Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Upgrade bcc and libbpf to fix BPF program compilation on 6.10 and later kernels #2041

Conversation

ddelnano
Copy link
Member

@ddelnano ddelnano commented Oct 9, 2024

Summary: Upgrade bcc and libbpf to fix BPF program compilation on 6.10 and later kernels

Bcc provides some "virtual" includes to BPF programs. The compat/linux/virtual_bpf.h file in particular needs to be kept in sync with libbpf and matches the header guard of the include/uapi/linux/bpf.h file. This means that while our linux headers were updated, our older bcc install was inserting an older copy of the uapi/linux/bpf.h file -- one that didn't contain the bpf_wq declaration.

  include/linux/bpf.h:348:10: error: invalid application of 'sizeof' to an incomplete type 'struct bpf_wq'
                  return sizeof(struct bpf_wq);
                         ^     ~~~~~~~~~~~~~~~
  include/linux/bpf.h:348:24: note: forward declaration of 'struct bpf_wq'
                  return sizeof(struct bpf_wq);
                                       ^
  include/linux/bpf.h:377:10: error: invalid application of '__alignof' to an incomplete type 'struct bpf_wq'
                  return __alignof__(struct bpf_wq);
                         ^          ~~~~~~~~~~~~~~~
  include/linux/bpf.h:377:29: note: forward declaration of 'struct bpf_wq'
                  return __alignof__(struct bpf_wq);

Note: while this fixes the 6.10 compilation issue, our 6.10 qemu build fails without disabling this logic. 6.10 kernels added BPF token support. This changes the BPF permission model slightly and causes the BPF instruction limit to be dependent on the permissions of the BPF syscall caller (linux source).

This new BPF token logic coupled with our qemu setup, causes our 6.10 build to fallback to the 4096 instruction limit. I'll be addressing this in #2040 and #2042. Those issues shouldn't block this change since that loop limit code can be bypasses at runtime with our current cli flags.

Relevant Issues: Closes #2035

Type of change: /kind bugfix

Test Plan: Built 6.10 and 6.11 kernels and the associated linux headers from #2036 and verified that a local qemu build passes

  • Verify #ci:bpf-build-all-kernels build passes

Changelog Message: Upgraded bcc and libbpf to support kernels 6.10 and later

@ddelnano ddelnano requested a review from a team as a code owner October 9, 2024 14:51
@ddelnano ddelnano force-pushed the ddelnano/upgrade-bcc-to-fix-6.10+-kernel-issues branch from 898bc47 to 34162ea Compare October 9, 2024 14:56
Comment on lines -149 to +152
sha256 = "4d503428c7aead070a59630dd0906318a430b3e279a35f51ec601fbdd7d31eb6",
strip_prefix = "libbpf-3b0973892891744d20ae79e99c0d1a26a59c4222",
sha256 = "859a31e9101237338d46eb62a62cb8fcb342c9ce0f9b9137e5a3a728c088c338",
strip_prefix = "libbpf-42065ea6627ff6e1ab4c65e51042a70fbf30ff7c",
urls = [
"https://github.com/libbpf/libbpf/archive/3b0973892891744d20ae79e99c0d1a26a59c4222.tar.gz",
"https://github.com/libbpf/libbpf/archive/42065ea6627ff6e1ab4c65e51042a70fbf30ff7c.tar.gz",
Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is the libbpf version that bcc v0.31.1 uses.

bcc

Comment on lines -130 to 135
sha256 = "d34f9484588a9c25be936c910c86f8b25b04e5b0c802d0630e77cc9a8a272aed",
strip_prefix = "bcc-e0698be7b797129cb113912e96ad741a551e2291",
sha256 = "416426fbe22d617d8aed088062f4489e69176136e99dc0b933df58e83d9175da",
strip_prefix = "bcc-e57be8465b9cf238f1c04b1c7e154fd1db85326d",
urls = [
"https://github.com/pixie-io/bcc/archive/e0698be7b797129cb113912e96ad741a551e2291.tar.gz",
"https://github.com/pixie-io/bcc/archive/e57be8465b9cf238f1c04b1c7e154fd1db85326d.tar.gz",
],
),
Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is the pixie9 branch, which rebased our patches on top of v0.31.0 tag (latest bcc release).

@ddelnano ddelnano changed the title Upgrade bcc and libbpf to fix BPF program compilation on 6.10 and later kernel Upgrade bcc and libbpf to fix BPF program compilation on 6.10 and later kernels Oct 11, 2024
Copy link
Contributor

@oazizi000 oazizi000 left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This should be safe for pre-6.10 kernels, so we should land this.

For 6.10+, investigation is needed to see if just our qemu test environment is broken or if there is a bigger issue that will affect the PEM more generally.

We are consciously decided to go ahead with this, and do the the investigation as a follow-up.

@ddelnano ddelnano merged commit 738111f into pixie-io:main Oct 11, 2024
48 checks passed
@ddelnano ddelnano deleted the ddelnano/upgrade-bcc-to-fix-6.10+-kernel-issues branch October 11, 2024 22:19
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

Socket tracer unable to start on 6.10 and later kernels
4 participants