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| author | Paul Burton <paul.burton@mips.com> | 2019-01-11 22:06:44 +0300 |
|---|---|---|
| committer | Masahiro Yamada <yamada.masahiro@socionext.com> | 2019-01-14 04:37:09 +0300 |
| commit | 16fd20aa98080c2fa666dc384036ec08c80af710 (patch) | |
| tree | d8265dede17c209f3328939ead6402383b345a84 /init | |
| parent | 2648ca1859bb48cacdbbaf60bbc0bfef74f13330 (diff) | |
| download | linux-16fd20aa98080c2fa666dc384036ec08c80af710.tar.xz | |
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')
| -rw-r--r-- | init/Kconfig | 1 |
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) help |