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authorPaul Burton <paul.burton@mips.com>2019-01-11 19:06:44 +0000
committerMasahiro Yamada <yamada.masahiro@socionext.com>2019-01-14 10:37:09 +0900
commit16fd20aa98080c2fa666dc384036ec08c80af710 (patch)
treed8265dede17c209f3328939ead6402383b345a84 /init/Kconfig
parent2648ca1859bb48cacdbbaf60bbc0bfef74f13330 (diff)
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kbuild: Disable LD_DEAD_CODE_DATA_ELIMINATION with ftrace & GCC <= 4.7
When building using GCC 4.7 or older, -ffunction-sections & the -pg flag used by ftrace are incompatible. This causes warnings or build failures (where -Werror applies) such as the following: arch/mips/generic/init.c: error: -ffunction-sections disabled; it makes profiling impossible This used to be taken into account by the ordering of calls to cc-option from within the top-level Makefile, which was introduced by commit 90ad4052e85c ("kbuild: avoid conflict between -ffunction-sections and -pg on gcc-4.7"). Unfortunately this was broken when the CONFIG_LD_DEAD_CODE_DATA_ELIMINATION cc-option check was moved to Kconfig in commit e85d1d65cd8a ("kbuild: test dead code/data elimination support in Kconfig"), because the flags used by this check no longer include -pg. Fix this by not allowing CONFIG_LD_DEAD_CODE_DATA_ELIMINATION to be enabled at the same time as ftrace/CONFIG_FUNCTION_TRACER when building using GCC 4.7 or older. Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes: e85d1d65cd8a ("kbuild: test dead code/data elimination support in Kconfig") Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Diffstat (limited to 'init/Kconfig')
-rw-r--r--init/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig
index d47cb77a220e..513fa544a134 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1124,6 +1124,7 @@ config LD_DEAD_CODE_DATA_ELIMINATION
bool "Dead code and data elimination (EXPERIMENTAL)"
depends on HAVE_LD_DEAD_CODE_DATA_ELIMINATION
depends on EXPERT
+ depends on !(FUNCTION_TRACER && CC_IS_GCC && GCC_VERSION < 40800)
depends on $(cc-option,-ffunction-sections -fdata-sections)
depends on $(ld-option,--gc-sections)
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