[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>

1 files changed, 124 insertions, 23 deletions

diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index a8e8802eed4d..054822a3e05e 100644
--- 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);