From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Horman Subject: Re: [PATCH 1/4 v2] compat: Add infrastructure to support symbol versioning Date: Fri, 26 Sep 2014 12:22:56 -0400 Message-ID: <20140926162256.GF5619@hmsreliant.think-freely.org> References: <1410809031-19114-2-git-send-email-nhorman@tuxdriver.com> <1411671152-27245-1-git-send-email-nhorman@tuxdriver.com> <20140926141608.GA10993@sivswdev02.ir.intel.com> <20140926151630.GD5619@hmsreliant.think-freely.org> <20140926153304.GA16923@sivswdev02.ir.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: dev-VfR2kkLFssw@public.gmane.org To: Sergio Gonzalez Monroy Return-path: Content-Disposition: inline In-Reply-To: <20140926153304.GA16923-IWE99D/oH1/+pXziaqXtF9h3ngVCH38I@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" On Fri, Sep 26, 2014 at 04:33:04PM +0100, Sergio Gonzalez Monroy wrote: > On Fri, Sep 26, 2014 at 11:16:30AM -0400, Neil Horman wrote: > > On Fri, Sep 26, 2014 at 03:16:08PM +0100, Sergio Gonzalez Monroy wrote: > > > On Thu, Sep 25, 2014 at 02:52:32PM -0400, Neil Horman wrote: > > > > Add initial pass header files to support symbol versioning. > > > > > > > > --- > > > > Change notes > > > > v2) > > > > * Fixed ifdef in rte_compat.h to test for RTE_BUILD_SHARED_LIB instead of the > > > > non-existant RTE_SYMBOL_VERSIONING > > > > > > > > * Fixed VERSION_SYMBOL macro to add the needed extra @ to make versioning work > > > > properly > > > > > > > > * Improved/Clarified documentation > > > > > > > > Signed-off-by: Neil Horman > > > > CC: Thomas Monjalon > > > > CC: "Richardson, Bruce" > > > > CC: "Gonzalez Monroy, Sergio" > > > > --- > > > > lib/Makefile | 1 + > > > > lib/librte_compat/Makefile | 38 ++++++++++++++++++ > > > > lib/librte_compat/rte_compat.h | 87 ++++++++++++++++++++++++++++++++++++++++++ > > > > mk/rte.lib.mk | 6 +++ > > > > 4 files changed, 132 insertions(+) > > > > create mode 100644 lib/librte_compat/Makefile > > > > create mode 100644 lib/librte_compat/rte_compat.h > > > > > > > > diff --git a/lib/Makefile b/lib/Makefile > > > > index 10c5bb3..a85b55b 100644 > > > > --- a/lib/Makefile > > > > +++ b/lib/Makefile > > > > @@ -32,6 +32,7 @@ > > > > include $(RTE_SDK)/mk/rte.vars.mk > > > > > > > > DIRS-$(CONFIG_RTE_LIBC) += libc > > > > +DIRS-y += librte_compat > > > > DIRS-$(CONFIG_RTE_LIBRTE_EAL) += librte_eal > > > > DIRS-$(CONFIG_RTE_LIBRTE_MALLOC) += librte_malloc > > > > DIRS-$(CONFIG_RTE_LIBRTE_RING) += librte_ring > > > > diff --git a/lib/librte_compat/Makefile b/lib/librte_compat/Makefile > > > > new file mode 100644 > > > > index 0000000..3415c7b > > > > --- /dev/null > > > > +++ b/lib/librte_compat/Makefile > > > > @@ -0,0 +1,38 @@ > > > > +# BSD LICENSE > > > > +# > > > > +# Copyright(c) 2010-2014 Neil Horman > > > > +# All rights reserved. > > > > +# > > > > +# Redistribution and use in source and binary forms, with or without > > > > +# modification, are permitted provided that the following conditions > > > > +# are met: > > > > +# > > > > +# * Redistributions of source code must retain the above copyright > > > > +# notice, this list of conditions and the following disclaimer. > > > > +# * Redistributions in binary form must reproduce the above copyright > > > > +# notice, this list of conditions and the following disclaimer in > > > > +# the documentation and/or other materials provided with the > > > > +# distribution. > > > > +# * Neither the name of Intel Corporation nor the names of its > > > > +# contributors may be used to endorse or promote products derived > > > > +# from this software without specific prior written permission. > > > > +# > > > > +# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS > > > > +# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT > > > > +# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR > > > > +# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT > > > > +# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, > > > > +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT > > > > +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, > > > > +# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY > > > > +# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT > > > > +# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE > > > > +# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. > > > > + > > > > +include $(RTE_SDK)/mk/rte.vars.mk > > > > + > > > > + > > > > +# install includes > > > > +SYMLINK-y-include := rte_compat.h > > > > + > > > > +include $(RTE_SDK)/mk/rte.lib.mk > > > > diff --git a/lib/librte_compat/rte_compat.h b/lib/librte_compat/rte_compat.h > > > > new file mode 100644 > > > > index 0000000..cff9aea > > > > --- /dev/null > > > > +++ b/lib/librte_compat/rte_compat.h > > > > @@ -0,0 +1,87 @@ > > > > +/*- > > > > + * BSD LICENSE > > > > + * > > > > + * Copyright(c) 2010-2014 Neil Horman . > > > > + * All rights reserved. > > > > + * > > > > + * Redistribution and use in source and binary forms, with or without > > > > + * modification, are permitted provided that the following conditions > > > > + * are met: > > > > + * > > > > + * * Redistributions of source code must retain the above copyright > > > > + * notice, this list of conditions and the following disclaimer. > > > > + * * Redistributions in binary form must reproduce the above copyright > > > > + * notice, this list of conditions and the following disclaimer in > > > > + * the documentation and/or other materials provided with the > > > > + * distribution. > > > > + * * Neither the name of Intel Corporation nor the names of its > > > > + * contributors may be used to endorse or promote products derived > > > > + * from this software without specific prior written permission. > > > > + * > > > > + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS > > > > + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT > > > > + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR > > > > + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT > > > > + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, > > > > + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT > > > > + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, > > > > + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY > > > > + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT > > > > + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE > > > > + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. > > > > + */ > > > > + > > > > +#ifndef _RTE_COMPAT_H_ > > > > +#define _RTE_COMPAT_H_ > > > > + > > > > +/* > > > > + * This is just a stringification macro for use below. > > > > + */ > > > > +#define SA(x) #x > > > > + > > > > +#ifdef RTE_BUILD_SHARED_LIB > > > > + > > > > +/* > > > > + * Provides backwards compatibility when updating exported functions. > > > > + * When a symol is exported from a library to provide an API, it also provides a > > > > + * calling convention (ABI) that is embodied in its name, return type, > > > > + * arguments, etc. On occasion that function may need to change to accomodate > > > > + * new functionality, behavior, etc. When that occurs, it is desireable to > > > > + * allow for backwards compatibility for a time with older binaries that are > > > > + * dynamically linked to the dpdk. to support that the __vsym and > > > > + * VERSION_SYMBOL macros are created. They, in conjunction with the > > > > + * _version.map file for a given library allow for multiple versions of > > > > + * a symbol to exist in a shared library so that older binaries need not be > > > > + * immediately recompiled. Their use is outlined in the following example: > > > > + * Assumptions: DPDK 1.(X) contains a function int foo(char *string) > > > > + * DPDK 1.(X+1) needs to change foo to be int foo(int index) > > > > + * > > > > + * To accomplish this: > > > > + * 1) Edit lib//library_version.map to add a DPDK_1.(X+1) node, in which > > > > + * foo is exported as a global symbol. Note that foo must be removed from the > > > > + * DPDK.(X) node, or you will see multiple symbol definitions > > > > + * > > > > > > By removing the symbol from the previous node in the version map, you make > > > it local instead of global and applications linked against DPDK 1.8 will fail > > > with the new library. > > > > > It sounds like you just did the remove part, and not the add part. What does > > your new version map file look like? > > > > Neil > > > > $ cat lib/librte_acl/rte_acl_version.map > DPDK_1.8 { > global: > rte_acl_find_existing; > rte_acl_free; > rte_acl_add_rules; > rte_acl_reset_rules; > rte_acl_build; > rte_acl_reset; > rte_acl_classify; > rte_acl_dump; > rte_acl_list_dump; > rte_acl_ipv4vlan_add_rules; > rte_acl_ipv4vlan_build; > rte_acl_classify_scalar; > rte_acl_classify_alg; > rte_acl_set_ctx_classify; > > local: *; > }; > > DPDK_1.9 { > global: > rte_acl_create; > } DPDK_1.8; > > > Anyway, if the DPDK_1.9 node was not defined, the dso would not have the symbol: > rte_acl_create@@DPDK_1.9 > > Sergio > > > > Following the steps you describe, if we create a new version of the function > > > rte_acl_create we would end up with the following dso: > > > > > > $ readelf -s x86_64-native-linuxapp-gcc/lib/librte_acl.so | grep "create\|\.symtab\|\.dynsym" > > > Symbol table '.dynsym' contains 42 entries: > > > 28: 0000000000001990 627 FUNC GLOBAL DEFAULT 12 rte_acl_create@@DPDK_1.9 > > > Symbol table '.symtab' contains 147 entries: > > > 94: 0000000000001960 36 FUNC LOCAL DEFAULT 12 rte_acl_create_v18 > > > 105: 0000000000001960 36 FUNC LOCAL DEFAULT 12 rte_acl_create@@DPDK_1.8 > > > 138: 0000000000001990 627 FUNC GLOBAL DEFAULT 12 rte_acl_create > > > > > > You can check that applications linked with the old lib will fail to run. > > > Note that to easily check this you should define the environment variable > > > LD_BIND_NOW to resolve all symbols at program startup (man ld.so). > > > > > > Sergio > > > Hm, thats odd, Using the same changes in my build here, I get both an exported global rte_acl_create@@DPDK_1.8 and @@DPDK_1.9 symbol. Let me take a closer look at it here once I get through the rest of my email Neil > > > > + * 2) rename the existing function int foo(char *string) to > > > > + * int __vsym foo_v18(char *string) > > > > + * > > > > + * 3) Add this macro immediately below the function > > > > + * VERSION_SYMBOL(foo, _v18, 1.8); > > > > + * > > > > + */ > > > > +#define VERSION_SYMBOL(b, e, v) __asm__(".symver " SA(b) SA(e) ", "SA(b)"@@DPDK_"SA(v)) > > > > +#define __vsym __attribute__((used)) > > > > + > > > > +#else > > > > +/* > > > > + * No symbol versioning in use > > > > + */ > > > > +#define VERSION_SYMBOL(b, e, v) > > > > +#define __vsym > > > > + > > > > +/* > > > > + * RTE_BUILD_SHARED_LIB > > > > + */ > > > > +#endif > > > > + > > > > + > > > > +#endif /* _RTE_COMPAT_H_ */ > > > > diff --git a/mk/rte.lib.mk b/mk/rte.lib.mk > > > > index f458258..82ac309 100644 > > > > --- a/mk/rte.lib.mk > > > > +++ b/mk/rte.lib.mk > > > > @@ -40,8 +40,12 @@ VPATH += $(SRCDIR) > > > > > > > > ifeq ($(RTE_BUILD_SHARED_LIB),y) > > > > LIB := $(patsubst %.a,%.so,$(LIB)) > > > > + > > > > +CPU_LDFLAGS += --version-script=$(EXPORT_MAP) > > > > + > > > > endif > > > > > > > > + > > > > _BUILD = $(LIB) > > > > _INSTALL = $(INSTALL-FILES-y) $(SYMLINK-FILES-y) $(RTE_OUTPUT)/lib/$(LIB) > > > > _CLEAN = doclean > > > > @@ -160,7 +164,9 @@ endif > > > > $(RTE_OUTPUT)/lib/$(LIB): $(LIB) > > > > @echo " INSTALL-LIB $(LIB)" > > > > @[ -d $(RTE_OUTPUT)/lib ] || mkdir -p $(RTE_OUTPUT)/lib > > > > +ifneq ($(LIB),) > > > > $(Q)cp -f $(LIB) $(RTE_OUTPUT)/lib > > > > +endif > > > > > > > > # > > > > # Clean all generated files > > > > -- > > > > 1.9.3 > > > > > > > >