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>,
Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH v2 dwarves 8/8] btf_encoder: support cross-compiled ELF binaries with different endianness
Date: Thu, 8 Oct 2020 16:40:00 -0700 [thread overview]
Message-ID: <20201008234000.740660-9-andrii@kernel.org> (raw)
In-Reply-To: <20201008234000.740660-1-andrii@kernel.org>
From: Andrii Nakryiko <andriin@fb.com>
Ensure that output BTF endianness corresponds to target ELF's endianness. This
makes it finally possible to use pahole to generate BTF for cross-compiled
kernels with different endianness.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
libbtf.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/libbtf.c b/libbtf.c
index 27aa3e5a986e..babf4fe8cd9e 100644
--- a/libbtf.c
+++ b/libbtf.c
@@ -87,6 +87,8 @@ struct btf_elf *btf_elf__new(const char *filename, Elf *elf)
btfe->raw_btf = true;
btfe->wordsize = sizeof(long);
btfe->is_big_endian = BYTE_ORDER == BIG_ENDIAN;
+ btf__set_endianness(btfe->btf,
+ btfe->is_big_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN);
return btfe;
}
@@ -118,8 +120,14 @@ struct btf_elf *btf_elf__new(const char *filename, Elf *elf)
}
switch (btfe->ehdr.e_ident[EI_DATA]) {
- case ELFDATA2LSB: btfe->is_big_endian = false; break;
- case ELFDATA2MSB: btfe->is_big_endian = true; break;
+ case ELFDATA2LSB:
+ btfe->is_big_endian = false;
+ btf__set_endianness(btfe->btf, BTF_LITTLE_ENDIAN);
+ break;
+ case ELFDATA2MSB:
+ btfe->is_big_endian = true;
+ btf__set_endianness(btfe->btf, BTF_BIG_ENDIAN);
+ break;
default:
fprintf(stderr, "%s: unknown elf endianness.\n", __func__);
goto errout;
@@ -704,6 +712,18 @@ static int btf_elf__write(const char *filename, struct btf *btf)
goto out;
}
+ switch (ehdr_mem.e_ident[EI_DATA]) {
+ case ELFDATA2LSB:
+ btf__set_endianness(btf, BTF_LITTLE_ENDIAN);
+ break;
+ case ELFDATA2MSB:
+ btf__set_endianness(btf, BTF_BIG_ENDIAN);
+ break;
+ default:
+ fprintf(stderr, "%s: unknown elf endianness.\n", __func__);
+ goto out;
+ }
+
/*
* First we look if there was already a .BTF section to overwrite.
*/
--
2.24.1
next prev parent reply other threads:[~2020-10-08 23:40 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 23:39 [PATCH v2 dwarves 0/8] Switch BTF loading and encoding to libbpf APIs Andrii Nakryiko
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 ` Andrii Nakryiko [this message]
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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