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Fix determine_ptr_size()_guessing

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zhang-mingyi66 2023-01-18 19:37:56 +08:00
parent b2837f70bb
commit 101e0389fb
2 changed files with 82 additions and 1 deletions
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77
backport-libbpf-Fix-determine_ptr_size-guessing.patch Normal file
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@ -0,0 +1,77 @@
From a5d75daa8c467a863ecf297982b70ed284adc0e9 Mon Sep 17 00:00:00 2001
From: Douglas Raillard <douglas.raillard@arm.com>
Date: Tue, 24 May 2022 10:44:47 +0100
Subject: [PATCH] libbpf: Fix determine_ptr_size() guessing
One strategy employed by libbpf to guess the pointer size is by finding
the size of "unsigned long" type. This is achieved by looking for a type
of with the expected name and checking its size.
Unfortunately, the C syntax is friendlier to humans than to computers
as there is some variety in how such a type can be named. Specifically,
gcc and clang do not use the same names for integer types in debug info:
- clang uses "unsigned long"
- gcc uses "long unsigned int"
Lookup all the names for such a type so that libbpf can hope to find the
information it wants.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220524094447.332186-1-douglas.raillard@arm.com
---
src/btf.c | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)
diff --git a/src/btf.c b/src/btf.c
index bb1e06eb1..3d6c30d9a 100644
--- a/src/btf.c
+++ b/src/btf.c
@@ -472,9 +472,22 @@ const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
static int determine_ptr_size(const struct btf *btf)
{
+ static const char * const long_aliases[] = {
+ "long",
+ "long int",
+ "int long",
+ "unsigned long",
+ "long unsigned",
+ "unsigned long int",
+ "unsigned int long",
+ "long unsigned int",
+ "long int unsigned",
+ "int unsigned long",
+ "int long unsigned",
+ };
const struct btf_type *t;
const char *name;
- int i, n;
+ int i, j, n;
if (btf->base_btf && btf->base_btf->ptr_sz > 0)
return btf->base_btf->ptr_sz;
@@ -485,15 +498,16 @@ static int determine_ptr_size(const struct btf *btf)
if (!btf_is_int(t))
continue;
+ if (t->size != 4 && t->size != 8)
+ continue;
+
name = btf__name_by_offset(btf, t->name_off);
if (!name)
continue;
- if (strcmp(name, "long int") == 0 ||
- strcmp(name, "long unsigned int") == 0) {
- if (t->size != 4 && t->size != 8)
- continue;
- return t->size;
+ for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
+ if (strcmp(name, long_aliases[j]) == 0)
+ return t->size;
}
}

6
libbpf.spec
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@ -4,7 +4,7 @@
Name: %{githubname}
Version: %{githubver}
Release: 2
Release: 3
Summary: Libbpf library
License: LGPLv2 or BSD
@ -16,6 +16,7 @@ Patch6000: backport-libbpf-Support-detecting-and-attaching-of-writable-t.patch
Patch6001: backport-libbpf-Ensure-functions-with-always_inline-attribute-are-inline.patch
Patch6002: backport-libbpf-Fix-the-name-of-a-reused-map.patch
Patch6003: backport-libbpf-preserve-errno-across-pr_warn-pr_info-pr_debug.patch
Patch6004: backport-libbpf-Fix-determine_ptr_size-guessing.patch
# This package supersedes libbpf from kernel-tools,
# which has default Epoch: 0. By having Epoch: 1
@ -67,6 +68,9 @@ developing applications that use %{name}
%{_libdir}/libbpf.a
%changelog
* Wed Jan 18 2023 zhangmingyi <zhangmingyi5@huawei.com> - 2:0.3-3
- Fix determine_ptr_size() guessing
* Sun Jan 15 2023 zhangmingyi <zhangmingyi5@huawei.com> - 2:0.3-2
- backporting: backport-libbpf-Ensure-functions-with-always_inline-attribute-are-inline.patch
backport-libbpf-Fix-the-name-of-a-reused-map.patch