linux-kernel - [PATCH AUTOSEL 5.3 34/49] ARM: 8903/1: ensure that usable memory in bank 0 starts from a PMD-aligned address

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Message-Id: <20190929173053.8400-34-sashal@kernel.org>
Date:   Sun, 29 Sep 2019 13:30:34 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mike Rapoport <mike.rapoport@...il.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.3 34/49] ARM: 8903/1: ensure that usable memory in bank 0 starts from a PMD-aligned address

From: Mike Rapoport <mike.rapoport@...il.com>

[ Upstream commit 00d2ec1e6bd82c0538e6dd3e4a4040de93ba4fef ]

The calculation of memblock_limit in adjust_lowmem_bounds() assumes that
bank 0 starts from a PMD-aligned address. However, the beginning of the
first bank may be NOMAP memory and the start of usable memory
will be not aligned to PMD boundary. In such case the memblock_limit will
be set to the end of the NOMAP region, which will prevent any memblock
allocations.

Mark the region between the end of the NOMAP area and the next PMD-aligned
address as NOMAP as well, so that the usable memory will start at
PMD-aligned address.

Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm/mm/mmu.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index d9a0038774a6d..d5e0b908f0bad 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1177,6 +1177,22 @@ void __init adjust_lowmem_bounds(void)
 	 */
 	vmalloc_limit = (u64)(uintptr_t)vmalloc_min - PAGE_OFFSET + PHYS_OFFSET;
 
+	/*
+	 * The first usable region must be PMD aligned. Mark its start
+	 * as MEMBLOCK_NOMAP if it isn't
+	 */
+	for_each_memblock(memory, reg) {
+		if (!memblock_is_nomap(reg)) {
+			if (!IS_ALIGNED(reg->base, PMD_SIZE)) {
+				phys_addr_t len;
+
+				len = round_up(reg->base, PMD_SIZE) - reg->base;
+				memblock_mark_nomap(reg->base, len);
+			}
+			break;
+		}
+	}
+
 	for_each_memblock(memory, reg) {
 		phys_addr_t block_start = reg->base;
 		phys_addr_t block_end = reg->base + reg->size;
-- 
2.20.1