Update: The following patch fix this issue, additional byteswap instructions in thumb2 mode. http://lists.infradead.org/pipermail/linux-arm-kernel/2014-January/225283.ht...
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:will.newton@linaro.org] Sent: Thursday, June 26, 2014 12:12 PM To: Joel (Xi Zhou) Zhou Cc: linaro-toolchain@lists.linaro.org Subject: Re: VFP in BE mode - undefined instruction vstmia
On 26 June 2014 16:27, Joel (Xi Zhou) Zhou joel.zhou@broadcom.com 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 ; 0x200The rootfs is busybox 1.22.1 compiled by Linaro BE hard floating toolchain.
https://releases.linaro.org/14.04/components/toolchain/binaries/gcc-linaro-a...
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.