| Message ID | 20230107212019.2575770-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] ARM: fix nm error message when GNU Make >= 4.4 is used | expand |
On Sun, Jan 8, 2023 at 6:20 AM Masahiro Yamada <masahiroy@kernel.org> wrote: > > Nathan Chancellor reports an error message from $(NM) if GNU Make 4.4 > is used to build the ARM decompressor. > > $ make-4.4 ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- O=build defconfig all > [snip] > LD vmlinux > NM System.map > SORTTAB vmlinux > OBJCOPY arch/arm/boot/Image > Kernel: arch/arm/boot/Image is ready > arm-linux-gnueabi-nm: 'arch/arm/boot/compressed/../../../../vmlinux': No such file > /bin/sh: 1: arithmetic expression: expecting primary: " " > LDS arch/arm/boot/compressed/vmlinux.lds > AS arch/arm/boot/compressed/head.o > GZIP arch/arm/boot/compressed/piggy_data > AS arch/arm/boot/compressed/piggy.o > CC arch/arm/boot/compressed/misc.o > > This occurs with GNU Make commit 98da874c4303 ("[SV 10593] Export > variables to $(shell ...) commands"), and the O= option is needed to > reproduce it. The generated zImage is correct despite the error message. > > As the commit description of 98da874c4303 [1] says, exported variables > are passed down to $(shell ) functions, which means exported recursive > variables might be expanded earlier than before, in the parse stage. > > The following test code demonstrates the change for GNU Make 4.4. > > [Test Makefile] > > $(shell echo hello > foo) > export foo = $(shell cat bar/../foo) > $(shell mkdir bar) > > all: > @echo $(foo) > > [GNU Make 4.3] > > $ rm -rf bar; make-4.3 > hello > > [GNU Make 4.4] > > $ rm -rf bar; make-4.4 > cat: bar/../foo: No such file or directory > hello > > The 'foo' is a resursively expanded (or lazily expanded) variable. > > GNU Make 4.3 expands it just before running the recipe '@echo $(foo)', > at this point, the directory 'bar' exists. > > GNU Make 4.4 expands it to evaluate $(shell mkdir bar) because 'foo' is > exported. At this point, the directory 'bar' does not exit yet. The cat > command cannot resolve the bar/../foo path, hence the error message. > > Let's get back to the kernel Makefile. > > 'KBSS_SZ' in arch/arm/boot/compressed/Makefile is a recursive variable, > which is referenced by 'LDFLAGS_vmlinux', which is also a recursive > variable. > > GNU Make 4.3 expands 'KBSS_SZ' just before running the recipes. Before > that, $(shell mkdir -p $(obj-dirs)) in scripts/Makefile.build creates > the output directory, arch/arm/boot/compressed. > > GNU Make 4.4 expands 'KBSS_SZ' in the parse stage because LDFLAGS_vmlinux > was (accidentally) exported by commit 5d4aeffbf709 ("kbuild: rebuild > .vmlinux.export.o when its prerequisite is updated"). $(NM) cannot > resolve the path arch/arm/boot/compressed/../../../../vmlinux. > > I admit this is a bug caused by 5d4aeffbf709 (I will fix it in the next > commit), but do not see any good reason in writing the vmlinux path in > such an indirect way. Just say 'vmlinux'. > > [1]: https://git.savannah.gnu.org/cgit/make.git/commit/?id=98da874c43035a490cdca81331724f233a3d0c9a > > Link: https://lore.kernel.org/all/Y7i8+EjwdnhHtlrr@dev-arch.thelio-3990X/ > Fixes: 5d4aeffbf709 ("kbuild: rebuild .vmlinux.export.o when its prerequisite is updated") > Reported-by: Nathan Chancellor <nathan@kernel.org> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > --- I changed my mind. I will fix 2/2 only for now, so that backing to stable kernels gets easier. I will send v2 with updated commit description.
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index 2ef651a78fa2..726ecabcef09 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -107,7 +107,7 @@ ccflags-remove-$(CONFIG_FUNCTION_TRACER) += -pg asflags-y := -DZIMAGE # Supply kernel BSS size to the decompressor via a linker symbol. -KBSS_SZ = $(shell echo $$(($$($(NM) $(obj)/../../../../vmlinux | \ +KBSS_SZ = $(shell echo $$(($$($(NM) vmlinux | \ sed -n -e 's/^\([^ ]*\) [ABD] __bss_start$$/-0x\1/p' \ -e 's/^\([^ ]*\) [ABD] __bss_stop$$/+0x\1/p') )) ) LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ)
Nathan Chancellor reports an error message from $(NM) if GNU Make 4.4 is used to build the ARM decompressor. $ make-4.4 ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- O=build defconfig all [snip] LD vmlinux NM System.map SORTTAB vmlinux OBJCOPY arch/arm/boot/Image Kernel: arch/arm/boot/Image is ready arm-linux-gnueabi-nm: 'arch/arm/boot/compressed/../../../../vmlinux': No such file /bin/sh: 1: arithmetic expression: expecting primary: " " LDS arch/arm/boot/compressed/vmlinux.lds AS arch/arm/boot/compressed/head.o GZIP arch/arm/boot/compressed/piggy_data AS arch/arm/boot/compressed/piggy.o CC arch/arm/boot/compressed/misc.o This occurs with GNU Make commit 98da874c4303 ("[SV 10593] Export variables to $(shell ...) commands"), and the O= option is needed to reproduce it. The generated zImage is correct despite the error message. As the commit description of 98da874c4303 [1] says, exported variables are passed down to $(shell ) functions, which means exported recursive variables might be expanded earlier than before, in the parse stage. The following test code demonstrates the change for GNU Make 4.4. [Test Makefile] $(shell echo hello > foo) export foo = $(shell cat bar/../foo) $(shell mkdir bar) all: @echo $(foo) [GNU Make 4.3] $ rm -rf bar; make-4.3 hello [GNU Make 4.4] $ rm -rf bar; make-4.4 cat: bar/../foo: No such file or directory hello The 'foo' is a resursively expanded (or lazily expanded) variable. GNU Make 4.3 expands it just before running the recipe '@echo $(foo)', at this point, the directory 'bar' exists. GNU Make 4.4 expands it to evaluate $(shell mkdir bar) because 'foo' is exported. At this point, the directory 'bar' does not exit yet. The cat command cannot resolve the bar/../foo path, hence the error message. Let's get back to the kernel Makefile. 'KBSS_SZ' in arch/arm/boot/compressed/Makefile is a recursive variable, which is referenced by 'LDFLAGS_vmlinux', which is also a recursive variable. GNU Make 4.3 expands 'KBSS_SZ' just before running the recipes. Before that, $(shell mkdir -p $(obj-dirs)) in scripts/Makefile.build creates the output directory, arch/arm/boot/compressed. GNU Make 4.4 expands 'KBSS_SZ' in the parse stage because LDFLAGS_vmlinux was (accidentally) exported by commit 5d4aeffbf709 ("kbuild: rebuild .vmlinux.export.o when its prerequisite is updated"). $(NM) cannot resolve the path arch/arm/boot/compressed/../../../../vmlinux. I admit this is a bug caused by 5d4aeffbf709 (I will fix it in the next commit), but do not see any good reason in writing the vmlinux path in such an indirect way. Just say 'vmlinux'. [1]: https://git.savannah.gnu.org/cgit/make.git/commit/?id=98da874c43035a490cdca81331724f233a3d0c9a Link: https://lore.kernel.org/all/Y7i8+EjwdnhHtlrr@dev-arch.thelio-3990X/ Fixes: 5d4aeffbf709 ("kbuild: rebuild .vmlinux.export.o when its prerequisite is updated") Reported-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- arch/arm/boot/compressed/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)