Messages in this thread | | | Date | Wed, 18 Mar 2020 12:06:59 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH v3] perf symbols: Consolidate symbol fixup issue |
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On Fri, Mar 06, 2020 at 09:57:58AM +0800, Leo Yan wrote: > After copying Arm64's perf archive with object files and perf.data file > to x86 laptop, the x86's perf kernel symbol resolution fails. It > outputs 'unknown' for all symbols parsing. > > This issue is root caused by the function elf__needs_adjust_symbols(), > x86 perf tool uses one weak version, Arm64 (and powerpc) has rewritten > their own version. elf__needs_adjust_symbols() decides if need to parse > symbols with the relative offset address; but x86 building uses the weak > function which misses to check for the elf type 'ET_DYN', so that it > cannot parse symbols in Arm DSOs due to the wrong result from > elf__needs_adjust_symbols(). > > The DSO parsing should not depend on any specific architecture perf > building; e.g. x86 perf tool can parse Arm and Arm64 DSOs, vice versa. > And confirmed by Naveen N. Rao that powerpc64 kernels are not being > built as ET_DYN anymore and change to ET_EXEC. > > This patch removes the arch specific functions for Arm64 and powerpc and > changes elf__needs_adjust_symbols() as a common function. > > In the common elf__needs_adjust_symbols(), it checks an extra condition > 'ET_DYN' for elf header type. With this fixing, the Arm64 DSO can be > parsed properly with x86's perf tool. > > Before: > > # perf script > main 3258 1 branches: 0 [unknown] ([unknown]) => ffff800010c4665c [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c46670 [unknown] ([kernel.kallsyms]) => ffff800010c4eaec [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eaec [unknown] ([kernel.kallsyms]) => ffff800010c4eb00 [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eb08 [unknown] ([kernel.kallsyms]) => ffff800010c4e780 [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4e7a0 [unknown] ([kernel.kallsyms]) => ffff800010c4eeac [unknown] ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eebc [unknown] ([kernel.kallsyms]) => ffff800010c4ed80 [unknown] ([kernel.kallsyms]) > > After: > > # perf script > main 3258 1 branches: 0 [unknown] ([unknown]) => ffff800010c4665c coresight_timeout+0x54 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c46670 coresight_timeout+0x68 ([kernel.kallsyms]) => ffff800010c4eaec etm4_enable_hw+0x3cc ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eaec etm4_enable_hw+0x3cc ([kernel.kallsyms]) => ffff800010c4eb00 etm4_enable_hw+0x3e0 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eb08 etm4_enable_hw+0x3e8 ([kernel.kallsyms]) => ffff800010c4e780 etm4_enable_hw+0x60 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4e7a0 etm4_enable_hw+0x80 ([kernel.kallsyms]) => ffff800010c4eeac etm4_enable+0x2d4 ([kernel.kallsyms]) > main 3258 1 branches: ffff800010c4eebc etm4_enable+0x2e4 ([kernel.kallsyms]) => ffff800010c4ed80 etm4_enable+0x1a8 ([kernel.kallsyms]) > > v3: Changed to check for ET_DYN across all architectures. > > v2: Fixed Arm64 and powerpc native building. > > Reported-by: Mike Leach <mike.leach@linaro.org> > Signed-off-by: Leo Yan <leo.yan@linaro.org> > Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
thanks, jirka
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