Re: [PATCH bpf-next 4/8] arm32, bpf: add support for unconditional bswap instruction

On Tue, Sep 05, 2023 at 09:06:17PM +0000, Puranjay Mohan wrote:

The cpuv4 added a new unconditional bswap instruction with following behaviour:

BPF_ALU64 | BPF_TO_LE | BPF_END with imm = 16/32/64 means: dst = bswap16(dst) dst = bswap32(dst) dst = bswap64(dst)

As we already support converting to big-endian from little-endian we can use the same for unconditional bswap. Since ARM32 is always little-endian, just treat the unconditional scenario

This is not true. Arm32 BPF is disabled for BE32 but not for BE8. It's entirely possible to build a kernel using BE8 for ARMv7 and have the BPF JIT enabled:

select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32

So it's not true to say "Since ARM32 is always little-endian".