From nobody Mon Sep 15 18:06:25 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 722C7C46467 for ; Wed, 11 Jan 2023 13:25:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238147AbjAKNZk (ORCPT ); Wed, 11 Jan 2023 08:25:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46706 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234247AbjAKNYE (ORCPT ); Wed, 11 Jan 2023 08:24:04 -0500 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7AAC35F55 for ; Wed, 11 Jan 2023 05:24:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1673443443; x=1704979443; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=SGiBGTV0pV1LSdKWzpftY7fVqqKe+kxFUGucNy6ovfQ=; b=Oy5FJwB+61G2i6gJr80oroQ8roSJKes7dWld9/8aSOTye5qGxlC3TRmL Ur2f9k2GaGa1crgRs28LsfST7JPDam1tprmYbEwDcCmCXiqVM2sOynNuD s0ln8ugV52Yb1TorUVcvxCG9JJ5La4TI+OERDVdcA3qXPMkBHRnMVEyNg OsLVpvJaeIWwsV4+NhXRV0wMhrpsbHbtXqyUg3IWz1mitveHjvjvWqIf7 79FOlQ/5TnnnnMl3bSDfqc2Cu2x0xH/4gCSPnsjlVq4O9xEx9ZBeW57iK gZcn25AhLCZJT7F+kPUiT1K2z1gVM7F/xGERKT97ke9sAUZ4ucf0ToSxB Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10586"; a="324646159" X-IronPort-AV: E=Sophos;i="5.96,317,1665471600"; d="scan'208";a="324646159" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2023 05:24:01 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10586"; a="720725511" X-IronPort-AV: E=Sophos;i="5.96,317,1665471600"; d="scan'208";a="720725511" Received: from bachaue1-mobl1.ger.corp.intel.com (HELO box.shutemov.name) ([10.252.37.250]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jan 2023 05:23:56 -0800 Received: by box.shutemov.name (Postfix, from userid 1000) id 3DF10109C8B; Wed, 11 Jan 2023 15:37:41 +0300 (+03) From: "Kirill A. Shutemov" To: Dave Hansen , Andy Lutomirski , Peter Zijlstra Cc: x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Bharata B Rao , Jacob Pan , Ashok Raj , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv14 06/17] x86/uaccess: Provide untagged_addr() and remove tags before address check Date: Wed, 11 Jan 2023 15:37:25 +0300 Message-Id: <20230111123736.20025-7-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.38.2 In-Reply-To: <20230111123736.20025-1-kirill.shutemov@linux.intel.com> References: <20230111123736.20025-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" untagged_addr() is a helper used by the core-mm to strip tag bits and get the address to the canonical shape based on rules of the current thread. It only handles userspace addresses. The untagging mask is stored in per-CPU variable and set on context switching to the task. The tags must not be included into check whether it's okay to access the userspace address. Strip tags in access_ok(). Signed-off-by: Kirill A. Shutemov --- arch/x86/include/asm/mmu.h | 3 +++ arch/x86/include/asm/mmu_context.h | 11 +++++++++++ arch/x86/include/asm/tlbflush.h | 10 ++++++++++ arch/x86/include/asm/uaccess.h | 31 ++++++++++++++++++++++++++++-- arch/x86/kernel/process.c | 3 +++ arch/x86/mm/init.c | 5 +++++ 6 files changed, 61 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index 22fc9fbf1d0a..9cac8c45a647 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -45,6 +45,9 @@ typedef struct { #ifdef CONFIG_ADDRESS_MASKING /* Active LAM mode: X86_CR3_LAM_U48 or X86_CR3_LAM_U57 or 0 (disabled) */ unsigned long lam_cr3_mask; + + /* Significant bits of the virtual address. Excludes tag bits. */ + u64 untag_mask; #endif =20 struct mutex lock; diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_= context.h index 8388fccc4700..1d0b743daebb 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -100,6 +100,12 @@ static inline unsigned long mm_lam_cr3_mask(struct mm_= struct *mm) static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm) { mm->context.lam_cr3_mask =3D oldmm->context.lam_cr3_mask; + mm->context.untag_mask =3D oldmm->context.untag_mask; +} + +static inline void mm_reset_untag_mask(struct mm_struct *mm) +{ + mm->context.untag_mask =3D -1UL; } =20 #else @@ -112,6 +118,10 @@ static inline unsigned long mm_lam_cr3_mask(struct mm_= struct *mm) static inline void dup_lam(struct mm_struct *oldmm, struct mm_struct *mm) { } + +static inline void mm_reset_untag_mask(struct mm_struct *mm) +{ +} #endif =20 #define enter_lazy_tlb enter_lazy_tlb @@ -138,6 +148,7 @@ static inline int init_new_context(struct task_struct *= tsk, mm->context.execute_only_pkey =3D -1; } #endif + mm_reset_untag_mask(mm); init_new_context_ldt(mm); return 0; } diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflus= h.h index e8b47f57bd4a..75bfaa421030 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -54,6 +54,15 @@ static inline void cr4_clear_bits(unsigned long mask) local_irq_restore(flags); } =20 +#ifdef CONFIG_ADDRESS_MASKING +DECLARE_PER_CPU(u64, tlbstate_untag_mask); + +static inline u64 current_untag_mask(void) +{ + return this_cpu_read(tlbstate_untag_mask); +} +#endif + #ifndef MODULE /* * 6 because 6 should be plenty and struct tlb_state will fit in two cache @@ -380,6 +389,7 @@ static inline void set_tlbstate_lam_mode(struct mm_stru= ct *mm) { this_cpu_write(cpu_tlbstate.lam, mm->context.lam_cr3_mask >> X86_CR3_LAM_U57_BIT); + this_cpu_write(tlbstate_untag_mask, mm->context.untag_mask); } =20 #else diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 1cc756eafa44..32c9dd052e43 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -7,11 +7,13 @@ #include #include #include +#include #include #include #include #include #include +#include =20 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP static inline bool pagefault_disabled(void); @@ -21,6 +23,31 @@ static inline bool pagefault_disabled(void); # define WARN_ON_IN_IRQ() #endif =20 +#ifdef CONFIG_ADDRESS_MASKING +/* + * Mask out tag bits from the address. + * + * Magic with the 'sign' allows to untag userspace pointer without any bra= nches + * while leaving kernel addresses intact. + */ +#define __untagged_addr(untag_mask, addr) ({ \ + u64 __addr =3D (__force u64)(addr); \ + s64 sign =3D (s64)__addr >> 63; \ + __addr &=3D untag_mask | sign; \ + (__force __typeof__(addr))__addr; \ +}) + +#define untagged_addr(addr) __untagged_addr(current_untag_mask(), addr) + +#define untagged_addr_remote(mm, addr) ({ \ + mmap_assert_locked(mm); \ + __untagged_addr((mm)->context.untag_mask, addr); \ +}) + +#else +#define untagged_addr(addr) (addr) +#endif + /** * access_ok - Checks if a user space pointer is valid * @addr: User space pointer to start of block to check @@ -38,10 +65,10 @@ static inline bool pagefault_disabled(void); * Return: true (nonzero) if the memory block may be valid, false (zero) * if it is definitely invalid. */ -#define access_ok(addr, size) \ +#define access_ok(addr, size) \ ({ \ WARN_ON_IN_IRQ(); \ - likely(__access_ok(addr, size)); \ + likely(__access_ok(untagged_addr(addr), size)); \ }) =20 #include diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 40d156a31676..ef6bde1d40d8 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -47,6 +47,7 @@ #include #include #include +#include =20 #include "process.h" =20 @@ -367,6 +368,8 @@ void arch_setup_new_exec(void) task_clear_spec_ssb_noexec(current); speculation_ctrl_update(read_thread_flags()); } + + mm_reset_untag_mask(current->mm); } =20 #ifdef CONFIG_X86_IOPL_IOPERM diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index d3987359d441..be5c7d1c0265 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -1044,6 +1044,11 @@ __visible DEFINE_PER_CPU_ALIGNED(struct tlb_state, c= pu_tlbstate) =3D { .cr4 =3D ~0UL, /* fail hard if we screw up cr4 shadow initialization */ }; =20 +#ifdef CONFIG_ADDRESS_MASKING +DEFINE_PER_CPU(u64, tlbstate_untag_mask); +EXPORT_PER_CPU_SYMBOL(tlbstate_untag_mask); +#endif + void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache) { /* entry 0 MUST be WB (hardwired to speed up translations) */ --=20 2.38.2