[PATCH] Don't overwrite initrd.

[PATCH] Don't overwrite initrd.

[Eric W. Biederman]

In 2.4.x we reserve the location of the initrd too late to keep it
from being overwritten by the struct mem_map array, and I'm tired of
being bitten by that bug.

This fixes that problem in two parts.

First it explicitly reserves moves bootmem_bitmap into the init_data
area of the kernel.  The dynamic allocation was silly when it had
to be covered by the early page tables.

Second it moves the initrd handling up before we do any early memory
allocations.

And third as a general clean up measure users of __pa and virt_to_bus
where changed to virt_to_phys as that is what those functions were
doing, getting the physical memory address of various pages.


diff -uNrX linux-exclude-files linux-2.4.9/arch/i386/kernel/setup.c linux-2.4.9.eb1/arch/i386/kernel/setup.c
--- linux-2.4.9/arch/i386/kernel/setup.c	Wed Jul 25 14:24:11 2001
+++ linux-2.4.9.eb1/arch/i386/kernel/setup.c	Wed Aug 29 21:40:37 2001
@@ -765,9 +765,32 @@
 	}
 }
 
+
+
+#define PFN_UP(x)	(((x) + PAGE_SIZE-1) >> PAGE_SHIFT)
+#define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
+#define PFN_PHYS(x)	((x) << PAGE_SHIFT)
+
+/*
+ * 128MB for vmalloc and initrd
+ */
+#define VMALLOC_RESERVE	(unsigned long)(128 << 20)
+#define MAXMEM		(unsigned long)(-PAGE_OFFSET-VMALLOC_RESERVE)
+#define MAXMEM_PFN	PFN_DOWN(MAXMEM)
+#define MAX_NONPAE_PFN	(1 << 20)
+
+/* On x86 for 1GB low mem the bootmem_bitmap is at worst 32k
+ * that is big but nothing to worry about.  This must be in the kernels
+ * initial page tables so don't even try to get fancy where we allocate it.
+ * This data must be aligned on a page boundary so since I don't
+ * have a handlig __aligned_page_size attribute I allocate an extra
+ * PAGE_SIZE -1 bytes.
+ */
+static unsigned char bootmem_bitmap[((MAXMEM_PFN +7)/8) + PAGE_SIZE -1] __initdata = { 0 };
+
 void __init setup_arch(char **cmdline_p)
 {
-	unsigned long bootmap_size, low_mem_size;
+	unsigned long bootmap_pfn, low_mem_size;
 	unsigned long start_pfn, max_pfn, max_low_pfn;
 	int i;
 
@@ -801,30 +824,18 @@
 	init_mm.end_data = (unsigned long) &_edata;
 	init_mm.brk = (unsigned long) &_end;
 
-	code_resource.start = virt_to_bus(&_text);
-	code_resource.end = virt_to_bus(&_etext)-1;
-	data_resource.start = virt_to_bus(&_etext);
-	data_resource.end = virt_to_bus(&_edata)-1;
+	code_resource.start = virt_to_phys(&_text);
+	code_resource.end = virt_to_phys(&_etext)-1;
+	data_resource.start = virt_to_phys(&_etext);
+	data_resource.end = virt_to_phys(&_edata)-1;
 
 	parse_mem_cmdline(cmdline_p);
 
-#define PFN_UP(x)	(((x) + PAGE_SIZE-1) >> PAGE_SHIFT)
-#define PFN_DOWN(x)	((x) >> PAGE_SHIFT)
-#define PFN_PHYS(x)	((x) << PAGE_SHIFT)
-
-/*
- * 128MB for vmalloc and initrd
- */
-#define VMALLOC_RESERVE	(unsigned long)(128 << 20)
-#define MAXMEM		(unsigned long)(-PAGE_OFFSET-VMALLOC_RESERVE)
-#define MAXMEM_PFN	PFN_DOWN(MAXMEM)
-#define MAX_NONPAE_PFN	(1 << 20)
-
 	/*
 	 * partially used pages are not usable - thus
 	 * we are rounding upwards:
 	 */
-	start_pfn = PFN_UP(__pa(&_end));
+	start_pfn = PFN_UP(virt_to_phys(&_end));
 
 	/*
 	 * Find the highest page frame number we have available
@@ -879,7 +890,8 @@
 	/*
 	 * Initialize the boot-time allocator (with low memory only):
 	 */
-	bootmap_size = init_bootmem(start_pfn, max_low_pfn);
+	bootmap_pfn = PFN_UP(virt_to_phys(&bootmem_bitmap));
+	init_bootmem(bootmap_pfn, max_low_pfn);
 
 	/*
 	 * Register fully available low RAM pages with the bootmem allocator.
@@ -915,14 +927,32 @@
 		size = last_pfn - curr_pfn;
 		free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
 	}
-	/*
-	 * Reserve the bootmem bitmap itself as well. We do this in two
-	 * steps (first step was init_bootmem()) because this catches
-	 * the (very unlikely) case of us accidentally initializing the
-	 * bootmem allocator with an invalid RAM area.
+	/* 
+	 * Reserve the kernel memory.
 	 */
-	reserve_bootmem(HIGH_MEMORY, (PFN_PHYS(start_pfn) +
-			 bootmap_size + PAGE_SIZE-1) - (HIGH_MEMORY));
+	reserve_bootmem(HIGH_MEMORY, PFN_PHYS(start_pfn) + 
+		PAGE_SIZE-1 - (HIGH_MEMORY));
+
+	/* 
+	 * Reserve the initrd 
+	 */
+#ifdef CONFIG_BLK_DEV_INITRD
+	initrd_start = 0;
+	initrd_end = 0;
+	if (LOADER_TYPE && INITRD_START && INITRD_SIZE) {
+		if (INITRD_START + INITRD_SIZE <= (max_low_pfn << PAGE_SHIFT)) {
+			reserve_bootmem(INITRD_START, INITRD_SIZE);
+			initrd_start = INITRD_START + PAGE_OFFSET;
+			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);
+		}
+	}
+#endif
 
 	/*
 	 * reserve physical page 0 - it's a special BIOS page on many boxes,
@@ -958,23 +988,6 @@
 	init_apic_mappings();
 #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;
-		}
-	}
-#endif
 
 	/*
 	 * Request address space for all standard RAM and ROM resources
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