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.

Sign up for GitHub

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

Jump to bottom

RFE: improve the internal syscall tables (gperf,CSV) #223

Closed
wants to merge 3 commits into from
Closed

RFE: improve the internal syscall tables (gperf,CSV) #223

wants to merge 3 commits into from

Commits on Mar 22, 2020

  1. arch: add an automatically generated syscall table in CSV format 

    Later patches will make use of this new syscall table format instead
of the manually maintained tables.

The new CSV syscall table was generated with the following command:

  # ./arch-syscall-validate -c <kernel_source_dir> > syscalls.csv

Signed-off-by: Paul Moore <paul@paul-moore.com>
    @pcmoore
    pcmoore committed Mar 22, 2020
    Configuration menu
    Copy the full SHA
    a394668 View commit details
    Browse the repository at this point in the history

  2. arch: use gperf to generate a perfact hash to lookup syscall names 

    This patch significantly improves the performance of
seccomp_syscall_resolve_name since it replaces the expensive strcmp
for each syscall in the database, with a lookup table.

The complexity for syscall_resolve_num is not changed and it
uses the linear search, that is anyway less expensive than
seccomp_syscall_resolve_name as it uses an index for comparison
instead of doing a string comparison.

On my machine, calling 1000 seccomp_syscall_resolve_name_arch and
seccomp_syscall_resolve_num_arch over the entire syscalls DB passed
from ~0.45 sec to ~0.06s.

PM: After talking with Giuseppe I made a number of additional
changes, some substantial, the highlights include:
* various style tweaks
* .gitignore fixes
* fixed subject line, tweaked the description
* dropped the arch-syscall-validate changes as they were masking
  other problems
* extracted the syscalls.csv and file deletions to other patches
  to keep this one more focused
* fixed the x86, x32, arm, all the MIPS ABIs, s390, and s390x ABIs as
  the syscall offsets were not properly incorporated into this change
* cleaned up the ABI specific headers
* cleaned up generate_syscalls_perf.sh and renamed to
  arch-gperf-generate
* fixed problems with automake's file packaging

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Reviewed-by: Tom Hromatka <tom.hromatka@oracle.com>
[PM: see notes in the "PM" section above]
Signed-off-by: Paul Moore <paul@paul-moore.com>
    @giuseppe @pcmoore
    giuseppe authored and pcmoore committed Mar 22, 2020
    Configuration menu
    Copy the full SHA
    20887d0 View commit details
    Browse the repository at this point in the history

  3. arch: remove the unused, manually generated syscall tables 

    Since the move to gperf and the automatically generated syscall table
in CSV format, these manually maintained tables are no longer needed.

Signed-off-by: Paul Moore <paul@paul-moore.com>
    @pcmoore
    pcmoore committed Mar 22, 2020
    Configuration menu
    Copy the full SHA
    c549b64 View commit details
    Browse the repository at this point in the history