linux-kernel - [PATCH 2/3] riscv: Make sure the linear mapping does not use the kernel mapping

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Date:   Tue, 29 Jun 2021 11:13:47 +0200
From:   Alexandre Ghiti <alex@...ti.fr>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Alexandre Ghiti <alex@...ti.fr>
Subject: [PATCH 2/3] riscv: Make sure the linear mapping does not use the kernel mapping

For 64-bit kernel, the end of the address space is occupied by the
kernel mapping and currently, the functions to populate the kernel page
tables (i.e. create_p*d_mapping) do not override existing mapping so we
must make sure the linear mapping does not map memory in the kernel mapping
by clipping the memory above the memory limit.

Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
---
 arch/riscv/mm/init.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 04a5db3a9788..a1a0c4afa80f 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -742,6 +742,8 @@ static void __init setup_vm_final(void)
 		if (start <= __pa(PAGE_OFFSET) &&
 		    __pa(PAGE_OFFSET) < end)
 			start = __pa(PAGE_OFFSET);
+		if (end >= __pa(PAGE_OFFSET) + memory_limit)
+			end = __pa(PAGE_OFFSET) + memory_limit;
 
 		map_size = best_map_size(start, end - start);
 		for (pa = start; pa < end; pa += map_size) {
-- 
2.30.2