On Tue, Sep 05, 2023 at 03:12:56PM +0000, Hengqi Chen wrote: > In current implementation, we assume that symbol found in .dynsym section > would have a version suffix and use it to compare with symbol user supplied. > According to the spec ([0]), this assumption is incorrect, the version info > of dynamic symbols are stored in .gnu.version and .gnu.version_d sections > of ELF objects. 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 > > In this case, specify pthread_rwlock_wrlock@@GLIBC_2.34 or > pthread_rwlock_wrlock@GLIBC_2.2.5 in bpf_uprobe_opts::func_name won't work. > Because the qualified name does NOT match `pthread_rwlock_wrlock` (without > version suffix) in .dynsym sections. > > This commit implements the symbol versioning for dynsym and allows user to > specify symbol in the following forms: > - func > - func@LIB_VERSION > - func@@LIB_VERSION > > In case of symbol conflicts, error out and users should resolve it by > specifying a qualified name. > > [0]: https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/symversion.html > > Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx> I have a question below, but other than that Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> thanks, jirka SNIP > @@ -119,6 +148,7 @@ static struct elf_sym *elf_sym_iter_next(struct elf_sym_iter *iter) > struct elf_sym *ret = &iter->sym; > GElf_Sym *sym = &ret->sym; > const char *name = NULL; > + GElf_Versym versym; > Elf_Scn *sym_scn; > size_t idx; > > @@ -138,12 +168,112 @@ static struct elf_sym *elf_sym_iter_next(struct elf_sym_iter *iter) > > iter->next_sym_idx = idx + 1; > ret->name = name; > + ret->ver = 0; > + ret->hidden = false; > + > + if (iter->versyms) { > + if (!gelf_getversym(iter->versyms, idx, &versym)) > + continue; > + ret->ver = versym & VERSYM_VERSION; > + ret->hidden = versym & VERSYM_HIDDEN; the doc mentions value 1 being special, also I can see readelf code checking on that.. is that taken into account? > + } > return ret; > } > > return NULL; > } > SNIP
