Messages in this thread Patch in this message | | | From | Sedat Dilek <> | Date | Tue, 14 Jul 2020 22:43:11 +0200 | Subject | Re: [PATCH v4 0/7] x86/boot: Remove runtime relocations from compressed kernel |
| |
On Tue, Jul 14, 2020 at 10:35 PM Arvind Sankar <nivedita@alum.mit.edu> wrote: > > On Tue, Jul 14, 2020 at 10:27:25PM +0200, Sedat Dilek wrote: > > On Tue, Jul 14, 2020 at 10:24 PM Sedat Dilek <sedat.dilek@gmail.com> wrote: > > > > > > On Tue, Jul 14, 2020 at 10:21 PM Arvind Sankar <nivedita@alum.mit.edu> wrote: > > > > > > > > On Tue, Jul 14, 2020 at 10:08:04PM +0200, Sedat Dilek wrote: > > > > > > > > > > > > > > In any case, I think the right fix here would be to add -pie and > > > > > > > --no-dynamic-linker to LDFLAGS_vmlinux instead of KBUILD_LDFLAGS. > > > > > > > > > > > > Hmm, you might be right with moving to LDFLAGS_vmlinux. > > > > > > > > > > > > > > > > We will need the "ifndef CONFIG_LD_IS_LLD" as -r and -pie cannot be > > > > > used together. > > > > > Is that the or not the fact when moving to LDFLAGS_vmlinux? > > > > > > > > LDFLAGS_vmlinux will only be used to link boot/compressed/vmlinux, > > > > whereas KBUILD_LDFLAGS is used for all linker invocations, and in > > > > particular the little link to do the modversions stuff ends up using it. > > > > > > > > So once we move -pie --no-dynamic-linker to the more correct > > > > LDFLAGS_vmlinux and/or stop modversions running, we'll be fine. Being > > > > able to use -pie with lld is one of the goals of this series. > > > > > > > > > > OK, I am doing a new full kernel build with: > > > > > > $ git diff arch/x86/boot/compressed/Makefile > > > diff --git a/arch/x86/boot/compressed/Makefile > > > b/arch/x86/boot/compressed/Makefile > > > index 789d5d14d8b0..056a738e47c6 100644 > > > --- a/arch/x86/boot/compressed/Makefile > > > +++ b/arch/x86/boot/compressed/Makefile > > > @@ -51,7 +51,7 @@ UBSAN_SANITIZE :=n > > > KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) > > > # Compressed kernel should be built as PIE since it may be loaded at any > > > # address by the bootloader. > > > -KBUILD_LDFLAGS += -pie $(call ld-option, --no-dynamic-linker) > > > +LDFLAGS_vmlinux += -pie $(call ld-option, --no-dynamic-linker) > > > LDFLAGS_vmlinux := -T > > > > > > hostprogs := mkpiggy > > > > > > - Sedat - > > > > Not my day - today. > > > > $ git diff arch/x86/boot/compressed/Makefile > > diff --git a/arch/x86/boot/compressed/Makefile > > b/arch/x86/boot/compressed/Makefile > > index 789d5d14d8b0..9784ed37a5d7 100644 > > --- a/arch/x86/boot/compressed/Makefile > > +++ b/arch/x86/boot/compressed/Makefile > > @@ -51,8 +51,8 @@ UBSAN_SANITIZE :=n > > KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) > > # Compressed kernel should be built as PIE since it may be loaded at any > > # address by the bootloader. > > -KBUILD_LDFLAGS += -pie $(call ld-option, --no-dynamic-linker) > > LDFLAGS_vmlinux := -T > > +LDFLAGS_vmlinux += -pie $(call ld-option, --no-dynamic-linker) > > > > hostprogs := mkpiggy > > HOST_EXTRACFLAGS += -I$(srctree)/tools/include > > > > - Sedat - > > Nope -- -T needs to be last, since it's (trickily) put together with the > first prerequisite $(obj)/vmlinux.lds.
Good I read this.
Checked the previous build-log:
ld.lld-11 -m elf_x86_64 -T arch/x86/boot/compressed/vmlinux.lds arch/x86/boot/compressed/kernel_info.o arch/x86/boot/compressed/head_64.o arch/x86/boot/compressed/misc.o arch/x86/boot/compressed/string.o arch/x86/boot/compressed/cmdline.o arch/x86/boot/compressed/error.o arch/x86/boot/compressed/piggy.o arch/x86/boot/compressed/cpuflags.o arch/x86/boot/compressed/early_serial_console.o arch/x86/boot/compressed/kaslr.o arch/x86/boot/compressed/kaslr_64.o arch/x86/boot/compressed/mem_encrypt.o arch/x86/boot/compressed/pgtable_64.o arch/x86/boot/compressed/acpi.o drivers/firmware/efi/libstub/lib.a arch/x86/boot/compressed/efi_thunk_64.o -o arch/x86/boot/compressed/vmlinux
So there is no -r option in this line.
If we move to LDFLAGS_vmlinux we can drop the "call ld-option" as both linker GNU/ld.bfd and LLVM/lld.ld support this?
Do we need to adjust the comments? # Compressed kernel should be built as PIE since it may be loaded at any # address by the bootloader
That's the minimal change needed:
$ git diff arch/x86/boot/compressed/Makefile diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 789d5d14d8b0..d0aafcd8cf6c 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -51,8 +51,8 @@ UBSAN_SANITIZE :=n KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE) # Compressed kernel should be built as PIE since it may be loaded at any # address by the bootloader. -KBUILD_LDFLAGS += -pie $(call ld-option, --no-dynamic-linker) -LDFLAGS_vmlinux := -T +LDFLAGS_vmlinux := -pie $(call ld-option, --no-dynamic-linker) +LDFLAGS_vmlinux += -T
hostprogs := mkpiggy HOST_EXTRACFLAGS += -I$(srctree)/tools/include - Sedat -
| |