Messages in this thread | | | Date | Thu, 8 Mar 2018 10:26:16 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v2] On ppc64le we HAVE_RELIABLE_STACKTRACE |
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On Mon, Mar 05, 2018 at 05:49:28PM +0100, Torsten Duwe wrote: > The "Power Architecture 64-Bit ELF V2 ABI" says in section 2.3.2.3: > > [...] There are several rules that must be adhered to in order to ensure > reliable and consistent call chain backtracing: > > * Before a function calls any other function, it shall establish its > own stack frame, whose size shall be a multiple of 16 bytes. > > – In instances where a function’s prologue creates a stack frame, the > back-chain word of the stack frame shall be updated atomically with > the value of the stack pointer (r1) when a back chain is implemented. > (This must be supported as default by all ELF V2 ABI-compliant > environments.) > [...] > – The function shall save the link register that contains its return > address in the LR save doubleword of its caller’s stack frame before > calling another function. > > To me this sounds like the equivalent of HAVE_RELIABLE_STACKTRACE. > This patch may be unneccessarily limited to ppc64le, but OTOH the only > user of this flag so far is livepatching, which is only implemented on > PPCs with 64-LE, a.k.a. ELF ABI v2. > > This change also implements save_stack_trace_tsk_reliable() for ppc64 > that checks for the above conditions, where possible. > > Signed-off-by: Torsten Duwe <duwe@suse.de>
This doesn't seem to address some of my previous concerns:
- Bailing on interrupt/exception frames
- Function graph tracing return address conversion
- kretprobes return address conversion
-- Josh
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