[PATCH] Change address of ppc64 initial segment table

On ppc64 machines with segment tables, CPU0's segment table is at a
fixed address, currently 0x9000. This patch moves it to the free
space at 0x6000, just below the fwnmi data area. This saves 8k of
space in vmlinux and the runtime kernel image.

Signed-off-by: David Gibson <[e-mail]>
Signed-off-by: Paul Mackerras <[e-mail]>

arch/ppc64/kernel/head.S

···
  * We layout physical memory as follows:
  * 0x0000 - 0x00ff : Secondary processor spin code
  * 0x0100 - 0x2fff : pSeries Interrupt prologs
- * 0x3000 - 0x6fff : interrupt support, iSeries and common interrupt prologs
+ * 0x3000 - 0x5fff : interrupt support, iSeries and common interrupt prologs
+ * 0x6000 - 0x6fff : Initial (CPU0) segment table
  * 0x7000 - 0x7fff : FWNMI data area
- * 0x9000 - 0x9fff : Initial segment table
+ * 0x8000 -        : Early init and support code
  */
 
 /*
···
 	b	1b
 
 /*
+ * Space for CPU0's segment table.
+ *
+ * On iSeries, the hypervisor must fill in at least one entry before
+ * we get control (with relocate on).  The address is give to the hv
+ * as a page number (see xLparMap in LparData.c), so this must be at a
+ * fixed address (the linker can't compute (u64)&initial_stab >>
+ * PAGE_SHIFT).
+ */
+	. = STAB0_PHYS_ADDR	/* 0x6000 */
+	.globl initial_stab
+initial_stab:
+	.space	4096
+
+/*
  * Data area reserved for FWNMI option.
  * This address (0x7000) is fixed by the RPA.
  */
···
 	.globl fwnmi_data_area
 fwnmi_data_area:
 	.space	PAGE_SIZE
-
-	/*
-	 * Space for the initial segment table
-	 * For LPAR, the hypervisor must fill in at least one entry
-	 * before we get control (with relocate on)
-	 */
-	. = STAB0_PHYS_ADDR
-	.globl __start_stab
-__start_stab:
-
-	. = (STAB0_PHYS_ADDR + PAGE_SIZE)
-	.globl __end_stab
-__end_stab:
 
 /*
  * On pSeries, secondary processors spin in the following code.

arch/ppc64/kernel/pacaData.c

···
 
 #define BOOTCPU_PACA_INIT(number)					    \
 {									    \
-	PACA_INIT_COMMON(number, 1, 0, STAB0_VIRT_ADDR)			    \
+	PACA_INIT_COMMON(number, 1, 0, (u64)&initial_stab)		    \
 	PACA_INIT_ISERIES(number)					    \
 }
 
···
 
 #define BOOTCPU_PACA_INIT(number)					    \
 {									    \
-	PACA_INIT_COMMON(number, 1, STAB0_PHYS_ADDR, STAB0_VIRT_ADDR)	    \
+	PACA_INIT_COMMON(number, 1, STAB0_PHYS_ADDR, (u64)&initial_stab)    \
 }
 #endif
 

include/asm-ppc64/mmu.h

···
 #define STE_VSID_SHIFT	12
 
 /* Location of cpu0's segment table */
-#define STAB0_PAGE	0x9
+#define STAB0_PAGE	0x6
 #define STAB0_PHYS_ADDR	(STAB0_PAGE<<PAGE_SHIFT)
-#define STAB0_VIRT_ADDR	(KERNELBASE+STAB0_PHYS_ADDR)
+
+#ifndef __ASSEMBLY__
+extern char initial_stab[];
+#endif /* ! __ASSEMBLY */
 
 /*
  * SLB