5b93049337
This patch adds a new way of extracting symbols from the built vDSO image. This is much simpler and less fragile than using ld -R; it removes the need to control the DSO layout quite so exactly. I was clearly unduly distracted by clever ld uses when I did the original vDSO implementation. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
79 lines
2.3 KiB
Makefile
79 lines
2.3 KiB
Makefile
#
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# x86-64 vDSO.
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#
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# files to link into the vdso
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# vdso-start.o has to be first
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vobjs-y := vdso-start.o vdso-note.o vclock_gettime.o vgetcpu.o vvar.o
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# files to link into kernel
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obj-y := vma.o vdso.o vdso-syms.o
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vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)
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$(obj)/vdso.o: $(obj)/vdso.so
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targets += vdso.so vdso.so.dbg vdso.lds $(vobjs-y) vdso-syms.o
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# The DSO images are built using a special linker script.
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quiet_cmd_syscall = SYSCALL $@
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cmd_syscall = $(CC) -m elf_x86_64 -nostdlib $(SYSCFLAGS_$(@F)) \
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-Wl,-T,$(filter-out FORCE,$^) -o $@
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export CPPFLAGS_vdso.lds += -P -C
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vdso-flags = -fPIC -shared -Wl,-soname=linux-vdso.so.1 \
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$(call ld-option, -Wl$(comma)--hash-style=sysv) \
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-Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
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SYSCFLAGS_vdso.so = $(vdso-flags)
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SYSCFLAGS_vdso.so.dbg = $(vdso-flags)
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$(obj)/vdso.o: $(src)/vdso.S $(obj)/vdso.so
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$(obj)/vdso.so: $(src)/vdso.lds $(vobjs) FORCE
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$(obj)/vdso.so.dbg: $(src)/vdso.lds $(vobjs) FORCE
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$(call if_changed,syscall)
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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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CFL := $(PROFILING) -mcmodel=small -fPIC -g0 -O2 -fasynchronous-unwind-tables -m64
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$(obj)/vclock_gettime.o: KBUILD_CFLAGS = $(CFL)
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$(obj)/vgetcpu.o: KBUILD_CFLAGS = $(CFL)
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# We also create a special relocatable object that should mirror the symbol
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# table and layout of the linked DSO. With ld -R we can then refer to
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# these symbols in the kernel code rather than hand-coded addresses.
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extra-y += vdso-syms.o
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$(obj)/built-in.o: $(obj)/vdso-syms.o
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$(obj)/built-in.o: ld_flags += -R $(obj)/vdso-syms.o
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SYSCFLAGS_vdso-syms.o = -r -d
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$(obj)/vdso-syms.o: $(src)/vdso.lds $(vobjs) FORCE
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$(call if_changed,syscall)
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targets += vdso-syms.lds
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obj-y += vdso-syms.lds
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#
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# Match symbols in the DSO that look like VDSO*; produce a file of constants.
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#
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sed-vdsosym := -e 's/^00*/0/' \
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-e 's/^\([0-9a-fA-F]*\) . \(VDSO[a-zA-Z0-9_]*\)$$/\2 = 0x\1;/p'
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quiet_cmd_vdsosym = VDSOSYM $@
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cmd_vdsosym = $(NM) $< | sed -n $(sed-vdsosym) | LC_ALL=C sort > $@
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$(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE
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$(call if_changed,vdsosym)
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quiet_cmd_vdso_install = INSTALL $@
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cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
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vdso.so:
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@mkdir -p $(MODLIB)/vdso
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$(call cmd,vdso_install)
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vdso_install: vdso.so
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