On Mon, Jun 16, 2014 at 8:42 AM, Rich Felker <dalias@xxxxxxxx> wrote: > On Mon, Jun 16, 2014 at 08:31:39AM -0700, Ian Lance Taylor wrote: >> On Mon, Jun 16, 2014 at 7:38 AM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: >> >> I think this issue started when some of the Go developers questioned >> >> why the kernel needed to provide a very complex interface--parsing an >> >> ELF shared shared library--for very simple functionality--looking up >> >> the address of a magic function. This approach has required special >> >> support not just in Go, but also in the dynamic linker and gdb, and >> >> does not work well for statically linked binaries. The support in gdb >> >> is perhaps a good idea, but elsewhere it does not make sense. >> >> >> >> So why not provide a simple interface? >> > >> > What good would it do now that everyone already supports it? >> >> Do statically linked binaries use the vDSO calls? > > Under glibc, I believe so (not checked). Under musl, yes, and even in > the dynamic-linked case we use the same code that's used for static > linking rather than trying to get the dynamic linker to do them > correctly. I still have some cruft lying around from where (in the > past) we tried to do it via the dynamic linker, but I'm probably going > to remove that and make the vdso behave as RTLD_LOCAL so that there's > no risk of weird symbols it exports interfering with the application > (applications could still make it global via an explicit dlopen). The > only reason for keeping it around at all in the dynamic linker is for > the sake of gdb. > What about backtrace_symbols, dl_addr, and the unwinder (e.g. siglongjmp)? It would be nice to wean the vdso off of frame pointers some day. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
