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X-CSE-ConnectionGUID: mJpp/UmVRqy1CCE1hF5Bqg== X-CSE-MsgGUID: zMImEg//TVW+URet2GAIXQ== X-IronPort-AV: E=McAfee;i="6800,10657,11533"; a="68971254" X-IronPort-AV: E=Sophos;i="6.18,214,1751266800"; d="scan'208";a="68971254" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2025 13:32:14 -0700 X-CSE-ConnectionGUID: cXWZ7dRGQvecpjyhpKanvw== X-CSE-MsgGUID: bpDPHCHLRsKzMlSFZem02A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,214,1751266800"; d="scan'208";a="169781042" Received: from bergbenj-mobl1.ger.corp.intel.com (HELO wieczorr-mobl1.intel.com) ([10.245.245.6]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2025 13:31:53 -0700 From: Maciej Wieczor-Retman To: sohil.mehta@intel.com, baohua@kernel.org, david@redhat.com, kbingham@kernel.org, weixugc@google.com, Liam.Howlett@oracle.com, alexandre.chartre@oracle.com, kas@kernel.org, mark.rutland@arm.com, trintaeoitogc@gmail.com, axelrasmussen@google.com, yuanchu@google.com, joey.gouly@arm.com, samitolvanen@google.com, joel.granados@kernel.org, graf@amazon.com, vincenzo.frascino@arm.com, kees@kernel.org, ardb@kernel.org, thiago.bauermann@linaro.org, glider@google.com, thuth@redhat.com, kuan-ying.lee@canonical.com, pasha.tatashin@soleen.com, nick.desaulniers+lkml@gmail.com, vbabka@suse.cz, kaleshsingh@google.com, justinstitt@google.com, catalin.marinas@arm.com, alexander.shishkin@linux.intel.com, samuel.holland@sifive.com, dave.hansen@linux.intel.com, corbet@lwn.net, xin@zytor.com, dvyukov@google.com, tglx@linutronix.de, scott@os.amperecomputing.com, jason.andryuk@amd.com, morbo@google.com, nathan@kernel.org, lorenzo.stoakes@oracle.com, mingo@redhat.com, brgerst@gmail.com, kristina.martsenko@arm.com, bigeasy@linutronix.de, luto@kernel.org, jgross@suse.com, jpoimboe@kernel.org, urezki@gmail.com, mhocko@suse.com, ada.coupriediaz@arm.com, hpa@zytor.com, maciej.wieczor-retman@intel.com, leitao@debian.org, peterz@infradead.org, wangkefeng.wang@huawei.com, surenb@google.com, ziy@nvidia.com, smostafa@google.com, ryabinin.a.a@gmail.com, ubizjak@gmail.com, jbohac@suse.cz, broonie@kernel.org, akpm@linux-foundation.org, guoweikang.kernel@gmail.com, rppt@kernel.org, pcc@google.com, jan.kiszka@siemens.com, nicolas.schier@linux.dev, will@kernel.org, andreyknvl@gmail.com, jhubbard@nvidia.com, bp@alien8.de Cc: x86@kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, linux-kbuild@vger.kernel.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v5 19/19] x86: Make software tag-based kasan available Date: Mon, 25 Aug 2025 22:24:44 +0200 Message-ID: <3db48135aec987c99e8e6601249d4a4c023703c4.1756151769.git.maciej.wieczor-retman@intel.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: F304640005 X-Stat-Signature: juyr6oq7pj1cjdgfpokexykqr4ztkqit X-Rspam-User: X-HE-Tag: 1756153935-643850 X-HE-Meta: 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 9Xdbbw9e fz8ashXjJOj1gNSzukDw45fHcnkHeRr6v69JgIstU4FIhH2C+LQtxUpja7kVkZ/v/a3nlt8x7cYyIO+mgjvsBBC70HvnfLJ6rrgXHD9MW/yITst058IboDyIE5hH5dP3GAqMILNjns8I1Ihtyd9m5oq7r5guDAtd0IvFTU0CrTKRHUdjW0YR/oMhFUBVEuUQKvWWKfNx5jWju/I3HGPdKUlfkb0ZcqdI5TfdC2TLITyTLn1OB+Sso5giqXDSVjnOrqANP X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Make CONFIG_KASAN_SW_TAGS available for x86 machines if they have ADDRESS_MASKING enabled (LAM) as that works similarly to Top-Byte Ignore (TBI) that allows the software tag-based mode on arm64 platform. Set scale macro based on KASAN mode: in software tag-based mode 16 bytes of memory map to one shadow byte and 8 in generic mode. Disable CONFIG_KASAN_INLINE and CONFIG_KASAN_STACK when CONFIG_KASAN_SW_TAGS is enabled on x86 until the appropriate compiler support is available. Signed-off-by: Maciej Wieczor-Retman --- Changelog v4: - Add x86 specific kasan_mem_to_shadow(). - Revert x86 to the older unsigned KASAN_SHADOW_OFFSET. Do the same to KASAN_SHADOW_START/END. - Modify scripts/gdb/linux/kasan.py to keep x86 using unsigned offset. - Disable inline and stack support when software tags are enabled on x86. Changelog v3: - Remove runtime_const from previous patch and merge the rest here. - Move scale shift definition back to header file. - Add new kasan offset for software tag based mode. - Fix patch message typo 32 -> 16, and 16 -> 8. - Update lib/Kconfig.kasan with x86 now having software tag-based support. Changelog v2: - Remove KASAN dense code. Documentation/arch/x86/x86_64/mm.rst | 6 ++++-- arch/x86/Kconfig | 4 +++- arch/x86/boot/compressed/misc.h | 1 + arch/x86/include/asm/kasan.h | 1 + arch/x86/kernel/setup.c | 2 ++ lib/Kconfig.kasan | 3 ++- scripts/gdb/linux/kasan.py | 4 ++-- 7 files changed, 15 insertions(+), 6 deletions(-) diff --git a/Documentation/arch/x86/x86_64/mm.rst b/Documentation/arch/x86/x86_64/mm.rst index a6cf05d51bd8..ccbdbb4cda36 100644 --- a/Documentation/arch/x86/x86_64/mm.rst +++ b/Documentation/arch/x86/x86_64/mm.rst @@ -60,7 +60,8 @@ Complete virtual memory map with 4-level page tables ffffe90000000000 | -23 TB | ffffe9ffffffffff | 1 TB | ... unused hole ffffea0000000000 | -22 TB | ffffeaffffffffff | 1 TB | virtual memory map (vmemmap_base) ffffeb0000000000 | -21 TB | ffffebffffffffff | 1 TB | ... unused hole - ffffec0000000000 | -20 TB | fffffbffffffffff | 16 TB | KASAN shadow memory + ffffec0000000000 | -20 TB | fffffbffffffffff | 16 TB | KASAN shadow memory (generic mode) + fffff40000000000 | -8 TB | fffffbffffffffff | 8 TB | KASAN shadow memory (software tag-based mode) __________________|____________|__________________|_________|____________________________________________________________ | | Identical layout to the 56-bit one from here on: @@ -130,7 +131,8 @@ Complete virtual memory map with 5-level page tables ffd2000000000000 | -11.5 PB | ffd3ffffffffffff | 0.5 PB | ... unused hole ffd4000000000000 | -11 PB | ffd5ffffffffffff | 0.5 PB | virtual memory map (vmemmap_base) ffd6000000000000 | -10.5 PB | ffdeffffffffffff | 2.25 PB | ... unused hole - ffdf000000000000 | -8.25 PB | fffffbffffffffff | ~8 PB | KASAN shadow memory + ffdf000000000000 | -8.25 PB | fffffbffffffffff | ~8 PB | KASAN shadow memory (generic mode) + ffeffc0000000000 | -6 PB | fffffbffffffffff | 4 PB | KASAN shadow memory (software tag-based mode) __________________|____________|__________________|_________|____________________________________________________________ | | Identical layout to the 47-bit one from here on: diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b8df57ac0f28..f44fec1190b6 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -69,6 +69,7 @@ config X86 select ARCH_CLOCKSOURCE_INIT select ARCH_CONFIGURES_CPU_MITIGATIONS select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE + select ARCH_DISABLE_KASAN_INLINE if X86_64 && KASAN_SW_TAGS select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64 select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG @@ -199,6 +200,7 @@ config X86 select HAVE_ARCH_JUMP_LABEL_RELATIVE select HAVE_ARCH_KASAN if X86_64 select HAVE_ARCH_KASAN_VMALLOC if X86_64 + select HAVE_ARCH_KASAN_SW_TAGS if ADDRESS_MASKING select HAVE_ARCH_KFENCE select HAVE_ARCH_KMSAN if X86_64 select HAVE_ARCH_KGDB @@ -403,7 +405,7 @@ config AUDIT_ARCH config KASAN_SHADOW_OFFSET hex - depends on KASAN + default 0xeffffc0000000000 if KASAN_SW_TAGS default 0xdffffc0000000000 config HAVE_INTEL_TXT diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index db1048621ea2..ded92b439ada 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -13,6 +13,7 @@ #undef CONFIG_PARAVIRT_SPINLOCKS #undef CONFIG_KASAN #undef CONFIG_KASAN_GENERIC +#undef CONFIG_KASAN_SW_TAGS #define __NO_FORTIFY diff --git a/arch/x86/include/asm/kasan.h b/arch/x86/include/asm/kasan.h index f3e34a9754d2..385f4e9daab3 100644 --- a/arch/x86/include/asm/kasan.h +++ b/arch/x86/include/asm/kasan.h @@ -7,6 +7,7 @@ #include #define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) #ifdef CONFIG_KASAN_SW_TAGS +#define KASAN_SHADOW_SCALE_SHIFT 4 /* * LLVM ABI for reporting tag mismatches in inline KASAN mode. diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 1b2edd07a3e1..5b819f84f6db 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1207,6 +1207,8 @@ void __init setup_arch(char **cmdline_p) kasan_init(); + kasan_init_sw_tags(); + /* * Sync back kernel address range. * diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index f82889a830fa..9ddbc6aeb5d5 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -100,7 +100,8 @@ config KASAN_SW_TAGS Requires GCC 11+ or Clang. - Supported only on arm64 CPUs and relies on Top Byte Ignore. + Supported on arm64 CPUs that support Top Byte Ignore and on x86 CPUs + that support Linear Address Masking. Consumes about 1/16th of available memory at kernel start and add an overhead of ~20% for dynamic allocations. diff --git a/scripts/gdb/linux/kasan.py b/scripts/gdb/linux/kasan.py index fca39968d308..4b86202b155f 100644 --- a/scripts/gdb/linux/kasan.py +++ b/scripts/gdb/linux/kasan.py @@ -7,7 +7,7 @@ # import gdb -from linux import constants, mm +from linux import constants, utils, mm from ctypes import c_int64 as s64 def help(): @@ -40,7 +40,7 @@ class KasanMemToShadow(gdb.Command): else: help() def kasan_mem_to_shadow(self, addr): - if constants.CONFIG_KASAN_SW_TAGS: + if constants.CONFIG_KASAN_SW_TAGS and not utils.is_target_arch('x86'): addr = s64(addr) return (addr >> self.p_ops.KASAN_SHADOW_SCALE_SHIFT) + self.p_ops.KASAN_SHADOW_OFFSET -- 2.50.1