| Message ID | 1460000983-28170-12-git-send-email-konrad.wilk@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Konrad, On 07/04/16 04:49, Konrad Rzeszutek Wilk wrote: > This change demonstrates how to generate an xSplice ELF payload. > > The idea here is that we want to patch in the hypervisor > the 'xen_version_extra' function with an function that will > return 'Hello World'. The 'xl info | grep extraversion' > will reflect the new value after the patching. > > To generate this ELF payload file we need: > - C code of the new code (xen_hello_world_func.c). > - C code generating the .xsplice.funcs structure > (xen_hello_world.c) > - The address of the old code (xen_extra_version). We > retrieve it by using 'nm --defined' on xen-syms. > - The size of the new and old code for which we use > nm --defined -S on our code and xen-syms respectively. > > There are two C files and one header files generated > during build. One could make this one C file if the > size of the newly patched function size was known in > advance (or an random value was choosen). > > There is also a strict order of compiling: > 1) xen_hello_world_func.c > 2) config.h - extract the size of the new function, > the old function and the old function address. > 3) xen_hello_world.c - which contains the .xsplice.funcs > structure. > 4) Link the object files in an xen_hello_world.xsplice file. > > The use-case is simple: > > $xen-xsplice load /usr/lib/debug/xen_hello_world.xsplice > $xen-xsplice list > ID | status > ----------------------------------------+------------ > xen_hello_world APPLIED > $xl info | grep extra > xen_extra : Hello World > $xen-xsplice revert xen_hello_world > Performing revert: completed > $xen-xsplice unload xen_hello_world > Performing unload: completed > $xl info | grep extra > xen_extra : -unstable > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> For the ARM bits: Acked-by: Julien Grall <julien.grall@arm.com> Regards,
On 07/04/16 04:49, Konrad Rzeszutek Wilk wrote: > This change demonstrates how to generate an xSplice ELF payload. > > The idea here is that we want to patch in the hypervisor > the 'xen_version_extra' function with an function that will > return 'Hello World'. The 'xl info | grep extraversion' > will reflect the new value after the patching. > > To generate this ELF payload file we need: > - C code of the new code (xen_hello_world_func.c). > - C code generating the .xsplice.funcs structure > (xen_hello_world.c) > - The address of the old code (xen_extra_version). We > retrieve it by using 'nm --defined' on xen-syms. > - The size of the new and old code for which we use > nm --defined -S on our code and xen-syms respectively. > > There are two C files and one header files generated > during build. One could make this one C file if the > size of the newly patched function size was known in > advance (or an random value was choosen). > > There is also a strict order of compiling: > 1) xen_hello_world_func.c > 2) config.h - extract the size of the new function, > the old function and the old function address. > 3) xen_hello_world.c - which contains the .xsplice.funcs > structure. > 4) Link the object files in an xen_hello_world.xsplice file. > > The use-case is simple: > > $xen-xsplice load /usr/lib/debug/xen_hello_world.xsplice > $xen-xsplice list > ID | status > ----------------------------------------+------------ > xen_hello_world APPLIED > $xl info | grep extra > xen_extra : Hello World > $xen-xsplice revert xen_hello_world > Performing revert: completed > $xen-xsplice unload xen_hello_world > Performing unload: completed > $xl info | grep extra > xen_extra : -unstable > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > > --- > Cc: Stefano Stabellini <stefano.stabellini@citrix.com> > Cc: Julien Grall <julien.grall@arm.com> > Cc: Keir Fraser <keir@xen.org> > Cc: Jan Beulich <jbeulich@suse.com> > Cc: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
> diff --git a/docs/misc/xsplice.markdown b/docs/misc/xsplice.markdown > index d4e7d75..8d2d413 100644 > --- a/docs/misc/xsplice.markdown > +++ b/docs/misc/xsplice.markdown > @@ -330,6 +330,41 @@ When reverting a patch, the hypervisor iterates over each `xsplice_patch_func` > and the core code copies the data from the undo buffer (private internal copy) > to `old_addr`. > > +### Example of .xsplice.funcs > + > +A simple example of what a payload file can be: > + > +<pre> > +/* MUST be in sync with hypervisor. */ > +struct xsplice_patch_func { > + const char *name; > + uint64_t new_addr; > + uint64_t old_addr; > + uint32_t new_size; > + uint32_t old_size; > + uint8_t pad[32]; > +}; > + > +/* Our replacement function for xen_extra_version. */ > +const char *xen_hello_world(void) > +{ > + return "Hello World"; > +} > + > +static unsigned char name[] = "xen_hello_world"; Which really ought to be 'xen_extra_version' as that is what we are patching. So changed that, along with: > diff --git a/xen/arch/x86/test/xen_hello_world.c b/xen/arch/x86/test/xen_hello_world.c > new file mode 100644 > index 0000000..67bbe65 > --- /dev/null > +++ b/xen/arch/x86/test/xen_hello_world.c > @@ -0,0 +1,30 @@ > +/* > + * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved. > + * > + */ > + > +#include <xen/types.h> > +#include <xen/xsplice.h> > +#include "config.h" > + > +static char xen_hello_world_name[] = "xen_hello_world"; This to be 'xen_extra_version' and named the variable 'patch_this_fnc' It has no bearing on the test-case at all, just a minor cosmetic item hence retained the Reviewed-by.
diff --git a/.gitignore b/.gitignore index b9c9550..8dc76b5 100644 --- a/.gitignore +++ b/.gitignore @@ -245,6 +245,8 @@ xen/arch/x86/efi.lds xen/arch/x86/efi/check.efi xen/arch/x86/efi/disabled xen/arch/x86/efi/mkreloc +xen/arch/x86/test/config.h +xen/arch/x86/test/xen_hello_world.xsplice xen/arch/*/efi/boot.c xen/arch/*/efi/compat.c xen/arch/*/efi/efi.h diff --git a/docs/misc/xsplice.markdown b/docs/misc/xsplice.markdown index d4e7d75..8d2d413 100644 --- a/docs/misc/xsplice.markdown +++ b/docs/misc/xsplice.markdown @@ -330,6 +330,41 @@ When reverting a patch, the hypervisor iterates over each `xsplice_patch_func` and the core code copies the data from the undo buffer (private internal copy) to `old_addr`. +### Example of .xsplice.funcs + +A simple example of what a payload file can be: + +<pre> +/* MUST be in sync with hypervisor. */ +struct xsplice_patch_func { + const char *name; + uint64_t new_addr; + uint64_t old_addr; + uint32_t new_size; + uint32_t old_size; + uint8_t pad[32]; +}; + +/* Our replacement function for xen_extra_version. */ +const char *xen_hello_world(void) +{ + return "Hello World"; +} + +static unsigned char name[] = "xen_hello_world"; + +struct xsplice_patch_func xsplice_hello_world = { + .name = name, + .new_addr = (unsigned long)(xen_hello_world), + .old_addr = 0xffff82d08013963c, /* Extracted from xen-syms. */ + .new_size = 13, /* To be be computed by scripts. */ + .old_size = 13, /* -----------""--------------- */ +} __attribute__((__section__(".xsplice.funcs"))); + +</pre> + +Code must be compiled with -fPIC. + ## Hypercalls We will employ the sub operations of the system management hypercall (sysctl). diff --git a/xen/Makefile b/xen/Makefile index c908544..cabb7b0 100644 --- a/xen/Makefile +++ b/xen/Makefile @@ -39,8 +39,8 @@ dist: install build install:: include/config/auto.conf -.PHONY: build install uninstall clean distclean cscope TAGS tags MAP gtags -build install uninstall debug clean distclean cscope TAGS tags MAP gtags:: +.PHONY: build install uninstall clean distclean cscope TAGS tags MAP gtags test +build install uninstall debug clean distclean cscope TAGS tags MAP gtags test:: ifneq ($(XEN_TARGET_ARCH),x86_32) $(MAKE) -f Rules.mk _$@ else @@ -76,6 +76,10 @@ _install: $(TARGET)$(CONFIG_XEN_INSTALL_SUFFIX) fi; \ fi +.PHONY: _test +_test: + $(MAKE) -f $(BASEDIR)/Rules.mk -C arch/$(TARGET_ARCH) test + .PHONY: _uninstall _uninstall: D=$(DESTDIR) _uninstall: T=$(notdir $(TARGET)) diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile index eae5cb3..bbd190e 100644 --- a/xen/arch/arm/Makefile +++ b/xen/arch/arm/Makefile @@ -57,6 +57,8 @@ ifeq ($(CONFIG_ARM_64),y) ln -sf $(notdir $@) ../../$(notdir $@).efi endif +test: + $(TARGET).axf: $(TARGET)-syms # XXX: VE model loads by VMA so instead of # making a proper ELF we link with LMA == VMA and adjust crudely diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile index 8a6a7d5..cd4abd6 100644 --- a/xen/arch/x86/Makefile +++ b/xen/arch/x86/Makefile @@ -76,6 +76,9 @@ $(TARGET): $(TARGET)-syms $(efi-y) boot/mkelf32 ./boot/mkelf32 $(TARGET)-syms $(TARGET) 0x100000 \ `$(NM) -nr $(TARGET)-syms | head -n 1 | sed -e 's/^\([^ ]*\).*/0x\1/'` +.PHONY: test +test: + $(MAKE) -f $(BASEDIR)/Rules.mk -C test xsplice ALL_OBJS := $(BASEDIR)/arch/x86/boot/built_in.o $(BASEDIR)/arch/x86/efi/built_in.o $(ALL_OBJS) @@ -179,3 +182,4 @@ clean:: rm -f $(BASEDIR)/.xen-syms.[0-9]* boot/.*.d rm -f $(BASEDIR)/.xen.efi.[0-9]* efi/*.o efi/.*.d efi/*.efi efi/disabled efi/mkreloc rm -f boot/reloc.S boot/reloc.lnk boot/reloc.bin + $(MAKE) -f $(BASEDIR)/Rules.mk -C test clean diff --git a/xen/arch/x86/test/Makefile b/xen/arch/x86/test/Makefile new file mode 100644 index 0000000..b9cf13c --- /dev/null +++ b/xen/arch/x86/test/Makefile @@ -0,0 +1,44 @@ +include $(XEN_ROOT)/Config.mk + +CODE_ADDR=$(shell nm --defined $(1) | grep $(2) | awk '{print "0x"$$1}') +CODE_SZ=$(shell nm --defined -S $(1) | grep $(2) | awk '{ print "0x"$$2}') + +.PHONY: default + +XSPLICE := xen_hello_world.xsplice + +default: xsplice + +install: xsplice + $(INSTALL_DATA) $(XSPLICE) $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE) +uninstall: + rm -f $(DESTDIR)$(DEBUG_DIR)/$(XSPLICE) + +.PHONY: clean +clean:: + rm -f *.o .*.o.d $(XSPLICE) config.h + +# +# To compute these values we need the binary files: xen-syms +# and xen_hello_world_func.o to be already compiled. +# +# We can be assured that xen-syms is already built as we are +# the last entry in the build target. +# +.PHONY: config.h +config.h: OLD_CODE=$(call CODE_ADDR,$(BASEDIR)/xen-syms,xen_extra_version) +config.h: OLD_CODE_SZ=$(call CODE_SZ,$(BASEDIR)/xen-syms,xen_extra_version) +config.h: NEW_CODE_SZ=$(call CODE_SZ,$<,xen_hello_world) +config.h: xen_hello_world_func.o + (set -e; \ + echo "#define NEW_CODE_SZ $(NEW_CODE_SZ)"; \ + echo "#define OLD_CODE_SZ $(OLD_CODE_SZ)"; \ + echo "#define OLD_CODE $(OLD_CODE)") > $@ + +.PHONY: xsplice +xsplice: config.h + # Need to have these done in sequential order + $(MAKE) -f $(BASEDIR)/Rules.mk xen_hello_world_func.o + $(MAKE) -f $(BASEDIR)/Rules.mk xen_hello_world.o + $(LD) $(LDFLAGS) -r -o $(XSPLICE) xen_hello_world_func.o \ + xen_hello_world.o diff --git a/xen/arch/x86/test/xen_hello_world.c b/xen/arch/x86/test/xen_hello_world.c new file mode 100644 index 0000000..67bbe65 --- /dev/null +++ b/xen/arch/x86/test/xen_hello_world.c @@ -0,0 +1,30 @@ +/* + * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved. + * + */ + +#include <xen/types.h> +#include <xen/xsplice.h> +#include "config.h" + +static char xen_hello_world_name[] = "xen_hello_world"; +extern const char *xen_hello_world(void); + +struct xsplice_patch_func __section(".xsplice.funcs") xsplice_xen_hello_world = { + .version = XSPLICE_PAYLOAD_VERSION, + .name = xen_hello_world_name, + .new_addr = (unsigned long)(xen_hello_world), + .old_addr = OLD_CODE, + .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_hello_world_func.c b/xen/arch/x86/test/xen_hello_world_func.c new file mode 100644 index 0000000..1ad002a --- /dev/null +++ b/xen/arch/x86/test/xen_hello_world_func.c @@ -0,0 +1,22 @@ +/* + * Copyright (c) 2016 Oracle and/or its affiliates. All rights reserved. + * + */ + +#include <xen/types.h> + +/* Our replacement function for xen_extra_version. */ +const char *xen_hello_world(void) +{ + return "Hello World"; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */
This change demonstrates how to generate an xSplice ELF payload. The idea here is that we want to patch in the hypervisor the 'xen_version_extra' function with an function that will return 'Hello World'. The 'xl info | grep extraversion' will reflect the new value after the patching. To generate this ELF payload file we need: - C code of the new code (xen_hello_world_func.c). - C code generating the .xsplice.funcs structure (xen_hello_world.c) - The address of the old code (xen_extra_version). We retrieve it by using 'nm --defined' on xen-syms. - The size of the new and old code for which we use nm --defined -S on our code and xen-syms respectively. There are two C files and one header files generated during build. One could make this one C file if the size of the newly patched function size was known in advance (or an random value was choosen). There is also a strict order of compiling: 1) xen_hello_world_func.c 2) config.h - extract the size of the new function, the old function and the old function address. 3) xen_hello_world.c - which contains the .xsplice.funcs structure. 4) Link the object files in an xen_hello_world.xsplice file. The use-case is simple: $xen-xsplice load /usr/lib/debug/xen_hello_world.xsplice $xen-xsplice list ID | status ----------------------------------------+------------ xen_hello_world APPLIED $xl info | grep extra xen_extra : Hello World $xen-xsplice revert xen_hello_world Performing revert: completed $xen-xsplice unload xen_hello_world Performing unload: completed $xl info | grep extra xen_extra : -unstable Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> --- Cc: Stefano Stabellini <stefano.stabellini@citrix.com> Cc: Julien Grall <julien.grall@arm.com> Cc: Keir Fraser <keir@xen.org> Cc: Jan Beulich <jbeulich@suse.com> Cc: Andrew Cooper <andrew.cooper3@citrix.com> v2: Do it using hypervisor Makefiles v3: Remove the stale linker file. Add Copyright and local definition block s/name/xen_hello_world_name/ v6: Remove the 'install', and 'uninstall' destinations. Remove xen/config.h from files. --- --- .gitignore | 2 ++ docs/misc/xsplice.markdown | 35 +++++++++++++++++++++++++ xen/Makefile | 8 ++++-- xen/arch/arm/Makefile | 2 ++ xen/arch/x86/Makefile | 4 +++ xen/arch/x86/test/Makefile | 44 ++++++++++++++++++++++++++++++++ xen/arch/x86/test/xen_hello_world.c | 30 ++++++++++++++++++++++ xen/arch/x86/test/xen_hello_world_func.c | 22 ++++++++++++++++ 8 files changed, 145 insertions(+), 2 deletions(-) create mode 100644 xen/arch/x86/test/Makefile create mode 100644 xen/arch/x86/test/xen_hello_world.c create mode 100644 xen/arch/x86/test/xen_hello_world_func.c