[MIPS] setup.c: cleanup bootmem_init()

This function although doing simple thing is hard to follow. It's
mainly due to:

    - a lot of #ifdef
    - bad local names
    - redundant tests

So this patch try to address these issues. It also do not use
max_pfn global which is marked as an unused exported symbol.

As a bonus side, it's now really easy to see what part of the
code is for no-numa system.

There's also no point to make this function inline.

Signed-off-by: Franck Bui-Huu <vagabon.xyz@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 57 insertions, 78 deletions

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 8c2b596a136f..bcbd926e58f7 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -96,6 +96,12 @@ void __init add_memory_region(phys_t start, phys_t size, long type)
         int x = boot_mem_map.nr_map;
         struct boot_mem_map_entry *prev = boot_mem_map.map + x - 1;
 
+        /* Sanity check */
+        if (start + size < start) {
+                printk("Trying to add an invalid memory region, skipped\n");
+                return;
+        }
+
         /*
          * Try to merge with previous entry if any.  This is far less than
          * perfect but is sufficient for most real world cases.
@@ -257,15 +263,16 @@ static inline int parse_rd_cmdline(unsigned long* rd_start, unsigned long* rd_en
         return 0;
 }
 
-#define MAXMEM          HIGHMEM_START
-#define MAXMEM_PFN      PFN_DOWN(MAXMEM)
-
-static inline void bootmem_init(void)
+/*
+ * Initialize the bootmem allocator. It also setup initrd related data
+ * if needed.
+ */
+static void __init bootmem_init(void)
 {
-        unsigned long start_pfn;
         unsigned long reserved_end = (unsigned long)&_end;
 #ifndef CONFIG_SGI_IP27
-        unsigned long first_usable_pfn;
+        unsigned long highest = 0;
+        unsigned long mapstart = -1UL;
         unsigned long bootmap_size;
         int i;
 #endif
@@ -281,7 +288,7 @@ static inline void bootmem_init(void)
                 unsigned long tmp;
                 u32 *initrd_header;
 
-                tmp = ((reserved_end + PAGE_SIZE-1) & PAGE_MASK) - sizeof(u32) * 2;
+                tmp = PAGE_ALIGN(reserved_end) - sizeof(u32) * 2;
                 if (tmp < reserved_end)
                         tmp += PAGE_SIZE;
                 initrd_header = (u32 *)tmp;
@@ -294,16 +301,15 @@ static inline void bootmem_init(void)
         }
 #endif  /* CONFIG_BLK_DEV_INITRD */
 
+#ifndef CONFIG_SGI_IP27
         /*
-         * Partially used pages are not usable - thus
-         * we are rounding upwards.
+         * reserved_end is now a pfn
          */
-        start_pfn = PFN_UP(CPHYSADDR(reserved_end));
+        reserved_end = PFN_UP(CPHYSADDR(reserved_end));
 
-#ifndef CONFIG_SGI_IP27
-        /* Find the highest page frame number we have available.  */
-        max_pfn = 0;
-        first_usable_pfn = -1UL;
+        /*
+         * Find the highest page frame number we have available.
+         */
         for (i = 0; i < boot_mem_map.nr_map; i++) {
                 unsigned long start, end;
 
@@ -312,56 +318,38 @@ static inline void bootmem_init(void)
 
                 start = PFN_UP(boot_mem_map.map[i].addr);
                 end = PFN_DOWN(boot_mem_map.map[i].addr
-                      + boot_mem_map.map[i].size);
+                                + boot_mem_map.map[i].size);
 
-                if (start >= end)
+                if (end > highest)
+                        highest = end;
+                if (end <= reserved_end)
                         continue;
-                if (end > max_pfn)
-                        max_pfn = end;
-                if (start < first_usable_pfn) {
-                        if (start > start_pfn) {
-                                first_usable_pfn = start;
-                        } else if (end > start_pfn) {
-                                first_usable_pfn = start_pfn;
-                        }
-                }
+                if (start >= mapstart)
+                        continue;
+                mapstart = max(reserved_end, start);
         }
 
         /*
          * Determine low and high memory ranges
          */
-        max_low_pfn = max_pfn;
-        if (max_low_pfn > MAXMEM_PFN) {
-                max_low_pfn = MAXMEM_PFN;
-#ifndef CONFIG_HIGHMEM
-                /* Maximum memory usable is what is directly addressable */
-                printk(KERN_WARNING "Warning only %ldMB will be used.\n",
-                       MAXMEM >> 20);
-                printk(KERN_WARNING "Use a HIGHMEM enabled kernel.\n");
+        if (highest > PFN_DOWN(HIGHMEM_START)) {
+#ifdef CONFIG_HIGHMEM
+                highstart_pfn = PFN_DOWN(HIGHMEM_START);
+                highend_pfn = highest;
 #endif
+                highest = PFN_DOWN(HIGHMEM_START);
         }
 
-#ifdef CONFIG_HIGHMEM
         /*
-         * Crude, we really should make a better attempt at detecting
-         * highstart_pfn
+         * Initialize the boot-time allocator with low memory only.
          */
-        highstart_pfn = highend_pfn = max_pfn;
-        if (max_pfn > MAXMEM_PFN) {
-                highstart_pfn = MAXMEM_PFN;
-                printk(KERN_NOTICE "%ldMB HIGHMEM available.\n",
-                       (highend_pfn - highstart_pfn) >> (20 - PAGE_SHIFT));
-        }
-#endif
-
-        /* Initialize the boot-time allocator with low memory only.  */
-        bootmap_size = init_bootmem(first_usable_pfn, max_low_pfn);
+        bootmap_size = init_bootmem(mapstart, highest);
 
         /*
          * Register fully available low RAM pages with the bootmem allocator.
          */
         for (i = 0; i < boot_mem_map.nr_map; i++) {
-                unsigned long curr_pfn, last_pfn, size;
+                unsigned long start, end, size;
 
                 /*
                  * Reserve usable memory.
@@ -369,49 +357,37 @@ static inline void bootmem_init(void)
                 if (boot_mem_map.map[i].type != BOOT_MEM_RAM)
                         continue;
 
-                /*
-                 * We are rounding up the start address of usable memory:
-                 */
-                curr_pfn = PFN_UP(boot_mem_map.map[i].addr);
-                if (curr_pfn >= max_low_pfn)
-                        continue;
-                if (curr_pfn < start_pfn)
-                        curr_pfn = start_pfn;
-
-                /*
-                 * ... and at the end of the usable range downwards:
-                 */
-                last_pfn = PFN_DOWN(boot_mem_map.map[i].addr
+                start = PFN_UP(boot_mem_map.map[i].addr);
+                end   = PFN_DOWN(boot_mem_map.map[i].addr
                                     + boot_mem_map.map[i].size);
-
-                if (last_pfn > max_low_pfn)
-                        last_pfn = max_low_pfn;
-
                 /*
-                 * Only register lowmem part of lowmem segment with bootmem.
+                 * We are rounding up the start address of usable memory
+                 * and at the end of the usable range downwards.
                  */
-                size = last_pfn - curr_pfn;
-                if (curr_pfn > PFN_DOWN(HIGHMEM_START))
-                        continue;
-                if (curr_pfn + size - 1 > PFN_DOWN(HIGHMEM_START))
-                        size = PFN_DOWN(HIGHMEM_START) - curr_pfn;
-                if (!size)
+                if (start >= max_low_pfn)
                         continue;
+                if (start < reserved_end)
+                        start = reserved_end;
+                if (end > max_low_pfn)
+                        end = max_low_pfn;
 
                 /*
-                 * ... finally, did all the rounding and playing
-                 * around just make the area go away?
+                 * ... finally, is the area going away?
                  */
-                if (last_pfn <= curr_pfn)
+                if (end <= start)
                         continue;
+                size = end - start;
 
                 /* Register lowmem ranges */
-                free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
-                memory_present(0, curr_pfn, curr_pfn + size - 1);
+                free_bootmem(PFN_PHYS(start), size << PAGE_SHIFT);
+                memory_present(0, start, end);
         }
 
-        /* Reserve the bootmap memory.  */
-        reserve_bootmem(PFN_PHYS(first_usable_pfn), bootmap_size);
+        /*
+         * Reserve the bootmap memory.
+         */
+        reserve_bootmem(PFN_PHYS(mapstart), bootmap_size);
+
 #endif /* CONFIG_SGI_IP27 */
 
 #ifdef CONFIG_BLK_DEV_INITRD
@@ -483,6 +459,9 @@ static void __init arch_mem_init(char **cmdline_p)
         paging_init();
 }
 
+#define MAXMEM          HIGHMEM_START
+#define MAXMEM_PFN      PFN_DOWN(MAXMEM)
+
 static inline void resource_init(void)
 {
         int i;