powerpc/32: make KVIRT_TOP dependent on FIXMAP_START

When we add KASAN shadow area, KVIRT_TOP can't be anymore fixed
at 0xfe000000.

This patch uses FIXADDR_START to define KVIRT_TOP.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/book3s/32/pgtable.h

@@ -134,15 +134,24 @@ static inline bool pte_user(pte_t pte)
 #define PGDIR_MASK	(~(PGDIR_SIZE-1))
 
 #define USER_PTRS_PER_PGD	(TASK_SIZE / PGDIR_SIZE)
+
+#ifndef __ASSEMBLY__
+
+int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
+
+#endif /* !__ASSEMBLY__ */
+
 /*
  * This is the bottom of the PKMAP area with HIGHMEM or an arbitrary
  * value (for now) on others, from where we can start layout kernel
  * virtual space that goes below PKMAP and FIXMAP
  */
+#include <asm/fixmap.h>
+
 #ifdef CONFIG_HIGHMEM
 #define KVIRT_TOP	PKMAP_BASE
 #else
-#define KVIRT_TOP	(0xfe000000UL)	/* for now, could be FIXMAP_BASE ? */
+#define KVIRT_TOP	FIXADDR_START
 #endif
 
 /*
@@ -373,8 +382,6 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
 #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) >> 3 })
 #define __swp_entry_to_pte(x)		((pte_t) { (x).val << 3 })
 
-int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
-
 /* Generic accessors to PTE bits */
 static inline int pte_write(pte_t pte)		{ return !!(pte_val(pte) & _PAGE_RW);}
 static inline int pte_read(pte_t pte)		{ return 1; }

arch/powerpc/include/asm/nohash/32/pgtable.h

@@ -64,15 +64,24 @@ extern int icache_44x_need_flush;
 #define pgd_ERROR(e) \
 	pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
 
+#ifndef __ASSEMBLY__
+
+int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
+
+#endif /* !__ASSEMBLY__ */
+
+
 /*
  * This is the bottom of the PKMAP area with HIGHMEM or an arbitrary
  * value (for now) on others, from where we can start layout kernel
  * virtual space that goes below PKMAP and FIXMAP
  */
+#include <asm/fixmap.h>
+
 #ifdef CONFIG_HIGHMEM
 #define KVIRT_TOP	PKMAP_BASE
 #else
-#define KVIRT_TOP	(0xfe000000UL)	/* for now, could be FIXMAP_BASE ? */
+#define KVIRT_TOP	FIXADDR_START
 #endif
 
 /*
@@ -379,8 +388,6 @@ static inline int pte_young(pte_t pte)
 #define __pte_to_swp_entry(pte)		((swp_entry_t) { pte_val(pte) >> 3 })
 #define __swp_entry_to_pte(x)		((pte_t) { (x).val << 3 })
 
-int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
-
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_POWERPC_NOHASH_32_PGTABLE_H */