Messages in this thread | | | Date | Wed, 17 Jun 2015 11:54:12 -0700 | Subject | Re: [BUG] perf report: fails to symbolize when vaddr is non zero for shared objects | From | Stephane Eranian <> |
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On Tue, Jun 16, 2015 at 7:34 AM, Arnaldo Carvalho de Melo <acme@redhat.com> wrote: > Em Tue, Jun 16, 2015 at 12:03:01AM -0700, Stephane Eranian escreveu: >> Hi, >> >> It has been brought to my attention that on systems where the text >> of shared libs is not loaded with a zero virtual address, perf report >> fails to symbolize >> correctly samples. This is true of older versions of perf and also the latest >> in tip.git. >> >> I looked at symbol-elf.c and I did not see a place where the vaddr was taken >> into account from the program headers in the case of ET_DYN. I see it for >> ET_EXE, though. >> >> $ readelf -e lib.so >> Type: DYN (Shared object file) >> .... >> Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align >> LOAD 0x000000 0x0000d000 0x0000d000 0x73657c 0x73657c R E 0x1000 >> >> If you get samples in the shared lib, they will be off, possibly >> attributed to the wrong >> functions. >> >> Could this be fixed quickly? > > You tell me, do you have a patch to propose? :-) > Well, need to make sure I understand the code flow in dso__load_sym() and callers. You have elf_read_maps() which seems to be reading the phdr but, it would need to be called systematically for ET_DYN. I will experiment with this. Worst case, we need to add another function to read the phdr and use the p_vaddr.
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