Dynamic symbols in shared library may have the same name, for example:
$ nm -D /lib/x86_64-linux-gnu/libc.so.6 | grep rwlock_wrlock
000000000009b1a0 T __pthread_rwlock_wrlock@GLIBC_2.2.5
000000000009b1a0 T pthread_rwlock_wrlock@@GLIBC_2.34
000000000009b1a0 T pthread_rwlock_wrlock@GLIBC_2.2.5
$ readelf -W --dyn-syms /lib/x86_64-linux-gnu/libc.so.6 | grep rwlock_wrlock
706: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 __pthread_rwlock_wrlock@GLIBC_2.2.5
2568: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 pthread_rwlock_wrlock@@GLIBC_2.34
2571: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 pthread_rwlock_wrlock@GLIBC_2.2.5
Currently, users can't attach a uprobe to pthread_rwlock_wrlock because
there are two symbols named pthread_rwlock_wrlock and both are global
bind. And libbpf considers it as a conflict.
Since both of them are at the same offset we could accept one of them
harmlessly. Note that we already does this in elf_resolve_syms_offsets.
Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx>
---
tools/lib/bpf/elf.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c
index 9d0296c1726a..5c9e588b17da 100644
--- a/tools/lib/bpf/elf.c
+++ b/tools/lib/bpf/elf.c
@@ -214,7 +214,10 @@ long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name)
if (ret > 0) {
/* handle multiple matches */
- if (last_bind != STB_WEAK && cur_bind != STB_WEAK) {
+ if (elf_sym_offset(sym) == ret) {
+ /* same offset, no problem */
+ continue;
+ } else if (last_bind != STB_WEAK && cur_bind != STB_WEAK) {
/* Only accept one non-weak bind. */
pr_warn("elf: ambiguous match for '%s', '%s' in '%s'\n",
sym->name, name, binary_path);
--
2.34.1
