linux-kernel - [PATCH 4.9 002/104] arm64: Initialise high

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Date:   Fri, 22 Dec 2017 09:45:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Steve Capper <steve.capper@....com>,
        Will Deacon <will.deacon@....com>
Subject: [PATCH 4.9 002/104] arm64: Initialise high_memory global variable earlier

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Steve Capper <steve.capper@....com>

commit f24e5834a2c3f6c5f814a417f858226f0a010ade upstream.

The high_memory global variable is used by
cma_declare_contiguous(.) before it is defined.

We don't notice this as we compute __pa(high_memory - 1), and it looks
like we're processing a VA from the direct linear map.

This problem becomes apparent when we flip the kernel virtual address
space and the linear map is moved to the bottom of the kernel VA space.

This patch moves the initialisation of high_memory before it used.

Fixes: f7426b983a6a ("mm: cma: adjust address limit to avoid hitting low/high memory boundary")
Signed-off-by: Steve Capper <steve.capper@....com>
Signed-off-by: Will Deacon <will.deacon@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/arm64/mm/init.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -296,6 +296,7 @@ void __init arm64_memblock_init(void)
 		arm64_dma_phys_limit = max_zone_dma_phys();
 	else
 		arm64_dma_phys_limit = PHYS_MASK + 1;
+	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 	dma_contiguous_reserve(arm64_dma_phys_limit);
 
 	memblock_allow_resize();
@@ -322,7 +323,6 @@ void __init bootmem_init(void)
 	sparse_init();
 	zone_sizes_init(min, max);
 
-	high_memory = __va((max << PAGE_SHIFT) - 1) + 1;
 	memblock_dump_all();
 }