Hi Will, On 25 June 2014 11:01, Will Deacon <will.dea...@arm.com> wrote: > On Fri, Jun 20, 2014 at 09:10:35AM +0100, Jean Pihet wrote: >> Hi Will, > > Hi Jean, > >> On 18 June 2014 14:53, Will Deacon <will.dea...@arm.com> wrote: >> > On Tue, Jun 17, 2014 at 06:11:05PM +0100, Jean Pihet wrote: >> >> Tested with perf record and tracepoints filtering (-e <tracepoint>), with >> >> unwinding using fp (--call-graph fp) and dwarf info (--call-graph dwarf). >> > >> > Whilst the old ACPS unwinding only needs PC, FP and SP, is this definitely >> > true for exidx and DWARF-based unwinding? Given that libunwind ends up >> > running a state machine for the latter, can we guarantee that we won't hit >> > instructions that require access to other general purpose registers? >> Yes. dwarf unwinding does not need anything extra. Once seeded all the >> rest is extracted from the dwarf trace info. > > Ok, but what if the LR isn't saved on the stack, for example? What if the > code you're trying to unwind is hand-written assembly annotated with CFI > directives? Then in that case the unwinding is not possible unless the hand-crafted asm is compatible with the requested unwinding method (fp, dwarf etc.). Do you expect problems there, if so can you give more details?
> > Will Jean -- 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/