[PATCH 5.4 107/191] powerpc: Dont add -mabi= flags when building with Clang

Greg Kroah-Hartman
2020-01-02T22:15:16Z

From: Nathan Chancellor <natechancellor@gmail.com>

[ Upstream commit 465bfd9c44dea6b55962b5788a23ac87a467c923 ]

When building pseries_defconfig, building vdso32 errors out:

error: unknown target ABI 'elfv1'

This happens because -m32 in clang changes the target to 32-bit,
which does not allow the ABI to be changed.

Commit 4dc831aa8813 ("powerpc: Fix compiling a BE kernel with a
powerpc64le toolchain") added these flags to fix building big endian
kernels with a little endian GCC.

Clang doesn't need -mabi because the target triple controls the
default value. -mlittle-endian and -mbig-endian manipulate the triple
into either powerpc64-* or powerpc64le-*, which properly sets the
default ABI.

Adding a debug print out in the PPC64TargetInfo constructor after line
383 above shows this:

$ echo | ./clang -E --target=powerpc64-linux -mbig-endian -o /dev/null -
Default ABI: elfv1

$ echo | ./clang -E --target=powerpc64-linux -mlittle-endian -o /dev/null -
Default ABI: elfv2

$ echo | ./clang -E --target=powerpc64le-linux -mbig-endian -o /dev/null -
Default ABI: elfv1

$ echo | ./clang -E --target=powerpc64le-linux -mlittle-endian -o /dev/null -
Default ABI: elfv2

Don't specify -mabi when building with clang to avoid the build error
with -m32 and not change any code generation.

-mcall-aixdesc is not an implemented flag in clang so it can be safely
excluded as well, see commit 238abecde8ad ("powerpc: Don't use gcc
specific options on clang").

pseries_defconfig successfully builds after this patch and
powernv_defconfig and ppc44x_defconfig don't regress.

Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
[mpe: Trim clang links in change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191119045712.39633-2-natechancellor@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/powerpc/Makefile | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 83522c9fc7b6..37ac731a556b 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -91,11 +91,13 @@ MULTIPLEWORD := -mmultiple
endif

ifdef CONFIG_PPC64
+ifndef CONFIG_CC_IS_CLANG
cflags-$(CONFIG_CPU_BIG_ENDIAN) += $(call cc-option,-mabi=elfv1)
cflags-$(CONFIG_CPU_BIG_ENDIAN) += $(call cc-option,-mcall-aixdesc)
aflags-$(CONFIG_CPU_BIG_ENDIAN) += $(call cc-option,-mabi=elfv1)
aflags-$(CONFIG_CPU_LITTLE_ENDIAN) += -mabi=elfv2
endif
+endif

ifndef CONFIG_CC_IS_CLANG
cflags-$(CONFIG_CPU_LITTLE_ENDIAN) += -mno-strict-align
@@ -141,6 +143,7 @@ endif
endif

CFLAGS-$(CONFIG_PPC64) := $(call cc-option,-mtraceback=no)
+ifndef CONFIG_CC_IS_CLANG
ifdef CONFIG_CPU_LITTLE_ENDIAN
CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv2,$(call cc-option,-mcall-aixdesc))
AFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv2)
@@ -149,6 +152,7 @@ CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv1)
CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mcall-aixdesc)
AFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mabi=elfv1)
endif
+endif
CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mcmodel=medium,$(call cc-option,-mminimal-toc))
CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mno-pointers-to-nested-functions)

--
2.20.1