c06fb25d1f
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60 lines
2.2 KiB
Diff
60 lines
2.2 KiB
Diff
From fab45b962749184e1a1a57c7c583782b78fad539 Mon Sep 17 00:00:00 2001
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From: Sam James <sam@gentoo.org>
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Date: Tue, 13 Aug 2024 20:49:06 +0100
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Subject: [PATCH] libbpf: Workaround -Wmaybe-uninitialized false positive
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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In `elf_close`, we get this with GCC 15 -O3 (at least):
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```
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In function ‘elf_close’,
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inlined from ‘elf_close’ at elf.c:53:6,
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inlined from ‘elf_find_func_offset_from_file’ at elf.c:384:2:
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elf.c:57:9: warning: ‘elf_fd.elf’ may be used uninitialized [-Wmaybe-uninitialized]
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57 | elf_end(elf_fd->elf);
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| ^~~~~~~~~~~~~~~~~~~~
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elf.c: In function ‘elf_find_func_offset_from_file’:
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elf.c:377:23: note: ‘elf_fd.elf’ was declared here
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377 | struct elf_fd elf_fd;
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| ^~~~~~
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In function ‘elf_close’,
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inlined from ‘elf_close’ at elf.c:53:6,
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inlined from ‘elf_find_func_offset_from_file’ at elf.c:384:2:
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elf.c:58:9: warning: ‘elf_fd.fd’ may be used uninitialized [-Wmaybe-uninitialized]
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58 | close(elf_fd->fd);
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| ^~~~~~~~~~~~~~~~~
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elf.c: In function ‘elf_find_func_offset_from_file’:
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elf.c:377:23: note: ‘elf_fd.fd’ was declared here
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377 | struct elf_fd elf_fd;
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| ^~~~~~
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```
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In reality, our use is fine, it's just that GCC doesn't model errno
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here (see linked GCC bug). Suppress -Wmaybe-uninitialized accordingly
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by initializing elf_fd.fd to -1 and elf_fd.elf to NULL.
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I've done this in two other functions as well given it could easily
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occur there too (same access/use pattern).
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Signed-off-by: Sam James <sam@gentoo.org>
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Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
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Link: https://gcc.gnu.org/PR114952
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Link: https://lore.kernel.org/bpf/14ec488a1cac02794c2fa2b83ae0cef1bce2cb36.1723578546.git.sam@gentoo.org
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---
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tools/lib/bpf/elf.c | 3 +++
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1 file changed, 3 insertions(+)
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--- a/tools/lib/bpf/elf.c
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+++ b/tools/lib/bpf/elf.c
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@@ -16,6 +16,9 @@ int elf_open(const char *binary_path, st
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int fd, ret;
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Elf *elf;
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+ elf_fd->elf = NULL;
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+ elf_fd->fd = -1;
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+
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if (elf_version(EV_CURRENT) == EV_NONE) {
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pr_warn("elf: failed to init libelf for %s\n", binary_path);
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return -LIBBPF_ERRNO__LIBELF;
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