Re: [PATCH] powerpc/Kconfig: Force THREAD_SHIFT to at least 14 with KASAN
From: Christophe Leroy <hidden>
Date: 2022-05-31 06:27:05
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Le 31/05/2022 à 08:16, Michael Ellerman a écrit :
Christophe Leroy [off-list ref] writes:quoted
Allthough 14 is the default THREAD_SHIFT when KASAN is selected, taking an old config may keep 13 when CONFIG_EXPERT is selected. Force it to 14 as a minimum when KASAN is selected. Also default to 15 when KASAN on PPC64. Reported-by: Erhard Furtner <redacted> Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/Kconfig | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)I was thinking of doing it in C, similar to the way arm64 handles it. Something like below. It means we always double the stack size when KASAN is enabled. I think it's preferable, as it will always work regardless of whether the user has an old .config (or is bisectting)?
Yes good idea. I leave it to you then. You can therefore also remove the default value for KASAN in Kconfig. Christophe
quoted hunk ↗ jump to hunk
cheersdiff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h index 125328d1b980..c9735f93f8e6 100644 --- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h@@ -14,12 +14,17 @@ #ifdef __KERNEL__ -#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT -#define THREAD_SHIFT PAGE_SHIFT +#ifdef CONFIG_KASAN +#define THREAD_SHIFT (CONFIG_THREAD_SHIFT + 1) #else #define THREAD_SHIFT CONFIG_THREAD_SHIFT #endif +#if defined(CONFIG_VMAP_STACK) && THREAD_SHIFT < PAGE_SHIFT +#undef THREAD_SHIFT +#define THREAD_SHIFT PAGE_SHIFT +#endif + #define THREAD_SIZE (1 << THREAD_SHIFT) /*