On Mon, Jun 29, 2015 at 02:23:51PM +0100, Adrian Hunter wrote: > On 29/06/15 15:30, Adrian Hunter wrote: > > On 29/06/15 12:02, Adrian Hunter wrote: > >> On 27/06/15 12:10, Will Deacon wrote: > >>> @@ -824,6 +823,14 @@ int dso__load_sym(struct dso *dso, struct map *map, > >>> sec = syms_ss->symtab; > >>> shdr = syms_ss->symshdr; > >>> > >>> + /* > >>> + * Older x86 kernels prelink the vDSO at a high address, so > >>> + * we need to reflect that in map->pgoff in order to talk to > >>> + * objdump. > >>> + */ > >>> + if (dso__is_vdso(dso)) > >>> + map->pgoff = shdr.sh_addr - shdr.sh_offset; > >> > >> In the case of perf tools, maps map memory addresses to file offsets. > >> That is used to read from the object file, so you can't change the map. > > > > So what about just this instead: > > > > if (dso__is_vdso(dso)) > > map->reloc = shdr.sh_addr - shdr.sh_offset; > > > > No that's no good either :-(
Yeah... we're fighting against symbol lookup wanting ->map_ip to give the address of the ELF symbol but unwinding wanting ->map_ip to give a relative offset for file reads. Also, the reloc is a bit weird and I think needs to be the other way around (i.e. we convert from a map-relative address to an objdump address by *subtracting* the reloc). Even with that change, I run into problems with annotate comparing ELF symbol addresses with map addresses. Urgh. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
