[PATCH] x86_64: Recover 1MB of kernel memory

Noticed by Jan Beulich.

When the kernel was moved from 1MB to 2MB in 2.6.17 the kernel reservation
code wasn't adjusted and it still reserved starting with 1MB. This means 1MB always
were lost.

This patch fixes this by reserving only starting with _text.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/e820.c

@@ -71,7 +71,11 @@ static inline int bad_addr(unsigned long *addrp, unsigned long size)
 #endif
 	/* kernel code + 640k memory hole (later should not be needed, but 
 	   be paranoid for now) */
-	if (last >= 640*1024 && addr < __pa_symbol(&_end)) { 
+	if (last >= 640*1024 && addr < 1024*1024) {
+		*addrp = 1024*1024;
+		return 1;
+	}
+	if (last >= __pa_symbol(&_text) && last < __pa_symbol(&_end)) {
 		*addrp = __pa_symbol(&_end);
 		return 1;
 	}

arch/x86_64/kernel/setup.c

@@ -521,8 +521,6 @@ static void discover_ebda(void)
 
 void __init setup_arch(char **cmdline_p)
 {
-	unsigned long kernel_end;
-
  	ROOT_DEV = old_decode_dev(ORIG_ROOT_DEV);
  	screen_info = SCREEN_INFO;
 	edid_info = EDID_INFO;
@@ -596,8 +594,8 @@ void __init setup_arch(char **cmdline_p)
 				(table_end - table_start) << PAGE_SHIFT);
 
 	/* reserve kernel */
-	kernel_end = round_up(__pa_symbol(&_end),PAGE_SIZE);
-	reserve_bootmem_generic(HIGH_MEMORY, kernel_end - HIGH_MEMORY);
+	reserve_bootmem_generic(__pa_symbol(&_text),
+				__pa_symbol(&_end) - __pa_symbol(&_text));
 
 	/*
 	 * reserve physical page 0 - it's a special BIOS page on many boxes,