x86: handle initrd that extends into unusable memory

On a system where system memory (according e820) is not covered by
mtrr, mtrr_trim_memory converts a portion of memory to reserved, but
bootloader has already put the initrd in that range.

Thus, we need to have 64bit to use relocate_initrd too.

[ Impact: fix using initrd when mtrr_trim_memory happen ]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: stable@kernel.org

arch/x86/kernel/setup.c

@@ -301,15 +301,13 @@ static void __init reserve_brk(void)
 
 #ifdef CONFIG_BLK_DEV_INITRD
 
-#ifdef CONFIG_X86_32
-
 #define MAX_MAP_CHUNK	(NR_FIX_BTMAPS << PAGE_SHIFT)
 static void __init relocate_initrd(void)
 {
 
 	u64 ramdisk_image = boot_params.hdr.ramdisk_image;
 	u64 ramdisk_size  = boot_params.hdr.ramdisk_size;
-	u64 end_of_lowmem = max_low_pfn << PAGE_SHIFT;
+	u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT;
 	u64 ramdisk_here;
 	unsigned long slop, clen, mapaddr;
 	char *p, *q;
@@ -365,14 +363,13 @@ static void __init relocate_initrd(void)
 		ramdisk_image, ramdisk_image + ramdisk_size - 1,
 		ramdisk_here, ramdisk_here + ramdisk_size - 1);
 }
-#endif
 
 static void __init reserve_initrd(void)
 {
 	u64 ramdisk_image = boot_params.hdr.ramdisk_image;
 	u64 ramdisk_size  = boot_params.hdr.ramdisk_size;
 	u64 ramdisk_end   = ramdisk_image + ramdisk_size;
-	u64 end_of_lowmem = max_low_pfn << PAGE_SHIFT;
+	u64 end_of_lowmem = max_low_pfn_mapped << PAGE_SHIFT;
 
 	if (!boot_params.hdr.type_of_loader ||
 	    !ramdisk_image || !ramdisk_size)
@@ -402,14 +399,8 @@ static void __init reserve_initrd(void)
 		return;
 	}
 
-#ifdef CONFIG_X86_32
 	relocate_initrd();
-#else
-	printk(KERN_ERR "initrd extends beyond end of memory "
-	       "(0x%08llx > 0x%08llx)\ndisabling initrd\n",
-	       ramdisk_end, end_of_lowmem);
-	initrd_start = 0;
-#endif
+
 	free_early(ramdisk_image, ramdisk_end);
 }
 #else