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Mon, 14 Feb 2022 16:42:06 +0000 Received: from sin.source.kernel.org ([2604:1380:40e1:4800::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nJeLl-00G3FF-5t; Mon, 14 Feb 2022 16:37:19 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 054B6CE198C; Mon, 14 Feb 2022 16:37:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9EC10C340F2; Mon, 14 Feb 2022 16:37:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644856633; bh=xPmHkcOVS/yITVJeEntOUBw+xw68iqOnYa2twIOtXYc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Mrqn5vxFjvUagN2pKvxkJBJGliaoy6MP0jFoyX87gnr3XzjUW97zOF2byukzKb7wT E7NJtDKT5zv31VRqv+qj0too8+wx5sD0RyH+MTT+msOF1jPOFyDDNvVoSgFUoy9QLD t5Lsiozlst1R3n+nWulzcvj+OboDpu885ft5vvuvmiKpyr9q37jLxwtuRMARpqWsIO GBpyEJ9KSTjS3eJz1YtPZ5AEx/LAzduOaPtX9npuQqJUzyrgXxlnqYD2lkogyB5K3z 8L8gKn2P4XZBENc6TnX7Y3RkjeTuj5E4MW+PVjIdx+wEaJHxpbaxGjuVjNKLr8MOwo NPAYqCu6fVtxg== From: Arnd Bergmann To: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org Cc: linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, ebiederm@xmission.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org Subject: [PATCH 08/14] arm64: simplify access_ok() Date: Mon, 14 Feb 2022 17:34:46 +0100 Message-Id: <20220214163452.1568807-9-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20220214163452.1568807-1-arnd@kernel.org> References: <20220214163452.1568807-1-arnd@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220214_083717_591065_F6B1DDA3 X-CRM114-Status: GOOD ( 20.31 ) X-Spam-Score: -5.4 (-----) X-Spam-Report: Spam detection software, running on the system "bombadil.infradead.org", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: From: Arnd Bergmann arm64 has an inline asm implementation of access_ok() that is derived from the 32-bit arm version and optimized for the case that both the limit and the size are variable. With set_fs() gone, the limi [...] Content analysis details: (-5.4 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -5.0 RCVD_IN_DNSWL_HI RBL: Sender listed at https://www.dnswl.org/, high trust [2604:1380:40e1:4800:0:0:0:1 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.2 DKIMWL_WL_HIGH DKIMwl.org - High trust sender X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org From: Arnd Bergmann arm64 has an inline asm implementation of access_ok() that is derived from the 32-bit arm version and optimized for the case that both the limit and the size are variable. With set_fs() gone, the limit is always constant, and the size usually is as well, so just using the default implementation reduces the check into a comparison against a constant that can be scheduled by the compiler. On a defconfig build, this saves over 28KB of .text. Signed-off-by: Arnd Bergmann Acked-by: Robin Murphy Acked-by: Mark Rutland --- arch/arm64/include/asm/uaccess.h | 28 +++++----------------------- 1 file changed, 5 insertions(+), 23 deletions(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 357f7bd9c981..e8dce0cc5eaa 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -26,6 +26,8 @@ #include #include +static inline int __access_ok(const void __user *ptr, unsigned long size); + /* * Test whether a block of memory is a valid user space address. * Returns 1 if the range is valid, 0 otherwise. @@ -33,10 +35,8 @@ * This is equivalent to the following test: * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX */ -static inline unsigned long __access_ok(const void __user *addr, unsigned long size) +static inline int access_ok(const void __user *addr, unsigned long size) { - unsigned long ret, limit = TASK_SIZE_MAX - 1; - /* * Asynchronous I/O running in a kernel thread does not have the * TIF_TAGGED_ADDR flag of the process owning the mm, so always untag @@ -46,27 +46,9 @@ static inline unsigned long __access_ok(const void __user *addr, unsigned long s (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR))) addr = untagged_addr(addr); - __chk_user_ptr(addr); - asm volatile( - // A + B <= C + 1 for all A,B,C, in four easy steps: - // 1: X = A + B; X' = X % 2^64 - " adds %0, %3, %2\n" - // 2: Set C = 0 if X > 2^64, to guarantee X' > C in step 4 - " csel %1, xzr, %1, hi\n" - // 3: Set X' = ~0 if X >= 2^64. For X == 2^64, this decrements X' - // to compensate for the carry flag being set in step 4. For - // X > 2^64, X' merely has to remain nonzero, which it does. - " csinv %0, %0, xzr, cc\n" - // 4: For X < 2^64, this gives us X' - C - 1 <= 0, where the -1 - // comes from the carry in being clear. Otherwise, we are - // testing X' - C == 0, subject to the previous adjustments. - " sbcs xzr, %0, %1\n" - " cset %0, ls\n" - : "=&r" (ret), "+r" (limit) : "Ir" (size), "0" (addr) : "cc"); - - return ret; + return likely(__access_ok(addr, size)); } -#define __access_ok __access_ok +#define access_ok access_ok #include