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btf: use byte-exact upstream a9355b201d16 extraction for resolve_btfids ELF_T_WORD fix

Replace the hand-written 0004 patch with the canonical git format-patch
output of upstream a9355b201d16 ("bpf: Fix libelf endian handling in
resolv_btfids", backport of 61e8aeda9398). Identical hunk; adds the full
upstream commit message for provenance.
TheWildJames hai 1 mes
pai
achega
0b53bbd41d

+ 45 - 1
.github/actions/btf/patches/0004-resolve_btfids-elf-word.patch

@@ -1,6 +1,47 @@
+From a9355b201d160aa777d1480911c9ee5c7deeb88b Mon Sep 17 00:00:00 2001
+From: Tony Ambardar <tony.ambardar@gmail.com>
+Date: Thu, 17 Jun 2021 23:14:04 -0700
+Subject: [PATCH] bpf: Fix libelf endian handling in resolv_btfids
+
+[ Upstream commit 61e8aeda9398925f8c6fc290585bdd9727d154c4 ]
+
+The vmlinux ".BTF_ids" ELF section is declared in btf_ids.h to hold a list
+of zero-filled BTF IDs, which is then patched at link-time with correct
+values by resolv_btfids. The section is flagged as "allocable" to preclude
+compression, but notably the section contents (BTF IDs) are untyped.
+
+When patching the BTF IDs, resolve_btfids writes in host-native endianness
+and relies on libelf for any required translation on reading and updating
+vmlinux. However, since the type of the .BTF_ids section content defaults
+to ELF_T_BYTE (i.e. unsigned char), no translation occurs. This results in
+incorrect patched values when cross-compiling to non-native endianness,
+and can manifest as kernel Oops and test failures which are difficult to
+troubleshoot [1].
+
+Explicitly set the type of patched data to ELF_T_WORD, the architecture-
+neutral ELF type corresponding to the u32 BTF IDs. This enables libelf to
+transparently perform any needed endian conversions.
+
+Fixes: fbbb68de80a4 ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object")
+Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
+Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
+Acked-by: Jiri Olsa <jolsa@redhat.com>
+Cc: Frank Eigler <fche@redhat.com>
+Cc: Mark Wielaard <mark@klomp.org>
+Cc: Jiri Olsa <jolsa@kernel.org>
+Cc: Yonghong Song <yhs@fb.com>
+Link: https://lore.kernel.org/bpf/CAPGftE_eY-Zdi3wBcgDfkz_iOr1KF10n=9mJHm1_a_PykcsoeA@mail.gmail.com [1]
+Link: https://lore.kernel.org/bpf/20210618061404.818569-1-Tony.Ambardar@gmail.com
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ tools/bpf/resolve_btfids/main.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
+index d636643ddd35..f32c059fbfb4 100644
 --- a/tools/bpf/resolve_btfids/main.c
 +++ b/tools/bpf/resolve_btfids/main.c
-@@ -649,6 +649,9 @@
+@@ -649,6 +649,9 @@ static int symbols_patch(struct object *obj)
  	if (sets_patch(obj))
  		return -1;
  
@@ -10,3 +51,6 @@
  	elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
  
  	err = elf_update(obj->efile.elf, ELF_C_WRITE);
+-- 
+2.55.0
+