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From: Andrii Nakryiko <andrii@kernel.org>
To: <dwarves@vger.kernel.org>
Cc: <bpf@vger.kernel.org>, <kernel-team@fb.com>, <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: [PATCH v2 dwarves 0/8] Switch BTF loading and encoding to libbpf APIs
Date: Thu, 8 Oct 2020 16:39:52 -0700
Message-ID: <20201008234000.740660-1-andrii@kernel.org> (raw)

This patch set switches pahole to use libbpf-provided BTF loading and encoding
APIs. This reduces pahole's own BTF encoding code, speeds up the process,
reduces amount of RAM needed for DWARF-to-BTF conversion. Also, pahole finally
gets support to generating BTF for cross-compiled ELF binaries with different
endianness (patch #8).

Additionally, patch #3 fixes previously missed problem with invalid array
index type generation.

Patches #4-7 are speeding up DWARF-to-BTF convertion/dedup pretty
significantly, saving overall about 9 seconds out of current 27 or so.

Patch #5 revamps how per-CPU BTF variables are emitted, eliminating repeated
and expensive looping over ELF symbols table. The critical detail that took
few hours of investigation is that when DW_AT_variable has
DW_AT_specification, variable address (to correlate with symbol's address) has
to be taken before specification is followed.

More details could be found in respective patches.

v1->v2:
  - rebase on latest dwarves master and fix var->spec's address problem.

Cc: Arnaldo Carvalho de Melo <acme@kernel.org>

Andrii Nakryiko (8):
  btf_loader: use libbpf to load BTF
  btf_encoder: use libbpf APIs to encode BTF type info
  btf_encoder: fix emitting __ARRAY_SIZE_TYPE__ as index range type
  btf_encoder: discard CUs after BTF encoding
  btf_encoder: revamp how per-CPU variables are encoded
  dwarf_loader: increase the size of lookup hash map
  strings: use BTF's string APIs for strings management
  btf_encoder: support cross-compiled ELF binaries with different
    endianness

 btf_encoder.c  | 370 +++++++++++++++------------
 btf_loader.c   | 244 +++++++-----------
 ctf_encoder.c  |   2 +-
 dwarf_loader.c |   2 +-
 libbtf.c       | 661 +++++++++++++++++++++----------------------------
 libbtf.h       |  41 ++-
 libctf.c       |  14 +-
 libctf.h       |   4 +-
 pahole.c       |   2 +-
 strings.c      |  91 +++----
 strings.h      |  32 +--
 11 files changed, 645 insertions(+), 818 deletions(-)

-- 
2.24.1


             reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-08 23:39 Andrii Nakryiko [this message]
2020-10-08 23:39 ` [PATCH v2 dwarves 1/8] btf_loader: use libbpf to load BTF Andrii Nakryiko
2020-10-09 14:53   ` Arnaldo Carvalho de Melo
2020-10-09 17:49     ` Andrii Nakryiko
2020-10-08 23:39 ` [PATCH v2 dwarves 2/8] btf_encoder: use libbpf APIs to encode BTF type info Andrii Nakryiko
2020-10-08 23:39 ` [PATCH v2 dwarves 3/8] btf_encoder: fix emitting __ARRAY_SIZE_TYPE__ as index range type Andrii Nakryiko
2020-10-08 23:39 ` [PATCH v2 dwarves 4/8] btf_encoder: discard CUs after BTF encoding Andrii Nakryiko
2020-10-09 15:47   ` Arnaldo Carvalho de Melo
2020-10-08 23:39 ` [PATCH v2 dwarves 5/8] btf_encoder: revamp how per-CPU variables are encoded Andrii Nakryiko
2020-10-09 15:53   ` Arnaldo Carvalho de Melo
2020-10-08 23:39 ` [PATCH v2 dwarves 6/8] dwarf_loader: increase the size of lookup hash map Andrii Nakryiko
2020-10-08 23:39 ` [PATCH v2 dwarves 7/8] strings: use BTF's string APIs for strings management Andrii Nakryiko
2020-10-08 23:40 ` [PATCH v2 dwarves 8/8] btf_encoder: support cross-compiled ELF binaries with different endianness Andrii Nakryiko
2020-10-09 16:22 ` [PATCH v2 dwarves 0/8] Switch BTF loading and encoding to libbpf APIs Arnaldo Carvalho de Melo
2020-10-09 17:59   ` Andrii Nakryiko

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