[dpdk-dev] [RFC PATCH 1/2] Add __rte_internal tag for functions and version target

[Neil Horman <nhorman@tuxdriver.com>]

This tag is meant to be used on function prototypes to identify
functions that are only meant to be used by internal DPDK libraries
(i.e. libraries that are built while building the SDK itself, as
identified by the defining of the BUILDING_RTE_SDK macro).  When that
flag is not set, it will resolve to an error function attribute, causing
build breakage for any compilation unit attempting to build it

Validate the use of this tag in much the same way we validate
__rte_experimental.  By adding an INTERNAL version to library map files,
we can exempt internal-only functions from ABI checking, and handle them
to ensure that symbols we wish to only be for internal use between dpdk
libraries are properly tagged with __rte_experimental

Note this patch updates the check-experimental-syms.sh script, which
normally only check the EXPERIMENTAL section to also check the INTERNAL
section now.  As such its been renamed to the now more appropriate
check-special-syms.sh

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
CC: Bruce Richardson <bruce.richardson@intel.com>
CC: Thomas Monjalon <thomas@monjalon.net>
---
 buildtools/check-experimental-syms.sh      | 24 +++++++++++++++++++++-
 lib/librte_eal/common/include/rte_compat.h | 12 +++++++++++
 mk/internal/rte.compile-pre.mk             |  6 +++---
 mk/target/generic/rte.vars.mk              |  2 +-
 4 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/buildtools/check-experimental-syms.sh b/buildtools/check-experimental-syms.sh
index 7d1f3a568..63682c677 100755
--- a/buildtools/check-experimental-syms.sh
+++ b/buildtools/check-experimental-syms.sh
@@ -31,10 +31,32 @@ do
 		cat >&2 <<- END_OF_MESSAGE
 		$SYM is not flagged as experimental
 		but is listed in version map
-		Please add __rte_experimental to the definition of $SYM
+		Please add __rte_experimental to the definition/prototype of $SYM
 		END_OF_MESSAGE
 		exit 1
 	fi
 done
+
+for i in `awk 'BEGIN {found=0}
+		/.*INTERNAL.*/ {found=1}
+		/.*}.*;/ {found=0}
+		/.*;/ {if (found == 1) print $1}' $MAPFILE`
+do
+	SYM=`echo $i | sed -e"s/;//"`
+	objdump -t $OBJFILE | grep -q "\.text.*$SYM$"
+	IN_TEXT=$?
+	objdump -t $OBJFILE | grep -q "\.text\.internal.*$SYM$"
+	IN_EXP=$?
+	if [ $IN_TEXT -eq 0 -a $IN_EXP -ne 0 ]
+	then
+		cat >&2 <<- END_OF_MESSAGE
+		$SYM is not flagged as internal 
+		but is listed in version map
+		Please add __rte_internal to the definition/prototype of $SYM
+		END_OF_MESSAGE
+		exit 1
+	fi
+done
+
 exit 0
 
diff --git a/lib/librte_eal/common/include/rte_compat.h b/lib/librte_eal/common/include/rte_compat.h
index 92ff28faf..739e8485c 100644
--- a/lib/librte_eal/common/include/rte_compat.h
+++ b/lib/librte_eal/common/include/rte_compat.h
@@ -89,4 +89,16 @@ __attribute__((section(".text.experimental")))
 
 #endif
 
+/*
+ * __rte_internal tags mark functions as internal only, If specified in public
+ * header files, this tag will resolve to an error directive, preventing
+ * external applications from attempting to make calls to functions not meant
+ * for consumption outside the dpdk library
+ */
+#ifdef BUILDING_RTE_SDK
+#define __rte_internal __attribute__((section(".text.internal")))
+#else
+#define __rte_internal __attribute__((error("This function cannot be used outside of the core DPDK library"), \
+	section(".text.internal")))
+#endif
 #endif /* _RTE_COMPAT_H_ */
diff --git a/mk/internal/rte.compile-pre.mk b/mk/internal/rte.compile-pre.mk
index 0cf3791b4..f1d97ef76 100644
--- a/mk/internal/rte.compile-pre.mk
+++ b/mk/internal/rte.compile-pre.mk
@@ -56,8 +56,8 @@ C_TO_O = $(CC) -Wp,-MD,$(call obj2dep,$(@)).tmp $(CPPFLAGS) $(CFLAGS) \
 C_TO_O_STR = $(subst ','\'',$(C_TO_O)) #'# fix syntax highlight
 C_TO_O_DISP = $(if $(V),"$(C_TO_O_STR)","  CC $(@)")
 endif
-EXPERIMENTAL_CHECK = $(RTE_SDK)/buildtools/check-experimental-syms.sh
-CHECK_EXPERIMENTAL = $(EXPERIMENTAL_CHECK) $(SRCDIR)/$(EXPORT_MAP) $@
+SPECIAL_SYM_CHECK = $(RTE_SDK)/buildtools/check-special-syms.sh
+CHECK_SPECIAL_SYMS = $(SPECIAL_SYM_CHECK) $(SRCDIR)/$(EXPORT_MAP) $@
 
 PMDINFO_GEN = $(RTE_SDK_BIN)/app/dpdk-pmdinfogen $@ $@.pmd.c
 PMDINFO_CC = $(CC) $(CPPFLAGS) $(CFLAGS) $(EXTRA_CFLAGS) -c -o $@.pmd.o $@.pmd.c
@@ -75,7 +75,7 @@ C_TO_O_DO = @set -e; \
 	echo $(C_TO_O_DISP); \
 	$(C_TO_O) && \
 	$(PMDINFO_TO_O) && \
-	$(CHECK_EXPERIMENTAL) && \
+	$(CHECK_SPECIAL_SYMS) && \
 	echo $(C_TO_O_CMD) > $(call obj2cmd,$(@)) && \
 	sed 's,'$@':,dep_'$@' =,' $(call obj2dep,$(@)).tmp > $(call obj2dep,$(@)) && \
 	rm -f $(call obj2dep,$(@)).tmp
diff --git a/mk/target/generic/rte.vars.mk b/mk/target/generic/rte.vars.mk
index 25a578ad7..ed6a0c87b 100644
--- a/mk/target/generic/rte.vars.mk
+++ b/mk/target/generic/rte.vars.mk
@@ -96,7 +96,7 @@ LDFLAGS += -L$(RTE_OUTPUT)/lib
 # defined.
 ifeq ($(BUILDING_RTE_SDK),1)
 # building sdk
-CFLAGS += -include $(RTE_OUTPUT)/include/rte_config.h
+CFLAGS += -include $(RTE_OUTPUT)/include/rte_config.h -DBUILDING_RTE_SDK
 else
 # if we are building an external application, include SDK's lib and
 # includes too
-- 
2.20.1