[PATCH v4] x86/setup: get ramdisk parameters only once

[Alexander Kuleshov]

The check and definitions related to ramdisk are similar in the
early_reserve_initrd() and reserve_initrd() functions.

This patch introduces struct ramdisk which contains information
about initrd. This structure will be filled in the setup_arch()
and passed to the reserve_initrd() and relocate_initrd() functions.

This allows us to not get/check ramdisk parameters from the bootparams
every time in the early_reserve_initrd(), reserve_initrd() and
relocate_initrd() function.

Additionally we save 85 bytes:

     text     data      bss       dec      hex filename
  9292602  5011696 15675392  29979690  1c9742a vmlinux.orig

     text     data      bss       dec     hex filename
  9292517  5011696 15675392  29979605 1c973d5 vmlinux


Signed-off-by: Alexander Kuleshov <kuleshovmail@xxxxxxxxx>
---
Tested as with virtual machine as with real hardware.

Changelog:

v4:

  * bool reserve_ramdisk moved to the struct ramdisk;
  * fields of struct ramdisk are renamed to more understandable
  names
  * early_reserve_initrd() removed as it contains only one call
  of memblock_resere. It was moved to the setup_arch
  * stubs added for get_ramdisk_image() and get_ramdisk_size()
  to prevent compilation error if CONFIG_BLK_DEV_INITRD=n
  * initialization of ramdisk->end_addr is moved from in-place
  initialization to prevent âramdisk_image.sizeâ is used uninitialized
  in this function warning.

v3: introduced ramdisk setup which is filled in th
setup_arch() and passed to the early_reserve_initrd()
and reserve_initrd().

v2: parameter of reserve_initrd() - int -> bool.
    commit message updated.

 arch/x86/kernel/setup.c | 105 +++++++++++++++++++++++++-----------------------
 1 file changed, 54 insertions(+), 51 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d3d80e6..0f0ba51 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -169,6 +169,15 @@ static struct resource bss_resource = {
 	.flags	= IORESOURCE_BUSY | IORESOURCE_MEM
 };
 
+/*
+ * ramdisk setup
+ */
+struct ramdisk {
+	u64 start_addr;		/* ramdisk load address */
+	u64 end_addr;		/* ramdisk end address */
+	u64 size;		/* ramdisk size */
+	bool reserve_ramdisk;	/* do initrd provided by bootloader */
+};
 
 #ifdef CONFIG_X86_32
 /* cpu data as detected by the assembly code in head.S */
@@ -318,90 +327,70 @@ static u64 __init get_ramdisk_size(void)
 	return ramdisk_size;
 }
 
-static void __init relocate_initrd(void)
+static void __init relocate_initrd(struct ramdisk *ramdisk)
 {
-	/* Assume only end is not page aligned */
-	u64 ramdisk_image = get_ramdisk_image();
-	u64 ramdisk_size  = get_ramdisk_size();
-	u64 area_size     = PAGE_ALIGN(ramdisk_size);
-
 	/* We need to move the initrd down into directly mapped mem */
 	relocated_ramdisk = memblock_find_in_range(0, PFN_PHYS(max_pfn_mapped),
-						   area_size, PAGE_SIZE);
+						   ramdisk->size, PAGE_SIZE);
 
 	if (!relocated_ramdisk)
 		panic("Cannot find place for new RAMDISK of size %lld\n",
-		      ramdisk_size);
+		      ramdisk->size);
 
 	/* Note: this includes all the mem currently occupied by
 	   the initrd, we rely on that fact to keep the data intact. */
-	memblock_reserve(relocated_ramdisk, area_size);
+	memblock_reserve(relocated_ramdisk, ramdisk->size);
 	initrd_start = relocated_ramdisk + PAGE_OFFSET;
-	initrd_end   = initrd_start + ramdisk_size;
+	initrd_end   = initrd_start + ramdisk->size;
 	printk(KERN_INFO "Allocated new RAMDISK: [mem %#010llx-%#010llx]\n",
-	       relocated_ramdisk, relocated_ramdisk + ramdisk_size - 1);
+	       relocated_ramdisk, relocated_ramdisk + ramdisk->size - 1);
 
-	copy_from_early_mem((void *)initrd_start, ramdisk_image, ramdisk_size);
+	copy_from_early_mem((void *)initrd_start, ramdisk->start_addr, ramdisk->size);
 
 	printk(KERN_INFO "Move RAMDISK from [mem %#010llx-%#010llx] to"
 		" [mem %#010llx-%#010llx]\n",
-		ramdisk_image, ramdisk_image + ramdisk_size - 1,
-		relocated_ramdisk, relocated_ramdisk + ramdisk_size - 1);
+		ramdisk->start_addr, ramdisk->start_addr + ramdisk->size - 1,
+		relocated_ramdisk, relocated_ramdisk + ramdisk->size - 1);
 }
 
-static void __init early_reserve_initrd(void)
-{
-	/* Assume only end is not page aligned */
-	u64 ramdisk_image = get_ramdisk_image();
-	u64 ramdisk_size  = get_ramdisk_size();
-	u64 ramdisk_end   = PAGE_ALIGN(ramdisk_image + ramdisk_size);
-
-	if (!boot_params.hdr.type_of_loader ||
-	    !ramdisk_image || !ramdisk_size)
-		return;		/* No initrd provided by bootloader */
-
-	memblock_reserve(ramdisk_image, ramdisk_end - ramdisk_image);
-}
-static void __init reserve_initrd(void)
+static void __init reserve_initrd(struct ramdisk *ramdisk)
 {
-	/* Assume only end is not page aligned */
-	u64 ramdisk_image = get_ramdisk_image();
-	u64 ramdisk_size  = get_ramdisk_size();
-	u64 ramdisk_end   = PAGE_ALIGN(ramdisk_image + ramdisk_size);
 	u64 mapped_size;
 
-	if (!boot_params.hdr.type_of_loader ||
-	    !ramdisk_image || !ramdisk_size)
-		return;		/* No initrd provided by bootloader */
-
 	initrd_start = 0;
 
 	mapped_size = memblock_mem_size(max_pfn_mapped);
-	if (ramdisk_size >= (mapped_size>>1))
+	if (ramdisk->size >= (mapped_size>>1))
 		panic("initrd too large to handle, "
 		       "disabling initrd (%lld needed, %lld available)\n",
-		       ramdisk_size, mapped_size>>1);
+		       ramdisk->size, mapped_size>>1);
 
-	printk(KERN_INFO "RAMDISK: [mem %#010llx-%#010llx]\n", ramdisk_image,
-			ramdisk_end - 1);
+	printk(KERN_INFO "RAMDISK: [mem %#010llx-%#010llx]\n",
+		ramdisk->start_addr, ramdisk->end_addr - 1);
 
-	if (pfn_range_is_mapped(PFN_DOWN(ramdisk_image),
-				PFN_DOWN(ramdisk_end))) {
+	if (pfn_range_is_mapped(PFN_DOWN(ramdisk->start_addr),
+				PFN_DOWN(ramdisk->end_addr))) {
 		/* All are mapped, easy case */
-		initrd_start = ramdisk_image + PAGE_OFFSET;
-		initrd_end = initrd_start + ramdisk_size;
+		initrd_start = ramdisk->start_addr + PAGE_OFFSET;
+		initrd_end = initrd_start + ramdisk->size;
 		return;
 	}
 
-	relocate_initrd();
+	relocate_initrd(ramdisk);
 
-	memblock_free(ramdisk_image, ramdisk_end - ramdisk_image);
+	memblock_free(ramdisk->start_addr,
+		ramdisk->end_addr - ramdisk->start_addr);
 }
 #else
-static void __init early_reserve_initrd(void)
+static u64 __init get_ramdisk_image(void)
+{
+	return 0;
+}
+static u64 __init get_ramdisk_size(void)
 {
+	return 0;
 }
-static void __init reserve_initrd(void)
+static void __init reserve_initrd(struct ramdisk *ramdisk)
 {
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
@@ -844,13 +833,26 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
  *
  * Note: On x86_64, fixmaps are ready for use even before this is called.
  */
-
 void __init setup_arch(char **cmdline_p)
 {
+	struct ramdisk ramdisk_image = {
+		.start_addr = get_ramdisk_image(),
+		.size  = get_ramdisk_size(),
+		.reserve_ramdisk = true
+	};
+
+	/* Assume only end is not page aligned */
+	ramdisk_image.end_addr = PAGE_ALIGN(ramdisk_image.start_addr + ramdisk_image.size),
+
 	memblock_reserve(__pa_symbol(_text),
 			 (unsigned long)__bss_stop - (unsigned long)_text);
 
-	early_reserve_initrd();
+	if (!boot_params.hdr.type_of_loader || !ramdisk_image.start_addr
+		|| !ramdisk_image.size)
+		ramdisk_image.reserve_ramdisk = false;	/* No initrd provided by bootloader */
+	else
+		memblock_reserve(ramdisk_image.start_addr,
+				ramdisk_image.end_addr - ramdisk_image.start_addr);
 
 	/*
 	 * At this point everything still needed from the boot loader
@@ -1135,7 +1137,8 @@ void __init setup_arch(char **cmdline_p)
 	/* Allocate bigger log buffer */
 	setup_log_buf(1);
 
-	reserve_initrd();
+	if (ramdisk_image.reserve_ramdisk)
+		reserve_initrd(&ramdisk_image);
 
 #if defined(CONFIG_ACPI) && defined(CONFIG_BLK_DEV_INITRD)
 	acpi_initrd_override((void *)initrd_start, initrd_end - initrd_start);
-- 
2.7.0.25.gfc10eb5