Re: [PATCH] ARM: disable broken eBPF JIT on the Risc PC

[Ethan Nelson-Moore]

Hi, David,

On Sun, Jun 14, 2026 at 4:58 AM David Laight
<david.laight.linux@xxxxxxxxx> wrote:
> Isn't it more the case that the ldrh/strh instructions were added for armv4.
> Whether the bus supports 16bit accesses is entirely different.

No, it is in fact the bus. While the Risc PC initially shipped with
ARMv3 CPUs, which the kernel no longer supports, it was later upgraded
to an ARMv4 StrongARM CPU. However, its bus was designed for ARMv3
CPUs and has no way to represent a half-word access to memory. This
means that ldrh/strh will execute (because the CPU supports them) but
do not function as intended.

Ethan