powerpc: Minor cleanups of kernel virt address space definitions

Make FIXADDR_TOP a compile time constant and cleanup a
couple of definitions relative to the layout of the kernel
address space on ppc32. We also print out that layout at
boot time for debugging purposes.

This is a pre-requisite for properly fixing non-coherent
DMA allocactions.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

5 files changed, 37 insertions, 12 deletions

diff --git a/arch/powerpc/include/asm/fixmap.h b/arch/powerpc/include/asm/fixmap.h
index d60fd18f428c..f1f4e23a84e9 100644
--- a/arch/powerpc/include/asm/fixmap.h
+++ b/arch/powerpc/include/asm/fixmap.h
@@ -14,8 +14,6 @@
 #ifndef _ASM_FIXMAP_H
 #define _ASM_FIXMAP_H
 
-extern unsigned long FIXADDR_TOP;
-
 #ifndef __ASSEMBLY__
 #include <linux/kernel.h>
 #include <asm/page.h>
@@ -24,6 +22,8 @@ extern unsigned long FIXADDR_TOP;
 #include <asm/kmap_types.h>
 #endif
 
+#define FIXADDR_TOP     ((unsigned long)(-PAGE_SIZE))
+
 /*
  * Here we define all the compile-time 'special' virtual
  * addresses. The point is to have a constant address at
diff --git a/arch/powerpc/include/asm/pgtable-ppc32.h b/arch/powerpc/include/asm/pgtable-ppc32.h
index ba45c997830f..28fe9d4bae35 100644
--- a/arch/powerpc/include/asm/pgtable-ppc32.h
+++ b/arch/powerpc/include/asm/pgtable-ppc32.h
@@ -10,7 +10,7 @@
 
 extern unsigned long va_to_phys(unsigned long address);
 extern pte_t *va_to_pte(unsigned long address);
-extern unsigned long ioremap_bot, ioremap_base;
+extern unsigned long ioremap_bot;
 
 #ifdef CONFIG_44x
 extern int icache_44x_need_flush;
@@ -56,8 +56,26 @@ extern int icache_44x_need_flush;
         printk("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
 
 /*
+ * 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
+ */
+#ifdef CONFIG_HIGHMEM
+#define KVIRT_TOP       PKMAP_BASE
+#else
+#define KVIRT_TOP       (0xfe000000UL)  /* for now, could be FIXMAP_BASE ? */
+#endif
+
+/*
+ * ioremap_bot starts at that address. Early ioremaps move down from there,
+ * until mem_init() at which point this becomes the top of the vmalloc
+ * and ioremap space
+ */
+#define IOREMAP_TOP     KVIRT_TOP
+
+/*
  * Just any arbitrary offset to the start of the vmalloc VM area: the
- * current 64MB value just means that there will be a 64MB "hole" after the
+ * current 16MB value just means that there will be a 64MB "hole" after the
  * physical memory until the kernel virtual memory starts.  That means that
  * any out-of-bounds memory accesses will hopefully be caught.
  * The vmalloc() routines leaves a hole of 4kB between each vmalloced
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 666a5e8a5be1..3de6a0d93824 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -168,12 +168,8 @@ void __init MMU_init(void)
                 ppc_md.progress("MMU:mapin", 0x301);
         mapin_ram();
 
-#ifdef CONFIG_HIGHMEM
-        ioremap_base = PKMAP_BASE;
-#else
-        ioremap_base = 0xfe000000UL;    /* for now, could be 0xfffff000 */
-#endif /* CONFIG_HIGHMEM */
-        ioremap_bot = ioremap_base;
+        /* Initialize early top-down ioremap allocator */
+        ioremap_bot = IOREMAP_TOP;
 
         /* Map in I/O resources */
         if (ppc_md.progress)
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index d0602a76bf7f..d3a4e67561fa 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -380,6 +380,19 @@ void __init mem_init(void)
                 bsssize >> 10,
                 initsize >> 10);
 
+#ifdef CONFIG_PPC32
+        pr_info("Kernel virtual memory layout:\n");
+        pr_info("  * 0x%08lx..0x%08lx  : fixmap\n", FIXADDR_START, FIXADDR_TOP);
+#ifdef CONFIG_HIGHMEM
+        pr_info("  * 0x%08lx..0x%08lx  : highmem PTEs\n",
+                PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP));
+#endif /* CONFIG_HIGHMEM */
+        pr_info("  * 0x%08lx..0x%08lx  : early ioremap\n",
+                ioremap_bot, IOREMAP_TOP);
+        pr_info("  * 0x%08lx..0x%08lx  : vmalloc & ioremap\n",
+                VMALLOC_START, VMALLOC_END);
+#endif /* CONFIG_PPC32 */
+
         mem_init_done = 1;
 }
 
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 430d0908fa50..5422169626ba 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -399,8 +399,6 @@ void kernel_map_pages(struct page *page, int numpages, int enable)
 #endif /* CONFIG_DEBUG_PAGEALLOC */
 
 static int fixmaps;
-unsigned long FIXADDR_TOP = (-PAGE_SIZE);
-EXPORT_SYMBOL(FIXADDR_TOP);
 
 void __set_fixmap (enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags)
 {