powerpc: Set entry point and text address in linker script

Currently we set the kernel entry point and the address of the text
section in the Makefile, using CONFIG_KERNEL_START.

But we've already got <asm/page.h> in the linker script, so we can just
use KERNELBASE directly. That means if we ever change KERNELBASE there's
one less place to change it.

And we can set the entry point with ENTRY().

There are zero differences from "readelf -a vmlinux" with or without this
patch.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>

arch/powerpc/Makefile

@@ -12,9 +12,6 @@
 # Rewritten by Cort Dougan and Paul Mackerras
 #
 
-# This must match PAGE_OFFSET in include/asm-powerpc/page.h.
-KERNELLOAD	:= $(CONFIG_KERNEL_START)
-
 HAS_BIARCH	:= $(call cc-option-yn, -m32)
 
 ifeq ($(CONFIG_PPC64),y)
@@ -59,7 +56,7 @@ override LD	+= -m elf$(SZ)ppc
 override CC	+= -m$(SZ)
 endif
 
-LDFLAGS_vmlinux	:= -Ttext $(KERNELLOAD) -Bstatic -e $(KERNELLOAD)
+LDFLAGS_vmlinux	:= -Bstatic
 
 # The -Iarch/$(ARCH)/include is temporary while we are merging
 CPPFLAGS	+= -Iarch/$(ARCH) -Iarch/$(ARCH)/include

arch/powerpc/kernel/vmlinux.lds.S

 #include <linux/config.h>
-#ifdef CONFIG_PPC64
 #include <asm/page.h>
-#else
-#define PAGE_SIZE	4096
-#endif
 #include <asm-generic/vmlinux.lds.h>
 
+ENTRY(_stext)
+
 #ifdef CONFIG_PPC64
 OUTPUT_ARCH(powerpc:common64)
 jiffies = jiffies_64;
@@ -21,6 +19,7 @@ SECTIONS
     *(.exit.data)
   }
 
+  . = KERNELBASE;
 
   /* Read-only sections, merged into text segment: */
 #ifdef CONFIG_PPC32