From: Nathan Chancellor <nathan@kernel.org>
To: masahiroy@kernel.org, ndesaulniers@google.com
Cc: nicolas@fjasle.eu, trix@redhat.com, linux-kbuild@vger.kernel.org,
llvm@lists.linux.dev, Nathan Chancellor <nathan@kernel.org>,
kernel test robot <lkp@intel.com>,
mpe@ellerman.id.au, npiggin@gmail.com,
christophe.leroy@csgroup.eu, linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 07/14] powerpc/vdso: Improve linker flags
Date: Wed, 04 Jan 2023 12:54:24 -0700 [thread overview]
Message-ID: <20221228-drop-qunused-arguments-v1-7-658cbc8fc592@kernel.org> (raw)
In-Reply-To: <20221228-drop-qunused-arguments-v1-0-658cbc8fc592@kernel.org>
When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, there
are several warnings in the PowerPC vDSO:
clang-16: error: -Wl,-soname=linux-vdso32.so.1: 'linker' input unused [-Werror,-Wunused-command-line-argument]
clang-16: error: -Wl,--hash-style=both: 'linker' input unused [-Werror,-Wunused-command-line-argument]
clang-16: error: argument unused during compilation: '-shared' [-Werror,-Wunused-command-line-argument]
clang-16: error: argument unused during compilation: '-nostdinc' [-Werror,-Wunused-command-line-argument]
clang-16: error: argument unused during compilation: '-Wa,-maltivec' [-Werror,-Wunused-command-line-argument]
The first group of warnings point out that linker flags were being added
to all invocations of $(CC), even though they will only be used during
the final vDSO link. Move those flags to ldflags-y.
The second group of warnings are compiler or assembler flags that will
be unused during linking. Filter them out from KBUILD_CFLAGS so that
they are not used during linking.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
Cc: mpe@ellerman.id.au
Cc: npiggin@gmail.com
Cc: christophe.leroy@csgroup.eu
Cc: linuxppc-dev@lists.ozlabs.org
---
arch/powerpc/kernel/vdso/Makefile | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index 45c0cc5d34b6..769b62832b38 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -47,13 +47,17 @@ KCOV_INSTRUMENT := n
UBSAN_SANITIZE := n
KASAN_SANITIZE := n
-ccflags-y := -shared -fno-common -fno-builtin -nostdlib -Wl,--hash-style=both
-ccflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
-
-CC32FLAGS := -Wl,-soname=linux-vdso32.so.1 -m32
+ccflags-y := -fno-common -fno-builtin
+ldflags-y := -Wl,--hash-style=both -nostdlib -shared
+ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
+# Filter flags that clang will warn are unused for linking
+ldflags-y += $(filter-out $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CFLAGS))
+
+CC32FLAGS := -m32
+LD32FLAGS := -Wl,-soname=linux-vdso32.so.1
AS32FLAGS := -D__VDSO32__
-CC64FLAGS := -Wl,-soname=linux-vdso64.so.1
+LD64FLAGS := -Wl,-soname=linux-vdso64.so.1
AS64FLAGS := -D__VDSO64__
targets += vdso32.lds
@@ -92,14 +96,14 @@ include/generated/vdso64-offsets.h: $(obj)/vdso64.so.dbg FORCE
# actual build commands
quiet_cmd_vdso32ld_and_check = VDSO32L $@
- cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) -z noexecstack ; $(cmd_vdso_check)
+ cmd_vdso32ld_and_check = $(VDSOCC) $(ldflags-y) $(CC32FLAGS) $(LD32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) -z noexecstack ; $(cmd_vdso_check)
quiet_cmd_vdso32as = VDSO32A $@
cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) $(AS32FLAGS) -c -o $@ $<
quiet_cmd_vdso32cc = VDSO32C $@
cmd_vdso32cc = $(VDSOCC) $(c_flags) $(CC32FLAGS) -c -o $@ $<
quiet_cmd_vdso64ld_and_check = VDSO64L $@
- cmd_vdso64ld_and_check = $(VDSOCC) $(c_flags) $(CC64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) -z noexecstack ; $(cmd_vdso_check)
+ cmd_vdso64ld_and_check = $(VDSOCC) $(ldflags-y) $(CC64FLAGS) $(LD64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) -z noexecstack ; $(cmd_vdso_check)
quiet_cmd_vdso64as = VDSO64A $@
cmd_vdso64as = $(VDSOCC) $(a_flags) $(CC64FLAGS) $(AS64FLAGS) -c -o $@ $<
--
2.39.0
next prev parent reply other threads:[~2023-01-04 19:54 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-04 19:54 [PATCH 00/14] Remove clang's -Qunused-arguments from KBUILD_CPPFLAGS Nathan Chancellor
2023-01-04 19:54 ` [PATCH 01/14] x86/boot/compressed: prefer cc-option for CFLAGS additions Nathan Chancellor
2023-01-04 19:54 ` [PATCH 02/14] MIPS: Always use -Wa,-msoft-float and eliminate GAS_HAS_SET_HARDFLOAT Nathan Chancellor
2023-01-09 21:18 ` Nick Desaulniers
2023-01-10 7:45 ` Philippe Mathieu-Daudé
2023-01-10 8:30 ` Thomas Bogendoerfer
2023-01-04 19:54 ` [PATCH 03/14] MIPS: Prefer cc-option for additions to cflags Nathan Chancellor
2023-01-09 21:21 ` Nick Desaulniers
2023-01-10 7:42 ` Philippe Mathieu-Daudé
2023-01-10 8:30 ` Thomas Bogendoerfer
2023-01-04 19:54 ` [PATCH 04/14] kbuild: Update assembler calls to use proper flags and language target Nathan Chancellor
2023-01-04 19:54 ` [PATCH 05/14] powerpc: Remove linker flag from KBUILD_AFLAGS Nathan Chancellor
2023-01-09 21:24 ` Nick Desaulniers
2023-01-04 19:54 ` [PATCH 06/14] powerpc/vdso: Remove unused '-s' flag from ASFLAGS Nathan Chancellor
2023-01-09 21:58 ` Nick Desaulniers
2023-01-09 22:15 ` Nathan Chancellor
2023-01-09 22:21 ` Nick Desaulniers
2023-01-09 22:23 ` Segher Boessenkool
2023-01-09 22:37 ` Nathan Chancellor
2023-01-09 22:47 ` Segher Boessenkool
2023-01-09 23:14 ` Nick Desaulniers
2023-01-10 0:51 ` Nathan Chancellor
2023-01-10 11:45 ` Segher Boessenkool
2023-01-10 15:02 ` Nathan Chancellor
[not found] ` <20230109222337.GM25951__25255.3859770828$1673303520$gmane$org@gate.crashing.org>
2023-01-10 0:22 ` Andreas Schwab
2023-01-10 0:43 ` Segher Boessenkool
2023-01-04 19:54 ` Nathan Chancellor [this message]
2023-01-09 22:08 ` [PATCH 07/14] powerpc/vdso: Improve linker flags Nick Desaulniers
2023-01-09 22:15 ` Nathan Chancellor
2023-01-04 19:54 ` [PATCH 08/14] powerpc/vdso: Remove an unsupported flag from vgettimeofday-32.o with clang Nathan Chancellor
2023-01-09 22:12 ` Nick Desaulniers
2023-01-09 22:38 ` Nathan Chancellor
2023-01-09 23:16 ` Nick Desaulniers
2023-01-04 19:54 ` [PATCH 09/14] s390/vdso: Drop unused '-s' flag from KBUILD_AFLAGS_64 Nathan Chancellor
2023-01-05 7:27 ` Sven Schnelle
2023-01-04 19:54 ` [PATCH 10/14] s390/vdso: Drop '-shared' from KBUILD_CFLAGS_64 Nathan Chancellor
2023-01-05 7:31 ` Sven Schnelle
2023-01-04 19:54 ` [PATCH 11/14] s390/purgatory: Remove unused '-MD' and unnecessary '-c' flags Nathan Chancellor
2023-01-05 7:33 ` Sven Schnelle
2023-01-04 19:54 ` [PATCH 12/14] drm/amd/display: Do not add '-mhard-float' to dml_ccflags for clang Nathan Chancellor
2023-01-05 14:21 ` Alex Deucher
2023-01-04 19:54 ` [PATCH 13/14] kbuild: Turn a couple more of clang's unused option warnings into errors Nathan Chancellor
2023-01-09 22:15 ` Nick Desaulniers
2023-01-04 19:54 ` [PATCH 14/14] kbuild: Stop using '-Qunused-arguments' with clang Nathan Chancellor
2023-01-09 22:17 ` Nick Desaulniers
2023-01-05 8:00 ` [PATCH 00/14] Remove clang's -Qunused-arguments from KBUILD_CPPFLAGS Heiko Carstens
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