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From: ryabinin.a.a@gmail.com (Andrey Ryabinin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()
Date: Tue, 11 Aug 2015 19:30:42 +0300	[thread overview]
Message-ID: <55CA2332.7040206@gmail.com> (raw)
In-Reply-To: <20150811154117.GH23307@e104818-lin.cambridge.arm.com>



On 08/11/2015 06:41 PM, Catalin Marinas wrote:
> On Tue, Aug 11, 2015 at 05:18:15AM +0300, Andrey Ryabinin wrote:
>> --- /dev/null
>> +++ b/mm/kasan/kasan_init.c
> [...]
>> +#if CONFIG_PGTABLE_LEVELS > 3
>> +pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
>> +#endif
>> +#if CONFIG_PGTABLE_LEVELS > 2
>> +pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> +#endif
>> +pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
> 
> Is there any problem if you don't add the #ifs here? Wouldn't the linker
> remove them if they are not used?
> 

AFAIK such optimization is possible if we build with -fdata-sections flag and
use --gc-sections flag in linker, but we don't do this.

WARNING: multiple messages have this Message-ID (diff)
From: Andrey Ryabinin <ryabinin.a.a@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>,
	linux-arm-kernel@lists.infradead.org, Yury <yury.norov@gmail.com>,
	Alexey Klimov <klimov.linux@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-mm@kvack.org, Linus Walleij <linus.walleij@linaro.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	David Keitel <dkeitel@codeaurora.org>,
	Alexander Potapenko <glider@google.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()
Date: Tue, 11 Aug 2015 19:30:42 +0300	[thread overview]
Message-ID: <55CA2332.7040206@gmail.com> (raw)
In-Reply-To: <20150811154117.GH23307@e104818-lin.cambridge.arm.com>



On 08/11/2015 06:41 PM, Catalin Marinas wrote:
> On Tue, Aug 11, 2015 at 05:18:15AM +0300, Andrey Ryabinin wrote:
>> --- /dev/null
>> +++ b/mm/kasan/kasan_init.c
> [...]
>> +#if CONFIG_PGTABLE_LEVELS > 3
>> +pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
>> +#endif
>> +#if CONFIG_PGTABLE_LEVELS > 2
>> +pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> +#endif
>> +pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
> 
> Is there any problem if you don't add the #ifs here? Wouldn't the linker
> remove them if they are not used?
> 

AFAIK such optimization is possible if we build with -fdata-sections flag and
use --gc-sections flag in linker, but we don't do this.

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WARNING: multiple messages have this Message-ID (diff)
From: Andrey Ryabinin <ryabinin.a.a@gmail.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>,
	linux-arm-kernel@lists.infradead.org, Yury <yury.norov@gmail.com>,
	Alexey Klimov <klimov.linux@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-mm@kvack.org, Linus Walleij <linus.walleij@linaro.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	David Keitel <dkeitel@codeaurora.org>,
	Alexander Potapenko <glider@google.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow()
Date: Tue, 11 Aug 2015 19:30:42 +0300	[thread overview]
Message-ID: <55CA2332.7040206@gmail.com> (raw)
In-Reply-To: <20150811154117.GH23307@e104818-lin.cambridge.arm.com>



On 08/11/2015 06:41 PM, Catalin Marinas wrote:
> On Tue, Aug 11, 2015 at 05:18:15AM +0300, Andrey Ryabinin wrote:
>> --- /dev/null
>> +++ b/mm/kasan/kasan_init.c
> [...]
>> +#if CONFIG_PGTABLE_LEVELS > 3
>> +pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
>> +#endif
>> +#if CONFIG_PGTABLE_LEVELS > 2
>> +pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> +#endif
>> +pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
> 
> Is there any problem if you don't add the #ifs here? Wouldn't the linker
> remove them if they are not used?
> 

AFAIK such optimization is possible if we build with -fdata-sections flag and
use --gc-sections flag in linker, but we don't do this.

  parent reply	other threads:[~2015-08-11 16:30 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-11  2:18 [PATCH v5 0/6] KASAN for amr64 Andrey Ryabinin
2015-08-11  2:18 ` Andrey Ryabinin
2015-08-11  2:18 ` Andrey Ryabinin
2015-08-11  2:18 ` [PATCH v5 1/6] x86/kasan: define KASAN_SHADOW_OFFSET per architecture Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18 ` [PATCH v5 2/6] x86/kasan, mm: introduce generic kasan_populate_zero_shadow() Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11 15:41   ` Catalin Marinas
2015-08-11 15:41     ` Catalin Marinas
2015-08-11 15:41     ` Catalin Marinas
2015-08-11 16:25     ` Andrey Ryabinin
2015-08-11 16:25       ` Andrey Ryabinin
2015-08-11 16:25       ` Andrey Ryabinin
2015-08-11 16:40       ` Catalin Marinas
2015-08-11 16:40         ` Catalin Marinas
2015-08-11 16:40         ` Catalin Marinas
2015-08-12  9:30         ` Andrey Ryabinin
2015-08-12  9:30           ` Andrey Ryabinin
2015-08-12  9:30           ` Andrey Ryabinin
2015-08-12  9:37           ` Will Deacon
2015-08-12  9:37             ` Will Deacon
2015-08-12  9:37             ` Will Deacon
2015-08-12 12:19             ` Andrey Ryabinin
2015-08-12 12:19               ` Andrey Ryabinin
2015-08-12 12:19               ` Andrey Ryabinin
2015-08-12 13:41               ` Will Deacon
2015-08-12 13:41                 ` Will Deacon
2015-08-12 13:41                 ` Will Deacon
2015-08-11 16:30     ` Andrey Ryabinin [this message]
2015-08-11 16:30       ` Andrey Ryabinin
2015-08-11 16:30       ` Andrey Ryabinin
2015-08-11  2:18 ` [PATCH v5 3/6] arm64: introduce VA_START macro - the first kernel virtual address Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18 ` [PATCH v5 4/6] arm64: move PGD_SIZE definition to pgalloc.h Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18 ` [PATCH v5 5/6] arm64: add KASAN support Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11 16:37   ` Catalin Marinas
2015-08-11 16:37     ` Catalin Marinas
2015-08-11 16:37     ` Catalin Marinas
2015-08-11  2:18 ` [PATCH v5 6/6] ARM64: kasan: print memory assignment Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin
2015-08-11  2:18   ` Andrey Ryabinin

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