From: Naveen N Rao naveen@kernel.org
commit 25ea739ea1d4d3de41acc4f4eb2d1a97eee0eb75 upstream.
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%3Ba=commit%3Bh=c09c8b42021180...
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: stable@vger.kernel.org Suggested-by: Joel Stanley joel@jms.id.au Signed-off-by: Naveen N Rao naveen@kernel.org Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://msgid.link/20230530061436.56925-1-naveen@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/Makefile | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -444,3 +444,11 @@ 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 \ + "${CONFIG_LD_VERSION}" = "23700" ; 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