The PowerPC vDSO is linked with $(CC) instead of $(LD), which means the
default linker of the compiler is used instead of the linker requested
by the builder.
$ make ARCH=powerpc LLVM=1 mrproper defconfig arch/powerpc/kernel/vdso/
...
$ llvm-readelf -p .comment arch/powerpc/kernel/vdso/vdso{32,64}.so.dbg
File: arch/powerpc/kernel/vdso/vdso32.so.dbg
String dump of section '.comment':
[ 0] clang version 14.0.0 (Fedora 14.0.0-1.fc37)
File: arch/powerpc/kernel/vdso/vdso64.so.dbg
String dump of section '.comment':
[ 0] clang version 14.0.0 (Fedora 14.0.0-1.fc37)
The compiler option '-fuse-ld' tells the compiler which linker to use
when it is invoked as both the compiler and linker. Use '-fuse-ld=lld'
when LD=ld.lld has been specified (CONFIG_LD_IS_LLD) so that the vDSO is
linked with the same linker as the rest of the kernel.
$ llvm-readelf -p .comment arch/powerpc/kernel/vdso/vdso{32,64}.so.dbg
File: arch/powerpc/kernel/vdso/vdso32.so.dbg
String dump of section '.comment':
[ 0] Linker: LLD 14.0.0
[ 14] clang version 14.0.0 (Fedora 14.0.0-1.fc37)
File: arch/powerpc/kernel/vdso/vdso64.so.dbg
String dump of section '.comment':
[ 0] Linker: LLD 14.0.0
[ 14] clang version 14.0.0 (Fedora 14.0.0-1.fc37)
LD can be a full path to ld.lld, which will not be handled properly by
'-fuse-ld=lld' if the full path to ld.lld is outside of the compiler's
search path. '-fuse-ld' can take a path to the linker but it is
deprecated in clang 12.0.0; '--ld-path' is preferred for this scenario.
Use '--ld-path' if it is supported, as it will handle a full path or
just 'ld.lld' properly. See the LLVM commit below for the full details
of '--ld-path'.
Link: https://github.com/ClangBuiltLinux/linux/issues/774
Link:
https://github.com/llvm/llvm-project/commit/1bc5c84710a8c73ef21295e63c19d10a8c71f2f5
Signed-off-by: Nathan Chancellor <nat...@kernel.org>
---
arch/powerpc/kernel/vdso/Makefile | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/kernel/vdso/Makefile
b/arch/powerpc/kernel/vdso/Makefile
index 954974287ee7..096b0bf1335f 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -48,6 +48,7 @@ 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
AS32FLAGS := -D__VDSO32__ -s
--
2.36.1
