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>

2 files changed, 20 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index fed9bf6187d1..3aec0b980f6a 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -98,7 +98,7 @@ static void __init move_device_tree(void)
 
         if ((memory_limit && (start + size) > memory_limit) ||
                         overlaps_crashkernel(start, size)) {
-                p = __va(memblock_alloc_base(size, PAGE_SIZE, memblock.rmo_size));
+                p = __va(memblock_alloc(size, PAGE_SIZE));
                 memcpy(p, initial_boot_params, size);
                 initial_boot_params = (struct boot_param_header *)p;
                 DBG("Moved device tree to 0x%p\n", p);
@@ -655,6 +655,21 @@ static void __init phyp_dump_reserve_mem(void)
 static inline void __init phyp_dump_reserve_mem(void) {}
 #endif /* CONFIG_PHYP_DUMP  && CONFIG_PPC_RTAS */
 
+static void set_boot_memory_limit(void)
+{
+#ifdef CONFIG_PPC32
+        /* 601 can only access 16MB at the moment */
+        if (PVR_VER(mfspr(SPRN_PVR)) == 1)
+                memblock_set_current_limit(0x01000000);
+        /* 8xx can only access 8MB at the moment */
+        else if (PVR_VER(mfspr(SPRN_PVR)) == 0x50)
+                memblock_set_current_limit(0x00800000);
+        else
+                memblock_set_current_limit(0x10000000);
+#else
+        memblock_set_current_limit(memblock.rmo_size);
+#endif
+}
 
 void __init early_init_devtree(void *params)
 {
@@ -683,6 +698,7 @@ void __init early_init_devtree(void *params)
 
         /* Scan memory nodes and rebuild MEMBLOCKs */
         memblock_init();
+
         of_scan_flat_dt(early_init_dt_scan_root, NULL);
         of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);
 
@@ -718,6 +734,8 @@ void __init early_init_devtree(void *params)
 
         DBG("Phys. mem: %llx\n", memblock_phys_mem_size());
 
+        set_boot_memory_limit();
+
         /* We may need to relocate the flat tree, do it now.
          * FIXME .. and the initrd too? */
         move_device_tree();
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index a10ffc85ada7..b7eb1ded3b5f 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -246,7 +246,7 @@ static void __init irqstack_early_init(void)
         unsigned int i;
 
         /* interrupt stacks must be in lowmem, we get that for free on ppc32
-         * as the memblock is limited to lowmem by MEMBLOCK_REAL_LIMIT */
+         * as the memblock is limited to lowmem by default */
         for_each_possible_cpu(i) {
                 softirq_ctx[i] = (struct thread_info *)
                         __va(memblock_alloc(THREAD_SIZE, THREAD_SIZE));