Naveen N Rao <nav...@kernel.org> writes: > binutils v2.37 drops unused section symbols, which prevents recordmcount > from capturing mcount locations in sections that have no non-weak > symbols. This results in a build failure with a message such as: > Cannot find symbol for section 12: .text.perf_callchain_kernel. > kernel/events/callchain.o: failed > > The change to binutils was reverted for v2.38, so this behavior is > specific to binutils v2.37: > https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=c09c8b42021180eee9495bd50d8b35e683d3901b > > Objtool is able to cope with such sections, so this issue is specific to > recordmcount. > > Fail the build and print a warning if binutils v2.37 is detected and if > we are using recordmcount. > > Cc: sta...@vger.kernel.org > Suggested-by: Joel Stanley <j...@jms.id.au> > Signed-off-by: Naveen N Rao <nav...@kernel.org> > --- > arch/powerpc/Makefile | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile > index dca73f673d7046..f0540c1f1377c8 100644 > --- a/arch/powerpc/Makefile > +++ b/arch/powerpc/Makefile > @@ -409,3 +409,11 @@ checkbin: > echo -n '*** Please use a different binutils version.' ; \ > false ; \ > fi > + @if test "x${CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT}" = "xy" -a \ > + "x${CONFIG_LD_IS_BFD}" = "xy" -a \ > + "x$(call ld-ifversion, -eq, 23700, y)" = "xy" ; then \ > + echo -n '*** binutils 2.37 drops unused section symbols, which > recordmcount ' ; \ > + echo 'is unable to handle.' ; \ > + echo '*** Please use a different binutils version.' ; \ > + false ; \ > + fi
Thanks for doing this. Masahiro wanted to remove ld-ifversion, he suggested to just check CONFIG_LD_VERSION directly instead. Mind doing a v2 with that change? https://lore.kernel.org/all/CAK7LNAQWtDHOs=k+qznt5u1widv86tchkj4zoer4wtvrb97...@mail.gmail.com/ cheers
