On Mon, Jun 19, 2023 at 11:37 PM Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote: > > The kernel compiled with multi_v7_defconfig + CONFIG_KASAN=y + > CONFIG_KASAN_INLINE=y does not boot. > > I do not think KASAN is the direct reason of the boot failure. > CONFIG_KASAN_INLINE is just one example configuration that grows the > image size significantly and makes a big distance between function > callers and callees. > > I see some veneers for __get_user_* in the bad kernel image. I am > not perfectly clear, but __get_user_* may not work with veneers for > some reasons. > > If I move the link order of arch/arm/lib/getuser.S, the veneers are > gone, and the kernel gets working again. > > I do not see a good reason that $(mmu-y) must be added to lib-y because > all the code in $(mmu-y) is mandatory. Add it to obj-y to move the code > to lower address. > > [1] multi_v7_defconfig (works) > > $ arm-linux-gnueabihf-nm vmlinux | grep __get_user_1 > c072a450 T __get_user_1 > c17ea033 r __kstrtab___get_user_1 > c18119fe r __kstrtabns___get_user_1 > c17c4878 r __ksymtab___get_user_1 > > [2] multi_v7_defconfig + CONFIG_KASAN_INLINE (does not work) > > $ arm-linux-gnueabihf-nm vmlinux | grep __get_user_1 > c341ec2c T __get_user_1 > c06e3580 t ____get_user_1_veneer > c0adc6c0 t ____get_user_1_veneer > c12cf054 t ____get_user_1_veneer > c43f42cc r __kstrtab___get_user_1 > c441c128 r __kstrtabns___get_user_1 > c43cead8 r __ksymtab___get_user_1 > > [3] multi_v7_defconfig + CONFIG_KASAN_INLINE + this patch (works) > > $ arm-linux-gnueabihf-nm vmlinux | grep __get_user_1 > c10975b0 T __get_user_1 > c43f42cc r __kstrtab___get_user_1 > c441c128 r __kstrtabns___get_user_1 > c43cead8 r __ksymtab___get_user_1 > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > --- > > arch/arm/lib/Makefile | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile > index 650404be6768..4d092ef87a1d 100644 > --- a/arch/arm/lib/Makefile > +++ b/arch/arm/lib/Makefile > @@ -28,7 +28,7 @@ endif > # using lib_ here won't override already available weak symbols > obj-$(CONFIG_UACCESS_WITH_MEMCPY) += uaccess_with_memcpy.o > > -lib-$(CONFIG_MMU) += $(mmu-y) > +obj-$(CONFIG_MMU) += $(mmu-y) > > ifeq ($(CONFIG_CPU_32v3),y) > lib-y += io-readsw-armv3.o io-writesw-armv3.o > -- > 2.39.2 > I also wonder why __get_user* is defined in arch/arm/lib/ instead of arch/arm/kernel/, but I might be a convention. x86 puts it in the lib directory, arch/x86/lib/getuser.S then other architectures copy the code structure. -- Best Regards Masahiro Yamada
