Xen devel - Jun 2011 - [PATCH] x86: allow Dom0 image to be compressed ELF

Rather than being able to decompress only the payloads of bzImage
containers, extend the logic to also decompress simple compressed ELF
images. At once, allow uncompressed bzImage payloads.

This is a prerequisite for native EFI booting support (where, in the
absence of a capable secondary boot loader, the image will always be
in compressed form).

Signed-off-by: Jan Beulich <jbeulich@novell.com>

--- a/xen/arch/x86/bzimage.c
+++ b/xen/arch/x86/bzimage.c
@@ -5,6 +5,7 @@
 #include <xen/string.h>
 #include <xen/types.h>
 #include <xen/decompress.h>
+#include <xen/libelf.h>
 #include <asm/bzimage.h>
 
 #define HEAPORDER 3
@@ -200,25 +201,36 @@ static __init int bzimage_check(struct s
     return 1;
 }
 
-int __init bzimage_headroom(char *image_start, unsigned long image_length)
+static unsigned long __initdata orig_image_len;
+
+unsigned long __init bzimage_headroom(char *image_start,
+                                      unsigned long image_length)
 {
     struct setup_header *hdr = (struct setup_header *)image_start;
-    char *img;
-    int err, headroom;
+    int err;
+    unsigned long headroom;
 
     err = bzimage_check(hdr, image_length);
-    if (err < 1)
+    if ( err < 0 )
         return 0;
 
-    img = image_start + (hdr->setup_sects+1) * 512;
-    img += hdr->payload_offset;
+    if ( err > 0 )
+    {
+        image_start += (hdr->setup_sects + 1) * 512 +
hdr->payload_offset;
+        image_length = hdr->payload_length;
+    }
+
+    if ( elf_is_elfbinary(image_start) )
+        return 0;
 
-    headroom = output_length(img, hdr->payload_length);
-    if (gzip_check(img, hdr->payload_length)) {
+    orig_image_len = image_length;
+    headroom = output_length(image_start, image_length);
+    if (gzip_check(image_start, image_length))
+    {
         headroom += headroom >> 12; /* Add 8 bytes for every 32K input
block */
         headroom += (32768 + 18); /* Add 32K + 18 bytes of extra headroom */
     } else
-        headroom += hdr->payload_length;
+        headroom += image_length;
     headroom = (headroom + 4095) & ~4095;
 
     return headroom;
@@ -230,18 +242,24 @@ int __init bzimage_parse(char *image_bas
     int err = bzimage_check(hdr, *image_len);
     unsigned long output_len;
 
-    if (err < 1)
+    if ( err < 0 )
         return err;
 
+    if ( err > 0 )
+    {
+        *image_start += (hdr->setup_sects + 1) * 512 +
hdr->payload_offset;
+        *image_len = hdr->payload_length;
+    }
+
+    if ( elf_is_elfbinary(*image_start) )
+        return 0;
+
     BUG_ON(!(image_base < *image_start));
 
-    *image_start += (hdr->setup_sects+1) * 512;
-    *image_start += hdr->payload_offset;
-    *image_len = hdr->payload_length;
-    output_len = output_length(*image_start, *image_len);
+    output_len = output_length(*image_start, orig_image_len);
 
-    if ( (err = perform_gunzip(image_base, *image_start, *image_len)) > 0 )
-        err = decompress(*image_start, *image_len, image_base);
+    if ( (err = perform_gunzip(image_base, *image_start, orig_image_len)) >
0 )
+        err = decompress(*image_start, orig_image_len, image_base);
 
     if ( !err )
     {
--- a/xen/include/asm-x86/bzimage.h
+++ b/xen/include/asm-x86/bzimage.h
@@ -4,7 +4,7 @@
 #include <xen/config.h>
 #include <xen/init.h>
 
-int bzimage_headroom(char *image_start, unsigned long image_length);
+unsigned long bzimage_headroom(char *image_start, unsigned long image_length);
 
 int bzimage_parse(char *image_base, char **image_start,
                   unsigned long *image_len);





_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel