How to debug u-boot data abort
AKASHI Takahiro
takahiro.akashi at linaro.org
Thu Mar 24 04:18:37 CET 2022
On Wed, Mar 23, 2022 at 09:27:08AM +0100, Heinrich Schuchardt wrote:
> On 3/23/22 08:45, qianfan wrote:
> >
> > 在 2022/3/23 10:28, qianfan 写道:
> > >
> > > Hi:
> > >
> > > I had a custom AM335X board connected my computer by usbnet. It always
> > > report data abort when 'dhcp':
> > >
> > > Next it the log:
> > >
> > > U-Boot 2022.01-rc1-00183-gfa5b4e2d19-dirty (Feb 25 2022 - 15:45:02 +0800)
> > >
> > > CPU : AM335X-GP rev 2.1
> > > Model: WISDOM AM335X CCT
> > > DRAM: 512 MiB
> > > NAND: 256 MiB
> > > MMC: OMAP SD/MMC: 0
> > > Loading Environment from NAND... *** Warning - bad CRC, using default
> > > environment
> > >
> > > Net: Could not get PHY for ethernet at 4a100000: addr 0
> > > eth2: ethernet at 4a100000, eth3: usb_ether
> > > Hit any key to stop autoboot: 0
> > > => setenv autoload no
> > > => dhcp
> > > using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
> > > MAC de:ad:be:ef:00:01
> > > HOST MAC de:ad:be:ef:00:00
> > > RNDIS ready
> > > musb-hdrc: peripheral reset irq lost!
> > > high speed config #2: 2 mA, Ethernet Gadget, using RNDIS
> > > USB RNDIS network up!
> > > BOOTP broadcast 1
> > > BOOTP broadcast 2
> > > BOOTP broadcast 3
> > > DHCP client bound to address 192.168.200.4 (757 ms)
> > > data abort
>
> This could be an alignment error.
>
> > > pc : [<9fe9b0a2>] lr : [<9febbc3f>]
> > > reloc pc : [<808130a2>] lr : [<80833c3f>]
>
> You can use these addresses together with the u-boot.map file to figure
> out in which function the abort occurs and from where it was called.
>
> Use 'arm-linux-gnueabihf-objdump -S -D' to find the exact code positions.
>
> > > sp : 9de53410 ip : 9de53578 fp : 00000001
> > > r10: 9de5345c r9 : 9de67e80 r8 : 9febbae5
> > > r7 : 9de72c30 r6 : 9feec710 r5 : 0000000d r4 : 00000018
> > > r3 : 3fdd8e04 r2 : 00000002 r1 : 9feec728 r0 : 9feec700
> > > Flags: Nzcv IRQs off FIQs on Mode SVC_32 (T)
> > > Code: f023 0303 60ca 4403 (6091) 685a
>
> This is how to find the exact instruction causing the problem:
>
> $ echo 'Code: f023 0303 60ca 4403 (6091) 685a' | \
> > ARCH=arm scripts/decodecode
> Code: f023 0303 60ca 4403 (6091) 685a
> All code
> ========
> 0: 23 f0 and %eax,%esi
> 2: 03 03 add (%rbx),%eax
> 4: ca 60 03 lret $0x360
> 7:* 44 91 rex.R xchg %eax,%ecx <--
> trapping instruction
> 9: 60 (bad)
> a: 5a pop %rdx
> b: 68 .byte 0x68
>
> Code starting with the faulting instruction
> ===========================================
> 0: 91 xchg %eax,%ecx
> 1: 60 (bad)
> 2: 5a pop %rdx
> 3: 68 .byte 0x68
The code looks like x86 instructions.
Please don't forget to add "CROSS_COMPILE=..." :)
Code: f023 0303 60ca 4403 (6091) 685a
All code
========
0: f023 0303 bic.w r3, r3, #3
4: 60ca str r2, [r1, #12]
6: 4403 add r3, r0
8:* 6091 str r1, [r2, #8] <-- trapping instruction
a: 685a ldr r2, [r3, #4]
Code starting with the faulting instruction
===========================================
0: 6091 str r1, [r2, #8]
2: 685a ldr r2, [r3, #4]
Then,
${CROSS_COMPILE}objdump --disassemble=malloc -lS ${BUILDDIR}/u-boot | grep -A 10 -B 20 ${PATTERN}
# Here, PATTERN may be the instruction ("6091") or the location ("8081496c" in your case?)
or similarly
${CROSS_COMPILE}gdb --batch -ex "disas/m ${LOC}" ${BUILDDIR}/u-boot | grep -A 10 -B 20 ${LOC}
# Here, LOC is your "reloc pc" (0x80817586)
gives you some hint about the exact location.
-Takahiro Akashi
> I hope this helps to figure out, where exactly the problem occurs
>
> Best regards
>
> Heinrich
>
> > > Resetting CPU ...
> > >
> > > resetting ...
> > >
> > >
> > > It's there has any doc about how to debug data abort? Or is the bug is
> > > already fixed?
> > >
> > > Thanks
> > >
> > This bug doesn't fixed on master code. I found v2021.01 is good and
> > v2021.04-rc2 is bad.
> >
> > Also I had tested this on beaglebone black with am335x_evm_defconfig,
> > has the simliar problem.
> >
> > find the first bug commit via 'git bisect': it told me that commit
> > e97eb638de0dc8f6e989e20eaeb0342f103cb917 broke it. But it is very
> > strange due to this commit doesn't touch any dhcp or network code.
> >
> > ➜ u-boot-main git:(e97eb638de) ✗ git bisect bug
> > e97eb638de0dc8f6e989e20eaeb0342f103cb917 is the first bug commit
> > commit e97eb638de0dc8f6e989e20eaeb0342f103cb917
> > Author: Heinrich Schuchardt <xypron.glpk at gmx.de>
> > Date: Wed Jan 20 22:21:53 2021 +0100
> >
> > fs: fat: consistent error handling for flush_dir()
> >
> > Provide function description for flush_dir().
> > Move all error messages for flush_dir() from the callers to the
> > function.
> > Move mapping of errors to -EIO to the function.
> > Always check return value of flush_dir() (Coverity CID 316362).
> >
> > In fat_unlink() return -EIO if flush_dirty_fat_buffer() fails.
> >
> > Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> >
> > :040000 040000 2281a449f2d134078d7faa1ee735a367b55aad7e
> > 77d188b1c99181fd71f2167fdeee3434a09db209 M fs
> >
> >
> > 184aa6504143b452132e28cd3ebecc7b941cdfa1 is the first commit before
> > e97eb638de0dc8f6e989e20eaeb0342f103cb917:
> >
> > * e97eb638de0dc8f6e989e20eaeb0342f103cb917 fs: fat: consistent error
> > handling for flush_dir()
> > * 184aa6504143b452132e28cd3ebecc7b941cdfa1 Merge tag
> > 'u-boot-rockchip-20210121' of
> > https://gitlab.denx.de/u-boot/custodians/u-boot-rockchip
> > |\
> > | * 9ddc0787bd660214366e386ce689dd78299ac9d0 pci: Add Rockchip dwc based
> > PCIe controller driver
> >
> > I checked 184aa6504143b452132e28cd3ebecc7b941cdfa1 can work fine.
> >
> > U-Boot 2021.01-00688-g184aa65041-dirty (Mar 23 2022 - 15:07:56 +0800)
> >
> > CPU : AM335X-GP rev 2.1
> > Model: TI AM335x BeagleBone Black
> > DRAM: 512 MiB
> > WDT: Started with servicing (60s timeout)
> > NAND: 0 MiB
> > MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
> > Loading Environment from FAT... <ethaddr> not set. Validating first
> > E-fuse MAC
> > Net: eth2: ethernet at 4a100000, eth3: usb_ether
> > Hit any key to stop autoboot: 0
> > => dhcp
> > ethernet at 4a100000 Waiting for PHY auto negotiation to complete.........
> > TIMEOUT !
> > using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
> > MAC de:ad:be:ef:00:01
> > HOST MAC de:ad:be:ef:00:00
> > RNDIS ready
> > musb-hdrc: peripheral reset irq lost!
> > high speed config #2: 2 mA, Ethernet Gadget, using RNDIS
> > USB RNDIS network up!
> > BOOTP broadcast 1
> > BOOTP broadcast 2
> > BOOTP broadcast 3
> > DHCP client bound to address 192.168.200.157 (757 ms)
> > Using usb_ether device
> > TFTP from server 192.168.200.1; our IP address is 192.168.200.157
> > Filename 'u-boot.img'.
> > Load address: 0x82000000
> > Loading: #################################################################
> > #################################################################
> > #################################################################
> > #########################
> > 2.5 MiB/s
> > done
> > Bytes transferred = 1123888 (112630 hex)
> > =>
> >
>
More information about the U-Boot
mailing list