From: Naveen N Rao <naveen@kernel.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, Joel Stanley <joel@jms.id.au>,
Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v2] powerpc: Fail build if using recordmcount with binutils v2.37
Date: Tue, 30 May 2023 11:44:36 +0530 [thread overview]
Message-ID: <20230530061436.56925-1-naveen@kernel.org> (raw)
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: stable@vger.kernel.org
Suggested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Naveen N Rao <naveen@kernel.org>
---
v2: Check directly against $CONFIG_LD_VERSION
arch/powerpc/Makefile | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index dca73f673d7046..fc76eb9830fdfa 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -409,3 +409,11 @@ checkbin:
echo -n '*** Please use a different binutils version.' ; \
false ; \
fi
+ @if test "x${CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT}" = "xy" -a \
+ "x${CONFIG_LD_IS_BFD}" = "xy" -a \
+ "${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
base-commit: 7b2f56d76feff3b494d6e77950ab97987323d3c5
--
2.40.1
next reply other threads:[~2023-05-30 6:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 6:14 Naveen N Rao [this message]
2023-07-03 5:26 ` [PATCH v2] powerpc: Fail build if using recordmcount with binutils v2.37 Michael Ellerman
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