On Mon, Sep 19, 2022 at 4:35 PM Guo Ren <guoren@xxxxxxxxxx> wrote: > > On Sun, Sep 11, 2022 at 12:07 AM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > On Sat, Sep 10, 2022, at 2:52 PM, Guo Ren wrote: > > > On Thu, Sep 8, 2022 at 3:37 PM Arnd Bergmann <arnd@xxxxxxxx> wrote: > > >> On Thu, Sep 8, 2022, at 4:25 AM, guoren@xxxxxxxxxx wrote: > > >> > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > >> - When VMAP_STACK is set, make it possible to select non-power-of-two > > >> stack sizes. Most importantly, 12KB should be a really interesting > > >> choice as 8KB is probably still not enough for many 64-bit workloads, > > >> but 16KB is often more than what you need. You probably don't > > >> want to allow 64BIT/8KB without VMAP_STACK anyway since that just > > >> makes it really hard to debug, so hiding the option when VMAP_STACK > > >> is disabled may also be a good idea. > > > I don't want this config to depend on VMAP_STACK. Some D1 chips would > > > run with an 8K stack size and !VMAP_STACK. > > > > That sounds like a really bad idea, why would you want to risk > > using such a small stack without CONFIG_VMAP_STACK? > > > > Are you worried about increased memory usage or something else? > > > > > /* 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) > > > > This doesn't actually allow additional THREAD_SIZE values, as you > > still round up to the nearest power of two. > > > > I think all the non-arch code can deal with non-power-of-2 > > sizes, so you'd just need > > > > #define THREAD_SIZE round_up(CONFIG_THREAD_SIZE, PAGE_SIZE) > > > > and fix up the risc-v specific code to do the right thing > > as well. I now see that THREAD_SIZE_ORDER is not actually > > used anywhere with CONFIG_VMAP_STACK, so I suppose that > > definition can be skipped, but you still need a THREAD_ALIGN > > definition that is a power of two and at least a page larger > > than THREAD_SIZE. > Sorry, I missed this part. I would RESEND v5 Hi Arnd, How about this one: (only THREAD_SIZE, no THREAD_ORDER&SHIFT.) commit 447cddede7898c35a9a3b8ab3d7bdb7b0de0714d (HEAD) Author: Guo Ren <guoren@xxxxxxxxxx> Date: Mon Sep 5 22:53:06 2022 -0400 riscv: Add config of thread stack size 0cac21b02ba5 ("riscv: 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@xxxxxxxxxxxxxxxxx> Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> Cc: Andreas Schwab <schwab@xxxxxxx> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index dfe600f3526c..8def456f328c 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -442,6 +442,16 @@ 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. + 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..181fdfbd5e99 100644 --- a/arch/riscv/include/asm/thread_info.h +++ b/arch/riscv/include/asm/thread_info.h @@ -11,24 +11,12 @@ #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 (PAGE_SIZE << THREAD_SIZE_ORDER) +#define THREAD_SIZE CONFIG_THREAD_SIZE /* * By aligning VMAP'd stacks to 2 * THREAD_SIZE, we can detect overflow by - * checking sp & (1 << THREAD_SHIFT), which we can do cheaply in the entry - * assembly. + * checking sp & THREAD_SIZE, which we can do cheaply in the entry assembly. */ #ifdef CONFIG_VMAP_STACK #define THREAD_ALIGN (2 * THREAD_SIZE) @@ -36,7 +24,6 @@ #define THREAD_ALIGN THREAD_SIZE #endif -#define THREAD_SHIFT (PAGE_SHIFT + THREAD_SIZE_ORDER) #define OVERFLOW_STACK_SIZE SZ_4K #define SHADOW_OVERFLOW_STACK_SIZE (1024) diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 426529b84db0..1e35fb3bdae5 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -29,8 +29,8 @@ _restore_kernel_tpsp: #ifdef CONFIG_VMAP_STACK addi sp, sp, -(PT_SIZE_ON_STACK) - srli sp, sp, THREAD_SHIFT - andi sp, sp, 0x1 + srli sp, sp, PAGE_SHIFT + andi sp, sp, (THREAD_SIZE >> PAGE_SHIFT) bnez sp, handle_kernel_stack_overflow REG_L sp, TASK_TI_KERNEL_SP(tp) #endif > > > > > Arnd > > > > -- > Best Regards > Guo Ren -- Best Regards Guo Ren