i386: handle an initrd in highmem (version 2)

The boot protocol has until now required that the initrd be located in
lowmem, which makes the lowmem/highmem boundary visible to the boot
loader.  This was exported to the bootloader via a compile-time
field.  Unfortunately, the vmalloc= command-line option breaks this
part of the protocol; instead of adding yet another hack that affects
the bootloader, have the kernel relocate the initrd down below the
lowmem boundary inside the kernel itself.

Note that this does not rely on HIGHMEM being enabled in the kernel.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 106 insertions, 24 deletions

diff --git a/arch/x86/kernel/setup_32.c b/arch/x86/kernel/setup_32.c
index 3bce4af60bb6..6802a383077d 100644
--- a/arch/x86/kernel/setup_32.c
+++ b/arch/x86/kernel/setup_32.c
@@ -188,9 +188,9 @@ extern int root_mountflags;
 
 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 __initdata command_line[COMMAND_LINE_SIZE];
 
@@ -252,7 +252,7 @@ static int __init parse_mem(char *arg)
                  * trim the existing memory map.
                  */
                 unsigned long long mem_size;
- 
+
                 mem_size = memparse(arg, &arg);
                 limit_regions(mem_size);
                 user_defined_memmap = 1;
@@ -391,7 +391,7 @@ 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
@@ -496,6 +496,100 @@ static inline void __init reserve_crashkernel(void)
 {}
 #endif
 
+#ifdef CONFIG_BLK_DEV_INITRD
+
+static bool do_relocate_initrd = false;
+
+static void __init reserve_initrd(void)
+{
+        unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
+        unsigned long ramdisk_size  = boot_params.hdr.ramdisk_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 (!boot_params.hdr.type_of_loader ||
+            !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 = boot_params.hdr.ramdisk_image;
+        unsigned long ramdisk_size  = boot_params.hdr.ramdisk_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;
@@ -551,26 +645,10 @@ void __init setup_bootmem_allocator(void)
          */
         find_smp_config();
 #endif
-        numa_kva_reserve();
 #ifdef CONFIG_BLK_DEV_INITRD
-        if (boot_params.hdr.type_of_loader && boot_params.hdr.ramdisk_image) {
-                unsigned long ramdisk_image = boot_params.hdr.ramdisk_image;
-                unsigned long ramdisk_size  = boot_params.hdr.ramdisk_size;
-                unsigned long ramdisk_end   = ramdisk_image + ramdisk_size;
-                unsigned long end_of_lowmem = max_low_pfn << PAGE_SHIFT;
-
-                if (ramdisk_end <= end_of_lowmem) {
-                        reserve_bootmem(ramdisk_image, ramdisk_size);
-                        initrd_start = ramdisk_image + PAGE_OFFSET;
-                        initrd_end = initrd_start+ramdisk_size;
-                } else {
-                        printk(KERN_ERR "initrd extends beyond end of memory "
-                               "(0x%08lx > 0x%08lx)\ndisabling initrd\n",
-                               ramdisk_end, end_of_lowmem);
-                        initrd_start = 0;
-                }
-        }
+        reserve_initrd();
 #endif
+        numa_kva_reserve();
         reserve_crashkernel();
 }
 
@@ -713,15 +791,19 @@ 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
+
         paravirt_post_allocator_init();
 
         dmi_scan_machine();
 
-        io_delay_init();;
+        io_delay_init();
 
 #ifdef CONFIG_X86_GENERICARCH
         generic_apic_probe();
-#endif  
+#endif
         if (efi_enabled)
                 efi_map_memmap();