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Thu, 04 Feb 2021 15:01:11 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l7g84-0006Yn-Ru; Thu, 04 Feb 2021 15:01:09 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4F1F364DBA; Thu, 4 Feb 2021 15:01:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612450867; bh=X3nDmJLqqvOAm1bXasPKKjZSRX+UA/YVvHhs0nTd4PE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Mg4bHqG1JiGD+kFpfyB7KEAJYbxncHFMReA4zfD++ymeCwsVKBWNIfoI4buqLZUoJ ohLIbTf2EidP0Mxo2YG6rqVGliuVwtlOAoRbQK4nJPtXk7zg7q0166rsx3lGydAqoC U2UoZ6WXgGwJ+HYL/oAmzNDtkyryGVFypiM5sGtafFhTCpok9WYOn4IA1VKGyI46W9 WO8/IItQpXGt02EujFUGVoU3orj4aRW/ERrrwvCuDWssqzDE/5/DK/Ba99eunJbxnC DINnx62rYn9eMMFfhELFw+UDZgfcz5J4l3i1Lm8sTdjnLkMGnaYoWpFMOSfcoFjunr Xx4S47isXTL2w== Date: Thu, 4 Feb 2021 15:01:01 +0000 From: Will Deacon To: Lecopzer Chen Subject: Re: [PATCH v2 1/4] arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC Message-ID: <20210204150100.GE20815@willie-the-truck> References: <20210204124543.GA20468@willie-the-truck> <20210204144612.75582-1-lecopzer@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210204144612.75582-1-lecopzer@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210204_100109_035568_9D66A00B X-CRM114-Status: GOOD ( 22.23 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: lecopzer.chen@mediatek.com, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, tyhicks@linux.microsoft.com, glider@google.com, vincenzo.frascino@arm.com, ardb@kernel.org, yj.chiang@mediatek.com, kasan-dev@googlegroups.com, dvyukov@google.com, aryabinin@virtuozzo.com, linux@roeck-us.net, andreyknvl@google.com, broonie@kernel.org, linux-mediatek@lists.infradead.org, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org, gustavoars@kernel.org, akpm@linux-foundation.org, robin.murphy@arm.com, rppt@kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Feb 04, 2021 at 10:46:12PM +0800, Lecopzer Chen wrote: > > On Sat, Jan 09, 2021 at 06:32:49PM +0800, Lecopzer Chen wrote: > > > Linux support KAsan for VMALLOC since commit 3c5c3cfb9ef4da9 > > > ("kasan: support backing vmalloc space with real shadow memory") > > > > > > Like how the MODULES_VADDR does now, just not to early populate > > > the VMALLOC_START between VMALLOC_END. > > > similarly, the kernel code mapping is now in the VMALLOC area and > > > should keep these area populated. > > > > > > Signed-off-by: Lecopzer Chen > > > --- > > > arch/arm64/mm/kasan_init.c | 23 ++++++++++++++++++----- > > > 1 file changed, 18 insertions(+), 5 deletions(-) > > > > > > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c > > > index d8e66c78440e..39b218a64279 100644 > > > --- a/arch/arm64/mm/kasan_init.c > > > +++ b/arch/arm64/mm/kasan_init.c > > > @@ -214,6 +214,7 @@ static void __init kasan_init_shadow(void) > > > { > > > u64 kimg_shadow_start, kimg_shadow_end; > > > u64 mod_shadow_start, mod_shadow_end; > > > + u64 vmalloc_shadow_start, vmalloc_shadow_end; > > > phys_addr_t pa_start, pa_end; > > > u64 i; > > > > > > @@ -223,6 +224,9 @@ static void __init kasan_init_shadow(void) > > > mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR); > > > mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END); > > > > > > + vmalloc_shadow_start = (u64)kasan_mem_to_shadow((void *)VMALLOC_START); > > > + vmalloc_shadow_end = (u64)kasan_mem_to_shadow((void *)VMALLOC_END); > > > + > > > /* > > > * We are going to perform proper setup of shadow memory. > > > * At first we should unmap early shadow (clear_pgds() call below). > > > @@ -241,12 +245,21 @@ static void __init kasan_init_shadow(void) > > > > > > kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END), > > > (void *)mod_shadow_start); > > > - kasan_populate_early_shadow((void *)kimg_shadow_end, > > > - (void *)KASAN_SHADOW_END); > > > + if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) { > > > > Do we really need yet another CONFIG option for KASAN? What's the use-case > > for *not* enabling this if you're already enabling one of the KASAN > > backends? > > As I know, KASAN_VMALLOC now only supports KASAN_GENERIC and also > KASAN_VMALLOC uses more memory to map real shadow memory (1/8 of vmalloc va). The shadow is allocated dynamically though, isn't it? > There should be someone can enable KASAN_GENERIC but can't use VMALLOC > due to memory issue. That doesn't sound particularly realistic to me. The reason I'm pushing here is because 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. So unless there's a really good reason not to do that, please can we make this unconditional for arm64? Pretty please? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel