On Tue, Jul 28, 2020 at 8:37 AM Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> wrote: > > When a tracing BPF program attempts to read memory without using the > bpf_probe_read() helper, the verifier marks the load instruction with > the BPF_PROBE_MEM flag. Since the arm64 JIT does not currently recognize > this flag it falls back to the interpreter. > > Add support for BPF_PROBE_MEM, by appending an exception table to the > BPF program. If the load instruction causes a data abort, the fixup > infrastructure finds the exception table and fixes up the fault, by > clearing the destination register and jumping over the faulting > instruction. > > To keep the compact exception table entry format, inspect the pc in > fixup_exception(). A more generic solution would add a "handler" field > to the table entry, like on x86 and s390. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> This patch looks good to me. Acked-by: Song Liu <songliubraving@xxxxxx> It is possible to add a selftest for this? I thought about this a little bit, but didn't get a good idea. Thanks, Song
