From: Neil Horman <nhorman@redhat.com>
Date: Mon, 18 Jan 2010 19:14:55 -0500
Subject: [x86] relocate initramfs so we can increase vmalloc space
Message-id: <20100118191455.GG27504@hmsreliant.think-freely.org>
Patchwork-id: 22633
O-Subject: [RHEL 5.5 PATCH] x86: relocate initramfs so that we can safely
	increase the vmalloc space
Bugzilla: 499253
RH-Acked-by: Thomas Graf <tgraf@redhat.com>
RH-Acked-by: Amerigo Wang <amwang@redhat.com>
RH-Acked-by: Anton Arapov <Anton@redhat.com>

hey all-
	This is a backport of upstream commit
cf8fa920cb4271f17e0265c863d64bea1b31941a.  Normally in x86 we're pretty tightly
constrained in how much we can increase our vmalloc space because we quickly
bump up against the end of our initramfs image.  If we specify too large a
vmalloc region on the command line, we fail to boot because the initrd runs into
that vmalloc space.  This backport is some code that HPA wrote some time ago to
allow the arch code to relocate the initramfs so that we can further increase
vmalloc space safely.  Tested by the customre requesting the feature (HP IIRC)
with good results.

Neil

Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index ea8b079..38ac780 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -160,9 +160,9 @@ extern int avoid_smi;
 
 unsigned long saved_videomode;
 
-#define RAMDISK_IMAGE_START_MASK  	0x07FF
+#define RAMDISK_IMAGE_START_MASK	0x07FF
 #define RAMDISK_PROMPT_FLAG		0x8000
-#define RAMDISK_LOAD_FLAG		0x4000	
+#define RAMDISK_LOAD_FLAG		0x4000
 
 static char command_line[COMMAND_LINE_SIZE];
 
@@ -1201,7 +1201,7 @@ static void __init reserve_ebda_region(void)
 	unsigned int addr;
 	addr = get_bios_ebda();
 	if (addr)
-		reserve_bootmem(addr, PAGE_SIZE);	
+		reserve_bootmem(addr, PAGE_SIZE);
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
@@ -1258,6 +1258,100 @@ extern unsigned long __init setup_memory(void);
 extern void zone_sizes_init(void);
 #endif /* !CONFIG_NEED_MULTIPLE_NODES */
 
+#ifdef CONFIG_BLK_DEV_INITRD
+
+static bool do_relocate_initrd = false;
+
+static void __init reserve_initrd(void)
+{
+	unsigned long ramdisk_image = INITRD_START;
+	unsigned long ramdisk_size  = INITRD_SIZE;
+	unsigned long ramdisk_end   = ramdisk_image + ramdisk_size;
+	unsigned long end_of_lowmem = max_low_pfn << PAGE_SHIFT;
+	unsigned long ramdisk_here;
+
+	initrd_start = 0;
+
+	if (!LOADER_TYPE ||
+	    !ramdisk_image || !ramdisk_size)
+		return;		/* No initrd provided by bootloader */
+
+	if (ramdisk_end < ramdisk_image) {
+		printk(KERN_ERR "initrd wraps around end of memory, "
+		       "disabling initrd\n");
+		return;
+	}
+	if (ramdisk_size >= end_of_lowmem/2) {
+		printk(KERN_ERR "initrd too large to handle, "
+		       "disabling initrd\n");
+		return;
+	}
+	if (ramdisk_end <= end_of_lowmem) {
+		/* All in lowmem, easy case */
+		reserve_bootmem(ramdisk_image, ramdisk_size);
+		initrd_start = ramdisk_image + PAGE_OFFSET;
+		initrd_end = initrd_start+ramdisk_size;
+		return;
+	}
+
+	/* We need to move the initrd down into lowmem */
+	ramdisk_here = (end_of_lowmem - ramdisk_size) & PAGE_MASK;
+
+	/* Note: this includes all the lowmem currently occupied by
+	   the initrd, we rely on that fact to keep the data intact. */
+	reserve_bootmem(ramdisk_here, ramdisk_size);
+	initrd_start = ramdisk_here + PAGE_OFFSET;
+	initrd_end   = initrd_start + ramdisk_size;
+
+	do_relocate_initrd = true;
+}
+
+#define MAX_MAP_CHUNK	(NR_FIX_BTMAPS << PAGE_SHIFT)
+
+static void __init relocate_initrd(void)
+{
+	unsigned long ramdisk_image = INITRD_START;
+	unsigned long ramdisk_size  = INITRD_SIZE;
+	unsigned long end_of_lowmem = max_low_pfn << PAGE_SHIFT;
+	unsigned long ramdisk_here;
+	unsigned long slop, clen, mapaddr;
+	char *p, *q;
+
+	if (!do_relocate_initrd)
+		return;
+
+	ramdisk_here = initrd_start - PAGE_OFFSET;
+
+	q = (char *)initrd_start;
+
+	/* Copy any lowmem portion of the initrd */
+	if (ramdisk_image < end_of_lowmem) {
+		clen = end_of_lowmem - ramdisk_image;
+		p = (char *)__va(ramdisk_image);
+		memcpy(q, p, clen);
+		q += clen;
+		ramdisk_image += clen;
+		ramdisk_size  -= clen;
+	}
+
+	/* Copy the highmem portion of the initrd */
+	while (ramdisk_size) {
+		slop = ramdisk_image & ~PAGE_MASK;
+		clen = ramdisk_size;
+		if (clen > MAX_MAP_CHUNK-slop)
+			clen = MAX_MAP_CHUNK-slop;
+		mapaddr = ramdisk_image & PAGE_MASK;
+		p = bt_ioremap(mapaddr, clen+slop);
+		memcpy(q, p+slop, clen);
+		bt_iounmap(p, clen+slop);
+		q += clen;
+		ramdisk_image += clen;
+		ramdisk_size  -= clen;
+	}
+}
+
+#endif /* CONFIG_BLK_DEV_INITRD */
+
 void __init setup_bootmem_allocator(void)
 {
 	unsigned long bootmap_size;
@@ -1315,22 +1409,9 @@ void __init setup_bootmem_allocator(void)
 #endif
 
 #ifdef CONFIG_BLK_DEV_INITRD
-	if (LOADER_TYPE && INITRD_START) {
-		if (INITRD_START + INITRD_SIZE <= (max_low_pfn << PAGE_SHIFT)) {
-			reserve_bootmem(INITRD_START, INITRD_SIZE);
-			initrd_start =
-				INITRD_START ? INITRD_START + PAGE_OFFSET : 0;
-			initrd_end = initrd_start+INITRD_SIZE;
-		}
-		else {
-			printk(KERN_ERR "initrd extends beyond end of memory "
-			    "(0x%08lx > 0x%08lx)\ndisabling initrd\n",
-			    INITRD_START + INITRD_SIZE,
-			    max_low_pfn << PAGE_SHIFT);
-			initrd_start = 0;
-		}
-	}
+	reserve_initrd();
 #endif
+
 #ifdef CONFIG_KEXEC
 	if ((crashk_res.start < crashk_res.end) &&
 	    (crashk_res.end <= (max_low_pfn << PAGE_SHIFT))) {
@@ -1599,6 +1680,9 @@ void __init setup_arch(char **cmdline_p)
 	/*
 	 * NOTE: at this point the bootmem allocator is fully available.
 	 */
+#ifdef CONFIG_BLK_DEV_INITRD
+	relocate_initrd();
+#endif
 
 	dmi_scan_machine();