From: Arnd Bergmann <arnd@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
linux-arch@vger.kernel.org, linux-mm@kvack.org,
linux-api@vger.kernel.org, arnd@arndb.de,
linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk
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,
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linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org,
Robin Murphy <robin.murphy@arm.com>
Subject: [PATCH v2 11/18] arm64: simplify access_ok()
Date: Wed, 16 Feb 2022 14:13:25 +0100 [thread overview]
Message-ID: <20220216131332.1489939-12-arnd@kernel.org> (raw)
In-Reply-To: <20220216131332.1489939-1-arnd@kernel.org>
From: Arnd Bergmann <arnd@arndb.de>
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.
Acked-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
arch/arm64/include/asm/uaccess.h | 34 ++++++++++----------------------
1 file changed, 10 insertions(+), 24 deletions(-)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 2e20879fe3cf..199c553b740a 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -26,6 +26,14 @@
#include <asm/memory.h>
#include <asm/extable.h>
+static inline int __access_ok(const void __user *ptr, unsigned long size)
+{
+ unsigned long limit = TASK_SIZE_MAX;
+ unsigned long addr = (unsigned long)ptr;
+
+ return (size <= limit) && (addr <= (limit - size));
+}
+
/*
* Test whether a block of memory is a valid user space address.
* Returns 1 if the range is valid, 0 otherwise.
@@ -33,10 +41,8 @@
* This is equivalent to the following test:
* (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX
*/
-static inline unsigned long __range_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
@@ -46,29 +52,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
(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(addr, size) __range_ok(addr, size)
-
/*
* User access enabling/disabling.
*/
--
2.29.2
next prev parent reply other threads:[~2022-02-16 13:17 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-16 13:13 [PATCH v2 00/18] clean up asm/uaccess.h, kill set_fs for good Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 01/18] uaccess: fix integer overflow on access_ok() Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 02/18] uaccess: fix nios2 and microblaze get_user_8() Arnd Bergmann
2022-02-16 13:35 ` David Laight
2022-02-18 6:25 ` Christoph Hellwig
2022-02-25 4:28 ` Dinh Nguyen
2022-02-16 13:13 ` [PATCH v2 03/18] nds32: fix access_ok() checks in get/put_user Arnd Bergmann
2022-02-18 6:25 ` Christoph Hellwig
2022-02-16 13:13 ` [PATCH v2 04/18] sparc64: add __{get,put}_kernel_nocheck() Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 05/18] x86: remove __range_not_ok() Arnd Bergmann
2022-02-18 6:28 ` Christoph Hellwig
2022-02-18 7:29 ` Arnd Bergmann
2022-02-18 15:45 ` David Laight
2022-02-16 13:13 ` [PATCH v2 06/18] x86: use more conventional access_ok() definition Arnd Bergmann
2022-02-18 6:29 ` Christoph Hellwig
2022-02-16 13:13 ` [PATCH v2 07/18] nios2: drop access_ok() check from __put_user() Arnd Bergmann
2022-02-18 6:29 ` Christoph Hellwig
2022-02-23 23:30 ` Dinh Nguyen
2022-02-24 7:05 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 08/18] uaccess: add generic __{get,put}_kernel_nofault Arnd Bergmann
2022-02-18 6:30 ` Christoph Hellwig
2022-02-18 8:55 ` Geert Uytterhoeven
2022-02-16 13:13 ` [PATCH v2 09/18] mips: use simpler access_ok() Arnd Bergmann
2022-02-21 13:24 ` Thomas Bogendoerfer
2022-02-21 14:31 ` Arnd Bergmann
2022-02-21 15:21 ` Thomas Bogendoerfer
2022-02-22 16:36 ` Thomas Bogendoerfer
2022-02-23 20:05 ` Linus Torvalds
2022-02-23 7:41 ` Thomas Bogendoerfer
2022-02-23 9:26 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 10/18] m68k: fix access_ok for coldfire Arnd Bergmann
2022-02-18 6:30 ` Christoph Hellwig
2022-02-18 9:00 ` Geert Uytterhoeven
2022-02-18 9:24 ` Arnd Bergmann
2022-02-16 13:13 ` Arnd Bergmann [this message]
2022-02-16 13:13 ` [PATCH v2 12/18] uaccess: fix type mismatch warnings from access_ok() Arnd Bergmann
2022-02-18 6:31 ` Christoph Hellwig
2022-02-25 4:30 ` Dinh Nguyen
2022-02-16 13:13 ` [PATCH v2 13/18] uaccess: generalize access_ok() Arnd Bergmann
2022-02-17 7:52 ` Arnd Bergmann
2022-02-17 19:15 ` Andy Lutomirski
2022-02-18 7:16 ` Arnd Bergmann
2022-02-18 9:30 ` David Laight
2022-02-18 18:07 ` Andy Lutomirski
2022-02-18 6:34 ` Christoph Hellwig
2022-02-18 7:23 ` Arnd Bergmann
2022-02-18 9:04 ` Geert Uytterhoeven
2022-02-24 8:29 ` Stafford Horne
2022-02-24 8:41 ` Arnd Bergmann
2022-02-25 4:31 ` Dinh Nguyen
2022-02-16 13:13 ` [PATCH v2 14/18] lib/test_lockup: fix kernel pointer check for separate address spaces Arnd Bergmann
2022-02-18 6:35 ` Christoph Hellwig
2022-02-18 7:15 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 15/18] sparc64: remove CONFIG_SET_FS support Arnd Bergmann
2022-02-16 18:34 ` Sam Ravnborg
2022-02-16 18:41 ` Sam Ravnborg
2022-02-16 22:01 ` Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 16/18] sh: " Arnd Bergmann
2022-02-18 6:36 ` Christoph Hellwig
2022-02-16 13:13 ` [PATCH v2 17/18] ia64: " Arnd Bergmann
2022-02-16 13:13 ` [PATCH v2 18/18] uaccess: drop maining CONFIG_SET_FS users Arnd Bergmann
2022-02-16 18:44 ` Sam Ravnborg
2022-02-16 22:02 ` Arnd Bergmann
2022-02-17 22:36 ` Eric W. Biederman
2022-02-18 6:37 ` Christoph Hellwig
2022-02-18 7:10 ` Arnd Bergmann
2022-02-24 8:45 ` Stafford Horne
2022-02-25 4:33 ` Dinh Nguyen
2022-02-17 7:20 ` [PATCH v2 00/18] clean up asm/uaccess.h, kill set_fs for good Christophe Leroy
2022-02-17 7:49 ` Arnd Bergmann
2022-02-18 2:21 ` Al Viro
2022-02-18 9:20 ` Arnd Bergmann
2022-02-18 1:50 ` Al Viro
2022-02-18 10:01 ` Christophe Leroy
2022-02-17 8:13 ` Arnd Bergmann
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