From: Daniel Borkmann <[email protected]>
Date: Mon, 17 Apr 2017 20:44:35 +0200
> On 04/17/2017 05:38 AM, David Miller wrote:
>> +/* Map BPF registers to SPARC registers */
>> +static const int bpf2sparc[] = {
>> + /* return value from in-kernel function, and exit value from eBPF */
>> + [BPF_REG_0] = I5,
>> +
>> + /* arguments from eBPF program to in-kernel function */
>> + [BPF_REG_1] = I0,
>> + [BPF_REG_2] = I1,
>> + [BPF_REG_3] = I2,
>> + [BPF_REG_4] = I3,
>> + [BPF_REG_5] = I4,
>> +
>> + /* callee saved registers that in-kernel function will preserve */
>> + [BPF_REG_6] = L0,
>> + [BPF_REG_7] = L1,
>> + [BPF_REG_8] = L2,
>> + [BPF_REG_9] = L3,
>> +
>> + /* read-only frame pointer to access stack */
>> + [BPF_REG_FP] = FP,
>
> On a quick initial glance, you also need to map BPF_REG_AX. If
> I understand the convention correctly, you could use L7 for that.
>
> You can test for it through tools/testing/selftests/bpf/test_kmod.sh
> which exercises the test_bpf.ko under various sysctl combinations as
> part of the BPF selftest suite.
Oh I see, it's used for constant blinding. I can use a global register
for that since it's only used as a temporary right?
