[Xen-devel] [PATCH v6 07/15] efi: build xen.gz with EFI code

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

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 <daniel.kiper@xxxxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v6 - suggestions/fixes:
   - improve efi_enabled() checks in efi_runtime_call()
     (suggested by Jan Beulich).

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 |   12 ++++--------
 xen/arch/x86/xen.lds.S    |    4 ++--
 xen/common/efi/boot.c     |    3 +++
 xen/common/efi/runtime.c  |    9 +++++++++
 5 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index a4fe740..2766bff 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -223,7 +223,7 @@ 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 ad3fdf7..442f3fc 100644
--- a/xen/arch/x86/efi/Makefile
+++ b/xen/arch/x86/efi/Makefile
@@ -1,18 +1,14 @@
 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); 
$(call create,runtime.o)))
-
-extra-$(efi) += boot.init.o relocs-dummy.o runtime.o compat.o buildid.o
+efi := $(if $(efi),$(shell rm disabled)y)
 
 %.o: %.ihex
        $(OBJCOPY) -I ihex -O binary $< $@
 
-stub.o: $(extra-y)
+obj-y := stub.o
+obj-$(efi) := boot.init.o compat.o relocs-dummy.o runtime.o
+extra-$(efi) += buildid.o
 nogcov-$(efi) += stub.o
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index d903c31..57f5368 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -271,10 +271,10 @@ 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 56544dc..1ef5d0b 100644
--- a/xen/common/efi/boot.c
+++ b/xen/common/efi/boot.c
@@ -1251,6 +1251,9 @@ 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 5f2de80..41f49f7 100644
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -174,6 +174,9 @@ 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:
@@ -308,6 +311,12 @@ int efi_runtime_call(struct xenpf_efi_runtime_call *op)
     EFI_STATUS status = EFI_NOT_STARTED;
     int rc = 0;
 
+    if ( !efi_enabled(EFI_BOOT) )
+        return -ENOSYS;
+
+    if ( !efi_enabled(EFI_RS) )
+        return -EOPNOTSUPP;
+
     switch ( op->function )
     {
     case XEN_EFI_get_time:
-- 
1.7.10.4


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