The addresses in call chains in perf.data files from simpleperf have already been adjusted to point into the call instruction. This is different from what we're used to from perf.data files generated by Linux perf.
If simpleperf does the unwinding of the user stack itself, the callchains are adjusted in libunwindstack,
i.e in the unwinder that's used by simpleperf:
The addresses in call chains in perf.data files from simpleperf have already been adjusted to point into the call instruction. This is different from what we're used to from perf.data files generated by Linux perf.
The adjustment happens in two places:
If the unwinding happens in the kernel, the callchains are adjusted in
SampleRecord::AdjustCallChainGeneratedByKernel().If simpleperf does the unwinding of the user stack itself, the callchains are adjusted in libunwindstack, i.e in the unwinder that's used by simpleperf:
https://cs.android.com/android/platform/superproject/+/main:system/unwinding/libunwindstack/Unwinder.cpp;l=177;drc=8e2c60d01e0928275d30f320c3f83ac4f29b880c https://cs.android.com/android/platform/superproject/+/main:system/unwinding/libunwindstack/Regs.cpp;l=175-224;drc=c0fa0c327e58eda604b2fd00b81f1c12817542d3