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Gcc recently implemented an optimization [1] for loading symbols without explicit alignment, aligning with the IBM Z ELF ABI. This ABI mandates symbols to reside on a 2-byte boundary, enabling the use of the larl instruction. However, kernel linker scripts may still generate unaligned symbols. To address this, a new -munaligned-symbols option has been introduced [2] in recent gcc versions. [1] https://gcc.gnu.org/pipermail/gcc-patches/2023-June/622872.html [2] https://gcc.gnu.org/pipermail/gcc-patches/2023-August/625986.html However, when -munaligned-symbols is used in vdso code, it leads to the following compilation error: `.data.rel.ro.local' referenced in section `.text' of arch/s390/kernel/vdso64/vdso64_generic.o: defined in discarded section `.data.rel.ro.local' of arch/s390/kernel/vdso64/vdso64_generic.o vdso linker script discards .data section to make it lightweight. However, -munaligned-symbols in vdso object files references literal pool and accesses _vdso_data. Hence, compile vdso code without -munaligned-symbols. This means in the future, vdso code should deal with alignment of newly introduced unaligned linker symbols. Acked-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Link: https://lore.kernel.org/r/20240219132734.22881-2-sumanthk@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
81 lines
2.6 KiB
Makefile
81 lines
2.6 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# List of files in the vdso
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KCOV_INSTRUMENT := n
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# Include the generic Makefile to check the built vdso.
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include $(srctree)/lib/vdso/Makefile
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obj-vdso64 = vdso_user_wrapper.o note.o
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obj-cvdso64 = vdso64_generic.o getcpu.o
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VDSO_CFLAGS_REMOVE := -pg $(CC_FLAGS_FTRACE) $(CC_FLAGS_EXPOLINE) $(CC_FLAGS_CHECK_STACK)
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CFLAGS_REMOVE_getcpu.o = $(VDSO_CFLAGS_REMOVE)
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CFLAGS_REMOVE_vdso64_generic.o = $(VDSO_CFLAGS_REMOVE)
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# Build rules
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targets := $(obj-vdso64) $(obj-cvdso64) vdso64.so vdso64.so.dbg
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obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
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obj-cvdso64 := $(addprefix $(obj)/, $(obj-cvdso64))
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KBUILD_AFLAGS += -DBUILD_VDSO
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KBUILD_CFLAGS += -DBUILD_VDSO -DDISABLE_BRANCH_PROFILING
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KBUILD_AFLAGS_64 := $(filter-out -m64,$(KBUILD_AFLAGS))
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KBUILD_AFLAGS_64 += -m64
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KBUILD_CFLAGS_64 := $(filter-out -m64,$(KBUILD_CFLAGS))
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KBUILD_CFLAGS_64 := $(filter-out -mno-pic-data-is-text-relative,$(KBUILD_CFLAGS_64))
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KBUILD_CFLAGS_64 := $(filter-out -munaligned-symbols,$(KBUILD_CFLAGS_64))
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KBUILD_CFLAGS_64 += -m64 -fPIC -fno-common -fno-builtin
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ldflags-y := -shared -soname=linux-vdso64.so.1 \
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--hash-style=both --build-id=sha1 -T
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$(targets:%=$(obj)/%.dbg): KBUILD_CFLAGS = $(KBUILD_CFLAGS_64)
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$(targets:%=$(obj)/%.dbg): KBUILD_AFLAGS = $(KBUILD_AFLAGS_64)
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obj-y += vdso64_wrapper.o
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targets += vdso64.lds
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CPPFLAGS_vdso64.lds += -P -C -U$(ARCH)
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# Disable gcov profiling, ubsan and kasan for VDSO code
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GCOV_PROFILE := n
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UBSAN_SANITIZE := n
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KASAN_SANITIZE := n
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KCSAN_SANITIZE := n
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# Force dependency (incbin is bad)
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$(obj)/vdso64_wrapper.o : $(obj)/vdso64.so
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quiet_cmd_vdso_and_check = VDSO $@
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cmd_vdso_and_check = $(cmd_ld); $(cmd_vdso_check)
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# link rule for the .so file, .lds has to be first
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$(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64) $(obj-cvdso64) FORCE
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$(call if_changed,vdso_and_check)
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# strip rule for the .so file
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$(obj)/%.so: OBJCOPYFLAGS := -S
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$(obj)/%.so: $(obj)/%.so.dbg FORCE
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$(call if_changed,objcopy)
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# assembly rules for the .S files
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$(obj-vdso64): %.o: %.S FORCE
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$(call if_changed_dep,vdso64as)
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$(obj-cvdso64): %.o: %.c FORCE
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$(call if_changed_dep,vdso64cc)
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# actual build commands
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quiet_cmd_vdso64as = VDSO64A $@
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cmd_vdso64as = $(CC) $(a_flags) -c -o $@ $<
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quiet_cmd_vdso64cc = VDSO64C $@
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cmd_vdso64cc = $(CC) $(c_flags) -c -o $@ $<
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# Generate VDSO offsets using helper script
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gen-vdsosym := $(srctree)/$(src)/gen_vdso_offsets.sh
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quiet_cmd_vdsosym = VDSOSYM $@
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cmd_vdsosym = $(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@
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include/generated/vdso64-offsets.h: $(obj)/vdso64.so.dbg FORCE
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$(call if_changed,vdsosym)
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