[PATCH] SPARC64: Fix "mem=xxx" handling.

We were not being careful enough.  When we trim the physical
memory areas, we have to make sure we don't remove the kernel
image or initial ramdisk image ranges.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index 09cb7fccc03a758ca2e0f8351734e8a550830c02..ab6d0ca718706fc575a17673459e6129f93643f5 100644 (file)
--- a/arch/sparc64/mm/init.c
+++ b/arch/sparc64/mm/init.c
@@ -872,6 +872,115 @@ static unsigned long __init choose_bootmap_pfn(unsigned long start_pfn,
        prom_halt();
 }
 
+static void __init trim_pavail(unsigned long *cur_size_p,
+                              unsigned long *end_of_phys_p)
+{
+       unsigned long to_trim = *cur_size_p - cmdline_memory_size;
+       unsigned long avoid_start, avoid_end;
+       int i;
+
+       to_trim = PAGE_ALIGN(to_trim);
+
+       avoid_start = avoid_end = 0;
+#ifdef CONFIG_BLK_DEV_INITRD
+       avoid_start = initrd_start;
+       avoid_end = PAGE_ALIGN(initrd_end);
+#endif
+
+       /* Trim some pavail[] entries in order to satisfy the
+        * requested "mem=xxx" kernel command line specification.
+        *
+        * We must not trim off the kernel image area nor the
+        * initial ramdisk range (if any).  Also, we must not trim
+        * any pavail[] entry down to zero in order to preserve
+        * the invariant that all pavail[] entries have a non-zero
+        * size which is assumed by all of the code in here.
+        */
+       for (i = 0; i < pavail_ents; i++) {
+               unsigned long start, end, kern_end;
+               unsigned long trim_low, trim_high, n;
+
+               kern_end = PAGE_ALIGN(kern_base + kern_size);
+
+               trim_low = start = pavail[i].phys_addr;
+               trim_high = end = start + pavail[i].reg_size;
+
+               if (kern_base >= start &&
+                   kern_base < end) {
+                       trim_low = kern_base;
+                       if (kern_end >= end)
+                               continue;
+               }
+               if (kern_end >= start &&
+                   kern_end < end) {
+                       trim_high = kern_end;
+               }
+               if (avoid_start &&
+                   avoid_start >= start &&
+                   avoid_start < end) {
+                       if (trim_low > avoid_start)
+                               trim_low = avoid_start;
+                       if (avoid_end >= end)
+                               continue;
+               }
+               if (avoid_end &&
+                   avoid_end >= start &&
+                   avoid_end < end) {
+                       if (trim_high < avoid_end)
+                               trim_high = avoid_end;
+               }
+
+               if (trim_high <= trim_low)
+                       continue;
+
+               if (trim_low == start && trim_high == end) {
+                       /* Whole chunk is available for trimming.
+                        * Trim all except one page, in order to keep
+                        * entry non-empty.
+                        */
+                       n = (end - start) - PAGE_SIZE;
+                       if (n > to_trim)
+                               n = to_trim;
+
+                       if (n) {
+                               pavail[i].phys_addr += n;
+                               pavail[i].reg_size -= n;
+                               to_trim -= n;
+                       }
+               } else {
+                       n = (trim_low - start);
+                       if (n > to_trim)
+                               n = to_trim;
+
+                       if (n) {
+                               pavail[i].phys_addr += n;
+                               pavail[i].reg_size -= n;
+                               to_trim -= n;
+                       }
+                       if (to_trim) {
+                               n = end - trim_high;
+                               if (n > to_trim)
+                                       n = to_trim;
+                               if (n) {
+                                       pavail[i].reg_size -= n;
+                                       to_trim -= n;
+                               }
+                       }
+               }
+
+               if (!to_trim)
+                       break;
+       }
+
+       /* Recalculate.  */
+       *cur_size_p = 0UL;
+       for (i = 0; i < pavail_ents; i++) {
+               *end_of_phys_p = pavail[i].phys_addr +
+                       pavail[i].reg_size;
+               *cur_size_p += pavail[i].reg_size;
+       }
+}
+
 static unsigned long __init bootmem_init(unsigned long *pages_avail,
                                         unsigned long phys_base)
 {
@@ -889,31 +998,13 @@ static unsigned long __init bootmem_init(unsigned long *pages_avail,
                end_of_phys_memory = pavail[i].phys_addr +
                        pavail[i].reg_size;
                bytes_avail += pavail[i].reg_size;
-               if (cmdline_memory_size) {
-                       if (bytes_avail > cmdline_memory_size) {
-                               unsigned long slack = bytes_avail - cmdline_memory_size;
-
-                               bytes_avail -= slack;
-                               end_of_phys_memory -= slack;
-
-                               pavail[i].reg_size -= slack;
-                               if ((long)pavail[i].reg_size <= 0L) {
-                                       pavail[i].phys_addr = 0xdeadbeefUL;
-                                       pavail[i].reg_size = 0UL;
-                                       pavail_ents = i;
-                               } else {
-                                       pavail[i+1].reg_size = 0Ul;
-                                       pavail[i+1].phys_addr = 0xdeadbeefUL;
-                                       pavail_ents = i + 1;
-                               }
-                               break;
-                       }
-               }
        }
 
-       *pages_avail = bytes_avail >> PAGE_SHIFT;
-
-       end_pfn = end_of_phys_memory >> PAGE_SHIFT;
+       /* Determine the location of the initial ramdisk before trying
+        * to honor the "mem=xxx" command line argument.  We must know
+        * where the kernel image and the ramdisk image are so that we
+        * do not trim those two areas from the physical memory map.
+        */
 
 #ifdef CONFIG_BLK_DEV_INITRD
        /* Now have to check initial ramdisk, so that bootmap does not overwrite it */
@@ -932,6 +1023,16 @@ static unsigned long __init bootmem_init(unsigned long *pages_avail,
                }
        }
 #endif 
+
+       if (cmdline_memory_size &&
+           bytes_avail > cmdline_memory_size)
+               trim_pavail(&bytes_avail,
+                           &end_of_phys_memory);
+
+       *pages_avail = bytes_avail >> PAGE_SHIFT;
+
+       end_pfn = end_of_phys_memory >> PAGE_SHIFT;
+
        /* Initialize the boot-time allocator. */
        max_pfn = max_low_pfn = end_pfn;
        min_low_pfn = (phys_base >> PAGE_SHIFT);