Em Mon, Jun 29, 2015 at 02:52:39PM +0100, Will Deacon escreveu: > 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.
Its been a long time that I looked at this, but perhaps these can help: /* rip/ip <-> addr suitable for passing to `objdump --start-address=` */ u64 map__rip_2objdump(struct map *map, u64 rip); /* objdump address -> memory address */ u64 map__objdump_2mem(struct map *map, u64 ip); The comments in the changeset that introduced it have more info: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7a2b6209863626cf8362e5ff4653491558f91e67 - Arnaldo - Arnaldo -- 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/
