xtensa: add HIGHMEM support

Introduce fixmap area just below the vmalloc region. Use it for atomic
mapping of high memory pages.
High memory on cores with cache aliasing is not supported and is still
to be implemented. Fail build for such configurations for now.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

1 files changed, 31 insertions, 14 deletions

diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
index 03bd025307e3..4224256bb215 100644
--- a/arch/xtensa/mm/init.c
+++ b/arch/xtensa/mm/init.c
@@ -20,6 +20,7 @@
 #include <linux/errno.h>
 #include <linux/bootmem.h>
 #include <linux/gfp.h>
+#include <linux/highmem.h>
 #include <linux/swap.h>
 #include <linux/mman.h>
 #include <linux/nodemask.h>
@@ -296,19 +297,13 @@ void __init bootmem_init(void)
 
 void __init zones_init(void)
 {
-        unsigned long zones_size[MAX_NR_ZONES];
-        int i;
-
         /* All pages are DMA-able, so we put them all in the DMA zone. */
-
-        zones_size[ZONE_DMA] = max_low_pfn - ARCH_PFN_OFFSET;
-        for (i = 1; i < MAX_NR_ZONES; i++)
-                zones_size[i] = 0;
-
+        unsigned long zones_size[MAX_NR_ZONES] = {
+                [ZONE_DMA] = max_low_pfn - ARCH_PFN_OFFSET,
 #ifdef CONFIG_HIGHMEM
-        zones_size[ZONE_HIGHMEM] = max_pfn - max_low_pfn;
+                [ZONE_HIGHMEM] = max_pfn - max_low_pfn,
 #endif
-
+        };
         free_area_init_node(0, zones_size, ARCH_PFN_OFFSET, NULL);
 }
 
@@ -318,16 +313,38 @@ void __init zones_init(void)
 
 void __init mem_init(void)
 {
-        max_mapnr = max_low_pfn - ARCH_PFN_OFFSET;
-        high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
-
 #ifdef CONFIG_HIGHMEM
-#error HIGHGMEM not implemented in init.c
+        unsigned long tmp;
+
+        reset_all_zones_managed_pages();
+        for (tmp = max_low_pfn; tmp < max_pfn; tmp++)
+                free_highmem_page(pfn_to_page(tmp));
 #endif
 
+        max_mapnr = max_pfn - ARCH_PFN_OFFSET;
+        high_memory = (void *)__va(max_low_pfn << PAGE_SHIFT);
+
         free_all_bootmem();
 
         mem_init_print_info(NULL);
+        pr_info("virtual kernel memory layout:\n"
+#ifdef CONFIG_HIGHMEM
+                "    pkmap   : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+                "    fixmap  : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+#endif
+                "    vmalloc : 0x%08x - 0x%08x  (%5u MB)\n"
+                "    lowmem  : 0x%08x - 0x%08lx  (%5lu MB)\n",
+#ifdef CONFIG_HIGHMEM
+                PKMAP_BASE, PKMAP_BASE + LAST_PKMAP * PAGE_SIZE,
+                (LAST_PKMAP*PAGE_SIZE) >> 10,
+                FIXADDR_START, FIXADDR_TOP,
+                (FIXADDR_TOP - FIXADDR_START) >> 10,
+#endif
+                VMALLOC_START, VMALLOC_END,
+                (VMALLOC_END - VMALLOC_START) >> 20,
+                PAGE_OFFSET, PAGE_OFFSET +
+                (max_low_pfn - min_low_pfn) * PAGE_SIZE,
+                ((max_low_pfn - min_low_pfn) * PAGE_SIZE) >> 20);
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD