[PATCH v4 30/34] xsplice/xen_replace_world: Test-case for XSPLICE_ACTION_REPLACE

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

With this third payload one can do:

-bash-4.1# xen-xsplice load xen_hello_world.xsplice
Uploading xen_hello_world.xsplice (10148 bytes)
Performing check: completed
Performing apply:. completed

[xen_hello_world depends on hypervisor build-id]
-bash-4.1# xen-xsplice load xen_bye_world.xsplice
Uploading xen_bye_world.xsplice (7076 bytes)
Performing check: completed
Performing apply:. completed
[xen_bye_world depends on xen_hello_world build-id]
-bash-4.1# xen-xsplice upload xen_replace_world xen_replace_world.xsplice
Uploading xen_replace_world.xsplice (7148 bytes)
-bash-4.1# xen-xsplice list
 ID                                     | status
----------------------------------------+------------
xen_hello_world                         | APPLIED
xen_bye_world                           | APPLIED
xen_replace_world                       | CHECKED
-bash-4.1# xen-xsplice replace xen_replace_world
Performing replace:. completed
-bash-4.1# xl info | grep extra
xen_extra              : Hello Again World!
-bash-4.1# xen-xsplice list
 ID                                     | status
----------------------------------------+------------
xen_hello_world                         | CHECKED
xen_bye_world                           | CHECKED
xen_replace_world                       | APPLIED

and revert both of the previous payloads and apply
the xen_replace_world.

All the magic of this is in the Makefile - we extract
the build-id from the hypervisor (xen-syms) and jam it
in the xen_replace_world as .xsplice.depends.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
Cc: Keir Fraser <keir@xen.org>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>

v1: Make the objcopy use -S to strip the name.
---
---
 xen/arch/x86/test/Makefile                 | 10 +++++++--
 xen/arch/x86/test/xen_replace_world.c      | 35 ++++++++++++++++++++++++++++++
 xen/arch/x86/test/xen_replace_world_func.c | 25 +++++++++++++++++++++
 3 files changed, 68 insertions(+), 2 deletions(-)
 create mode 100644 xen/arch/x86/test/xen_replace_world.c
 create mode 100644 xen/arch/x86/test/xen_replace_world_func.c

diff --git a/xen/arch/x86/test/Makefile b/xen/arch/x86/test/Makefile
index a84c609..c9bcb1c 100644
--- a/xen/arch/x86/test/Makefile
+++ b/xen/arch/x86/test/Makefile
@@ -8,15 +8,18 @@ ifdef CONFIG_XSPLICE
 
 XSPLICE := xen_hello_world.xsplice
 XSPLICE_BYE := xen_bye_world.xsplice
+XSPLICE_REPLACE := xen_replace_world.xsplice
 
 default: xsplice
 
 install: xsplice
 	$(INSTALL_DATA) $(XSPLICE) $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE)
 	$(INSTALL_DATA) $(XSPLICE_BYE) $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE_BYE)
+	$(INSTALL_DATA) $(XSPLICE_REPLACE) $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE_REPLACE)
 uninstall:
 	rm -f $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE)
 	rm -f $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE_BYE)
+	rm -f $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE_REPLACE)
 else
 default:
 install:
@@ -54,7 +57,6 @@ build_id.o:
 		   --rename-section=.data=.xsplice.depends -S $@.bin $@
 	rm -f $@.bin
 
-
 #
 # Extract the build-id of the xen_hello_world.xsplice
 # (which xen_bye_world will depend on).
@@ -78,4 +80,8 @@ xsplice: config.h build_id.o
 	$(MAKE) -f $(BASEDIR)/Rules.mk hello_world_build_id.o
 	$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(XSPLICE_BYE) \
 		xen_bye_world_func.o xen_bye_world.o hello_world_build_id.o
-
+	$(MAKE) -f $(BASEDIR)/Rules.mk xen_replace_world_func.o
+	$(MAKE) -f $(BASEDIR)/Rules.mk xen_replace_world.o
+	$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(XSPLICE_REPLACE) \
+		 xen_replace_world_func.o \
+		 xen_replace_world.o build_id.o
diff --git a/xen/arch/x86/test/xen_replace_world.c b/xen/arch/x86/test/xen_replace_world.c
new file mode 100644
index 0000000..72871f7
--- /dev/null
+++ b/xen/arch/x86/test/xen_replace_world.c
@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved.
+ *
+ */
+
+#include <xen/config.h>
+#include <xen/types.h>
+#include <xen/xsplice_patch.h>
+#include <xen/xsplice.h>
+#include "config.h"
+#include <xen/lib.h>
+
+static char xen_replace_world_name[] = "xen_replace_world";
+extern const char *xen_replace_world(void);
+
+/* External symbol. */
+extern const char *xen_extra_version(void);
+
+struct xsplice_patch_func __section(".xsplice.funcs") xsplice_xen_replace_world = {
+    .name = xen_replace_world_name,
+    .new_addr = (unsigned long)(xen_replace_world),
+    .old_addr = (unsigned long)(xen_extra_version),
+    .new_size = NEW_CODE_SZ,
+    .old_size = OLD_CODE_SZ,
+};
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/x86/test/xen_replace_world_func.c b/xen/arch/x86/test/xen_replace_world_func.c
new file mode 100644
index 0000000..75ee3b5
--- /dev/null
+++ b/xen/arch/x86/test/xen_replace_world_func.c
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved.
+ *
+ */
+
+#include <xen/config.h>
+#include <xen/types.h>
+#include <asm/nops.h>
+#include <asm/alternative.h>
+
+/* Our replacement function for xen_hello_world. */
+const char *xen_replace_world(void)
+{
+    return "Hello Again World!";
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
-- 
2.5.0


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