memblock: Introduce default allocation limit and use it to replace explicit ones

This introduce memblock.current_limit which is used to limit allocations
from memblock_alloc() or memblock_alloc_base(..., MEMBLOCK_ALLOC_ACCESSIBLE).

The old MEMBLOCK_ALLOC_ANYWHERE changes value from 0 to ~(u64)0 and can still
be used with memblock_alloc_base() to allocate really anywhere.

It is -no-longer- cropped to MEMBLOCK_REAL_LIMIT which disappears.

Note to archs: I'm leaving the default limit to MEMBLOCK_ALLOC_ANYWHERE. I
strongly recommend that you ensure that you set an appropriate limit
during boot in order to guarantee that an memblock_alloc() at any time
results in something that is accessible with a simple __va().

The reason is that a subsequent patch will introduce the ability for
the array to resize itself by reallocating itself. The MEMBLOCK core will
honor the current limit when performing those allocations.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 15 insertions, 1 deletions

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 3cf3304e901d..c4f6e53264ed 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -34,6 +34,7 @@ struct memblock_type {
 struct memblock {
         unsigned long debug;
         u64 rmo_size;
+        u64 current_limit;
         struct memblock_type memory;
         struct memblock_type reserved;
 };
@@ -46,11 +47,16 @@ extern long memblock_add(u64 base, u64 size);
 extern long memblock_remove(u64 base, u64 size);
 extern long __init memblock_free(u64 base, u64 size);
 extern long __init memblock_reserve(u64 base, u64 size);
+
 extern u64 __init memblock_alloc_nid(u64 size, u64 align, int nid);
 extern u64 __init memblock_alloc(u64 size, u64 align);
+
+/* Flags for memblock_alloc_base() amd __memblock_alloc_base() */
+#define MEMBLOCK_ALLOC_ANYWHERE (~(u64)0)
+#define MEMBLOCK_ALLOC_ACCESSIBLE       0
+
 extern u64 __init memblock_alloc_base(u64 size,
                 u64, u64 max_addr);
-#define MEMBLOCK_ALLOC_ANYWHERE 0
 extern u64 __init __memblock_alloc_base(u64 size,
                 u64 align, u64 max_addr);
 extern u64 __init memblock_phys_mem_size(void);
@@ -66,6 +72,14 @@ extern void memblock_dump_all(void);
 /* Provided by the architecture */
 extern u64 memblock_nid_range(u64 start, u64 end, int *nid);
 
+/**
+ * memblock_set_current_limit - Set the current allocation limit to allow
+ *                         limiting allocations to what is currently
+ *                         accessible during boot
+ * @limit: New limit value (physical address)
+ */
+extern void memblock_set_current_limit(u64 limit);
+
 
 /*
  * pfn conversion functions