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From:   Lecopzer Chen <lecopzer.chen@mediatek.com>
To:     <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <kasan-dev@googlegroups.com>,
        <catalin.marinas@arm.com>, <will@kernel.org>
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        <andreyknvl@gmail.com>, <dvyukov@google.com>,
        <akpm@linux-foundation.org>, <tyhicks@linux.microsoft.com>,
        <maz@kernel.org>, <rppt@kernel.org>, <linux@roeck-us.net>,
        <gustavoars@kernel.org>, <yj.chiang@mediatek.com>,
        Lecopzer Chen <lecopzer.chen@mediatek.com>
Subject: [PATCH v4 5/5] arm64: Kconfig: select KASAN_VMALLOC if KANSAN_GENERIC is enabled
Date:   Wed, 24 Mar 2021 12:05:22 +0800
Message-ID: <20210324040522.15548-6-lecopzer.chen@mediatek.com>
In-Reply-To: <20210324040522.15548-1-lecopzer.chen@mediatek.com>
References: <20210324040522.15548-1-lecopzer.chen@mediatek.com>
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Before this patch, someone who wants to use VMAP_STACK when
KASAN_GENERIC enabled must explicitly select KASAN_VMALLOC.

From Will's suggestion [1]:
  > I would _really_ like to move to VMAP stack unconditionally, and
  > that would effectively force KASAN_VMALLOC to be set if KASAN is in use

Because VMAP_STACK now depends on either HW_TAGS or KASAN_VMALLOC if
KASAN enabled, in order to make VMAP_STACK selected unconditionally,
we bind KANSAN_GENERIC and KASAN_VMALLOC together.

Note that SW_TAGS supports neither VMAP_STACK nor KASAN_VMALLOC now,
so this is the first step to make VMAP_STACK selected unconditionally.

Bind KANSAN_GENERIC and KASAN_VMALLOC together is supposed to cost more
memory at runtime, thus the alternative is using SW_TAGS KASAN instead.

[1]: https://lore.kernel.org/lkml/20210204150100.GE20815@willie-the-truck/

Suggested-by: Will Deacon <will@kernel.org>
Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
---
 arch/arm64/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 3e54fa938234..07762359d741 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -195,6 +195,7 @@ config ARM64
 	select IOMMU_DMA if IOMMU_SUPPORT
 	select IRQ_DOMAIN
 	select IRQ_FORCED_THREADING
+	select KASAN_VMALLOC if KASAN_GENERIC
 	select MODULES_USE_ELF_RELA
 	select NEED_DMA_MAP_STATE
 	select NEED_SG_DMA_LENGTH
-- 
2.25.1