Messages in this thread | | | Date | Fri, 26 Jun 2015 13:23:08 +0100 | From | Will Deacon <> | Subject | Re: [PATCH] perf tools: don't adjust symbols in vDSO |
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On Thu, Jun 25, 2015 at 02:32:13PM +0100, Adrian Hunter wrote: > On 24/06/15 19:17, Will Deacon wrote: > > Commit 922d0e4d9f04 ("perf tools: Adjust symbols in VDSO") changed the > > ELF symbol parsing so that the vDSO is treated the same as ET_EXEC and > > ET_REL binaries despite being an ET_DYN. > > > > This causes objdump, which expects relative addresses, not to produce > > any output in conjunction with perf annotate, which cheerfully passes > > absolute addresses when trying to disassemble vDSO functions. > > > > This patch avoids marking the vDSO as requiring adjustment of symbol > > addresses, allowing the relative program counter to be used instead. > > > > Cc: Vladimir Nikulichev <nvs@tbricks.com> > > Cc: Adrian Hunter <adrian.hunter@intel.com> > > Cc: Namhyung Kim <namhyung@kernel.org> > > Reported-by: Kristina Martsenko <kristina.martsenko@arm.com> > > Signed-off-by: Will Deacon <will.deacon@arm.com> > > --- > > > > Not sure why I've just started seeing this, but it appears to affect > > both x86 and arm64. Also, if I revert the patch above then the issue > > it supposedly fixed doesn't resurface. Maybe it was just masking another > > bug that has since been addressed? > > No the problem still appears on older kernels.
Can you be more specific, please? I tried with a 3.16 kernel (that I happen to be running on my box) but perf doesn't even detect the vdso there, regardless of this patch.
> Probably could look at the vdso section/program headers to decide if it > needs adjustment or not.
Did the x86 kernel change in this regard? Why isn't the vDSO always ET_DYN?
Will
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