[RFC PATCH v6 18/34] dyndbg: prevent build bugs via -DNO_DYNAMIC_DEBUG_TABLE

Jim Cromie
2021-05-29T20:03:02Z

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.

Reported-by: <lkp@intel.com> # 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 := y
diff --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 not
diff --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