[PATCH RFC] powerpc/mm: Support bootmem for PPC64 again

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

CONFIG_NO_BOOTMEM is enabled on PPC platforms by default. However,
user might disable that to have bootmem for other purpose. So it's
resonable to support it.

This implements setup_bootmem() which is called by initmem_init()
to setup bootmem node and its free bitmap. In the meantime, the
free pages frames tracked by memblock are released to bootmem.
In theory, we also need similar thing for PPC32 platforms. However,
I don't have machine for testing. So that would be something later
when I have hardware to test.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c | 38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 669a15e..288b1b5 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -951,6 +951,41 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
 	NODE_DATA(nid)->node_spanned_pages = spanned_pages;
 }
 
+#ifndef CONFIG_NO_BOOTMEM
+static void __init setup_bootmem(struct pglist_data *pgdat,
+				 unsigned long start_pfn,
+				 unsigned long end_pfn)
+{
+	unsigned long map_size, addr;
+	phys_addr_t cur[2], range[2];
+	u64 i;
+
+	/* Memory required for bootmem bitmap */
+	map_size = bootmem_bootmap_pages(end_pfn - start_pfn);
+	map_size <<= PAGE_SHIFT;
+	addr = memblock_alloc_try_nid(map_size,
+				      SMP_CACHE_BYTES, pgdat->node_id);
+
+	/* Initialize bootmem allocator */
+	pgdat->bdata = &bootmem_node_data[pgdat->node_id];
+	init_bootmem_node(pgdat, PHYS_PFN(addr), start_pfn, end_pfn);
+
+	/* Release free pages in memblock */
+	range[0] = PFN_PHYS(start_pfn);
+	range[1] = PFN_PHYS(end_pfn);
+	for_each_free_mem_range(i, pgdat->node_id, MEMBLOCK_NONE,
+				&cur[0], &cur[1], NULL) {
+		cur[0] = clamp(cur[0], range[0], range[1]);
+		cur[1] = clamp(cur[1], range[0], range[1]);
+		if (cur[0] >= cur[1])
+			continue;
+
+		memblock_free_early_nid(cur[0], cur[1] - cur[0],
+					pgdat->node_id);
+	}
+}
+#endif /* !CONFIG_NO_BOOTMEM */
+
 void __init initmem_init(void)
 {
 	int nid, cpu;
@@ -977,6 +1012,9 @@ void __init initmem_init(void)
 
 		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
 		setup_node_data(nid, start_pfn, end_pfn);
+#ifndef CONFIG_NO_BOOTMEM
+		setup_bootmem(NODE_DATA(nid), start_pfn, end_pfn);
+#endif
 		sparse_memory_present_with_active_regions(nid);
 	}
 
-- 
2.1.0