tools/lib/bpf/btf.c | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-)
From: Douglas Raillard <douglas.raillard@arm.com>
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.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
---
tools/lib/bpf/btf.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)
CHANGELOG
v2:
* Added missing case for "long"
v3:
* Refactor a bit to use a table
* Provide the type names used by gcc and clang in commit msg
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1383e26c5d1f..65c492a6807f 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -470,12 +470,25 @@ const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
return btf_type_by_id((struct btf *)btf, type_id);
}
+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",
+};
+
static int determine_ptr_size(const struct btf *btf)
{
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;
@@ -489,12 +502,12 @@ static int determine_ptr_size(const struct btf *btf)
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;
- }
+ if (t->size != 4 && t->size != 8)
+ continue;
+
+ for (j = 0; j < ARRAY_SIZE(long_aliases); j++)
+ if (!strcmp(name, long_aliases[j]))
+ return t->size;
}
return -1;
--
2.25.1
Hello: This patch was applied to bpf/bpf-next.git (master) by Andrii Nakryiko <andrii@kernel.org>: On Tue, 24 May 2022 10:44:47 +0100 you wrote: > From: Douglas Raillard <douglas.raillard@arm.com> > > 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: > > [...] Here is the summary with links: - [v3] libbpf: Fix determine_ptr_size() guessing https://git.kernel.org/bpf/bpf-next/c/8a140f1b12f7 You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
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