f1c2bb8b99
Until now UML had no x86_64 vDSO. So glibc always used the vsyscall page for gettimeday() and friends. Calls to gettimeday() returned falsely the host time and confused some programs. This patch adds a vDSO which turns all __vdso_* calls into a system call so that UML can trap them. As glibc still uses the vsyscall page for static binaries this patch improves the situation only for dynamic binaries. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
91 lines
2.3 KiB
Makefile
91 lines
2.3 KiB
Makefile
#
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# Building vDSO images for x86.
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#
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VDSO64-y := y
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vdso-install-$(VDSO64-y) += vdso.so
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# files to link into the vdso
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vobjs-y := vdso-note.o um_vdso.o
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# files to link into kernel
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obj-$(VDSO64-y) += vdso.o vma.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 $(vobjs-y)
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export CPPFLAGS_vdso.lds += -P -C
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VDSO_LDFLAGS_vdso.lds = -m64 -Wl,-soname=linux-vdso.so.1 \
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-Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
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$(obj)/vdso.o: $(src)/vdso.S $(obj)/vdso.so
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$(obj)/vdso.so.dbg: $(src)/vdso.lds $(vobjs) FORCE
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$(call if_changed,vdso)
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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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#
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# Don't omit frame pointers for ease of userspace debugging, but do
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# optimize sibling calls.
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#
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CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \
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$(filter -g%,$(KBUILD_CFLAGS)) $(call cc-option, -fno-stack-protector) \
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-fno-omit-frame-pointer -foptimize-sibling-calls
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$(vobjs): KBUILD_CFLAGS += $(CFL)
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#
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# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
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#
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CFLAGS_REMOVE_vdso-note.o = -pg
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CFLAGS_REMOVE_um_vdso.o = -pg
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targets += vdso-syms.lds
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obj-$(VDSO64-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 $@
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define cmd_vdsosym
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$(NM) $< | LC_ALL=C sed -n $(sed-vdsosym) | LC_ALL=C sort > $@
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endef
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$(obj)/%-syms.lds: $(obj)/%.so.dbg FORCE
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$(call if_changed,vdsosym)
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#
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# The DSO images are built using a special linker script.
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#
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quiet_cmd_vdso = VDSO $@
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cmd_vdso = $(CC) -nostdlib -o $@ \
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$(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
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-Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \
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sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'
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VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
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GCOV_PROFILE := n
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#
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# Install the unstripped copy of vdso*.so listed in $(vdso-install-y).
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#
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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-install-y): %.so: $(obj)/%.so.dbg FORCE
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@mkdir -p $(MODLIB)/vdso
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$(call cmd,vdso_install)
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PHONY += vdso_install $(vdso-install-y)
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vdso_install: $(vdso-install-y)
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