[Qemu-devel] bug in new ubfx code

[Ard Biesheuvel]

Hi all,

I tracked down a boot issue I was having with running the kernel under
AArch64 system emulation to commit

It appears that ubfx is executing incorrectly: the following code

    .global _start
_start:
    mov x1, #0x1124
    ubfx x2, x1, #28, #4

built with

aarch64-linux-gnu-gcc -o /tmp/ubfx /tmp/ubfx.s -nostartfiles
aarch64-linux-gnu-objcopy -O binary /tmp/ubfx.bin /tmp/ubfx

and executed with

qemu-system-aarch64 -M virt -cpu cortex-a53 -kernel /tmp/ubfx -s -S -nographic

produces the value 0x1124000000000 in x2 (as can be observed via GDB),
while the expected value is 0

Regards,
Ard.