 94 21 ff e8 stwu r1,-24(r1)
fff24f84: 7c 08 02 a6 mflr r0
fff24f88: 93 e1 00 10 stw r31,16(r1)
fff24f8c: 90 01 00 1c stw r0,28(r1)
fff24f90: 7c 7f 1b 78 mr r31,r3
fff24f94: 40 a2 00 0c bne+ fff24fa0 <serial_putc+0x24>
fff24f98: 38 60 00 0d li r3,13
fff24f9c: 4b ff ff e1 bl fff24f7c <serial_putc>
fff24fa0: 3d 20 f0 00 lis r9,-4096
fff24fa4: a1 29 00 02 lhz r9,2(r9)
fff24fa8: 3d 29 f0 00 addis r9,r9,-4096
fff24fac: 81 69 00 04 lwz r11,4(r9)
fff24fb0: a8 09 00 00 lha r0,0(r9)
fff24fb4: 2c 00 00 00 cmpwi r0,0
fff24fb8: 41 80 ff f8 blt+ fff24fb0 <serial_putc+0x34>
fff24fbc: 38 00 00 01 li r0,1
fff24fc0: 9b eb 00 00 stb r31,0(r11)
fff24fc4: b0 09 00 02 sth r0,2(r9)
fff24fc8: a0 09 00 00 lhz r0,0(r9)
fff24fcc: 83 e1 00 10 lwz r31,16(r1)
fff24fd0: 64 00 ff ff oris r0,r0,65535
fff24fd4: 60 00 80 00 ori r0,r0,32768
fff24fd8: b0 09 00 00 sth r0,0(r9)
fff24fdc: 80 01 00 1c lwz r0,28(r1)
fff24fe0: 38 21 00 18 addi r1,r1,24
fff24fe4: 7c 08 03 a6 mtlr r0
fff24fe8: 4e 80 00 20 blr
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