Bug 23975 - "init (1): undefined instruction: pc=b6fce0a8" during mounting ARM BE Root file system
Summary: "init (1): undefined instruction: pc=b6fce0a8" during mounting ARM BE Root fi...
Status: RESOLVED INVALID
Alias: None
Product: glibc
Classification: Unclassified
Component: libc (show other bugs)
Version: 2.26
: P2 critical
Target Milestone: ---
Assignee: Not yet assigned to anyone
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-12-11 07:28 UTC by Pankaj Pandey
Modified: 2018-12-15 15:43 UTC (History)
1 user (show)

See Also:
Host:
Target:
Build:
Last reconfirmed:
fweimer: security-


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Description Pankaj Pandey 2018-12-11 07:28:32 UTC
Hi,

I am getting below  mentioned error when kernel is trying to mount Big
endian NFS root filesystem.

[ 9.091012] devtmpfs: mounted
[ 9.094985] Freeing unused kernel memory: 1024K
[ 9.114876] init (1): undefined instruction: pc=b6fce0a8
[ 9.120227] CPU: 1 PID: 1 Comm: init Not tainted 4.14.34-rt25-yocto-standard #1
[ 9.127602] Hardware name: BRCM XGS iProc
[ 9.131672] task: de460000 task.stack: de45a000
[ 9.136196] PC is at 0xb6fce0a8
[ 9.139330] LR is at 0x23
[ 9.142000] pc : [<b6fce0a8>] lr : [<00000023>] psr: 000f0210
[ 9.148254] sp : bef36c28 ip : b6fefd50 fp : bef36c8c
[ 9.153531] r10: b6ff0908 r9 : 00000002 r8 : bef36c58
[ 9.158753] r7 : 00001040 r6 : 6ffffdff r5 : 00001040 r4 : 00000000
[ 9.165318] r3 : 00000000 r2 : 00000000 r1 : 00000001 r0 : 00000001
[ 9.171894] Flags: nzcv IRQs on FIQs on Mode USER_32 ISA ARM Segment user
[ 9.179103] Control: 12c5387d Table: 7c4f804a DAC: 00000055
[ 9.184891] Code: 347287e1 901b02ee 0020a0e3 013007e2 (a10472f3)
[ 9.191275] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x00000004
[ 9.191275]
[ 9.200399] CPU: 1 PID: 1 Comm: init Not tainted 4.14.34-rt25-yocto-standard #1
[ 9.207695] Hardware name: BRCM XGS iProc
[ 9.211721] [<c0110a40>] (unwind_backtrace) from [<c010c148>]
(show_stack+0x10/0x14)
[ 9.219468] [<c010c148>] (show_stack) from [<c0843948>] (dump_stack+0x78/0x8c)
[ 9.226685] [<c0843948>] (dump_stack) from [<c0133944>] (panic+0xdc/0x248)
[ 9.233555] [<c0133944>] (panic) from [<c01386ac>] (complete_and_exit+0x0/0x1c)
[ 9.240853] [<c01386ac>] (complete_and_exit) from [<de45be78>] (0xde45be78)
[ 9.247807] CPU0: stopping
[ 9.250521] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.14.34-rt25-yocto-standard #1
[ 9.258250] Hardware name: BRCM XGS iProc
[ 9.262267] [<c0110a40>] (unwind_backtrace) from [<c010c148>]
(show_stack+0x10/0x14)
[ 9.269997] [<c010c148>] (show_stack) from [<c0843948>] (dump_stack+0x78/0x8c)
[ 9.277211] [<c0843948>] (dump_stack) from [<c010f89c>] (handle_IPI+0x3ec/0x3fc)
[ 9.284590] [<c010f89c>] (handle_IPI) from [<c0101458>]
(gic_handle_irq+0x90/0x94)
[ 9.292142] [<c0101458>] (gic_handle_irq) from [<c010cd0c>]
(__irq_svc+0x6c/0xbc)
[ 9.299605] Exception stack(0xc0c01f48 to 0xc0c01f90)
[ 9.304642] 1f40: 00000000 c09e8220 1e014000 c0118d00 ffffe000 c0c115f8
[ 9.312802] 1f60: c0c115a8 c0c927d9 c095cbdc deffccc0 c0b52e38
00000000 00000017 c0c01f98
[ 9.320959] 1f80: c0108728 c010872c 60000213 ffffffff
[ 9.326005] [<c010cd0c>] (__irq_svc) from [<c010872c>] (arch_cpu_idle+0x38/0x3c)
[ 9.333392] [<c010872c>] (arch_cpu_idle) from [<c01720a4>] (do_idle+0xd0/0x138)
[ 9.340690] [<c01720a4>] (do_idle) from [<c01723b4>]
(cpu_startup_entry+0x18/0x1c)
[ 9.348254] [<c01723b4>] (cpu_startup_entry) from [<c0b00c70>]
(start_kernel+0x3ac/0x3b8)
[ 9.356418] ---[ end Kernel panic - not syncing: Attempted to kill
init! exitcode=0x00000004

I am using yocto armeb(big-endian)  toolchain which is having
GCC-7.3.0, glibc-2.26 and Binutils-2.29.

This yocto tool-chain has built with below mentioned arguments.

 "-march=armv7-a -mfloat-abi=hard -mcpu=cortex-a9 -mfpu=neon"

My target is also  armv7-a and cortex-a9.  I am not sure where exactly
the issue but as per investigation I have  doubt in glibc.  Highly
appreciate

if anyone give some pointer regarding this issue. And I also found
same issue when I used buildroot armeb toolchain with older gcc-4.7
and glibc-2.20 version.
Comment 1 Andreas Schwab 2018-12-11 09:57:53 UTC
This is the _kernel_ executing an undefined instruction.  This has nothing to do with userspace.