build: fix enforce unique symbols for recent clang version

clang 6.0 and newer behave like gcc in regards for the FILE symbol, so
only the filename rather than the full path to the source file.

clang 3.8.1-24 (in our debian:stretch container) and 3.5.0-10
(in our debian:jessie container) do store the full path to the source
file in the FILE symbol.

Also we have commit 81ecb38b83 ("build: provide option to disambiguate
symbol names") which were using clang 5, and LLVM's commit f5040b9685a7
[1] ("Make .file directive to have basename only") which is part of
"llvmorg-6.0.0" tag but not "release/5.x" branch. Both suggest that
clang change of behavior happened with clang 6.0.

This means that we also need to check clang version to figure out
which command we need to use to redefine symbol.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
[1] https://github.com/llvm/llvm-project/commit/f5040b9685a760e584c576e9185295e54635d51e

diff --git a/xen/Rules.mk b/xen/Rules.mk
index 60d1d6c4f58312825d6d83fb9f2e5cc420d560b1..1e7f47a3d8a870b9e73d880e0c02538eb87232e9 100644 (file)
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -166,7 +166,7 @@ SRCPATH := $(patsubst $(BASEDIR)/%,%,$(CURDIR))
 quiet_cmd_cc_o_c = CC      $@
 ifeq ($(CONFIG_ENFORCE_UNIQUE_SYMBOLS),y)
     cmd_cc_o_c = $(CC) $(c_flags) -c $< -o $(dot-target).tmp -MQ $@
-    ifeq ($(CONFIG_CC_IS_CLANG),y)
+    ifeq ($(CONFIG_CC_IS_CLANG)$(call clang-ifversion,-lt,600,y),yy)
         cmd_objcopy_fix_sym = $(OBJCOPY) --redefine-sym $<=$(SRCPATH)/$< $(dot-target).tmp $@
     else
         cmd_objcopy_fix_sym = $(OBJCOPY) --redefine-sym $(<F)=$(SRCPATH)/$< $(dot-target).tmp $@

diff --git a/xen/scripts/Kbuild.include b/xen/scripts/Kbuild.include
index f75d724ed7fd37af5415405484fee28aa263ea63..2d482d1cb9417aa6c61a5398f27c3cc4c233ee18 100644 (file)
--- a/xen/scripts/Kbuild.include
+++ b/xen/scripts/Kbuild.include
@@ -59,6 +59,8 @@ ld-option = $(call success,$(LD) -v $(1))
 # Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
 cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
 
+clang-ifversion = $(shell [ $(CONFIG_CLANG_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4))
+
 # Shorthand for $(MAKE) clean
 # Usage:
 # $(MAKE) $(clean) dir