__do_user_fault(struct task_struct *tsk, unsigned long addr,

unsigned int fsr, unsigned int sig, int code,

struct pt_regs *regs)

{

struct siginfo si;

#ifdef CONFIG_DEBUG_USER // 1. 配置內核

if (user_debug & UDBG_SEGV) {

printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0xlx, code 0xxn",

tsk->comm, sig, addr, fsr);

show_pte(tsk->mm, addr);

show_regs(regs);

}

#endif

2. uboot: set bootargs user_debug=0xff

set bootargs console=ttySAC0 root=/dev/nfs nfsroot=192.168.1.123:/work/nfs_root/first_fs ip=192.168.1.17 ipaddr=192.168.1.17 user_debug=0xff

3. 執(zhí)行APP

./test_debug

a = 0x12

pgd = c04c8000

[00000000] *pgd=33d08031, *pte=00000000, *ppte=00000000

Pid: 772, comm: test_debug

CPU: 0 Not tainted (2.6.22.6 #1)

PC is at 0x84ac

LR is at 0x84d0

pc : [<000084ac>] lr : [<000084d0>] psr: 60000010

sp : bed9fe40 ip : bed9fe54 fp : bed9fe50

r10: 4013365c r9 : 00000000 r8 : 00008514

r7 : 00000001 r6 : 000085cc r5 : 00008568 r4 : bed9fec4

r3 : 00000012 r2 : 00000000 r1 : 00001000 r0 : 00000000

Flags: nZCv IRQs on FIQs on Mode USER_32 Segment user

Control: c000717f Table: 304c8000 DAC: 00000015

[] (show_regs+0x0/0x4c) from [] (__do_user_fault+0x5c/0xa4)

r4:c04a6840

[] (__do_user_fault+0x0/0xa4) from [] (do_page_fault+0x1dc/0x20c)

r7:c00261e0 r6:c0024cf8 r5:c04a6840 r4:ffffffec

[] (do_page_fault+0x0/0x20c) from [] (do_DataAbort+0x3c/0xa0)

[] (do_DataAbort+0x0/0xa0) from [] (ret_from_exception+0x0/0x10)

Exception stack(0xc3e7bfb0 to 0xc3e7bff8)

bfa0: 00000000 00001000 00000000 00000012

bfc0: bed9fec4 00008568 000085cc 00000001 00008514 00000000 4013365c bed9fe50

bfe0: bed9fe54 bed9fe40 000084d0 000084ac 60000010 ffffffff

r8:00008514 r7:00000001 r6:000085cc r5:00008568 r4:c039bfc8

Segmentation fault

Stack:

00000000 becd3e64 becd3e54 000084d0 000084a0 00000000 becd3e78 becd3e68

Cs sp return addr Bs sp

000084f0 000084c4 00000000 becd3e98 becd3e7c 00008554 000084e4 00000000

ret addr As sp ret addr mains sp

00000012 becd3ec4 00000001 00000000 becd3e9c 40034f14 00008524 00000000

ret addr callers sp

對于動態(tài)鏈接，已經退出的程序不好確定動態(tài)庫的地址

00000000 0000839c 00000000 00000000 4001d594 000083c4 000085cc 4000c02c

becd3ec4 becd3f7b 00000000 becd3f88 becd3f92 becd3f99 becd3fad becd3fb8

becd3fdb becd3fe9 00000000 00000010 00000003 00000006 00001000 00000011

00000064 00000003 00008034 00000004 00000020 00000005 00000006 00000007

40000000 00000008 00000000 00000009 0000839c 0000000b 00000000 0000000c

00000000 0000000d 00000000 0000000e 00000000 00000017 00000000 0000000f

becd3f77 00000000 00000000 00000000 00000000 76000000 2e006c34 7365742f

65645f74 00677562 52455355 6f6f723d 4f480074 2f3d454d 61706900 3d726464

2e323931 2e383631 37312e31 52455400 74763d4d 00323031 48544150 62732f3d

2f3a6e69 2f727375 6e696273 69622f3a 752f3a6e 622f7273 53006e69 4c4c4548

69622f3d 68732f6e 44575000 2e002f3d 7365742f 65645f74 00677562 00000000

4. 反匯編app:

arm-linux-objdump -D test_debug > test_debug.dis

對于靜態(tài)鏈接的test_debug

arm-linux-gcc -otest_debugtest_debug.c -static

PC is at 0x81e0

LR is at 0x8204

pc : [<000081e0>] lr : [<00008204>] psr: 60000010

sp : be93dc60 ip : be93dc74 fp : be93dc70

r10: 000085f4 r9 : 00008248 r8 : be93deb4

r7 : 00000001 r6 : 00000000 r5 : be93dd3e r4 : 00000000

r3 : 00000012 r2 : 00000000 r1 : 00001000 r0 : 00000000

Flags: nZCv IRQs on FIQs on Mode USER_32 Segment user

Stack:

00000000 be93dc84 be93dc74 00008204 000081d4 00000000 be93dc98 be93dc88

Csp ret addr Bsp

00008224 000081f8 00000000 be93dcb8 be93dc9c 00008288 00008218 00000000

ret addr Asp ret addr mainsp

00000012 be93deb4 00000001 00000000 be93dcbc 000084ac 00008258 756e694c

ret addr __libc_start_mainsp

00000078 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 32393100

3836312e 312e312e 00000037 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 2e320000

32322e36 0000362e 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 23000000

54203335 4d206575 31207961 31322035 3a34303a 43203834 32205453 00323130

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

766d7261 006c7434 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

6f6e2800 0029656e 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 000080f8 00008680 00000000 be93deb4 be93df6a 00000000 be93df77

be93df81 be93df92 be93df99 be93dfad be93dfb8 be93dfdb be93dfe9 00000000

00000010 00000003 00000006 00001000 00000011 00000064 00000003 00008034

00000004 00000020 00000005 00000003 00000007 00000000 00000008 00000000

00000009 000080d0 0000000b 00000000 0000000c 00000000 0000000d 00000000

0000000e 00000000 00000017 00000000 0000000f be93df66 00000000 00000000

00000000 34760000 2f2e006c 74736574 6265645f 55006775 3d524553 746f6f72

444c4f00 3d445750 6f72702f 34372f63 4f480033 2f3d454d 61706900 3d726464

2e323931 2e383631 37312e31 52455400 74763d4d 00323031 48544150 62732f3d

2f3a6e69 2f727375 6e696273 69622f3a 752f3a6e 622f7273 53006e69 4c4c4548

69622f3d 68732f6e 44575000 2e002f3d 7365742f 65645f74 00677562 00000000