From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
[ Upstream commit 3e8635fb2e072672cbc650989ffedf8300ad67fb ]
KASAN causes increased stack usage, which can lead to stack overflows.
The logic in Kconfig to suggest a larger default doesn't work if a user
has CONFIG_EXPERT enabled and has an existing .config with a smaller
value.
Follow the lead of x86 and arm64, and force the thread size to be
increased when KASAN is enabled.
That also has the effect of enlarging the stack for 64-bit KASAN builds,
which is also desirable.
Fixes: edbadaf06710 ("powerpc/kasan: Fix stack overflow by increasing THREAD_SHIFT")
Reported-by: Erhard Furtner <erhard_f@xxxxxxxxxxx>
Reported-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
[mpe: Use MIN_THREAD_SHIFT as suggested by Christophe]
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220601143114.133524-1-mpe@xxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/powerpc/Kconfig | 1 -
arch/powerpc/include/asm/thread_info.h | 10 ++++++++--
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 5afa0ebd78ca..78dd6be8b31d 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -786,7 +786,6 @@ config THREAD_SHIFT
range 13 15
default "15" if PPC_256K_PAGES
default "14" if PPC64
- default "14" if KASAN
default "13"
help
Used to define the stack size. The default is almost always what you
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 46a210b03d2b..6de3517bea94 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -14,10 +14,16 @@
#ifdef __KERNEL__
-#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT
+#ifdef CONFIG_KASAN
+#define MIN_THREAD_SHIFT (CONFIG_THREAD_SHIFT + 1)
+#else
+#define MIN_THREAD_SHIFT CONFIG_THREAD_SHIFT
+#endif
+
+#if defined(CONFIG_VMAP_STACK) && MIN_THREAD_SHIFT < PAGE_SHIFT
#define THREAD_SHIFT PAGE_SHIFT
#else
-#define THREAD_SHIFT CONFIG_THREAD_SHIFT
+#define THREAD_SHIFT MIN_THREAD_SHIFT
#endif
#define THREAD_SIZE (1 << THREAD_SHIFT)
--
2.35.1
