Re: [RFC PATCH v5 17/28] dyndbg: prevent build bugs via -DNO_DYNAMIC_DEBUG_TABLE
From: Ard Biesheuvel <ardb@kernel.org>
Date: 2021-05-12 14:58:14
Also in:
linux-efi, linux-mm, lkml, sparclinux
On Tue, 11 May 2021 at 20:51, Jim Cromie [off-list ref] wrote:
The next patch adds DEFINE_DYNAMIC_DEBUG_TABLE(), which broke several subtrees, including efi, vdso, and some of arch/*/boot/compressed, with various relocation errors, iirc. Avoid those problems by adding a define to suppress the "transparent" DEFINE_DYNAMIC_DEBUG_TABLE() invocation. I found the x86 problems myself, lkp@intel.com found arm & sparc problems, and may yet find others.
Given that I was only cc'ed on this patch in isolation, would you mind adding more clarification here? What is DEFINE_DYNAMIC_DEBUG_TABLE() supposed to do, and why is it breaking standalone binaries?
quoted hunk ↗ jump to hunk
Reported-by: <redacted> # on [jimc:lkp-test/dyndbg-diet] recently Signed-off-by: Jim Cromie <jim.cromie@gmail.com> --- arch/arm/boot/compressed/Makefile | 2 ++ arch/sparc/vdso/Makefile | 2 ++ arch/x86/boot/compressed/Makefile | 1 + arch/x86/entry/vdso/Makefile | 3 +++ arch/x86/purgatory/Makefile | 1 + drivers/firmware/efi/libstub/Makefile | 3 ++- 6 files changed, 11 insertions(+), 1 deletion(-)diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index fd94e27ba4fa..72f056a00ad4 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile@@ -82,6 +82,8 @@ compress-$(CONFIG_KERNEL_LZMA) = lzma compress-$(CONFIG_KERNEL_XZ) = xzkern compress-$(CONFIG_KERNEL_LZ4) = lz4 +KBUILD_CFLAGS += -DNO_DYNAMIC_DEBUG_TABLE + libfdt_objs := fdt_rw.o fdt_ro.o fdt_wip.o fdt.o ifeq ($(CONFIG_ARM_ATAG_DTB_COMPAT),y)diff --git a/arch/sparc/vdso/Makefile b/arch/sparc/vdso/Makefile index c5e1545bc5cf..960ed0fb6804 100644 --- a/arch/sparc/vdso/Makefile +++ b/arch/sparc/vdso/Makefile@@ -30,6 +30,8 @@ obj-y += $(vdso_img_objs) targets += $(vdso_img_cfiles) targets += $(vdso_img_sodbg) $(vdso_img-y:%=vdso%.so) +KBUILD_CFLAGS += -DNO_DYNAMIC_DEBUG_TABLE + CPPFLAGS_vdso.lds += -P -C VDSO_LDFLAGS_vdso.lds = -m elf64_sparc -soname linux-vdso.so.1 --no-undefined \diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index e0bc3988c3fa..ada4eb960d95 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile@@ -31,6 +31,7 @@ targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \ KBUILD_CFLAGS := -m$(BITS) -O2 KBUILD_CFLAGS += -fno-strict-aliasing -fPIE KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING +KBUILD_CFLAGS += -DNO_DYNAMIC_DEBUG_TABLE cflags-$(CONFIG_X86_32) := -march=i386 cflags-$(CONFIG_X86_64) := -mcmodel=small -mno-red-zone KBUILD_CFLAGS += $(cflags-y)diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 05c4abc2fdfd..619878f2c427 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile@@ -29,6 +29,9 @@ vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o vobjs32-y += vdso32/vclock_gettime.o vobjs-$(CONFIG_X86_SGX) += vsgx.o +# avoid a x86_64_RELATIVE error +KBUILD_CFLAGS += -DNO_DYNAMIC_DEBUG_TABLE + # files to link into kernel obj-y += vma.o extable.o KASAN_SANITIZE_vma.o := ydiff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile index 95ea17a9d20c..95ba7b18410f 100644 --- a/arch/x86/purgatory/Makefile +++ b/arch/x86/purgatory/Makefile@@ -35,6 +35,7 @@ PURGATORY_CFLAGS_REMOVE := -mcmodel=kernel PURGATORY_CFLAGS := -mcmodel=large -ffreestanding -fno-zero-initialized-in-bss -g0 PURGATORY_CFLAGS += $(DISABLE_STACKLEAK_PLUGIN) -DDISABLE_BRANCH_PROFILING PURGATORY_CFLAGS += -fno-stack-protector +PURGATORY_CFLAGS += -DNO_DYNAMIC_DEBUG_TABLE # Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That # in turn leaves some undefined symbols like __fentry__ in purgatory and notdiff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index c23466e05e60..def8febefbd3 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile@@ -13,7 +13,8 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \ -Wno-pointer-sign \ $(call cc-disable-warning, address-of-packed-member) \ $(call cc-disable-warning, gnu) \ - -fno-asynchronous-unwind-tables + -fno-asynchronous-unwind-tables \ + -DNO_DYNAMIC_DEBUG_TABLE # arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly # disable the stackleak plugin --2.31.1
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