Update:
The following patch fix this issue, additional byteswap instructions in thumb2
mode.
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-January/225283.html
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index b3fb8c9..1879e8d 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -451,9 +451,11 @@ __und_usr_thumb:
.arch armv6t2
#endif
2: ldrht r5, [r4]
+ARM_BE8(rev16 r5, r5) @ little endian instruction
cmp r5, #0xe800 @ 32bit instruction if xx != 0
blo __und_usr_fault_16 @ 16bit undefined instruction
3: ldrht r0, [r2]
+ARM_BE8(rev16 r0, r0) @ little endian instruction
add r2, r2, #2 @ r2 is PC + 2, make it PC + 4
str r2, [sp, #S_PC] @ it's a 2x16bit instr, update
orr r0, r0, r5, lsl #16
-----Original Message-----
From: Will Newton [mailto:[email protected]]
Sent: Thursday, June 26, 2014 12:12 PM
To: Joel (Xi Zhou) Zhou
Cc: [email protected]
Subject: Re: VFP in BE mode - undefined instruction vstmia
On 26 June 2014 16:27, Joel (Xi Zhou) Zhou <[email protected]> wrote:
> Hi all,
>
>
>
> I’m working on booting Linaro LSK 3.10.40 kernel in be8 mode on our
> Cortex-A9 system.
>
> There is an issue related to VFP instruction. It complain “vstmia” is an
> undefined instruction.
>
> The VFP is supported in CPU and CONFIG_VFP and CONFIG_VFPv3 are enabled in
> kernel config.
>
> Are there any patch need to be done for VFP in BE mode?
>
>
>
> The booting log show as following:
>
> call sys_access(/init)
>
> Freeing unused kernel memory: 2832K (c0600000 - c08c4000)
>
> kernel_init: try to execute '/init' (ramdisk_execute_command)
>
> en->run_init_process(/init)
>
> init (1): undefined instruction: pc=0000aab8
>
> Code: f00f dff8 2a20 1268 (acec) 108b
>
> Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
>
>
>
> The disassembly code show the undefined instruction is “vstmia”.
>
> armeb-linux-gnueabihf-objdump -D busybox_unstripped > busy.asm
>
> 0000aa90 <__sigsetjmp>:
>
> ...
>
> aab6: 6812 ldr r2, [r2, #0]
>
> aab8: ecac 8b10 vstmia ip!, {d8-d15}
>
> aabc: f412 7f00 tst.w r2, #512 ; 0x200
>
>
>
> The rootfs is busybox 1.22.1 compiled by Linaro BE hard floating toolchain.
>
> https://releases.linaro.org/14.04/components/toolchain/binaries/gcc-linaro-armeb-linux-gnueabihf-4.8-2014.04_linux.tar.xz
The instruction is valid and encoded correctly as far as I can tell. I
would suspect that this exception may be related to the kernel VFP
handling code.
--
Will Newton
Toolchain Working Group, Linaro
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