x86, vdso: Error out if the vdso contains external references (05d0b088) · Commits · 戴 / test

The vdso is a piece of userspace code which is supposed to be fully self-contained. Any external (undefined) reference is an error, and should be caught at compile time. This was giving us trouble when compiling with -Os on gcc 4.5.0, for example (failed inline). The need to do a buildtime check was pointed out by Andi Kleen. Reported-by:

Andi Kleen <andi@firstfloor.org> LKML-Reference: <tip-*@vger.kernel.org> Signed-off-by:

H. Peter Anvin <hpa@linux.intel.com>

arch/x86/vdso/Makefile

+2 −1

Original line number	Diff line number	Diff line
		@@ -120,7 +120,8 @@ $(obj)/vdso32-syms.lds: $(vdso32.so-y:%=$(obj)/vdso32-%-syms.lds) FORCE
		quiet_cmd_vdso = VDSO $@
		cmd_vdso = $(CC) -nostdlib -o $@ \
		$(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
		-Wl,-T,$(filter %.lds,$^) $(filter %.o,$^)
		-Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \
		sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'

		VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
		GCOV_PROFILE := n

arch/x86/vdso/checkundef.sh

0 → 100755

+10 −0

Original line number	Diff line number	Diff line
		#!/bin/sh
		nm="$1"
		file="$2"
		"$nm" "$file" \| grep '^ *U' > /dev/null 2>&1
		if [ $? -eq 1 ]; then
		exit 0
		else
		echo "$file: undefined symbols found" >&2
		exit 1
		fi

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