[PATCH V5 10/11] riscv: Add config of thread stack size

[guoren at kernel.org]

From: Guo Ren <guoren at linux.alibaba.com>

0cac21b02ba5 ("risc v: use 16KB kernel stack on 64-bit") increase the
thread size mandatory, but some scenarios, such as D1 with a small
memory footprint, would suffer from that. After independent irq stack
support, let's give users a choice to determine their custom stack size.

Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
Signed-off-by: Guo Ren <guoren at kernel.org>
Cc: Andreas Schwab <schwab at suse.de>
---
 arch/riscv/Kconfig                   | 18 ++++++++++++++++++
 arch/riscv/include/asm/thread_info.h | 12 +-----------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index dfe600f3526c..8241b12399d7 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -442,6 +442,24 @@ config IRQ_STACKS
 	  Add independent irq & softirq stacks for percpu to prevent kernel stack
 	  overflows. We may save some memory footprint by disabling IRQ_STACKS.
 
+config THREAD_SIZE
+	int "Kernel stack size (in bytes)" if EXPERT
+	range 4096 65536
+	default 8192 if 32BIT && !KASAN
+	default 32768 if 64BIT && KASAN
+	default 16384
+	help
+	  Specify the Pages of thread stack size (from 4KB to 64KB), which also
+	  affects irq stack size, which is equal to thread stack size.
+
+config THREAD_SIZE_ORDER
+	int
+	default 0 if THREAD_SIZE = 4096
+	default 1 if THREAD_SIZE <= 8192
+	default 2 if THREAD_SIZE <= 16384
+	default 3 if THREAD_SIZE <= 32768
+	default 4
+
 endmenu # "Platform type"
 
 menu "Kernel features"
diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h
index 043da8ccc7e6..c970d41dc4c6 100644
--- a/arch/riscv/include/asm/thread_info.h
+++ b/arch/riscv/include/asm/thread_info.h
@@ -11,18 +11,8 @@
 #include <asm/page.h>
 #include <linux/const.h>
 
-#ifdef CONFIG_KASAN
-#define KASAN_STACK_ORDER 1
-#else
-#define KASAN_STACK_ORDER 0
-#endif
-
 /* thread information allocation */
-#ifdef CONFIG_64BIT
-#define THREAD_SIZE_ORDER	(2 + KASAN_STACK_ORDER)
-#else
-#define THREAD_SIZE_ORDER	(1 + KASAN_STACK_ORDER)
-#endif
+#define THREAD_SIZE_ORDER	CONFIG_THREAD_SIZE_ORDER
 #define THREAD_SIZE		(PAGE_SIZE << THREAD_SIZE_ORDER)
 
 /*
-- 
2.36.1