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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 06/17] xen/livepatch/x86/arm32: Force .livepatch.depends section to be uint32_t aligned.
By default when using objcopy we lose the alignment when we copy it from
xen-syms -
with the result that alignment (on ARM32 for example) can be 1:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
..
[ 6] .livepatch.depend PROGBITS 00000000 000093 000024 00 A 0 0 1
That, combined with wacky offset means it will be loaded in
memory with the wrong alignment:
(XEN) livepatch.c:425: livepatch: xen_bye_world: Loaded .livepatch.depends at
000a08043
And later we get:
(XEN) livepatch.c:501: livepatch: xen_bye_world: .livepatch.depends is not
aligned properly!
This fix forces all the test-cases to be built with a
.livepatch.depends structure containing the build-id extracted from
the hypervisor (except the xen_bye_world test-case).
We use the 'mkhex' tool instead of 'xxd' as the end result is an 'unsigned'
instead of 'char' type array - which naturally forces the alignment to be of
four.
Also the 'mkhex' tools allows us to pass the section name as parameter.
The end result is much better alignment:
[ 7] .livepatch.depend PROGBITS 00000000 000094 000024 00 A 0 0 4
Note that thanks to 'unsigned int .. __note_depends' the symbol becomes
global:
$ readelf --symbols *.livepatch | grep depen
23: 0000000000000000 36 OBJECT GLOBAL HIDDEN 6 note_depends
49: 0000000000000000 36 OBJECT GLOBAL HIDDEN 17 note_depends
16: 0000000000000000 36 OBJECT GLOBAL HIDDEN 3 note_depends
21: 0000000000000000 36 OBJECT GLOBAL HIDDEN 6 note_depends
See patch titled: "livepatch/arm/x86: Strip note_depends symbol from
test-cases."
which fixes this.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
v2: First version
---
docs/misc/livepatch.markdown | 2 ++
xen/test/livepatch/Makefile | 56 +++++++++++++++-------------------
xen/test/livepatch/xen_bye_world.c | 1 +
xen/test/livepatch/xen_hello_world.c | 1 +
xen/test/livepatch/xen_nop.c | 1 +
xen/test/livepatch/xen_replace_world.c | 1 +
6 files changed, 31 insertions(+), 31 deletions(-)
diff --git a/docs/misc/livepatch.markdown b/docs/misc/livepatch.markdown
index 505dc37cda..922a64436f 100644
--- a/docs/misc/livepatch.markdown
+++ b/docs/misc/livepatch.markdown
@@ -430,6 +430,8 @@ checksum, MD5 checksum or any unique value.
The size of these structures varies with the --build-id linker option.
+On ARM32 this section must by four-byte aligned.
+
## Hypercalls
We will employ the sub operations of the system management hypercall (sysctl).
diff --git a/xen/test/livepatch/Makefile b/xen/test/livepatch/Makefile
index 6831383db1..89ad89dfd5 100644
--- a/xen/test/livepatch/Makefile
+++ b/xen/test/livepatch/Makefile
@@ -1,15 +1,7 @@
include $(XEN_ROOT)/Config.mk
-ifeq ($(XEN_TARGET_ARCH),x86_64)
-OBJCOPY_MAGIC := -I binary -O elf64-x86-64 -B i386:x86-64
-endif
-ifeq ($(XEN_TARGET_ARCH),arm64)
-OBJCOPY_MAGIC := -I binary -O elf64-littleaarch64 -B aarch64
-endif
-ifeq ($(XEN_TARGET_ARCH),arm32)
-OBJCOPY_MAGIC := -I binary -O elf32-littlearm -B arm
-endif
-
+NOTE_SYMBOL = "note_depends"
+NOTE_DEPENDS = "const __section(\".livepatch.depends\") $(NOTE_SYMBOL)"
CODE_ADDR=$(shell nm --defined $(1) | grep $(2) | awk '{print "0x"$$1}')
CODE_SZ=$(shell nm --defined -S $(1) | grep $(2) | awk '{ print "0x"$$2}')
@@ -38,7 +30,7 @@ uninstall:
.PHONY: clean
clean::
- rm -f *.o .*.o.d *.livepatch config.h
+ rm -f *.o .*.o.d *.livepatch config.h livepatch_depends.h
hello_world_livepatch_depends.h *.bin
#
# To compute these values we need the binary files: xen-syms
@@ -56,10 +48,10 @@ config.h: xen_hello_world_func.o
echo "#define MINOR_VERSION_ADDR $(MINOR_VERSION_ADDR)"; \
echo "#define OLD_CODE_SZ $(OLD_CODE_SZ)") > $@
-xen_hello_world.o: config.h
+xen_hello_world.o: config.h livepatch_depends.h
.PHONY: $(LIVEPATCH)
-$(LIVEPATCH): xen_hello_world_func.o xen_hello_world.o note.o
+$(LIVEPATCH): xen_hello_world_func.o xen_hello_world.o
$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH) $^
#
@@ -71,40 +63,42 @@ $(LIVEPATCH): xen_hello_world_func.o xen_hello_world.o
note.o
# not be built (it is for EFI builds), and that we do not have
# the note.o.bin to muck with (as it gets deleted)
#
-.PHONY: note.o
-note.o:
- $(OBJCOPY) -O binary --only-section=.note.gnu.build-id
$(BASEDIR)/xen-syms $@.bin
- $(OBJCOPY) $(OBJCOPY_MAGIC) \
-
--rename-section=.data=.livepatch.depends,alloc,load,readonly,data,contents -S
$@.bin $@
- rm -f $@.bin
+.PHONY: note.bin
+note.bin:
+ $(OBJCOPY) -O binary --only-section=.note.gnu.build-id
$(BASEDIR)/xen-syms $@
+
+.PHONY: livepatch_depends.h
+livepatch_depends.h: note.bin
+ $(shell (../../../tools/firmware/hvmloader/mkhex $(NOTE_DEPENDS) $^ >
$@))
#
# Extract the build-id of the xen_hello_world.livepatch
# (which xen_bye_world will depend on).
#
-.PHONY: hello_world_note.o
-hello_world_note.o: $(LIVEPATCH)
- $(OBJCOPY) -O binary --only-section=.note.gnu.build-id $(LIVEPATCH)
$@.bin
- $(OBJCOPY) $(OBJCOPY_MAGIC) \
-
--rename-section=.data=.livepatch.depends,alloc,load,readonly,data,contents -S
$@.bin $@
- rm -f $@.bin
+.PHONY: hello_world_note.bin
+hello_world_note.bin: $(LIVEPATCH)
+ $(OBJCOPY) -O binary --only-section=.note.gnu.build-id $(LIVEPATCH) $@
+
+.PHONY: hello_world_livepatch_depends.h
+hello_world_livepatch_depends.h: hello_world_note.bin
+ $(shell (../../../tools/firmware/hvmloader/mkhex $(NOTE_DEPENDS) $^ >
$@))
-xen_bye_world.o: config.h
+xen_bye_world.o: config.h hello_world_livepatch_depends.h
.PHONY: $(LIVEPATCH_BYE)
-$(LIVEPATCH_BYE): xen_bye_world_func.o xen_bye_world.o hello_world_note.o
+$(LIVEPATCH_BYE): xen_bye_world_func.o xen_bye_world.o
$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_BYE) $^
-xen_replace_world.o: config.h
+xen_replace_world.o: config.h livepatch_depends.h
.PHONY: $(LIVEPATCH_REPLACE)
-$(LIVEPATCH_REPLACE): xen_replace_world_func.o xen_replace_world.o note.o
+$(LIVEPATCH_REPLACE): xen_replace_world_func.o xen_replace_world.o
$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_REPLACE) $^
-xen_nop.o: config.h
+xen_nop.o: config.h livepatch_depends.h
.PHONY: $(LIVEPATCH_NOP)
-$(LIVEPATCH_NOP): xen_nop.o note.o
+$(LIVEPATCH_NOP): xen_nop.o
$(LD) $(LDFLAGS) $(build_id_linker) -r -o $(LIVEPATCH_NOP) $^
.PHONY: livepatch
diff --git a/xen/test/livepatch/xen_bye_world.c
b/xen/test/livepatch/xen_bye_world.c
index 2700f0eedd..935e76ca8b 100644
--- a/xen/test/livepatch/xen_bye_world.c
+++ b/xen/test/livepatch/xen_bye_world.c
@@ -10,6 +10,7 @@
#include <xen/livepatch.h>
#include <public/sysctl.h>
+#include "hello_world_livepatch_depends.h"
static const char bye_world_patch_this_fnc[] = "xen_extra_version";
extern const char *xen_bye_world(void);
diff --git a/xen/test/livepatch/xen_hello_world.c
b/xen/test/livepatch/xen_hello_world.c
index 02f3f85dc0..988a3b14f4 100644
--- a/xen/test/livepatch/xen_hello_world.c
+++ b/xen/test/livepatch/xen_hello_world.c
@@ -11,6 +11,7 @@
#include <xen/livepatch_payload.h>
#include <public/sysctl.h>
+#include "livepatch_depends.h"
static const char hello_world_patch_this_fnc[] = "xen_extra_version";
extern const char *xen_hello_world(void);
diff --git a/xen/test/livepatch/xen_nop.c b/xen/test/livepatch/xen_nop.c
index a224b7c670..8d0c8f5097 100644
--- a/xen/test/livepatch/xen_nop.c
+++ b/xen/test/livepatch/xen_nop.c
@@ -7,6 +7,7 @@
#include <xen/types.h>
#include <public/sysctl.h>
+#include "livepatch_depends.h"
/*
* All of the .new_size and .old_addr are based on assumptions that the
diff --git a/xen/test/livepatch/xen_replace_world.c
b/xen/test/livepatch/xen_replace_world.c
index 78a8f528b3..a653cc4268 100644
--- a/xen/test/livepatch/xen_replace_world.c
+++ b/xen/test/livepatch/xen_replace_world.c
@@ -9,6 +9,7 @@
#include <xen/livepatch.h>
#include <public/sysctl.h>
+#include "livepatch_depends.h"
static const char xen_replace_world_name[] = "xen_extra_version";
extern const char *xen_replace_world(void);
--
2.13.3
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