[Xen-devel] [PATCH 4/4] xen/ubsan: Introduce and use CONFIG_UBSAN

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Tested with GCC 4.9 of Debian Jessie.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Tim Deegan <tim@xxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>

TODO at some future point: Fix the following known issues:

  Clang 3.9 - linker error in shadow/multi.c with fetch_type_names[].  With
  UBSAN enabled, it appears that dead code elimination doesn't remove the
  single reference to fetch_type_names[] which lives behind DEBUG_TRACE_DUMP.

  Clang 4.0 - ABI change with the hooks.
---
 xen/Kconfig                |  6 ++++++
 xen/Kconfig.debug          |  8 ++++++++
 xen/Rules.mk               |  4 ++++
 xen/arch/x86/Kconfig       |  1 +
 xen/common/Makefile        |  1 +
 xen/common/ubsan/ubsan.c   | 22 +++++++++++++++-------
 xen/include/xen/compiler.h |  1 +
 7 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/xen/Kconfig b/xen/Kconfig
index 65d491d..f57cefd 100644
--- a/xen/Kconfig
+++ b/xen/Kconfig
@@ -38,4 +38,10 @@ config LTO
 
          If unsure, say N.
 
+#
+# For architectures that know their GCC __int128 support is sound
+#
+config ARCH_SUPPORTS_INT128
+       bool
+
 source "Kconfig.debug"
diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug
index 195d504..e63b533 100644
--- a/xen/Kconfig.debug
+++ b/xen/Kconfig.debug
@@ -121,6 +121,14 @@ config SCRUB_DEBUG
          Verify that pages that need to be scrubbed before being allocated to
          a guest are indeed scrubbed.
 
+config UBSAN
+       bool "Undefined behaviour sanitizer"
+       depends on X86
+       ---help---
+         Enable undefined behaviour sanitizer.
+
+         If unsure, say N here.
+
 endif # DEBUG || EXPERT
 
 endmenu
diff --git a/xen/Rules.mk b/xen/Rules.mk
index cafc67b..2659f8a 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -119,6 +119,10 @@ ifeq ($(CONFIG_GCOV),y)
 $(filter-out %.init.o $(nogcov-y),$(obj-y) $(obj-bin-y) $(extra-y)): CFLAGS += 
-fprofile-arcs -ftest-coverage
 endif
 
+ifeq ($(CONFIG_UBSAN),y)
+$(filter-out %.init.o $(noubsan-y),$(obj-y) $(obj-bin-y) $(extra-y)): CFLAGS 
+= -fsanitize=undefined
+endif
+
 ifeq ($(CONFIG_LTO),y)
 CFLAGS += -flto
 LDFLAGS-$(clang) += -plugin LLVMgold.so
diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
index 30c2769..f77e6fc 100644
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -5,6 +5,7 @@ config X86
        def_bool y
        select ACPI
        select ACPI_LEGACY_TABLES_LOOKUP
+       select ARCH_SUPPORTS_INT128
        select COMPAT
        select CORE_PARKING
        select HAS_ALTERNATIVE
diff --git a/xen/common/Makefile b/xen/common/Makefile
index 39e2614..66cc2c8 100644
--- a/xen/common/Makefile
+++ b/xen/common/Makefile
@@ -75,6 +75,7 @@ tmem-$(CONFIG_COMPAT) += compat/tmem_xen.o
 obj-$(CONFIG_TMEM) += $(tmem-y)
 
 subdir-$(CONFIG_GCOV) += gcov
+subdir-$(CONFIG_UBSAN) += ubsan
 
 subdir-y += libelf
 subdir-$(CONFIG_HAS_DEVICE_TREE) += libfdt
diff --git a/xen/common/ubsan/ubsan.c b/xen/common/ubsan/ubsan.c
index e44c8ce..b601af9 100644
--- a/xen/common/ubsan/ubsan.c
+++ b/xen/common/ubsan/ubsan.c
@@ -10,13 +10,21 @@
  *
  */
 
-#include <linux/bitops.h>
-#include <linux/bug.h>
-#include <linux/ctype.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/types.h>
-#include <linux/sched.h>
+#include <xen/bitops.h>
+#include <xen/kernel.h>
+#include <xen/lib.h>
+#include <xen/types.h>
+#include <xen/spinlock.h>
+#include <xen/percpu.h>
+
+#define pr_err(...) printk(XENLOG_ERR __VA_ARGS__)
+struct xen_ubsan { int in_ubsan; };
+static DEFINE_PER_CPU(struct xen_ubsan[1], in_ubsan);
+#undef current
+#define current this_cpu(in_ubsan)
+#define dump_stack dump_execution_state
+#define u64 long long unsigned int
+#define s64 long long int
 
 #include "ubsan.h"
 
diff --git a/xen/include/xen/compiler.h b/xen/include/xen/compiler.h
index 533a8ea..e4d706f 100644
--- a/xen/include/xen/compiler.h
+++ b/xen/include/xen/compiler.h
@@ -15,6 +15,7 @@
 #define noinline      __attribute__((__noinline__))
 
 #define noreturn      __attribute__((__noreturn__))
+#define __noreturn    noreturn
 
 #define __packed      __attribute__((__packed__))
 
-- 
2.1.4


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