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
base-commit: 7b2f56d76feff3b494d6e77950ab97987323d3c5
--
2.40.1
