107521e803
When building the 32-bit VDSO, we are building 32-bit code as part of
a 64-bit kernel build. That requires us to tweak the cflags to trick
the compiler into building 32-bit code for us. The main way we do that
is by passing -m32, but there are other options that affect code
generation and ABI selection.
In particular when building vgettimeofday.c, we end up passing
-mcall-aixdesc because it's in KBUILD_CFLAGS, which causes the
compiler to generate function descriptors, and dot symbols, eg:
$ nm arch/powerpc/kernel/vdso32/vgettimeofday.o
000005d0 T .__c_kernel_clock_getres
00000024 D __c_kernel_clock_getres
...
We get away with that at the moment because we also use the DOTSYM
macro, and that is also incorrectly prepending a '.' in 32-bit VDSO
code due to a separate bug.
But we shouldn't be generating function descriptors for this file,
there's no 32-bit ABI that includes function descriptors, so the
resulting object file is some frankenstein and it's surprising that it
even links.
So filter out all the ABI-related options we add to CFLAGS for 64-bit
builds, so that they're not used when building 32-bit code. With that
we only see regular text symbols:
$ nm arch/powerpc/kernel/vdso32/vgettimeofday.o michael@alpine1-p1
000005d0 T __c_kernel_clock_getres
00000000 T __c_kernel_clock_gettime
00000200 T __c_kernel_clock_gettime64
00000410 T __c_kernel_gettimeofday
00000650 T __c_kernel_time
Fixes: ab037dd87a ("powerpc/vdso: Switch VDSO to generic C implementation.")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201218111619.1206391-2-mpe@ellerman.id.au
77 lines
2.5 KiB
Makefile
77 lines
2.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# List of files in the vdso, has to be asm only for now
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ARCH_REL_TYPE_ABS := R_PPC_JUMP_SLOT|R_PPC_GLOB_DAT|R_PPC_ADDR32|R_PPC_ADDR24|R_PPC_ADDR16|R_PPC_ADDR16_LO|R_PPC_ADDR16_HI|R_PPC_ADDR16_HA|R_PPC_ADDR14|R_PPC_ADDR14_BRTAKEN|R_PPC_ADDR14_BRNTAKEN|R_PPC_REL24
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include $(srctree)/lib/vdso/Makefile
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obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o getcpu.o
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ifneq ($(c-gettimeofday-y),)
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CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
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CFLAGS_vgettimeofday.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
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CFLAGS_vgettimeofday.o += $(call cc-option, -fno-stack-protector)
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CFLAGS_vgettimeofday.o += -DDISABLE_BRANCH_PROFILING
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CFLAGS_vgettimeofday.o += -ffreestanding -fasynchronous-unwind-tables
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CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
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endif
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# Build rules
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ifdef CROSS32_COMPILE
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VDSOCC := $(CROSS32_COMPILE)gcc
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else
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VDSOCC := $(CC)
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endif
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CC32FLAGS :=
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ifdef CONFIG_PPC64
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CC32FLAGS += -m32
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KBUILD_CFLAGS := $(filter-out -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc,$(KBUILD_CFLAGS))
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endif
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targets := $(obj-vdso32) vdso32.so.dbg
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obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
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GCOV_PROFILE := n
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KCOV_INSTRUMENT := n
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UBSAN_SANITIZE := n
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KASAN_SANITIZE := n
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ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
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-Wl,-soname=linux-vdso32.so.1 -Wl,--hash-style=both
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asflags-y := -D__VDSO32__ -s
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obj-y += vdso32_wrapper.o
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targets += vdso32.lds
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CPPFLAGS_vdso32.lds += -P -C -Upowerpc
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# Force dependency (incbin is bad)
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$(obj)/vdso32_wrapper.o : $(obj)/vdso32.so.dbg
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# link rule for the .so file, .lds has to be first
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$(obj)/vdso32.so.dbg: $(src)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday.o FORCE
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$(call if_changed,vdso32ld_and_check)
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# assembly rules for the .S files
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$(obj-vdso32): %.o: %.S FORCE
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$(call if_changed_dep,vdso32as)
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$(obj)/vgettimeofday.o: %.o: %.c FORCE
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$(call if_changed_dep,vdso32cc)
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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/vdso32-offsets.h: $(obj)/vdso32.so.dbg FORCE
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$(call if_changed,vdsosym)
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# actual build commands
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quiet_cmd_vdso32ld_and_check = VDSO32L $@
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cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) ; $(cmd_vdso_check)
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quiet_cmd_vdso32as = VDSO32A $@
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cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) -c -o $@ $<
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quiet_cmd_vdso32cc = VDSO32C $@
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cmd_vdso32cc = $(VDSOCC) $(c_flags) $(CC32FLAGS) -c -o $@ $<
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