From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0884C433E0 for ; Tue, 22 Dec 2020 20:04:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E9C920771 for ; Tue, 22 Dec 2020 20:04:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727394AbgLVUEO (ORCPT ); Tue, 22 Dec 2020 15:04:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:47712 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726275AbgLVUEN (ORCPT ); Tue, 22 Dec 2020 15:04:13 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 48F9B21D81; Tue, 22 Dec 2020 20:03:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1608667412; bh=uJ4An1wnldMhr2Wy6GlXvJSV0e7Q73eZYXMEC7AsUTo=; h=Date:From:To:Subject:In-Reply-To:From; b=1sqhDCabdwBndTgXl9gB0zYgBUGv6HEwCfc4htKOC0Mc/bujXB+NigFe3kL67q4dG rDYlegh+SMODa8IsDSB7aTcIPNkn8/IVUVQS4YkKMk5aJddD+QYx//CWbtulJBRiTu NWnY8bEm+HRGPRcgGhKOdXPzFU+3mfBtrVlIoRgQ= Date: Tue, 22 Dec 2020 12:03:31 -0800 From: Andrew Morton To: akpm@linux-foundation.org, andreyknvl@google.com, aryabinin@virtuozzo.com, Branislav.Rankov@arm.com, catalin.marinas@arm.com, dvyukov@google.com, elver@google.com, eugenis@google.com, glider@google.com, gor@linux.ibm.com, kevin.brodsky@arm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, Vincenzo.Frascino@arm.com, will.deacon@arm.com Subject: [patch 59/60] kasan, mm: allow cache merging with no metadata Message-ID: <20201222200331.wcT_Yhdtg%akpm@linux-foundation.org> In-Reply-To: <20201222115844.d30aaef7df6f5b120d3e0c3d@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Andrey Konovalov Subject: kasan, mm: allow cache merging with no metadata The reason cache merging is disabled with KASAN is because KASAN puts its metadata right after the allocated object. When the merged caches have slightly different sizes, the metadata ends up in different places, which KASAN doesn't support. It might be possible to adjust the metadata allocation algorithm and make it friendly to the cache merging code. Instead this change takes a simpler approach and allows merging caches when no metadata is present. Which is the case for hardware tag-based KASAN with kasan.mode=prod. Link: https://lkml.kernel.org/r/37497e940bfd4b32c0a93a702a9ae4cf061d5392.1606162397.git.andreyknvl@google.com Link: https://linux-review.googlesource.com/id/Ia114847dfb2244f297d2cb82d592bf6a07455dba Co-developed-by: Vincenzo Frascino Signed-off-by: Vincenzo Frascino Signed-off-by: Andrey Konovalov Reviewed-by: Dmitry Vyukov Reviewed-by: Marco Elver Tested-by: Vincenzo Frascino Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Vasily Gorbik Cc: Will Deacon Signed-off-by: Andrew Morton --- include/linux/kasan.h | 21 +++++++++++++++++++-- mm/kasan/common.c | 11 +++++++++++ mm/slab_common.c | 3 ++- 3 files changed, 32 insertions(+), 3 deletions(-) --- a/include/linux/kasan.h~kasan-mm-allow-cache-merging-with-no-metadata +++ a/include/linux/kasan.h @@ -82,17 +82,30 @@ struct kasan_cache { }; #ifdef CONFIG_KASAN_HW_TAGS + DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled); + static __always_inline bool kasan_enabled(void) { return static_branch_likely(&kasan_flag_enabled); } -#else + +#else /* CONFIG_KASAN_HW_TAGS */ + static inline bool kasan_enabled(void) { return true; } -#endif + +#endif /* CONFIG_KASAN_HW_TAGS */ + +slab_flags_t __kasan_never_merge(void); +static __always_inline slab_flags_t kasan_never_merge(void) +{ + if (kasan_enabled()) + return __kasan_never_merge(); + return 0; +} void __kasan_unpoison_range(const void *addr, size_t size); static __always_inline void kasan_unpoison_range(const void *addr, size_t size) @@ -239,6 +252,10 @@ static inline bool kasan_enabled(void) { return false; } +static inline slab_flags_t kasan_never_merge(void) +{ + return 0; +} static inline void kasan_unpoison_range(const void *address, size_t size) {} static inline void kasan_alloc_pages(struct page *page, unsigned int order) {} static inline void kasan_free_pages(struct page *page, unsigned int order) {} --- a/mm/kasan/common.c~kasan-mm-allow-cache-merging-with-no-metadata +++ a/mm/kasan/common.c @@ -86,6 +86,17 @@ asmlinkage void kasan_unpoison_task_stac } #endif /* CONFIG_KASAN_STACK */ +/* + * Only allow cache merging when stack collection is disabled and no metadata + * is present. + */ +slab_flags_t __kasan_never_merge(void) +{ + if (kasan_stack_collection_enabled()) + return SLAB_KASAN; + return 0; +} + void __kasan_alloc_pages(struct page *page, unsigned int order) { u8 tag; --- a/mm/slab_common.c~kasan-mm-allow-cache-merging-with-no-metadata +++ a/mm/slab_common.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -53,7 +54,7 @@ static DECLARE_WORK(slab_caches_to_rcu_d */ #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ - SLAB_FAILSLAB | SLAB_KASAN) + SLAB_FAILSLAB | kasan_never_merge()) #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ SLAB_CACHE_DMA32 | SLAB_ACCOUNT) _