linux-kernel - [PATCH AUTOSEL 6.2 05/10] of: fdt: Scan /memreserve/ last

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Message-Id: <20230511193850.623289-5-sashal@kernel.org>
Date:   Thu, 11 May 2023 15:38:43 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Lucas Tanure <tanure@...ux.com>, Rob Herring <robh@...nel.org>,
        Sasha Levin <sashal@...nel.org>, robh+dt@...nel.org,
        frowand.list@...il.com, devicetree@...r.kernel.org
Subject: [PATCH AUTOSEL 6.2 05/10] of: fdt: Scan /memreserve/ last

From: Lucas Tanure <tanure@...ux.com>

[ Upstream commit b413281876292de44ae84e9a9ce9d62e47f266e9 ]

Change the scanning /memreserve/ and /reserved-memory node order to fix
Kernel panic on Khadas Vim3 Board.

If /memreserve/ goes first, the memory is reserved, but nomap can't be
applied to the region. So the memory won't be used by Linux, but it is
still present in the linear map as normal memory, which allows
speculation. Legitimate access to adjacent pages will cause the CPU
to end up prefetching into them leading to Kernel panic.

So /reserved-memory node should go first, as it has a more updated
description of the memory regions and can apply flags, like nomap.

Link: https://lore.kernel.org/all/CAJX_Q+1Tjc+-TjZ6JW9X0NxEdFe=82a9626yL63j7uVD4LpxEA@mail.gmail.com/
Signed-off-by: Lucas Tanure <tanure@...ux.com>
Link: https://lore.kernel.org/r/20230424113846.46382-1-tanure@linux.com
Signed-off-by: Rob Herring <robh@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/of/fdt.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index d1a68b6d03b3f..c28aedd7ae1f7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -635,6 +635,9 @@ void __init early_init_fdt_scan_reserved_mem(void)
 	if (!initial_boot_params)
 		return;
 
+	fdt_scan_reserved_mem();
+	fdt_reserve_elfcorehdr();
+
 	/* Process header /memreserve/ fields */
 	for (n = 0; ; n++) {
 		fdt_get_mem_rsv(initial_boot_params, n, &base, &size);
@@ -643,8 +646,6 @@ void __init early_init_fdt_scan_reserved_mem(void)
 		memblock_reserve(base, size);
 	}
 
-	fdt_scan_reserved_mem();
-	fdt_reserve_elfcorehdr();
 	fdt_init_reserved_mem();
 }
 
-- 
2.39.2