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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1680115078; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=R0ZTLDK0+ErC3gsprSGJ+tiVFRHa88yHqEYRk0ERiZ0=; b=oP2VA3+D9Qr8dKR4UOrrmrc1+nxlHZsTDv96qHpFlLIIE0qAxFcHxNtGpjSuXYDtYGe7g0 R9YJpt11ce2lsJJGHndi0vAWGx+Lrt1/J0xo2kovQdSX5r6myxaV5UGnajysVl3a/fkg9M 5PYt++7HFPVvKJdr1l9qX0EEByPuMKk= From: andrey.konovalov@linux.dev To: Marco Elver , Catalin Marinas Cc: Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, Vincenzo Frascino , Will Deacon , linux-arm-kernel@lists.infradead.org, Peter Collingbourne , Evgenii Stepanov , Andrew Morton , linux-mm@kvack.org, Weizhao Ouyang , linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH v2 3/5] arm64: mte: Rename TCO routines Date: Wed, 29 Mar 2023 20:37:46 +0200 Message-Id: <74d26337b2360733956114069e96ff11c296a944.1680114854.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1761729193588409111?= X-GMAIL-MSGID: =?utf-8?q?1761729193588409111?= From: Vincenzo Frascino The TCO related routines are used in uaccess methods and load_unaligned_zeropad() but are unrelated to both even if the naming suggest otherwise. Improve the readability of the code moving the away from uaccess.h and pre-pending them with "mte". Cc: Will Deacon Signed-off-by: Vincenzo Frascino Signed-off-by: Catalin Marinas Signed-off-by: Andrey Konovalov --- Chages v1->v2: - Drop __ from mte_disable/enable_tco names, as those functions are to be exported to KASAN code. --- arch/arm64/include/asm/mte-kasan.h | 81 +++++++++++++++++++++++++ arch/arm64/include/asm/mte.h | 12 ---- arch/arm64/include/asm/uaccess.h | 66 +++----------------- arch/arm64/include/asm/word-at-a-time.h | 4 +- 4 files changed, 93 insertions(+), 70 deletions(-) diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h index 9f79425fc65a..2e98028c1965 100644 --- a/arch/arm64/include/asm/mte-kasan.h +++ b/arch/arm64/include/asm/mte-kasan.h @@ -13,8 +13,73 @@ #include +#ifdef CONFIG_KASAN_HW_TAGS + +/* Whether the MTE asynchronous mode is enabled. */ +DECLARE_STATIC_KEY_FALSE(mte_async_or_asymm_mode); + +static inline bool system_uses_mte_async_or_asymm_mode(void) +{ + return static_branch_unlikely(&mte_async_or_asymm_mode); +} + +#else /* CONFIG_KASAN_HW_TAGS */ + +static inline bool system_uses_mte_async_or_asymm_mode(void) +{ + return false; +} + +#endif /* CONFIG_KASAN_HW_TAGS */ + #ifdef CONFIG_ARM64_MTE +/* + * The Tag Check Flag (TCF) mode for MTE is per EL, hence TCF0 + * affects EL0 and TCF affects EL1 irrespective of which TTBR is + * used. + * The kernel accesses TTBR0 usually with LDTR/STTR instructions + * when UAO is available, so these would act as EL0 accesses using + * TCF0. + * However futex.h code uses exclusives which would be executed as + * EL1, this can potentially cause a tag check fault even if the + * user disables TCF0. + * + * To address the problem we set the PSTATE.TCO bit in uaccess_enable() + * and reset it in uaccess_disable(). + * + * The Tag check override (TCO) bit disables temporarily the tag checking + * preventing the issue. + */ +static inline void mte_disable_tco(void) +{ + asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(0), + ARM64_MTE, CONFIG_KASAN_HW_TAGS)); +} + +static inline void mte_enable_tco(void) +{ + asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(1), + ARM64_MTE, CONFIG_KASAN_HW_TAGS)); +} + +/* + * These functions disable tag checking only if in MTE async mode + * since the sync mode generates exceptions synchronously and the + * nofault or load_unaligned_zeropad can handle them. + */ +static inline void __mte_disable_tco_async(void) +{ + if (system_uses_mte_async_or_asymm_mode()) + mte_disable_tco(); +} + +static inline void __mte_enable_tco_async(void) +{ + if (system_uses_mte_async_or_asymm_mode()) + mte_enable_tco(); +} + /* * These functions are meant to be only used from KASAN runtime through * the arch_*() interface defined in asm/memory.h. @@ -138,6 +203,22 @@ void mte_enable_kernel_asymm(void); #else /* CONFIG_ARM64_MTE */ +static inline void mte_disable_tco(void) +{ +} + +static inline void mte_enable_tco(void) +{ +} + +static inline void __mte_disable_tco_async(void) +{ +} + +static inline void __mte_enable_tco_async(void) +{ +} + static inline u8 mte_get_ptr_tag(void *ptr) { return 0xFF; diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h index 20dd06d70af5..c028afb1cd0b 100644 --- a/arch/arm64/include/asm/mte.h +++ b/arch/arm64/include/asm/mte.h @@ -178,14 +178,6 @@ static inline void mte_disable_tco_entry(struct task_struct *task) } #ifdef CONFIG_KASAN_HW_TAGS -/* Whether the MTE asynchronous mode is enabled. */ -DECLARE_STATIC_KEY_FALSE(mte_async_or_asymm_mode); - -static inline bool system_uses_mte_async_or_asymm_mode(void) -{ - return static_branch_unlikely(&mte_async_or_asymm_mode); -} - void mte_check_tfsr_el1(void); static inline void mte_check_tfsr_entry(void) @@ -212,10 +204,6 @@ static inline void mte_check_tfsr_exit(void) mte_check_tfsr_el1(); } #else -static inline bool system_uses_mte_async_or_asymm_mode(void) -{ - return false; -} static inline void mte_check_tfsr_el1(void) { } diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 5c7b2f9d5913..30ea7b5c3ccb 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -136,55 +136,9 @@ static inline void __uaccess_enable_hw_pan(void) CONFIG_ARM64_PAN)); } -/* - * The Tag Check Flag (TCF) mode for MTE is per EL, hence TCF0 - * affects EL0 and TCF affects EL1 irrespective of which TTBR is - * used. - * The kernel accesses TTBR0 usually with LDTR/STTR instructions - * when UAO is available, so these would act as EL0 accesses using - * TCF0. - * However futex.h code uses exclusives which would be executed as - * EL1, this can potentially cause a tag check fault even if the - * user disables TCF0. - * - * To address the problem we set the PSTATE.TCO bit in uaccess_enable() - * and reset it in uaccess_disable(). - * - * The Tag check override (TCO) bit disables temporarily the tag checking - * preventing the issue. - */ -static inline void __uaccess_disable_tco(void) -{ - asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(0), - ARM64_MTE, CONFIG_KASAN_HW_TAGS)); -} - -static inline void __uaccess_enable_tco(void) -{ - asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(1), - ARM64_MTE, CONFIG_KASAN_HW_TAGS)); -} - -/* - * These functions disable tag checking only if in MTE async mode - * since the sync mode generates exceptions synchronously and the - * nofault or load_unaligned_zeropad can handle them. - */ -static inline void __uaccess_disable_tco_async(void) -{ - if (system_uses_mte_async_or_asymm_mode()) - __uaccess_disable_tco(); -} - -static inline void __uaccess_enable_tco_async(void) -{ - if (system_uses_mte_async_or_asymm_mode()) - __uaccess_enable_tco(); -} - static inline void uaccess_disable_privileged(void) { - __uaccess_disable_tco(); + mte_disable_tco(); if (uaccess_ttbr0_disable()) return; @@ -194,7 +148,7 @@ static inline void uaccess_disable_privileged(void) static inline void uaccess_enable_privileged(void) { - __uaccess_enable_tco(); + mte_enable_tco(); if (uaccess_ttbr0_enable()) return; @@ -302,8 +256,8 @@ do { \ #define get_user __get_user /* - * We must not call into the scheduler between __uaccess_enable_tco_async() and - * __uaccess_disable_tco_async(). As `dst` and `src` may contain blocking + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As `dst` and `src` may contain blocking * functions, we must evaluate these outside of the critical section. */ #define __get_kernel_nofault(dst, src, type, err_label) \ @@ -312,10 +266,10 @@ do { \ __typeof__(src) __gkn_src = (src); \ int __gkn_err = 0; \ \ - __uaccess_enable_tco_async(); \ + __mte_enable_tco_async(); \ __raw_get_mem("ldr", *((type *)(__gkn_dst)), \ (__force type *)(__gkn_src), __gkn_err, K); \ - __uaccess_disable_tco_async(); \ + __mte_disable_tco_async(); \ \ if (unlikely(__gkn_err)) \ goto err_label; \ @@ -388,8 +342,8 @@ do { \ #define put_user __put_user /* - * We must not call into the scheduler between __uaccess_enable_tco_async() and - * __uaccess_disable_tco_async(). As `dst` and `src` may contain blocking + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As `dst` and `src` may contain blocking * functions, we must evaluate these outside of the critical section. */ #define __put_kernel_nofault(dst, src, type, err_label) \ @@ -398,10 +352,10 @@ do { \ __typeof__(src) __pkn_src = (src); \ int __pkn_err = 0; \ \ - __uaccess_enable_tco_async(); \ + __mte_enable_tco_async(); \ __raw_put_mem("str", *((type *)(__pkn_src)), \ (__force type *)(__pkn_dst), __pkn_err, K); \ - __uaccess_disable_tco_async(); \ + __mte_disable_tco_async(); \ \ if (unlikely(__pkn_err)) \ goto err_label; \ diff --git a/arch/arm64/include/asm/word-at-a-time.h b/arch/arm64/include/asm/word-at-a-time.h index 1c8e4f2490bf..f3b151ed0d7a 100644 --- a/arch/arm64/include/asm/word-at-a-time.h +++ b/arch/arm64/include/asm/word-at-a-time.h @@ -55,7 +55,7 @@ static inline unsigned long load_unaligned_zeropad(const void *addr) { unsigned long ret; - __uaccess_enable_tco_async(); + __mte_enable_tco_async(); /* Load word from unaligned pointer addr */ asm( @@ -65,7 +65,7 @@ static inline unsigned long load_unaligned_zeropad(const void *addr) : "=&r" (ret) : "r" (addr), "Q" (*(unsigned long *)addr)); - __uaccess_disable_tco_async(); + __mte_disable_tco_async(); return ret; }