[PATCH v2] powerpc/64: BE option to use ELFv2 ABI for big endian kernels
Nicholas Piggin
npiggin at gmail.com
Tue May 4 19:13:39 AEST 2021
Excerpts from Michal Suchánek's message of May 4, 2021 6:17 am:
> On Mon, May 03, 2021 at 11:34:25AM +0200, Michal Suchánek wrote:
>> On Mon, May 03, 2021 at 09:11:16AM +0200, Michal Suchánek wrote:
>> > On Mon, May 03, 2021 at 10:58:33AM +1000, Nicholas Piggin wrote:
>> > > Excerpts from Michal Suchánek's message of May 3, 2021 2:57 am:
>> > > > On Tue, Apr 28, 2020 at 09:25:17PM +1000, Nicholas Piggin wrote:
>> > > >> Provide an option to use ELFv2 ABI for big endian builds. This works on
>> > > >> GCC and clang (since 2014). It is less well tested and supported by the
>> > > >> GNU toolchain, but it can give some useful advantages of the ELFv2 ABI
>> > > >> for BE (e.g., less stack usage). Some distros even build BE ELFv2
>> > > >> userspace.
>> > > >
>> > > > Fixes BTFID failure on BE for me and the ELF ABIv2 kernel boots.
>> > >
>> > > What's the BTFID failure? Anything we can do to fix it on the v1 ABI or
>> > > at least make it depend on BUILD_ELF_V2?
>> >
>> > Looks like symbols are prefixed with a dot in ABIv1 and BTFID tool is
>> > not aware of that. It can be disabled on ABIv1 easily.
>> >
>> > Thanks
>> >
>> > Michal
>> >
>> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
>> > index 678c13967580..e703c26e9b80 100644
>> > --- a/lib/Kconfig.debug
>> > +++ b/lib/Kconfig.debug
>> > @@ -305,6 +305,7 @@ config DEBUG_INFO_BTF
>> > bool "Generate BTF typeinfo"
>> > depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED
>> > depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
>> > + depends on !PPC64 || BUILD_ELF_V2
>> > help
>> > Generate deduplicated BTF type information from DWARF debug info.
>> > Turning this on expects presence of pahole tool, which will convert
>> >
>> > >
>> > > >
>> > > > Tested-by: Michal Suchánek <msuchanek at suse.de>
>> > > >
>> > > > Also can we enable mprofile on BE now?
>> > > >
>> > > > I don't see anything endian-specific in the mprofile code at a glance
>> > > > but don't have any idea how to test it.
>> > >
>> > > AFAIK it's just a different ABI for the _mcount call so just running
>> > > some ftrace and ftrace with call graph should test it reasonably well.
>>
>> It does not crash and burn but there are some regressions from LE to BE
>> on the ftrace kernel selftest:
>>
>> --- ftraceLE.txt 2021-05-03 11:19:14.830000000 +0200
>> +++ ftraceBE.txt 2021-05-03 11:27:24.770000000 +0200
>> @@ -7,8 +7,8 @@
>> [n] Change the ringbuffer size [PASS]
>> [n] Snapshot and tracing setting [PASS]
>> [n] trace_pipe and trace_marker [PASS]
>> -[n] Test ftrace direct functions against tracers [UNRESOLVED]
>> -[n] Test ftrace direct functions against kprobes [UNRESOLVED]
>> +[n] Test ftrace direct functions against tracers [FAIL]
>> +[n] Test ftrace direct functions against kprobes [FAIL]
>> [n] Generic dynamic event - add/remove kprobe events [PASS]
>> [n] Generic dynamic event - add/remove synthetic events [PASS]
>> [n] Generic dynamic event - selective clear (compatibility) [PASS]
>> @@ -16,10 +16,10 @@
>> [n] event tracing - enable/disable with event level files [PASS]
>> [n] event tracing - restricts events based on pid notrace filtering [PASS]
>> [n] event tracing - restricts events based on pid [PASS]
>> -[n] event tracing - enable/disable with subsystem level files [PASS]
>> +[n] event tracing - enable/disable with subsystem level files [FAIL]
>> [n] event tracing - enable/disable with top level files [PASS]
>> -[n] Test trace_printk from module [UNRESOLVED]
>> -[n] ftrace - function graph filters with stack tracer [PASS]
>> +[n] Test trace_printk from module [FAIL]
>> +[n] ftrace - function graph filters with stack tracer [FAIL]
>> [n] ftrace - function graph filters [PASS]
>> [n] ftrace - function trace with cpumask [PASS]
>> [n] ftrace - test for function event triggers [PASS]
>> @@ -27,7 +27,7 @@
>> [n] ftrace - function pid notrace filters [PASS]
>> [n] ftrace - function pid filters [PASS]
>> [n] ftrace - stacktrace filter command [PASS]
>> -[n] ftrace - function trace on module [UNRESOLVED]
>> +[n] ftrace - function trace on module [FAIL]
>> [n] ftrace - function profiler with function tracing [PASS]
>> [n] ftrace - function profiling [PASS]
>> [n] ftrace - test reading of set_ftrace_filter [PASS]
>> @@ -44,10 +44,10 @@
>> [n] Kprobe event argument syntax [PASS]
>> [n] Kprobe dynamic event with arguments [PASS]
>> [n] Kprobes event arguments with types [PASS]
>> -[n] Kprobe event user-memory access [UNSUPPORTED]
>> +[n] Kprobe event user-memory access [FAIL]
>> [n] Kprobe event auto/manual naming [PASS]
>> [n] Kprobe dynamic event with function tracer [PASS]
>> -[n] Kprobe dynamic event - probing module [UNRESOLVED]
>> +[n] Kprobe dynamic event - probing module [FAIL]
>> [n] Create/delete multiprobe on kprobe event [PASS]
>> [n] Kprobe event parser error log check [PASS]
>> [n] Kretprobe dynamic event with arguments [PASS]
>> @@ -57,11 +57,11 @@
>> [n] Kprobe events - probe points [PASS]
>> [n] Kprobe dynamic event - adding and removing [PASS]
>> [n] Uprobe event parser error log check [PASS]
>> -[n] test for the preemptirqsoff tracer [UNSUPPORTED]
>> -[n] Meta-selftest: Checkbashisms [UNRESOLVED]
>> +[n] test for the preemptirqsoff tracer [FAIL]
>> +[n] Meta-selftest: Checkbashisms [FAIL]
>> [n] Test wakeup RT tracer [PASS]
>> [n] Test wakeup tracer [PASS]
>> -[n] event trigger - test inter-event histogram trigger expected fail actions [XFAIL]
>> +[n] event trigger - test inter-event histogram trigger expected fail actions [FAIL]
>> [n] event trigger - test field variable support [PASS]
>> [n] event trigger - test inter-event combined histogram trigger [PASS]
>> [n] event trigger - test multiple actions on hist trigger [PASS]
>> @@ -96,7 +96,8 @@
>> [n] (instance) event tracing - enable/disable with event level files [PASS]
>> [n] (instance) event tracing - restricts events based on pid notrace filtering [PASS]
>> [n] (instance) event tracing - restricts events based on pid [PASS]
>> -[n] (instance) event tracing - enable/disable with subsystem level files [PASS]
>> +[n] (instance) event tracing - enable/disable with subsystem level files [FAIL]
>> +rmdir: failed to remove '/sys/kernel/tracing/instances/ftracetest.mceByV': Device or resource busy
>> [n] (instance) ftrace - test for function event triggers [PASS]
>> [n] (instance) ftrace - function pid notrace filters [PASS]
>> [n] (instance) ftrace - function pid filters [PASS]
>>
>> I needed to add a test timeout to get this far because
>> "event tracing - enable/disable with subsystem level files" gets stuck.
>
> There is some regression from mprofile on BE ABIv2
>
> --- ftraceBEv2.txt 2021-05-03 18:11:01.100000000 +0200
> +++ ftraceBE.mprofile.txt 2021-05-03 11:27:24.770000000 +0200
> @@ -19,7 +19,7 @@
> [n] event tracing - enable/disable with subsystem level files [FAIL]
> [n] event tracing - enable/disable with top level files [PASS]
> [n] Test trace_printk from module [FAIL]
> -[n] ftrace - function graph filters with stack tracer [PASS]
> +[n] ftrace - function graph filters with stack tracer [FAIL]
> [n] ftrace - function graph filters [PASS]
> [n] ftrace - function trace with cpumask [PASS]
> [n] ftrace - test for function event triggers [PASS]
> @@ -31,7 +31,7 @@
> [n] ftrace - function profiler with function tracing [PASS]
> [n] ftrace - function profiling [PASS]
> [n] ftrace - test reading of set_ftrace_filter [PASS]
> -[n] ftrace - Max stack tracer [PASS]
> +[n] ftrace - Max stack tracer [FAIL]
> [n] ftrace - test for function traceon/off triggers [PASS]
> [n] ftrace - test tracing error log support [PASS]
> [n] Test creation and deletion of trace instances while setting an event [PASS]
Hmm, I don't see an obvious case where the stack layout is based on
BE when it should be using ELF ABI version, or ftrace_64_mprofile.S
depends on LE. +Naveen
>
> but generally the ftrace on BE is broken overall. The test
> "event tracing - enable/disable with subsystem level files" gets stuck
> and has to be killed by timeout. Running the testsuite twice the test
> "Basic test for tracers" locks up the machine regardless of using
> mprofile. The ABIV1 is even much worse with the exception of
> "(instance) event tracing - enable/disable with subsystem level files"
> which regresses on BE ABIv2 in general.
Wow it has fixed quite a few! That event tracing one hardly looks like
a difficult test, hopefully should be something trivial.
Thanks for testing.
Thanks,
Nick
>
> --- ftraceBEv1.txt 2021-05-03 22:09:10.690000000 +0200
> +++ ftraceBEv2.txt 2021-05-03 18:11:01.100000000 +0200
> @@ -9,10 +9,10 @@
> [n] trace_pipe and trace_marker [PASS]
> [n] Test ftrace direct functions against tracers [FAIL]
> [n] Test ftrace direct functions against kprobes [FAIL]
> -[n] Generic dynamic event - add/remove kprobe events [FAIL]
> +[n] Generic dynamic event - add/remove kprobe events [PASS]
> [n] Generic dynamic event - add/remove synthetic events [PASS]
> -[n] Generic dynamic event - selective clear (compatibility) [FAIL]
> -[n] Generic dynamic event - generic clear event [FAIL]
> +[n] Generic dynamic event - selective clear (compatibility) [PASS]
> +[n] Generic dynamic event - generic clear event [PASS]
> [n] event tracing - enable/disable with event level files [PASS]
> [n] event tracing - restricts events based on pid notrace filtering [PASS]
> [n] event tracing - restricts events based on pid [PASS]
> @@ -23,39 +23,39 @@
> [n] ftrace - function graph filters [PASS]
> [n] ftrace - function trace with cpumask [PASS]
> [n] ftrace - test for function event triggers [PASS]
> -[n] ftrace - function glob filters [FAIL]
> +[n] ftrace - function glob filters [PASS]
> [n] ftrace - function pid notrace filters [PASS]
> [n] ftrace - function pid filters [PASS]
> [n] ftrace - stacktrace filter command [PASS]
> [n] ftrace - function trace on module [FAIL]
> [n] ftrace - function profiler with function tracing [PASS]
> [n] ftrace - function profiling [PASS]
> -[n] ftrace - test reading of set_ftrace_filter [FAIL]
> +[n] ftrace - test reading of set_ftrace_filter [PASS]
> [n] ftrace - Max stack tracer [PASS]
> [n] ftrace - test for function traceon/off triggers [PASS]
> [n] ftrace - test tracing error log support [PASS]
> [n] Test creation and deletion of trace instances while setting an event [PASS]
> [n] Test creation and deletion of trace instances [PASS]
> -[n] Kprobe dynamic event - adding and removing [FAIL]
> -[n] Kprobe dynamic event - busy event check [FAIL]
> -[n] Kprobe dynamic event with arguments [FAIL]
> -[n] Kprobe event with comm arguments [FAIL]
> -[n] Kprobe event string type argument [FAIL]
> -[n] Kprobe event symbol argument [FAIL]
> -[n] Kprobe event argument syntax [FAIL]
> -[n] Kprobes event arguments with types [FAIL]
> +[n] Kprobe dynamic event - adding and removing [PASS]
> +[n] Kprobe dynamic event - busy event check [PASS]
> +[n] Kprobe event with comm arguments [PASS]
> +[n] Kprobe event string type argument [PASS]
> +[n] Kprobe event symbol argument [PASS]
> +[n] Kprobe event argument syntax [PASS]
> +[n] Kprobe dynamic event with arguments [PASS]
> +[n] Kprobes event arguments with types [PASS]
> [n] Kprobe event user-memory access [FAIL]
> [n] Kprobe event auto/manual naming [PASS]
> -[n] Kprobe dynamic event with function tracer [FAIL]
> +[n] Kprobe dynamic event with function tracer [PASS]
> [n] Kprobe dynamic event - probing module [FAIL]
> -[n] Create/delete multiprobe on kprobe event [FAIL]
> -[n] Kprobe event parser error log check [FAIL]
> -[n] Kretprobe dynamic event with arguments [FAIL]
> -[n] Kretprobe dynamic event with maxactive [FAIL]
> -[n] Kretprobe %return suffix test [FAIL]
> -[n] Register/unregister many kprobe events [FAIL]
> -[n] Kprobe events - probe points [FAIL]
> -[n] Kprobe dynamic event - adding and removing [FAIL]
> +[n] Create/delete multiprobe on kprobe event [PASS]
> +[n] Kprobe event parser error log check [PASS]
> +[n] Kretprobe dynamic event with arguments [PASS]
> +[n] Kretprobe dynamic event with maxactive [PASS]
> +[n] Kretprobe %return suffix test [PASS]
> +[n] Register/unregister many kprobe events [PASS]
> +[n] Kprobe events - probe points [PASS]
> +[n] Kprobe dynamic event - adding and removing [PASS]
> [n] Uprobe event parser error log check [PASS]
> [n] test for the preemptirqsoff tracer [FAIL]
> [n] Meta-selftest: Checkbashisms [FAIL]
> @@ -96,7 +96,8 @@
> [n] (instance) event tracing - enable/disable with event level files [PASS]
> [n] (instance) event tracing - restricts events based on pid notrace filtering [PASS]
> [n] (instance) event tracing - restricts events based on pid [PASS]
> -[n] (instance) event tracing - enable/disable with subsystem level files [PASS]
> +[n] (instance) event tracing - enable/disable with subsystem level files [FAIL]
> +rmdir: failed to remove '/sys/kernel/tracing/instances/ftracetest.lxCI5k': Device or resource busy
> [n] (instance) ftrace - test for function event triggers [PASS]
> [n] (instance) ftrace - function pid notrace filters [PASS]
> [n] (instance) ftrace - function pid filters [PASS]
>
>
> Thanks
>
> Michal
>
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