[v5,11/16] efi: build xen.gz with EFI code

Commit Message

Daniel Kiper Aug. 19, 2016, 10:43 p.m. UTC

Build xen.gz with EFI code. We need this to support multiboot2
protocol on EFI platforms.

If we wish to load non-ELF file using multiboot (v1) or multiboot2 then
it must contain "linear" (or "flat") representation of code and data.
This is requirement of both boot protocols. Currently, PE file contains
many sections which are not "linear" (one after another without any holes)
or even do not have representation in a file (e.g. BSS). From EFI point
of view everything is OK and works. However, this file layout cannot be
properly interpreted by multiboot protocols family. In theory there is
a chance that we could build proper PE file (from multiboot protocols POV)
using current build system. However, it means that xen.efi further diverge
from Xen ELF file (in terms of contents and build method). On the other
hand ELF has all needed properties. So, it means that this is good starting
point for further development. Additionally, I think that this is also good
starting point for further xen.efi code and build optimizations. It looks
that there is a chance that finally we can generate xen.efi directly from
Xen ELF using just simple objcopy or other tool. This way we will have one
Xen binary which can be loaded by three boot protocols: EFI native loader,
multiboot (v1) and multiboot2.

Signed-off-by: Daniel Kiper <[e-mail]>
Acked-by: Jan Beulich <[e-mail]>
---
v5 - suggestions/fixes:
   - properly calculate efi symbol address in
     xen/arch/x86/xen.lds.S (I hope that this
     change does not invalidate Jan's ACK).

v4 - suggestions/fixes:
   - functions should return -ENOSYS instead
     of -EOPNOTSUPP if EFI runtime services
     are not available
     (suggested by Jan Beulich),
   - remove stale bits from xen/arch/x86/Makefile
     (suggested by Jan Beulich).

v3 - suggestions/fixes:
   - check for EFI platform in EFI code
     (suggested by Jan Beulich),
   - fix Makefiles
     (suggested by Jan Beulich),
   - improve commit message
     (suggested by Jan Beulich).

v2 - suggestions/fixes:
   - build EFI code only if it is supported in a given build environment
     (suggested by Jan Beulich).
---
 xen/arch/x86/Makefile     |    2 +-
 xen/arch/x86/efi/Makefile |   11 +++--------
 xen/arch/x86/xen.lds.S    |    4 ++--
 xen/common/efi/boot.c     |    3 +++
 xen/common/efi/runtime.c  |    6 ++++++
 5 files changed, 15 insertions(+), 11 deletions(-)

Comments

Jan Beulich Aug. 25, 2016, 12:23 p.m. UTC | #1

>>> On 20.08.16 at 00:43, <[e-mail]> wrote:
> Build xen.gz with EFI code. We need this to support multiboot2
> protocol on EFI platforms.
> 
> If we wish to load non-ELF file using multiboot (v1) or multiboot2 then
> it must contain "linear" (or "flat") representation of code and data.
> This is requirement of both boot protocols. Currently, PE file contains
> many sections which are not "linear" (one after another without any holes)
> or even do not have representation in a file (e.g. BSS). From EFI point
> of view everything is OK and works. However, this file layout cannot be
> properly interpreted by multiboot protocols family. In theory there is
> a chance that we could build proper PE file (from multiboot protocols POV)
> using current build system. However, it means that xen.efi further diverge
> from Xen ELF file (in terms of contents and build method). On the other
> hand ELF has all needed properties. So, it means that this is good starting
> point for further development. Additionally, I think that this is also good
> starting point for further xen.efi code and build optimizations. It looks
> that there is a chance that finally we can generate xen.efi directly from
> Xen ELF using just simple objcopy or other tool. This way we will have one
> Xen binary which can be loaded by three boot protocols: EFI native loader,
> multiboot (v1) and multiboot2.
> 
> Signed-off-by: Daniel Kiper <[e-mail]>
> Acked-by: Jan Beulich <[e-mail]>
> ---
> v5 - suggestions/fixes:
>    - properly calculate efi symbol address in
>      xen/arch/x86/xen.lds.S (I hope that this
>      change does not invalidate Jan's ACK).

Looks okay. But there's one more thing:

> @@ -309,6 +312,9 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *op)
>      EFI_STATUS status = EFI_NOT_STARTED;
>      int rc = 0;
>  
> +    if ( !efi_enabled(EFI_RS) )
> +        return -ENOSYS;

I think this should be two checks:

    if ( !efi_enabled(EFI_BOOT) )
        return -ENOSYS;
    if ( !efi_enabled(EFI_RS) )
        return -EOPNOTSUPP;

Jan

Patch

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index b18f033..71ec34e 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -211,7 +211,7 @@  efi/mkreloc: efi/mkreloc.c
 clean::
 	rm -f asm-offsets.s *.lds boot/*.o boot/*~ boot/core boot/mkelf32
 	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 $(BASEDIR)/.xen.efi.[0-9]* efi/*.efi efi/disabled efi/mkreloc
 	rm -f boot/reloc.S boot/reloc.lnk boot/reloc.bin
 	rm -f note.o
 	$(MAKE) -f $(BASEDIR)/Rules.mk -C test clean
diff --git a/xen/arch/x86/efi/Makefile b/xen/arch/x86/efi/Makefile
index 5099430..2a7d3e5 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -1,14 +1,9 @@ 
 CFLAGS += -fshort-wchar
 
-obj-y += stub.o
-
-create = test -e $(1) || touch -t 199901010000 $(1)
-
 efi := y$(shell rm -f disabled)
 efi := $(if $(efi),$(shell $(CC) $(filter-out $(CFLAGS-y) .%.d,$(CFLAGS)) -c check.c 2>disabled && echo y))
 efi := $(if $(efi),$(shell $(LD) -mi386pep --subsystem=10 -o check.efi check.o 2>disabled && echo y))
-efi := $(if $(efi),$(shell rm disabled)y,$(shell $(call create,boot.init.o); $(call create,runtime.o)))
+efi := $(if $(efi),$(shell rm disabled)y)
 
-extra-$(efi) += boot.init.o relocs-dummy.o runtime.o compat.o
-
-stub.o: $(extra-y)
+obj-y := stub.o
+obj-$(efi) := boot.init.o compat.o relocs-dummy.o runtime.o
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 2d1d43d..40eb4c5 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -262,10 +262,10 @@  SECTIONS
   .pad : {
     . = ALIGN(MB(16));
   } :text
-#else
-  efi = .;
 #endif
 
+  efi = DEFINED(efi) ? efi : .;
+
   /* Sections to be discarded */
   /DISCARD/ : {
        *(.exit.text)
diff --git a/xen/common/efi/boot.c b/xen/common/efi/boot.c
index d7c484e..48ef8ad 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1249,6 +1249,9 @@  void __init efi_init_memory(void)
     } *extra, *extra_head = NULL;
 #endif
 
+    if ( !efi_enabled(EFI_BOOT) )
+        return;
+
     printk(XENLOG_INFO "EFI memory map:%s\n",
            map_bs ? " (mapping BootServices)" : "");
     for ( i = 0; i < efi_memmap_size; i += efi_mdesc_size )
diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c
index 6bffda0..64c632c 100644
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -175,6 +175,9 @@  int efi_get_info(uint32_t idx, union xenpf_efi_info *info)
 {
     unsigned int i, n;
 
+    if ( !efi_enabled(EFI_BOOT) )
+        return -ENOSYS;
+
     switch ( idx )
     {
     case XEN_FW_EFI_VERSION:
@@ -309,6 +312,9 @@  int efi_runtime_call(struct xenpf_efi_runtime_call *op)
     EFI_STATUS status = EFI_NOT_STARTED;
     int rc = 0;
 
+    if ( !efi_enabled(EFI_RS) )
+        return -ENOSYS;
+
     switch ( op->function )
     {
     case XEN_EFI_get_time: