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mm: autopatch: fix 32bit kasan can not boot on T5W [1/1]

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PD#SWPL-225609

Problem:
If enabled 32bit kasan on T5W with VMAP, kernel can not boot.
This case can not happen on T5D.

Solution:
Rootcause is bss cleared but real data keeps in cache, not flushed
into DDR, and physical kasan shadow page soon be mapped to shadow
memory while in shadow virtual address we see random data, which
caused kasan check failed in vmap fixup function and crashed. So
just add a dcache flush function call after bss cleared.

Verify:
T5W

Change-Id: I864e4d29e75ef3b55fd39b3d76734ff0fbced908
Signed-off-by: Jianxiong Pan <jianxiong.pan@amlogic.com>
This commit is contained in:
Jianxiong Pan
2025-08-19 09:33:46 +08:00
committed by gerrit autosubmit
parent 5724876ed7
commit ba5cfe4dbd
1 changed files with 56 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
auto_patch/common16-6.12/common/04_memory/0018-mm-autopatch-fix-32bit-kasan-cant-boot-on-T5W-1-1.patch
+56
View File
@@ -0,0 +1,56 @@
From 5176f8ce39cf8ef417ce721dc40cbde0a7f4eee9 Mon Sep 17 00:00:00 2001
From: Jianxiong Pan <jianxiong.pan@amlogic.com>
Date: Tue, 19 Aug 2025 09:31:15 +0800
Subject: [PATCH] mm: autopatch: fix 32bit kasan can not boot on T5W [1/1]
PD#SWPL-225609
Problem:
If enabled 32bit kasan on T5W with VMAP, kernel can not boot.
This case can not happen on T5D.
Solution:
Rootcause is bss cleared but real data keeps in cache, not flushed
into DDR, and physical kasan shadow page soon be mapped to shadow
memory while in shadow virtual address we see random data, which
caused kasan check failed in vmap fixup function and crashed. So
just add a dcache flush function call after bss cleared.
Verify:
T5W
Change-Id: I7c36effe2704c0e73110e93e4b8b64936fcdaf60
Signed-off-by: Jianxiong Pan <jianxiong.pan@amlogic.com>
---
arch/arm/kernel/head-common.S | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index 42cae73fcc19d..9c3bafb2834ed 100644
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -105,6 +105,21 @@ __mmap_switched:
mov r1, #0
bl __memset @ clear .bss
+#if defined (CONFIG_KASAN) && defined (CONFIG_AMLOGIC_VMAP)
+ /* After bss cleard, kasan_early_shadow_page are 0 in cache
+ * But on A55 it's physical memory keeps random data, this
+ * physical page will be mapped to shadow memory very soon(few
+ * lines behind) in function kasan_early_init, this caused kasan
+ * shadow memory check failed and crashed in function
+ * fixup_init_thread_union(). However, this problem don't see on
+ * A35 processor. Rootcause may related with core's cache replace/
+ * clean policy.
+ */
+ push {r0-r12, lr}
+ bl v7_flush_dcache_all
+ pop {r0-r12, lr}
+#endif
+
adr_l r0, init_task @ get swapper task_struct
set_current r0, r1
--
2.50.1