[Xen-devel] [PATCH v3 09/16] efi: explicitly define efi struct in xen/arch/x86/efi/stub.c

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

Existing solution does not allocate space for this symbol and any
references to acpi20, etc. does not make sense. As I saw any efi.*
references are protected by relevant ifs but we should not do that
because it makes code very fragile. If somebody does not know how
efi symbol is created he/she may assume that it always represent
valid structure and do invalid references somewhere.

Additionally, following patch adds efi struct flags member which
is used during runtime to differentiate between legacy BIOS and
EFI platforms and multiboot2 and EFI native loader. So, efi symbol
have to proper representation in ELF and PE Xen image. Hence,
define efi struct in xen/arch/x86/efi/stub.c and remove efi
symbol from ld script.

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
 xen/arch/x86/efi/stub.c |    8 ++++++++
 xen/arch/x86/xen.lds.S  |    2 --
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/efi/stub.c b/xen/arch/x86/efi/stub.c
index 07c2bd0..e6c99b5 100644
--- a/xen/arch/x86/efi/stub.c
+++ b/xen/arch/x86/efi/stub.c
@@ -8,6 +8,14 @@
 const bool_t efi_enabled = 0;
 #endif
 
+struct efi __read_mostly efi = {
+       .acpi    = EFI_INVALID_TABLE_ADDR,
+       .acpi20  = EFI_INVALID_TABLE_ADDR,
+       .mps     = EFI_INVALID_TABLE_ADDR,
+       .smbios  = EFI_INVALID_TABLE_ADDR,
+       .smbios3 = EFI_INVALID_TABLE_ADDR
+};
+
 void __init efi_init_memory(void) { }
 
 void efi_update_l4_pgtable(unsigned int l4idx, l4_pgentry_t l4e) { }
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 6802da1..6376bfa 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -227,8 +227,6 @@ SECTIONS
   .pad : {
     . = ALIGN(MB(16));
   } :text
-#else
-  efi = .;
 #endif
 
   /* Sections to be discarded */
-- 
1.7.10.4


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