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Subject[patch 34/50] SPARC64: Fix "mem=xxx" handling.
-stable review patch.  If anyone has any objections, please let us know.
------------------

From: David Miller <davem@davemloft.net>

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>

---
arch/sparc64/mm/init.c | 147 +++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 124 insertions(+), 23 deletions(-)

--- linux-2.6.19.1.orig/arch/sparc64/mm/init.c
+++ linux-2.6.19.1/arch/sparc64/mm/init.c
@@ -872,6 +872,115 @@ static unsigned long __init choose_bootm
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
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
}
}
#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);
--
-
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