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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] build: provide option to disambiguate symbol names
commit 81ecb38b83b0e9e11d9baecaa36458edc44a3edb
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Nov 28 17:47:25 2019 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Nov 28 17:47:25 2019 +0100
build: provide option to disambiguate symbol names
The .file assembler directives generated by the compiler do not include
any path components (gcc) or just the ones specified on the command line
(clang, at least version 5), and hence multiple identically named source
files (in different directories) may produce identically named static
symbols (in their kallsyms representation). The binary diffing algorithm
used by xen-livepatch, however, depends on having unique symbols.
Make the ENFORCE_UNIQUE_SYMBOLS Kconfig option control the (build)
behavior, and if enabled use objcopy to prepend the (relative to the
xen/ subdirectory) path to the compiler invoked STT_FILE symbols. Note
that this build option is made no longer depend on LIVEPATCH, but merely
defaults to its setting now.
Conditionalize explicit .file directive insertion in C files where it
exists just to disambiguate names in a less generic manner; note that
at the same time the redundant emission of STT_FILE symbols gets
suppressed for clang. Assembler files as well as multiply compiled C
ones using __OBJECT_FILE__ are left alone for the time being.
Since we now expect there not to be any duplicates anymore, also don't
force the selection of the option to 'n' anymore in allrandom.config.
Similarly COVERAGE no longer suppresses duplicate symbol warnings if
enforcement is in effect, which in turn allows
SUPPRESS_DUPLICATE_SYMBOL_WARNINGS to simply depend on
!ENFORCE_UNIQUE_SYMBOLS.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Acked-by: Wei Liu <wl@xxxxxxx>
Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Tested-by: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/Kconfig.debug | 2 +-
xen/Rules.mk | 14 +++++++++++++-
xen/arch/x86/x86_64/compat.c | 2 +-
xen/arch/x86/x86_64/mm.c | 2 +-
xen/arch/x86/x86_64/physdev.c | 2 +-
xen/arch/x86/x86_64/platform_hypercall.c | 2 +-
xen/common/Kconfig | 7 +++----
xen/common/compat/domain.c | 2 +-
xen/common/compat/kernel.c | 2 +-
xen/common/compat/memory.c | 2 +-
xen/common/compat/multicall.c | 2 +-
xen/include/xen/config.h | 8 ++++++++
xen/tools/kconfig/allrandom.config | 1 -
13 files changed, 33 insertions(+), 15 deletions(-)
diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
index 22573e74db..cf42e5e7a0 100644
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -38,7 +38,7 @@ config FRAME_POINTER
config COVERAGE
bool "Code coverage support"
depends on !LIVEPATCH
- select SUPPRESS_DUPLICATE_SYMBOL_WARNINGS
+ select SUPPRESS_DUPLICATE_SYMBOL_WARNINGS if !ENFORCE_UNIQUE_SYMBOLS
---help---
Enable code coverage support.
diff --git a/xen/Rules.mk b/xen/Rules.mk
index 3090ea7828..b0bc7601c1 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -194,12 +194,24 @@ FORCE:
.PHONY: clean
clean:: $(addprefix _clean_, $(subdir-all))
- rm -f *.o *~ core $(DEPS_RM)
+ rm -f *.o .*.o.tmp *~ core $(DEPS_RM)
_clean_%/: FORCE
$(MAKE) -f $(BASEDIR)/Rules.mk -C $* clean
+SRCPATH := $(patsubst $(BASEDIR)/%,%,$(CURDIR))
+
%.o: %.c Makefile
+ifeq ($(CONFIG_ENFORCE_UNIQUE_SYMBOLS),y)
+ $(CC) $(CFLAGS) -c $< -o $(@D)/.$(@F).tmp
+ifeq ($(clang),y)
+ $(OBJCOPY) --redefine-sym $<=$(SRCPATH)/$< $(@D)/.$(@F).tmp $@
+else
+ $(OBJCOPY) --redefine-sym $(<F)=$(SRCPATH)/$< $(@D)/.$(@F).tmp $@
+endif
+ rm -f $(@D)/.$(@F).tmp
+else
$(CC) $(CFLAGS) -c $< -o $@
+endif
%.o: %.S Makefile
$(CC) $(AFLAGS) -c $< -o $@
diff --git a/xen/arch/x86/x86_64/compat.c b/xen/arch/x86/x86_64/compat.c
index edc3115902..179d0c637a 100644
--- a/xen/arch/x86/x86_64/compat.c
+++ b/xen/arch/x86/x86_64/compat.c
@@ -2,7 +2,7 @@
* compat.c
*/
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/hypercall.h>
#include <compat/xen.h>
diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index fa55f3474e..8ea09ecc30 100644
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -16,7 +16,7 @@
* with this program; If not, see <http://www.gnu.org/licenses/>.
*/
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/lib.h>
#include <xen/init.h>
diff --git a/xen/arch/x86/x86_64/physdev.c b/xen/arch/x86/x86_64/physdev.c
index c5a00ea93f..0a50cbd4d8 100644
--- a/xen/arch/x86/x86_64/physdev.c
+++ b/xen/arch/x86/x86_64/physdev.c
@@ -2,7 +2,7 @@
* physdev.c
*/
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/types.h>
#include <xen/guest_access.h>
diff --git a/xen/arch/x86/x86_64/platform_hypercall.c
b/xen/arch/x86/x86_64/platform_hypercall.c
index 8fa2543a2d..fbba893a47 100644
--- a/xen/arch/x86/x86_64/platform_hypercall.c
+++ b/xen/arch/x86/x86_64/platform_hypercall.c
@@ -2,7 +2,7 @@
* platform_hypercall.c
*/
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/lib.h>
#include <compat/platform.h>
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index f754741972..2f516da101 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -373,8 +373,7 @@ config FAST_SYMBOL_LOOKUP
config ENFORCE_UNIQUE_SYMBOLS
bool "Enforce unique symbols"
- default y
- depends on LIVEPATCH
+ default LIVEPATCH
---help---
Multiple symbols with the same name aren't generally a problem
unless livepatching is to be used.
@@ -387,8 +386,8 @@ config ENFORCE_UNIQUE_SYMBOLS
livepatch build and apply correctly.
config SUPPRESS_DUPLICATE_SYMBOL_WARNINGS
- bool "Suppress duplicate symbol warnings" if !ENFORCE_UNIQUE_SYMBOLS
- default y if !ENFORCE_UNIQUE_SYMBOLS
+ bool "Suppress duplicate symbol warnings"
+ depends on !ENFORCE_UNIQUE_SYMBOLS
---help---
Multiple symbols with the same name aren't generally a problem
unless Live patching is to be used, so these warnings can be
diff --git a/xen/common/compat/domain.c b/xen/common/compat/domain.c
index 2531fa7421..11c6afc463 100644
--- a/xen/common/compat/domain.c
+++ b/xen/common/compat/domain.c
@@ -3,7 +3,7 @@
*
*/
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/lib.h>
#include <xen/sched.h>
diff --git a/xen/common/compat/kernel.c b/xen/common/compat/kernel.c
index 64232669d2..5c6e7322f8 100644
--- a/xen/common/compat/kernel.c
+++ b/xen/common/compat/kernel.c
@@ -2,7 +2,7 @@
* kernel.c
*/
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/init.h>
#include <xen/lib.h>
diff --git a/xen/common/compat/memory.c b/xen/common/compat/memory.c
index 10a954f281..3851f756c7 100644
--- a/xen/common/compat/memory.c
+++ b/xen/common/compat/memory.c
@@ -1,4 +1,4 @@
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/types.h>
#include <xen/hypercall.h>
diff --git a/xen/common/compat/multicall.c b/xen/common/compat/multicall.c
index 43d2d8152d..a0e9918f48 100644
--- a/xen/common/compat/multicall.c
+++ b/xen/common/compat/multicall.c
@@ -2,7 +2,7 @@
* multicall.c
*/
-asm(".file \"" __FILE__ "\"");
+EMIT_FILE;
#include <xen/types.h>
#include <xen/multicall.h>
diff --git a/xen/include/xen/config.h b/xen/include/xen/config.h
index a106380a23..b76222ecf6 100644
--- a/xen/include/xen/config.h
+++ b/xen/include/xen/config.h
@@ -11,7 +11,15 @@
#ifndef __ASSEMBLY__
#include <xen/compiler.h>
+
+#if defined(CONFIG_ENFORCE_UNIQUE_SYMBOLS) || defined(__clang__)
+# define EMIT_FILE asm ( "" )
+#else
+# define EMIT_FILE asm ( ".file \"" __FILE__ "\"" )
+#endif
+
#endif
+
#include <asm/config.h>
#define EXPORT_SYMBOL(var)
diff --git a/xen/tools/kconfig/allrandom.config
b/xen/tools/kconfig/allrandom.config
index c480896b96..76f74320b5 100644
--- a/xen/tools/kconfig/allrandom.config
+++ b/xen/tools/kconfig/allrandom.config
@@ -2,4 +2,3 @@
CONFIG_GCOV_FORMAT_AUTODETECT=y
CONFIG_UBSAN=n
-CONFIG_ENFORCE_UNIQUE_SYMBOLS=n
--
generated by git-patchbot for /home/xen/git/xen.git#master
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