Re: [Xen-devel] [PATCH v5 11/16] livepatch: tests: Make them compile under ARM64

[Julien Grall <julien.grall@xxxxxxx>]

Hi Konrad,

On 21/09/16 18:32, Konrad Rzeszutek Wilk wrote:
> We need to two things:
> 1) Wrap the platform-specific objcopy parameters in defines
>    The input and output parameters for $(OBJCOPY) are different
>    based on the platforms. As such provide them in the
>    OBJCOPY_MAGIC define and use that.
>
> 2) The alternative is a bit different (exists only under ARM64
>    and x86), while and there are no exceptions under ARM at all.
>    We use the LIVEPATCH_FEATURE CPU id feature for ARM similar to
>    how it is done on x86.
>
> We are not yet attempting to build them under ARM32 so
> that is still ifdefed out.
>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>
> ---
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Tim Deegan <tim@xxxxxxx>
> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
>
> v1: First submission
> v2: Corrected description by Julien
>     Add #ifeq instead of #else for ARM case.
> v3: Moved 'asm(alter..)' by one space to the left.
> v4: Rebase on top of "livepatch/tests: Make .livepatch.depends be read-only"
>     Rewrote the commit description 2) a bit.
> ---
>  xen/test/Makefile                         |  2 +-
>  xen/test/livepatch/Makefile               | 12 ++++++++++--
>  xen/test/livepatch/xen_hello_world_func.c |  7 +++++++
>  3 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/xen/test/Makefile b/xen/test/Makefile
> index 8c53040..95c1755 100644
> --- a/xen/test/Makefile
> +++ b/xen/test/Makefile
> @@ -1,6 +1,6 @@
>  .PHONY: tests
>  tests:
I am wondering if there is any way to use the
> -ifeq ($(XEN_TARGET_ARCH),x86_64)
> +ifneq $(XEN_TARGET_ARCH),arm32)
NIT: I am wondering if you could instead use CONFIG_LIVEPATCH here, so 
the tests would only be built when livepatch is enabled.
>         $(MAKE) -f $(BASEDIR)/Rules.mk -C livepatch livepatch
>  endif
>
> diff --git a/xen/test/livepatch/Makefile b/xen/test/livepatch/Makefile
> index 48ff843..5db4d9c 100644
> --- a/xen/test/livepatch/Makefile
> +++ b/xen/test/livepatch/Makefile
> @@ -1,5 +1,12 @@
>  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 ($(XEN_TARGET_ARCH),arm64)
> +OBJCOPY_MAGIC := -I binary -O elf64-littleaarch64 -B aarch64
> +endif
> +
>  CODE_ADDR=$(shell nm --defined $(1) | grep $(2) | awk '{print "0x"$$1}')
>  CODE_SZ=$(shell nm --defined -S $(1) | grep $(2) | awk '{ print "0x"$$2}')
>
> @@ -54,8 +61,9 @@ $(LIVEPATCH): xen_hello_world_func.o xen_hello_world.o note.o
>  .PHONY: note.o
>  note.o:
>         $(OBJCOPY) -O binary --only-section=.note.gnu.build-id 
> $(BASEDIR)/xen-syms $@.bin
> -       $(OBJCOPY) -I binary -O elf64-x86-64 -B i386:x86-64 \
> +       $(OBJCOPY) $(OBJCOPY_MAGIC) \
>                    
> --rename-section=.data=.livepatch.depends,alloc,load,readonly,data,contents -S 
> $@.bin $@
> +                  --rename-section=.data=.livepatch.depends -S $@.bin $@
I am not sure why you added this line. Did you intend to replace the 
previous one?
>         rm -f $@.bin
>
>  #
> @@ -65,7 +73,7 @@ note.o:
>  .PHONY: hello_world_note.o
>  hello_world_note.o: $(LIVEPATCH)
>         $(OBJCOPY) -O binary --only-section=.note.gnu.build-id $(LIVEPATCH) 
> $@.bin
> -       $(OBJCOPY)  -I binary -O elf64-x86-64 -B i386:x86-64 \
> +       $(OBJCOPY) $(OBJCOPY_MAGIC) \
>                    
> --rename-section=.data=.livepatch.depends,alloc,load,readonly,data,contents -S 
> $@.bin $@
>         rm -f $@.bin
>
> diff --git a/xen/test/livepatch/xen_hello_world_func.c 
> b/xen/test/livepatch/xen_hello_world_func.c
> index 0321f3e..c5c0da1 100644
> --- a/xen/test/livepatch/xen_hello_world_func.c
> +++ b/xen/test/livepatch/xen_hello_world_func.c
> @@ -7,14 +7,17 @@
>
>  #include <asm/alternative.h>
>  #include <asm/livepatch.h>
> +#ifdef CONFIG_X86
>  #include <asm/nops.h>
>  #include <asm/uaccess.h>
>
>  static unsigned long *non_canonical_addr = (unsigned long 
> *)0xdead000000000000ULL;
> +#endif
>
>  /* Our replacement function for xen_extra_version. */
>  const char *xen_hello_world(void)
>  {
> +#ifdef CONFIG_X86
>      unsigned long tmp;
>      int rc;
>
> @@ -25,6 +28,10 @@ const char *xen_hello_world(void)
>       */
>      rc = __get_user(tmp, non_canonical_addr);
>      BUG_ON(rc != -EFAULT);
> +#endif
> +#ifdef CONFIG_ARM_64
NIT: I would use:

#if defined(CONFIG_ARM) && defined(CONFIG_HAS_ALTERNATIVE)

in order to handle alternative if we decide to add support for ARM32.

> +    asm(ALTERNATIVE("nop", "nop", LIVEPATCH_FEATURE));
> +#endif
>
>      return "Hello World";
>  }
Regards,

--
Julien Grall

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