Unable to single step under ppc?
Wang, Baojun
wangbj at lzu.edu.cn
Sun Oct 28 20:05:28 EST 2007
On Saturday 27 October 2007 07:14:45, you wrote：
> >>> stw r0,INT_FRAME_SIZE+4(r1)
> >>>
> >>> stw r31,INT_FRAME_SIZE+128(r1)
> >>>
> >>> lwz r5,EVENTS_USER_ADDR_OFFSET(r4)
> >>> mr r31,r5 /* r31 to hold new_domain->events_user_addr */
> >>>
> >>> cmpwi r3,0
> >>> beq 1f
> >>>
> >>> mtctr r3
>
> ^^^^^ whats in R3 then ? Having 0 in r3 seems plain
> wrong !
>
> > hi, If they were not setup properly in tlb, then we should get a
> > DataTLBError/InstructionTLBError, I single stepped(stepi) to the `mtctr'
> > insn, then set a breakpoint at DataTLBError/InstructionTLBError, but both
> > of them were not triggered. Also, when I was at `mtctr', I could not
> > single step (use stepi) thus unable to debug the program.
>
> If you cant single step over this instruction then the address
> you are loading must have some problem.
>
> hofrat
Hi, I'm using bdi2000/gdb to debug a program which is like a module (the
excutable is loaded by myself), but I can not single step while executing
`bctrl', where ctr contains the valid address for the _start() function, it
is valid because I could use `x' or `disas' command to display the contents
of register `ctr', however when `bctrl' execute, I got unable to access
address xxx, what the problem could be? Could somebody give me some hints?
Thanks very much.
here is a sample debug session:
(gdb) b jump_xm_dom
Breakpoint 1 at 0xc001e694
(gdb) c
Continuing.
Breakpoint 1, 0xc001e694 in jump_xm_dom ()
Current language: auto; currently asm
(gdb) disas $pc $pc+32
Dump of assembler code from 0xc001e694 to 0xc001e6b4:
0xc001e694 <jump_xm_dom+16>: lwz r5,36(r4)
0xc001e698 <jump_xm_dom+20>: mr r31,r5
0xc001e69c <jump_xm_dom+24>: cmpwi r3,0
0xc001e6a0 <jump_xm_dom+28>: beq- 0xc001e6c0 <jump_xm_dom+60>
0xc001e6a4 <jump_xm_dom+32>: mfmsr r11
0xc001e6a8 <jump_xm_dom+36>: stw r11,240(r1) /* store old msr */
0xc001e6ac <jump_xm_dom+40>: andi. r11,r11,16384 /* drop privilege */
0xc001e6b0 <jump_xm_dom+44>: mtmsr r11
End of assembler dump.
(gdb) nexti
0xc001e698 in jump_xm_dom ()
(gdb)
0xc001e69c in jump_xm_dom ()
(gdb)
0xc001e6a0 in jump_xm_dom ()
(gdb)
0xc001e6a4 in jump_xm_dom ()
(gdb)
0xc001e6a8 in jump_xm_dom ()
(gdb)
0xc001e6ac in jump_xm_dom ()
(gdb)
0xc001e6b0 in jump_xm_dom ()
(gdb) disas $pc $pc+32
Dump of assembler code from 0xc001e6b0 to 0xc001e6d0:
0xc001e6b0 <jump_xm_dom+44>: mtmsr r11
0xc001e6b4 <jump_xm_dom+48>: mtctr r3 /* r3 contains _start() address */
0xc001e6b8 <jump_xm_dom+52>: bctrl
0xc001e6bc <jump_xm_dom+56>: li r3,0
0xc001e6c0 <jump_xm_dom+60>: lwz r31,320(r1) /* restore r31 */
0xc001e6c4 <jump_xm_dom+64>: lwz r11,240(r1) /* restore msr */
0xc001e6c8 <jump_xm_dom+68>: mtmsr r11
0xc001e6cc <jump_xm_dom+72>: lwz r0,196(r1)
End of assembler dump.
(gdb) nexti
0xc001e6b4 in jump_xm_dom ()
(gdb)
0xc001e6b8 in jump_xm_dom ()
(gdb) info registers
r0 0xc001b908 3221338376
r1 0xd1072e60 3506908768
r2 0xc0549b70 3226770288
r3 0x10000094 268435604
r4 0xd106c000 3506880512
r5 0x2000000 33554432
r6 0xc014033c 3222537020
r7 0xc0240000 3223584768
r8 0x20000 131072
r9 0xc02c0000 3224109056
r10 0x0 0
r11 0x0 0
r12 0x0 0
r13 0x0 0
r14 0x0 0
r15 0x0 0
r16 0x0 0
r17 0x0 0
r18 0x0 0
r19 0x0 0
r20 0x0 0
r21 0x0 0
r22 0x0 0
r23 0x0 0
r24 0x0 0
r25 0x0 0
r26 0x0 0
r27 0x0 0
r28 0x0 0
r29 0xc02c0000 3224109056
r30 0x0 0
r31 0x2000000 33554432
pc 0xc001e6b8 3221350072
cr 0x28000022 671088674
lr 0xc001b908 3221338376
---Type <return> to continue, or q <return> to quit---
ctr 0x10000094 268435604
xer 0x0 0
(gdb) x/32b $r3
0x10000094: 0x94 0x21 0xff 0x40 0x7c 0x08 0x02 0xa6
0x1000009c: 0x90 0x01 0x00 0xc4 0x7f 0xe3 0xfb 0x78
0x100000a4: 0x3d 0x20 0x10 0x01 0x90 0x69 0x07 0xa0
0x100000ac: 0x48 0x00 0x02 0x55 0x80 0x01 0x00 0xc4
(gdb) disas $r3 $r3+32
Dump of assembler code from 0x10000094 to 0x100000b4:
0x10000094: stwu r1,-192(r1)
0x10000098: mflr r0
0x1000009c: stw r0,196(r1)
0x100000a0: mr r3,r31
0x100000a4: lis r9,4097
0x100000a8: stw r3,1952(r9)
0x100000ac: bl 0x10000300
0x100000b0: lwz r0,196(r1)
End of assembler dump.
(gdb) nexti
Cannot access memory at address 0xd1072e60 /* this is the SP address */
(gdb)
0x10000094 in ?? ()
Cannot access memory at address 0x10000094 /* r3 or ctr address */
(gdb)
the address 0x10000094 is accessable before `bctrl' we could see.. Is it
because $r3 is just contain a address just for data access not instruction
access? the page prot is: _PAGE_PRESENT | _PAGE_RW | _PAGE_HWEXEC |
_PAGE_WRENABLE | _PAGE_USER, I think it's ready for exec..
Regards,
Wang
--
Wang, Baojun Lanzhou University
Distributed & Embedded System Lab http://dslab.lzu.edu.cn
School of Information Science and Engeneering wangbj at lzu.edu.cn
Tianshui South Road 222. Lanzhou 730000 .P.R.China
Tel:+86-931-8912025 Fax:+86-931-8912022
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