linux-kernel - [PATCH] arm64: Clear the initial ID map correctly before remapping

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Message-ID: <20240621092809.162-1-yuzenghui@huawei.com>
Date: Fri, 21 Jun 2024 17:28:09 +0800
From: Zenghui Yu <yuzenghui@...wei.com>
To: <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
CC: <catalin.marinas@....com>, <will@...nel.org>, <ardb@...nel.org>,
	<wanghaibin.wang@...wei.com>, Zenghui Yu <yuzenghui@...wei.com>
Subject: [PATCH] arm64: Clear the initial ID map correctly before remapping

In the attempt to clear and recreate the initial ID map for LPA2, we
wrongly use 'start - end' as the map size and make the memset() almost a
nop.

Fix it by passing the correct map size.

Fixes: 9684ec186f8f ("arm64: Enable LPA2 at boot if supported by the system")
Signed-off-by: Zenghui Yu <yuzenghui@...wei.com>
---

Found by code inspection (don't have the appropriate HW to test it).

 arch/arm64/kernel/pi/map_kernel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/pi/map_kernel.c b/arch/arm64/kernel/pi/map_kernel.c
index 5fa08e13e17e..f374a3e5a5fe 100644
--- a/arch/arm64/kernel/pi/map_kernel.c
+++ b/arch/arm64/kernel/pi/map_kernel.c
@@ -173,7 +173,7 @@ static void __init remap_idmap_for_lpa2(void)
 	 * Don't bother with the FDT, we no longer need it after this.
 	 */
 	memset(init_idmap_pg_dir, 0,
-	       (u64)init_idmap_pg_dir - (u64)init_idmap_pg_end);
+	       (u64)init_idmap_pg_end - (u64)init_idmap_pg_dir);
 
 	create_init_idmap(init_idmap_pg_dir, mask);
 	dsb(ishst);
-- 
2.33.0