[dpdk-dev] [PATCH 1/4 v3] compat: Add infrastructure to support symbol versioning

Sergio Gonzalez Monroy sergio.gonzalez.monroy at intel.com
Tue Sep 30 10:13:13 CEST 2014


On Mon, Sep 29, 2014 at 11:44:03AM -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
> 
> v3)
> * Added missing macros to fully export the symver directive specification
> 
> Signed-off-by: Neil Horman <nhorman at tuxdriver.com>
> CC: Thomas Monjalon <thomas.monjalon at 6wind.com>
> CC: "Richardson, Bruce" <bruce.richardson at intel.com>
> CC: "Gonzalez Monroy, Sergio" <sergio.gonzalez.monroy at intel.com>
> ---
>  lib/Makefile                   |  1 +
>  lib/librte_compat/Makefile     | 38 ++++++++++++++++++
>  lib/librte_compat/rte_compat.h | 90 ++++++++++++++++++++++++++++++++++++++++++
>  mk/rte.lib.mk                  |  6 +++
>  4 files changed, 135 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 <nhorman at tuxdriver.com>
> +#   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..0b76771
> --- /dev/null
> +++ b/lib/librte_compat/rte_compat.h
> @@ -0,0 +1,90 @@
> +/*-
> + *   BSD LICENSE
> + *
> + *   Copyright(c) 2010-2014 Neil Horman <nhorman at tuxdriver.com>.
> + *   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
> + * <library>_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>/library_version.map to add a DPDK_1.(X+1) node, in which
> + * foo is exported as a global symbol.
> + *
> + * 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);
> + *
> + * 4) Implement a new version of foo.
> + *
> + */
> +#define VERSION_SYMBOL(b, e, v) __asm__(".symver " SA(b) SA(e) ", "SA(b)"@DPDK_"SA(v))
> +#define BASE_SYMBOL(b, n) __asm__(".symver " SA(n) ", "SA(b)"@")
> +#define BIND_DEFAULT_SYMBOL(b, v) __asm__(".symver " SA(b) ", "SA(b)"@@DPDK_"SA(v))
> +#define __vsym __attribute__((used))

I think it would be useful to provide an example for the new macros.

> +
> +#else
> +/*
> + * No symbol versioning in use
> + */
> +#define VERSION_SYMBOL(b, e, v)
> +#define __vsym

Both new macros missing for non shared lib build.

Sergio

> +
> +/*
> + * 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
> 


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