Re: [microblaze-uclinux] Re: [PATCH 1/2] microblaze: add stack unwinder

From: Michal Simek
Date: Mon Apr 26 2010 - 11:35:17 EST

Steven J. Magnani wrote:
On Fri, 2010-04-16 at 10:32 +0200, Michal Simek wrote:
Please apply this patch and do the same testing as I did.

diff --git a/arch/microblaze/kernel/reset.c b/arch/microblaze/kernel/reset.c
index a1721a3..76f6587 100644
--- a/arch/microblaze/kernel/reset.c
+++ b/arch/microblaze/kernel/reset.c
@@ -112,8 +112,8 @@ void of_platform_reset_gpio_probe(void)
void machine_restart(char *cmd)
{
printk(KERN_NOTICE "Machine restart...\n");
+ machine_shutdown();
gpio_system_reset();
- dump_stack();
while (1)
;
}
@@ -121,6 +121,7 @@ void machine_restart(char *cmd)
void machine_shutdown(void)
{
printk(KERN_NOTICE "Machine shutdown...\n");
+ dump_stack();
while (1)
;
}

I get this:

Call Trace:
[<20003008>] microblaze_unwind+0x68/0x94
[<20002c24>] show_stack+0x134/0x174
[<20002c80>] dump_stack+0x1c/0x3c
[<20001d84>] machine_shutdown+0x30/0x40
[<20001dc0>] machine_restart+0x2c/0x48
[<2002a540>] kernel_restart+0x5c/0x80
[<2002a6b8>] sys_reboot+0x11c/0x218
SYSCALL
[<2d5c0248>] PID 118 [reboot]

Is your problem on a MMU or noMMU system?

If the unwinder stops early, it found a return address outside the
kernel text, or couldn't find the addik that creates a stack frame - but
there's not enough information here to tell what happened. In your case
the backtrace goes off the rails before getting to the frame for
dump_stack(), which is where the stack dump begins. We'd need to see the
21 words preceding the dump (show_stack's frame is 13 words, and
microblaze_unwind's is 8) to know why.

Can you uncomment the #define DEBUG in unwind.c and try it again?

I finally looked at it and here is what I found.

# ./reboot
Restarting system.
Machine restart...
Machine shutdown...
Stack:
4f3ffdc8: 48004aec 00000008
4f3ffdd0: 00000000 00000001 4f3e0150 00000001 4f3ffdec 48004b14 481dc68c 48241318
4f3ffdf0: ffffffff 00001099 00003fff 482f49cc 4801f518 481dc6a4 48241318 ffffffff
4f3ffe10: 00001083 00003fff 482f49cc 48020150 481e3048 00000000 000001a2 00000000
4f3ffe30: 00000000 00000000 28121969 48006b38 48240dc0 481d549c 481d53a8 481d549c
4f3ffe50: 00aa4812 481d523c 0000c350 00000035 48029618 4f3ffe70 000001a2 4f96c04c
4f3ffe70: 481d6390 0000c350 4f3fff58 4f3ffee0 481d639c 481d6370 00000009 4f3ffee0
4f3ffe90: 00000000 00000000 00000000 4f3ffee0 48029df4 00000001 4f3e0150 00000001
4f3ffeb0: 00000001 00000001 00000000 00000001 00000001 48029f34 4801b2a8 4800c5e0
4f3ffed0: 00000020 00000000 0000c350 00000000 00000001 00000000 00000000 00000035
4f3ffef0: 00ab0b62 00000035 00aa4812 480294e0 482425c0 00000000 00000000 00000000
4f3fff10: 0000c350 00000001 0000c350 4f3ead40 4f3fff58 00000001 00000000 00000000
4f3fff30: 00000001 4f3e0150 00000001 48006b38 00000000 4f3eaf68 00000000 00010000
4f3fff50: 00000000 00000000 00000000 fee1dead 01234567 00000000 00000000 4f3eaebc
4f3fff70: 00000000 00000000 00000000 fee1dead 28121969 01234567 00000008 00000000
4f3fff90: 00000000 28121969 00000058 00000000 4f3e0320 4f3e0274 00000000 00000000
4f3fffb0: 7fffff82 00000000 00000000 00000000 fee1dead 01234567 00000000 00000000
4f3fffd0: 00000001 4f3e0150 00000001 00000000 00000000 4f96c04c 4f3e0324 000001a0
4f3ffff0: 00000000 00000000 000001a0 00000000


Call Trace:
Unwinding with PC=480050d4, FP=4f3ffd74
[<480050d4>] microblaze_unwind+0xa8/0xc4
pc 0x480050ac instr 0x30210024
Invalid frame size -36 at 0x480050ac
Failed to find previous stack frame

Below is the dump - then you can see that 36 is correct.
That could be due to different toolchain behavior.

Thanks,
Michal


4800502c <microblaze_unwind>:
4800502c: b000482f imm 18479
48005030: e86043a8 lwi r3, r0, 17320 // 482f43a8 <mbc>
48005034: 3021ffdc addik r1, r1, -36
48005038: fa61001c swi r19, r1, 28
4800503c: fac10020 swi r22, r1, 32
48005040: f9e10000 swi r15, r1, 0
48005044: e8830020 lwi r4, r3, 32
48005048: 12650000 addk r19, r5, r0
4800504c: 99fc2000 brald r15, r4
48005050: 12c60000 addk r22, r6, r0
48005054: b000482f imm 18479
48005058: e86043a8 lwi r3, r0, 17320 // 482f43a8 <mbc>
4800505c: e8830008 lwi r4, r3, 8
48005060: 99fc2000 brald r15, r4
48005064: 80000000 or r0, r0, r0
48005068: be130068 beqid r19, 104 // 480050d0
4800506c: 10b30000 addk r5, r19, r0
48005070: b0004800 imm 18432
48005074: 30c069e0 addik r6, r0, 27104 // 480069e0 <_switch_to>
48005078: 165f9800 rsubk r18, r31, r19
4800507c: be120034 beqid r18, 52 // 480050b0
48005080: 11360000 addk r9, r22, r0
48005084: e8730004 lwi r3, r19, 4
48005088: 10b30000 addk r5, r19, r0
4800508c: e903004c lwi r8, r3, 76
48005090: e8e3003c lwi r7, r3, 60
48005094: b9f4fc7c brlid r15, -900 // 48004d10 <microblaze_unwind_inner>
48005098: 11360000 addk r9, r22, r0
4800509c: e9e10000 lwi r15, r1, 0
480050a0: ea61001c lwi r19, r1, 28
480050a4: eac10020 lwi r22, r1, 32
480050a8: b60f0008 rtsd r15, 8
480050ac: 30210024 addik r1, r1, 36
480050b0: e8730004 lwi r3, r19, 4
480050b4: 30631f68 addik r3, r3, 8040
480050b8: e903003c lwi r8, r3, 60
480050bc: e8c30080 lwi r6, r3, 128
480050c0: e8e30004 lwi r7, r3, 4
480050c4: b9f4fc4c brlid r15, -948 // 48004d10 <microblaze_unwind_inner>
480050c8: 80000000 or r0, r0, r0
480050cc: b800ffd0 bri -48 // 4800509c
480050d0: 80e10000 or r7, r1, r0
480050d4: b8d40008 brlid r6, 8
480050d8: 80000000 or r0, r0, r0
480050dc: 11130000 addk r8, r19, r0
480050e0: 11360000 addk r9, r22, r0
480050e4: b9f4fc2c brlid r15, -980 // 48004d10 <microblaze_unwind_inner>
480050e8: 10bf0000 addk r5, r31, r0
480050ec: b800ffb0 bri -80 // 4800509c







Thanks,
------------------------------------------------------------------------
Steven J. Magnani "I claim this network for MARS!
www.digidescorp.com Earthling, return my space modulator!"

#include <standard.disclaimer>


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--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian
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