Re: [PATCH] RISC-V/bpf: Enable bpf_probe_read{, str}()

Andrii Nakryiko
2022-07-06T05:01:21Z

On Sun, Jul 3, 2022 at 10:53 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Sun, Jul 03, 2022 at 09:09:24PM +0800, Yixun Lan wrote:
> > Enable this option to fix a bcc error in RISC-V platform
> >
> > And, the error shows as follows:
>
> These should not be enabled on new platforms. Use the proper helpers
> to probe kernel vs user pointers instead.

riscv existed as of [0], so I'd argue it is a proper bug fix, as
corresponding select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE should
have been added back then.

But I also agree that BCC tools should be updated to use proper
bpf_probe_read_{kernel,user}[_str()] helpers, please contribute such
fixes to BCC tools and BCC itself as well. Cc'ed Alan as his ksnoop in
libbpf-tools seems to be using bpf_probe_read() as well and needs to
be fixed.

[0] 0ebeea8ca8a4 ("bpf: Restrict bpf_probe_read{, str}() only to
archs where they work")