[PATCH 5.12 020/161] kbuild: Quote OBJCOPY var to avoid a pahole call break the build

[Greg Kroah-Hartman]

From: Javier Martinez Canillas <javierm@xxxxxxxxxx>

[ Upstream commit ff2e6efda0d5c51b33e2bcc0b0b981ac0a0ef214 ]

The ccache tool can be used to speed up cross-compilation, by calling the
compiler and binutils through ccache. For example, following should work:

    $ export ARCH=arm64 CROSS_COMPILE="ccache aarch64-linux-gnu-"

    $ make M=drivers/gpu/drm/rockchip/

but pahole fails to extract the BTF info from DWARF, breaking the build:

      CC [M]  drivers/gpu/drm/rockchip//rockchipdrm.mod.o
      LD [M]  drivers/gpu/drm/rockchip//rockchipdrm.ko
      BTF [M] drivers/gpu/drm/rockchip//rockchipdrm.ko
    aarch64-linux-gnu-objcopy: invalid option -- 'J'
    Usage: aarch64-linux-gnu-objcopy [option(s)] in-file [out-file]
     Copies a binary file, possibly transforming it in the process
    ...
    make[1]: *** [scripts/Makefile.modpost:156: __modpost] Error 2
    make: *** [Makefile:1866: modules] Error 2

this fails because OBJCOPY is set to "ccache aarch64-linux-gnu-copy" and
later pahole is executed with the following command line:

    LLVM_OBJCOPY=$(OBJCOPY) $(PAHOLE) -J --btf_base vmlinux $@

which gets expanded to:

    LLVM_OBJCOPY=ccache aarch64-linux-gnu-objcopy pahole -J ...

instead of:

    LLVM_OBJCOPY="ccache aarch64-linux-gnu-objcopy" pahole -J ...

Fixes: 5f9ae91f7c0d ("kbuild: Build kernel module BTFs if BTF is enabled and pahole supports it")
Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210526215228.3729875-1-javierm@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 scripts/Makefile.modfinal | 2 +-
 scripts/link-vmlinux.sh   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 735e11e9041b..19468831fcc7 100644
--- a/scripts/Makefile.modfinal
+++ b/scripts/Makefile.modfinal
@@ -59,7 +59,7 @@ quiet_cmd_ld_ko_o = LD [M]  $@
 quiet_cmd_btf_ko = BTF [M] $@
       cmd_btf_ko = 							\
 	if [ -f vmlinux ]; then						\
-		LLVM_OBJCOPY=$(OBJCOPY) $(PAHOLE) -J --btf_base vmlinux $@; \
+		LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base vmlinux $@; \
 	else								\
 		printf "Skipping BTF generation for %s due to unavailability of vmlinux\n" $@ 1>&2; \
 	fi;
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 3b261b0f74f0..0a16928e495b 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -228,7 +228,7 @@ gen_btf()
 	vmlinux_link ${1}
 
 	info "BTF" ${2}
-	LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
+	LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${1}
 
 	# Create ${2} which contains just .BTF section but no symbols. Add
 	# SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
-- 
2.30.2