From: Andrii Nakryiko <andriin@fb.com>
To: <dwarves@vger.kernel.org>
Cc: <bpf@vger.kernel.org>, Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH dwarves 11/11] btf_encoder: support cross-compiled ELF binaries with different endianness
Date: Tue, 29 Sep 2020 21:27:42 -0700 [thread overview]
Message-ID: <20200930042742.2525310-12-andriin@fb.com> (raw)
In-Reply-To: <20200930042742.2525310-1-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 4829651b76c4..6b0fb4e4c137 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;
}
@@ -117,8 +119,14 @@ 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;
@@ -701,6 +709,18 @@ 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
prev parent reply other threads:[~2020-09-30 4:28 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 4:27 [PATCH dwarves 00/11] Switch BTF loading and encoding to libbpf APIs Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 01/11] libbpf: update to latest libbpf version Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 02/11] btf_encoder: detect BTF encoding errors and exit Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 03/11] dwarves: expose and maintain active debug info loader operations Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 04/11] btf_loader: use libbpf to load BTF Andrii Nakryiko
2020-10-08 18:06 ` Arnaldo Carvalho de Melo
2020-10-08 19:32 ` Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 05/11] btf_encoder: use libbpf APIs to encode BTF type info Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 06/11] btf_encoder: fix emitting __ARRAY_SIZE_TYPE__ as index range type Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 07/11] btf_encoder: discard CUs after BTF encoding Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 08/11] btf_encoder: revamp how per-CPU variables are encoded Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 09/11] dwarf_loader: increase the size of lookup hash map Andrii Nakryiko
2020-09-30 4:27 ` [PATCH dwarves 10/11] strings: use BTF's string APIs for strings management Andrii Nakryiko
2020-09-30 4:27 ` Andrii Nakryiko [this message]
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