From 42be9559071c84ffd64865680e012b0c8252c2c7 Mon Sep 17 00:00:00 2001
From: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Date: Thu, 5 Jul 2018 18:41:13 -0700
Subject: [PATCH] arm64: mm/memblock: Update memory limit calculation

The system RAM region would not be ideally contiguous from
start to end of DRAM. Detect any offset/holes present in the
DDR region and update the memory limit being set, so that the
DRAM end address is aligned to the memory block size. This is
a requirement for mem-offline framework to work properly.

Change-Id: I97cb0cce70e7c414ae2d200a4a3f714d145c0e64
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
---
 arch/arm64/mm/init.c     | 16 ++++++++++++++--
 include/linux/memblock.h |  1 +
 mm/memblock.c            |  5 +++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 3710fb71b50b..20982031fad8 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -30,6 +30,7 @@
 #include <linux/crash_dump.h>
 #include <linux/memory.h>
 #include <linux/libfdt.h>
+#include <linux/memblock.h>
 
 #include <asm/boot.h>
 #include <asm/fixmap.h>
@@ -268,9 +269,10 @@ static void __init update_memory_limit(void)
 	unsigned long node, mp;
 	const char *p;
 	unsigned long long ram_sz, sz;
+	phys_addr_t end_addr, addr_aligned, offset;
 	int ret;
 
-	ram_sz = memblock_end_of_DRAM() - memblock_start_of_DRAM();
+	ram_sz = memblock_phys_mem_size();
 	node = of_get_flat_dt_subnode_by_name(dt_root, "mem-offline");
 	if (node == -FDT_ERR_NOTFOUND) {
 		pr_err("mem-offine node not found in FDT\n");
@@ -294,7 +296,17 @@ static void __init update_memory_limit(void)
 	}
 	sz = ram_sz - ((ram_sz * mp) / 100);
 	memory_limit = (phys_addr_t)sz;
-	memory_limit = ALIGN(memory_limit, MIN_MEMORY_BLOCK_SIZE);
+	end_addr = memblock_max_addr(memory_limit);
+	addr_aligned = ALIGN(end_addr, MIN_MEMORY_BLOCK_SIZE);
+	offset = addr_aligned - end_addr;
+
+	if (offset > MIN_MEMORY_BLOCK_SIZE / 2) {
+		addr_aligned = ALIGN_DOWN(end_addr, MIN_MEMORY_BLOCK_SIZE);
+		offset = end_addr - addr_aligned;
+		memory_limit -= offset;
+	} else {
+		memory_limit += offset;
+	}
 
 	pr_notice("Memory limit set/overridden to %lldMB\n",
 							memory_limit >> 20);
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index f491690d54c6..ead74b4b6725 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -441,6 +441,7 @@ phys_addr_t memblock_reserved_size(void);
 phys_addr_t memblock_mem_size(unsigned long limit_pfn);
 phys_addr_t memblock_start_of_DRAM(void);
 phys_addr_t memblock_end_of_DRAM(void);
+phys_addr_t memblock_max_addr(phys_addr_t limit);
 void memblock_enforce_memory_limit(phys_addr_t memory_limit);
 void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size);
 void memblock_mem_limit_remove_map(phys_addr_t limit);
diff --git a/mm/memblock.c b/mm/memblock.c
index c4b16cae2bc9..184d3636f85a 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -1645,6 +1645,11 @@ static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)
 	return max_addr;
 }
 
+phys_addr_t __init_memblock memblock_max_addr(phys_addr_t limit)
+{
+	return __find_max_addr(limit);
+}
+
 void __init memblock_enforce_memory_limit(phys_addr_t limit)
 {
 	phys_addr_t max_addr = PHYS_ADDR_MAX;