From nobody Tue Feb 10 00:59:37 2026 Received: from mail-07.mail-europe.com (mail-0701.mail-europe.com [51.83.17.38]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1C4B634DCF7 for ; Mon, 12 Jan 2026 17:27:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=51.83.17.38 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768238880; cv=none; b=paaAiZGZRDziXrOpGyxDkLHQQVYvzh6m8SKcXqdMQJET37EGdmtMc/OznCg0uZ1h4D1XSbkHw8ODVFGgnh/0TAW9v9CNpG7iGeamPCMZK4K4jJBOx/Ggk55tk7AT6AB4dnEc6WLjOhj+PILbZZ92pyMUc5mp3l1bKkXzzz7+MMM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768238880; c=relaxed/simple; bh=GEz+2VQvEoIvaf/5b06kvAVrpBdGWmz3kFBnPleUPQw=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=mmJg3Jy3ORKGav3BHBgfn1D3u2ehwyTy1pIMUqVDRfNFvM8VWs2yr+gHMcP3JQ20fgNz+xUMmUH5i4lArPjSt36SMlzrpSDT6IBr/vVePoPJ1s9I3QM06PhlOCXRtPne//c8G1QVclScPFHLw/9zBVpbtWA24BPEGFSsMEZgU8A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pm.me; spf=fail smtp.mailfrom=pm.me; dkim=pass (2048-bit key) header.d=pm.me header.i=@pm.me header.b=E0ml2UWO; arc=none smtp.client-ip=51.83.17.38 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=pm.me Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=pm.me Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=pm.me header.i=@pm.me header.b="E0ml2UWO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail3; t=1768238867; x=1768498067; bh=yESMxyUg3nEjWhMgjSTmmglxLz0NhSPoNJMpCNZiqMs=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector; b=E0ml2UWO0gaxz3PTlf5/zQnrEZwbNK1fh90WlTa6MRRxNcNMudGUpmXCGS3M43yvJ v3HX/WOpOlX9oJbHzJhPhS4APnzjFNJnoy1deGRnXpXtkUFzZniYhHHp/FaXdEMc7E 0sMy/Msr7YzONOEnaGMVxr1Nhvt90ikcXoMs0GlLRKyqoQuyehKnbo8xm49ydX/HWd ScRWr5adodhfyXmAcnMPre9jyC8WWhwh2P9Pbn0O4Zf4qszckK5DporB8Ci6CFVYJU 6/86ZdNwyYkqKpqAJRGc1G2BOUxMPRw8XN6LT218d003Ct6KHLbq7ghHQ73zaGQzYj vDbo+AfBRb5Dg== Date: Mon, 12 Jan 2026 17:27:43 +0000 To: Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Axel Rasmussen , Yuanchu Xie , Wei Xu From: Maciej Wieczor-Retman Cc: m.wieczorretman@pm.me, Maciej Wieczor-Retman , kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v8 04/14] x86/kasan: Add arch specific kasan functions Message-ID: <785eb728e2cc897e05ee709d42214172be481ab9.1768233085.git.m.wieczorretman@pm.me> In-Reply-To: References: Feedback-ID: 164464600:user:proton X-Pm-Message-ID: 10432f028dc5aec035899d14c4ef5f6e6dbe8005 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Maciej Wieczor-Retman KASAN's software tag-based mode needs multiple macros/functions to handle tag and pointer interactions - to set, retrieve and reset tags from the top bits of a pointer. Mimic functions currently used by arm64 but change the tag's position to bits [60:57] in the pointer. Signed-off-by: Maciej Wieczor-Retman Reviewed-by: Andrey Ryabinin --- Changelog v7: - Add KASAN_TAG_BYTE_MASK to avoid circular includes and avoid removing KASAN_TAG_MASK from mmzone.h. - Remove Andrey's Acked-by tag. Changelog v6: - Remove empty line after ifdef CONFIG_KASAN_SW_TAGS - Add ifdef 64 bit to avoid problems in vdso32. - Add Andrey's Acked-by tag. Changelog v4: - Rewrite __tag_set() without pointless casts and make it more readable. Changelog v3: - Reorder functions so that __tag_*() etc are above the arch_kasan_*() ones. - Remove CONFIG_KASAN condition from __tag_set() arch/x86/include/asm/kasan.h | 42 ++++++++++++++++++++++++++++++++++-- include/linux/kasan-tags.h | 2 ++ include/linux/mmzone.h | 2 +- 3 files changed, 43 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/kasan.h b/arch/x86/include/asm/kasan.h index d7e33c7f096b..eab12527ed7f 100644 --- a/arch/x86/include/asm/kasan.h +++ b/arch/x86/include/asm/kasan.h @@ -3,6 +3,8 @@ #define _ASM_X86_KASAN_H =20 #include +#include +#include #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) #define KASAN_SHADOW_SCALE_SHIFT 3 =20 @@ -24,8 +26,43 @@ KASAN_SHADOW_SCALE_SHIFT))) =20 #ifndef __ASSEMBLER__ +#include +#include +#include + +#ifdef CONFIG_KASAN_SW_TAGS +#define __tag_shifted(tag) FIELD_PREP(GENMASK_ULL(60, 57), tag) +#define __tag_reset(addr) (sign_extend64((u64)(addr), 56)) +#define __tag_get(addr) ((u8)FIELD_GET(GENMASK_ULL(60, 57), (u64)addr)) +#else +#define __tag_shifted(tag) 0UL +#define __tag_reset(addr) (addr) +#define __tag_get(addr) 0 +#endif /* CONFIG_KASAN_SW_TAGS */ + +#ifdef CONFIG_64BIT +static inline void *__tag_set(const void *__addr, u8 tag) +{ + u64 addr =3D (u64)__addr; + + addr &=3D ~__tag_shifted(KASAN_TAG_BYTE_MASK); + addr |=3D __tag_shifted(tag & KASAN_TAG_BYTE_MASK); + + return (void *)addr; +} +#else +static inline void *__tag_set(void *__addr, u8 tag) +{ + return __addr; +} +#endif + +#define arch_kasan_set_tag(addr, tag) __tag_set(addr, tag) +#define arch_kasan_reset_tag(addr) __tag_reset(addr) +#define arch_kasan_get_tag(addr) __tag_get(addr) =20 #ifdef CONFIG_KASAN + void __init kasan_early_init(void); void __init kasan_init(void); void __init kasan_populate_shadow_for_vaddr(void *va, size_t size, int nid= ); @@ -34,8 +71,9 @@ static inline void kasan_early_init(void) { } static inline void kasan_init(void) { } static inline void kasan_populate_shadow_for_vaddr(void *va, size_t size, int nid) { } -#endif =20 -#endif +#endif /* CONFIG_KASAN */ + +#endif /* __ASSEMBLER__ */ =20 #endif diff --git a/include/linux/kasan-tags.h b/include/linux/kasan-tags.h index ad5c11950233..e4f26bec3673 100644 --- a/include/linux/kasan-tags.h +++ b/include/linux/kasan-tags.h @@ -10,6 +10,8 @@ #define KASAN_TAG_WIDTH 0 #endif =20 +#define KASAN_TAG_BYTE_MASK ((1UL << KASAN_TAG_WIDTH) - 1) + #ifndef KASAN_TAG_KERNEL #define KASAN_TAG_KERNEL 0xFF /* native kernel pointers tag */ #endif diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 75ef7c9f9307..3839052121d4 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -1177,7 +1177,7 @@ static inline bool zone_is_empty(const struct zone *z= one) #define NODES_MASK ((1UL << NODES_WIDTH) - 1) #define SECTIONS_MASK ((1UL << SECTIONS_WIDTH) - 1) #define LAST_CPUPID_MASK ((1UL << LAST_CPUPID_SHIFT) - 1) -#define KASAN_TAG_MASK ((1UL << KASAN_TAG_WIDTH) - 1) +#define KASAN_TAG_MASK KASAN_TAG_BYTE_MASK #define ZONEID_MASK ((1UL << ZONEID_SHIFT) - 1) =20 static inline enum zone_type memdesc_zonenum(memdesc_flags_t flags) --=20 2.52.0