Messages in this thread | | | Date | Mon, 7 May 2018 10:42:08 -0500 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v3] On ppc64le we HAVE_RELIABLE_STACKTRACE |
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On Fri, May 04, 2018 at 02:38:34PM +0200, 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. > > Feel free to add other ppc variants, but so far only ppc64le got tested. > > This change also implements save_stack_trace_tsk_reliable() for ppc64le > that checks for the above conditions, where possible. > > Signed-off-by: Torsten Duwe <duwe@suse.de> > Signed-off-by: Nicolai Stange <nstange@suse.de>
The subject doesn't actively describe what the patch does, maybe change it to something like:
powerpc: Add support for HAVE_RELIABLE_STACKTRACE
or maybe
powerpc: Add support for livepatch consistency model
Otherwise it looks great to me.
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
-- Josh
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