@@ -18,6 +18,7 @@ CODE_SZ=$(shell nm --defined -S $(1) | grep $(2) | awk '{ print "0x"$$2}')
LIVEPATCH := xen_hello_world.livepatch
LIVEPATCH_BYE := xen_bye_world.livepatch
LIVEPATCH_REPLACE := xen_replace_world.livepatch
+LIVEPATCH_NOP := xen_nop.livepatch
default: livepatch
@@ -25,10 +26,12 @@ install: livepatch
$(INSTALL_DATA) $(LIVEPATCH) $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH)
$(INSTALL_DATA) $(LIVEPATCH_BYE) $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH_BYE)
$(INSTALL_DATA) $(LIVEPATCH_REPLACE) $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH_REPLACE)
+ $(INSTALL_DATA) $(LIVEPATCH_NOP) $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH_NOP)
uninstall:
rm -f $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH)
rm -f $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH_BYE)
rm -f $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH_REPLACE)
+ rm -f $(DESTDIR)$(DEBUG_DIR)/$(LIVEPATCH_NOP)
.PHONY: clean
clean::
@@ -41,9 +44,13 @@ clean::
.PHONY: config.h
config.h: OLD_CODE_SZ=$(call CODE_SZ,$(BASEDIR)/xen-syms,xen_extra_version)
config.h: NEW_CODE_SZ=$(call CODE_SZ,$<,xen_hello_world)
+config.h: MINOR_VERSION_SZ=$(call CODE_SZ,$(BASEDIR)/xen-syms,xen_minor_version)
+config.h: MINOR_VERSION_ADDR=$(call CODE_ADDR,$(BASEDIR)/xen-syms,xen_minor_version)
config.h: xen_hello_world_func.o
(set -e; \
echo "#define NEW_CODE_SZ $(NEW_CODE_SZ)"; \
+ echo "#define MINOR_VERSION_SZ $(MINOR_VERSION_SZ)"; \
+ echo "#define MINOR_VERSION_ADDR $(MINOR_VERSION_ADDR)"; \
echo "#define OLD_CODE_SZ $(OLD_CODE_SZ)") > $@
xen_hello_world.o: config.h
@@ -91,5 +98,11 @@ xen_replace_world.o: config.h
$(LIVEPATCH_REPLACE): xen_replace_world_func.o xen_replace_world.o note.o
$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_REPLACE) $^
+xen_nop.o: config.h
+
+.PHONY: $(LIVEPATCH_NOP)
+$(LIVEPATCH_NOP): xen_nop.o note.o
+ $(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_NOP) $^
+
.PHONY: livepatch
-livepatch: $(LIVEPATCH) $(LIVEPATCH_BYE) $(LIVEPATCH_REPLACE)
+livepatch: $(LIVEPATCH) $(LIVEPATCH_BYE) $(LIVEPATCH_REPLACE) $(LIVEPATCH_NOP)
new file mode 100644
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved.
+ *
+ */
+
+#include "config.h"
+#include <xen/types.h>
+
+#include <public/sysctl.h>
+
+/*
+ * All of the .new_size and .old_addr are based on assumptions that the
+ * code for 'xen_minor_version' is compiled in specific way. Before
+ * running this test-case you MUST verify that the assumptions are
+ * correct (Hint: make debug and look in xen.s).
+ */
+struct livepatch_func __section(".livepatch.funcs") livepatch_nop = {
+ .version = LIVEPATCH_PAYLOAD_VERSION,
+ .old_size = MINOR_VERSION_SZ,
+
+#ifdef CONFIG_X86
+ .old_addr = (void *)MINOR_VERSION_ADDR,
+ /* Everything but the last instruction: "req". */
+ .new_size = MINOR_VERSION_SZ-1,
+#endif
+
+#ifdef CONFIG_ARM_64
+ .old_addr = (void *)MINOR_VERSION_ADDR,
+ /* Replace the first one: "mov w0, #0x8". */
+ .new_size = 4,
+#endif
+
+#ifdef CONFIG_ARM_32
+ /* Skip the first instruction: "push {fp}". */
+ .old_addr = (void *)(MINOR_VERSION_ADDR + 4),
+ /* And replace the next three instructions. */
+ .new_size = 3 * 4,
+#endif
+};
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
The test-case is quite simple - we NOP the 'xen_minor_version'. The amount of NOPs depends on the architecture. On x86 the function is 11 bytes long: 55 push %rbp <- NOP 48 89 e5 mov %rsp,%rbp <- NOP b8 04 00 00 00 mov $0x4,%eax <- NOP 5d pop %rbp <- NOP c3 retq We can NOP everything but the last instruction (so 10 bytes). On ARM64 its 8 bytes: 52800100 mov w0, #0x8 <- NOP d65f03c0 ret We can NOP the first instruction. While on ARM32 there are 24 bytes: e52db004 push {fp} e28db000 add fp, sp, #0 <- NOP e3a00008 mov r0, #8 <- NOP e24bd000 sub sp, fp, #0 <- NOP e49db004 pop {fp} e12fff1e bx lr And we can NOP instruction 2,3, and 4. Granted this code may be different per compiler! Hence if anybody does run this test-case - they should verify that the assumptions made here are correct. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- Cc: Julien Grall <julien.grall@arm.com> Cc: Stefano Stabellini <sstabellini@kernel.org> Cc: Jan Beulich <jbeulich@suse.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> v3: New submission. --- xen/test/livepatch/Makefile | 15 +++++++++++++- xen/test/livepatch/xen_nop.c | 49 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 63 insertions(+), 1 deletion(-) create mode 100644 xen/test/livepatch/xen_nop.c