bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Florent Revest <revest@chromium.org>
To: bpf@vger.kernel.org
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
	kpsingh@kernel.org, jackmanb@google.com,
	linux@rasmusvillemoes.dk, linux-kernel@vger.kernel.org,
	Florent Revest <revest@chromium.org>
Subject: [PATCH bpf-next 0/2] Implement BPF formatted output helpers with bstr_printf
Date: Fri, 23 Apr 2021 03:15:15 +0200	[thread overview]
Message-ID: <20210423011517.4069221-1-revest@chromium.org> (raw)

Our formatted output helpers are currently implemented with
snprintf-like functions which take arguments as va_list but the types
stored in a va_list need to be known at compilation time which causes
problems when dealing with arguments from the BPF world that are always
u64 but considered differently depending on the format specifiers they
are associated with at runtime.

This series replaces snprintf usages with bstr_printf calls. This lets
us construct a binary representation of arguments in bpf_printf_prepare
at runtime that matches an ABI that is neither arch nor compiler

This solves a bug reported by Rasmus Villemoes that would mangle
arguments on 32 bit machines.

Florent Revest (2):
  seq_file: Add a seq_bprintf function
  bpf: Implement formatted output helpers with bstr_printf

 fs/seq_file.c            |  18 ++++
 include/linux/bpf.h      |  22 +----
 include/linux/seq_file.h |   4 +
 init/Kconfig             |   1 +
 kernel/bpf/helpers.c     | 188 +++++++++++++++++++++------------------
 kernel/bpf/verifier.c    |   2 +-
 kernel/trace/bpf_trace.c |  34 +++----
 7 files changed, 137 insertions(+), 132 deletions(-)


             reply	other threads:[~2021-04-23  1:15 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23  1:15 Florent Revest [this message]
2021-04-23  1:15 ` [PATCH bpf-next 1/2] seq_file: Add a seq_bprintf function Florent Revest
2021-04-23  1:15 ` [PATCH bpf-next 2/2] bpf: Implement formatted output helpers with bstr_printf Florent Revest
2021-04-23  9:27   ` Rasmus Villemoes
2021-04-23 13:45     ` Florent Revest
2021-04-23  8:50 ` [PATCH bpf-next 0/2] Implement BPF " Rasmus Villemoes
2021-04-23 13:26   ` Florent Revest
2021-04-23 14:31     ` Rasmus Villemoes

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210423011517.4069221-1-revest@chromium.org \
    --to=revest@chromium.org \
    --cc=andrii@kernel.org \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=jackmanb@google.com \
    --cc=kpsingh@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@rasmusvillemoes.dk \


* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).