On Tue, Jun 30, 2015 at 10:57:04AM +0100, Adrian Hunter wrote: > On 29/06/15 16:52, Will Deacon wrote: > > 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. > > Adding or subtracting shouldn't matter.
I was referring to the subtraction in map__rip_2objdump, but you've addressed that below. > This seems to work (without any other changes): > > if (dso__is_vdso(dso)) > map->reloc = map->start - shdr.sh_addr + shdr.sh_offset; > > Haven't tested 32-bit yet though. FWIW, this works on arm64 and x86_64 with my testing: Tested-by: Will Deacon <will.dea...@arm.com> Cheers, 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/
