[Xen-devel] [PATCH v2 2/2] arch/x86/xen: Silence compiler warnings

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

Compiler complains in the following way when x86 32-bit kernel
with Xen support is build:

  CC      arch/x86/xen/enlighten.o
arch/x86/xen/enlighten.c: In function âxen_start_kernelâ:
arch/x86/xen/enlighten.c:1726:3: warning: right shift count >= width of type 
[enabled by default]

Such line contains following EFI initialization code:

boot_params.efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 32);

There is no issue if x86 64-bit kernel is build. However, 32-bit case
generate warning (even if that code will not be executed because Xen
does not work on 32-bit EFI platforms) due to __pa() returning unsigned long
type which has 32-bits width. So move whole EFI initialization stuff
to separate function and build it conditionally to avoid above mentioned
warning on x86 32-bit architecture.

Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
---
v2 - suggestions/fixes:
   - move xen_efi_init() to separate module
     (suggested by Konrad Rzeszutek Wilk).
---
 arch/x86/xen/Makefile    |    1 +
 arch/x86/xen/efi.c       |   43 +++++++++++++++++++++++++++++++++++++++++++
 arch/x86/xen/enlighten.c |   15 +--------------
 arch/x86/xen/xen-ops.h   |    8 ++++++++
 4 files changed, 53 insertions(+), 14 deletions(-)
 create mode 100644 arch/x86/xen/efi.c

diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile
index 96ab2c0..7322755 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -22,3 +22,4 @@ obj-$(CONFIG_PARAVIRT_SPINLOCKS)+= spinlock.o
 obj-$(CONFIG_XEN_DEBUG_FS)     += debugfs.o
 obj-$(CONFIG_XEN_DOM0)         += apic.o vga.o
 obj-$(CONFIG_SWIOTLB_XEN)      += pci-swiotlb-xen.o
+obj-$(CONFIG_XEN_EFI)          += efi.o
diff --git a/arch/x86/xen/efi.c b/arch/x86/xen/efi.c
new file mode 100644
index 0000000..a02e09e
--- /dev/null
+++ b/arch/x86/xen/efi.c
@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2014 Oracle Co., Daniel Kiper
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/efi.h>
+#include <linux/init.h>
+#include <linux/string.h>
+
+#include <xen/xen-ops.h>
+
+#include <asm/setup.h>
+
+void __init xen_efi_init(void)
+{
+       efi_system_table_t *efi_systab_xen;
+
+       efi_systab_xen = xen_efi_probe();
+
+       if (efi_systab_xen == NULL)
+               return;
+
+       strncpy((char *)&boot_params.efi_info.efi_loader_signature, "Xen",
+                       sizeof(boot_params.efi_info.efi_loader_signature));
+       boot_params.efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
+       boot_params.efi_info.efi_systab_hi = (__u32)(__pa(efi_systab_xen) >> 
32);
+
+       set_bit(EFI_BOOT, &efi.flags);
+       set_bit(EFI_PARAVIRT, &efi.flags);
+       set_bit(EFI_64BIT, &efi.flags);
+}
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index bc89647..2cd0463 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -32,7 +32,6 @@
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/edd.h>
-#include <linux/efi.h>
 
 #include <xen/xen.h>
 #include <xen/events.h>
@@ -1521,7 +1520,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
 {
        struct physdev_set_iopl set_iopl;
        int rc;
-       efi_system_table_t *efi_systab_xen;
 
        if (!xen_start_info)
                return;
@@ -1717,18 +1715,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 
        xen_setup_runstate_info(0);
 
-       efi_systab_xen = xen_efi_probe();
-
-       if (efi_systab_xen) {
-               strncpy((char *)&boot_params.efi_info.efi_loader_signature, 
"Xen",
-                               
sizeof(boot_params.efi_info.efi_loader_signature));
-               boot_params.efi_info.efi_systab = (__u32)__pa(efi_systab_xen);
-               boot_params.efi_info.efi_systab_hi = 
(__u32)(__pa(efi_systab_xen) >> 32);
-
-               set_bit(EFI_BOOT, &efi.flags);
-               set_bit(EFI_PARAVIRT, &efi.flags);
-               set_bit(EFI_64BIT, &efi.flags);
-       }
+       xen_efi_init();
 
        /* Start the world */
 #ifdef CONFIG_X86_32
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index c834d4b..75f98fe 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -104,6 +104,14 @@ static inline void __init xen_init_apic(void)
 }
 #endif
 
+#ifdef CONFIG_XEN_EFI
+extern void xen_efi_init(void);
+#else
+static inline void __init xen_efi_init(void)
+{
+}
+#endif
+
 /* Declare an asm function, along with symbols needed to make it
    inlineable */
 #define DECL_ASM(ret, name, ...)               \
-- 
1.7.10.4


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