From: Alexei Starovoitov <a...@fb.com> Date: Wed, 31 May 2017 15:41:09 -0700
> On 5/31/17 11:45 AM, Alexei Starovoitov wrote: >> On 5/31/17 11:43 AM, David Miller wrote: >>> From: Alexei Starovoitov <a...@fb.com> >>> Date: Wed, 31 May 2017 11:39:37 -0700 >>> >>>> On 5/31/17 11:15 AM, David Miller wrote: >>>>> From: Alexei Starovoitov <a...@fb.com> >>>>> Date: Tue, 30 May 2017 13:31:32 -0700 >>>>> >>>>>> test_bpf.ko doesn't call verifier before selecting interpreter or >>>>>> JITing, >>>>>> hence the tests need to manually specify the amount of stack they >>>>>> consume. >>>>>> >>>>>> Signed-off-by: Alexei Starovoitov <a...@kernel.org> >>>>>> Acked-by: Daniel Borkmann <dan...@iogearbox.net> >>>>> >>>>> I do not like this and the previous patch, it seems so error prone. >>>> >>>> in what sense 'error prone' ? >>> >>> In the sense that a human computes these numbers, and nothing checks >>> if it is correct or not until program perhaps crashes if the value is >>> wrong. >> >> right. that's how all these tests are. >> See bpf_fill_ld_abs_vlan_push_pop() for example. >> If that codegen has a bug, it will crash the kernel. >> That's why it's done from kernel module to do things >> that user space cannot do. > > btw, when added a bunch of these '.stack_depth = 40' > I was thinking to randomize these values in [40, 512] > range to stress test interpreter and JITs more, > but then decided not to do that to avoid questions > why these numbers don't match the instructions. > Now I'm thinking we should actually do it for two reasons: > - to stress test stuff > - and to demonstrate more clearly that test_bpf.ko can > really do things that user space cannot and that's the > purpose of this .ko > Thoughts? Ok I've applied the base series for now. Feel free to build that kind of stuff on top. Thanks for explaining.
