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From: Emil Tsalapatis <emil@etsalapatis.com>
To: bpf@vger.kernel.org
Cc: andrii@kernel.org, eddyz87@gmail.com, ast@kernel.org,
	daniel@iogearbox.net, john.fastabend@gmail.com, memxor@gmail.com,
	yonghong.song@linux.dev, Emil Tsalapatis <emil@etsalapatis.com>
Subject: [PATCH v3 3/5] libbpf: turn relo_core->sym_off unsigned
Date: Mon, 15 Dec 2025 11:13:11 -0500	[thread overview]
Message-ID: <20251215161313.10120-4-emil@etsalapatis.com> (raw)
In-Reply-To: <20251215161313.10120-1-emil@etsalapatis.com>

The symbols' relocation offsets in BPF are stored in an int field,
but cannot actually be negative. When in the next patch libbpf relocates
globals to the end of the arena, it is also possible to have valid
offsets > 2GiB that are used to calculate the final relo offsets.
Avoid accidentally interpreting large offsets as negative by turning
the sym_off field unsigned.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 tools/lib/bpf/libbpf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index c7c79014d46c..5e66bbc2ab85 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -380,7 +380,7 @@ struct reloc_desc {
 		const struct bpf_core_relo *core_relo; /* used when type == RELO_CORE */
 		struct {
 			int map_idx;
-			int sym_off;
+			unsigned int sym_off;
 			/*
 			 * The following two fields can be unionized, as the
 			 * ext_idx field is used for extern symbols, and the
@@ -763,7 +763,7 @@ struct bpf_object {
 
 	struct {
 		struct bpf_program *prog;
-		int sym_off;
+		unsigned int sym_off;
 		int fd;
 	} *jumptable_maps;
 	size_t jumptable_map_cnt;
-- 
2.49.0


  parent reply	other threads:[~2025-12-15 16:13 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-12-15 16:13 [PATCH v3 0/5] libbpf: move arena variables out of the zero page Emil Tsalapatis
2025-12-15 16:13 ` [PATCH v3 1/5] selftests/bpf: explicitly account for globals in verifier_arena_large Emil Tsalapatis
2025-12-15 16:13 ` [PATCH v3 2/5] bpf/verifier: do not limit maximum direct offset into arena map Emil Tsalapatis
2025-12-15 20:19   ` Eduard Zingerman
2025-12-16 17:25     ` Emil Tsalapatis
2025-12-16 20:13       ` Eduard Zingerman
2025-12-16 21:48         ` Emil Tsalapatis
2025-12-15 16:13 ` Emil Tsalapatis [this message]
2025-12-15 16:37   ` [PATCH v3 3/5] libbpf: turn relo_core->sym_off unsigned bot+bpf-ci
2025-12-15 17:08     ` Emil Tsalapatis
2025-12-15 20:05   ` Eduard Zingerman
2025-12-15 16:13 ` [PATCH v3 4/5] libbpf: move arena globals to the end of the arena Emil Tsalapatis
2025-12-15 21:12   ` Eduard Zingerman
2025-12-15 16:13 ` [PATCH v3 5/5] selftests/bpf: add tests for the arena offset of globals Emil Tsalapatis
2025-12-15 21:26   ` Eduard Zingerman
2025-12-16  2:28     ` Emil Tsalapatis

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