Hi,
Some platforms, such as Blackfin, have a special prefix for assembly
symbols as opposed to C symbols. For this reason, a function named
"foo()" in C will in fact be visible as a symbol called "_foo" in the
ELF binary.
The current linker version script logic in libgcc doesn't take into
account this situation properly. The Blackfin specific
libgcc/config/bfin/libgcc-glibc.ver has an additional "_" in front of
every symbol so that it matches the output of "nm" (which gets parsed to
produce the final linker version script). But due to this additional
"_", ld no longer matches with the symbols since "ld" does the matching
with the original symbol name, not the one prefixed with "_".
Due to this, none of the symbols in libgcc/config/bfin/libgcc-glibc.ver
are actually matched with symbols in libgcc. This causes all libgcc
symbols to be left as "LOCAL", which causes lots of "undefined
reference" whenever some C or C++ code that calls a function of libgcc
is compiled.
To address this, this commit introduces a "skip_underscore" variable to
the mkmap-symver script. It tells mkmap-symver to ignore the leading
underscore from the "nm" output.
Note that this new argument is different from the existing
"leading_underscore" argument, which *adds* an additional underscore to
the generated linker version script.
Having this functionality paves the way to using the generic linker
version information for Blackfin, instead of using a custom one.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Waldemar Brodkorb <wbx@openadk.org>
2016-11-06 Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
PR gcc/74748
* libgcc/mkmap-symver.awk: add support for skip_underscore