From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DEB62FA3728 for ; Wed, 16 Oct 2019 12:12:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABF2A2067D for ; Wed, 16 Oct 2019 12:12:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404949AbfJPMMk (ORCPT ); Wed, 16 Oct 2019 08:12:40 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:49960 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403786AbfJPMMj (ORCPT ); Wed, 16 Oct 2019 08:12:39 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.2 #3 (Red Hat Linux)) id 1iKiAK-0007Zv-Hm; Wed, 16 Oct 2019 12:12:32 +0000 Date: Wed, 16 Oct 2019 13:12:32 +0100 From: Al Viro To: Linus Torvalds Cc: Guenter Roeck , Linux Kernel Mailing List , linux-fsdevel , Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , linux-arch@vger.kernel.org Subject: [RFC] change of calling conventions for arch_futex_atomic_op_inuser() Message-ID: <20191016121232.GA28742@ZenIV.linux.org.uk> References: <20191010195504.GI26530@ZenIV.linux.org.uk> <20191011001104.GJ26530@ZenIV.linux.org.uk> <20191013181333.GK26530@ZenIV.linux.org.uk> <20191013191050.GL26530@ZenIV.linux.org.uk> <20191013195949.GM26530@ZenIV.linux.org.uk> <20191015180846.GA31707@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191015180846.GA31707@ZenIV.linux.org.uk> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 15, 2019 at 07:08:46PM +0100, Al Viro wrote: > [futex folks and linux-arch Cc'd] > Another question: right now we have > if (!access_ok(uaddr, sizeof(u32))) > return -EFAULT; > > ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr); > if (ret) > return ret; > in kernel/futex.c. Would there be any objections to moving access_ok() > inside the instances and moving pagefault_disable()/pagefault_enable() outside? > > Reasons: > * on x86 that would allow folding access_ok() with STAC into > user_access_begin(). The same would be doable on other usual suspects > (arm, arm64, ppc, riscv, s390), bringing access_ok() next to their > STAC counterparts. > * pagefault_disable()/pagefault_enable() pair is universal on > all architectures, really meant to by the nature of the beast and > lifting it into kernel/futex.c would get the same situation as with > futex_atomic_cmpxchg_inatomic(). Which also does access_ok() inside > the primitive (also foldable into user_access_begin(), at that). > * access_ok() would be closer to actual memory access (and > out of the generic code). > > Comments? FWIW, completely untested patch follows; just the (semimechanical) conversion of calling conventions, no per-architecture followups included. Could futex folks ACK/NAK that in principle? commit 7babb6ad28cb3e80977fb6bd0405e3f81a943161 Author: Al Viro Date: Tue Oct 15 16:54:41 2019 -0400 arch_futex_atomic_op_inuser(): move access_ok() in and pagefault_disable() - out Signed-off-by: Al Viro diff --git a/arch/alpha/include/asm/futex.h b/arch/alpha/include/asm/futex.h index bfd3c01038f8..da67afd578fd 100644 --- a/arch/alpha/include/asm/futex.h +++ b/arch/alpha/include/asm/futex.h @@ -31,7 +31,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, { int oldval = 0, ret; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -53,8 +54,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h index 9d0d070e6c22..607d1c16d4dd 100644 --- a/arch/arc/include/asm/futex.h +++ b/arch/arc/include/asm/futex.h @@ -75,10 +75,12 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, { int oldval = 0, ret; + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; + #ifndef CONFIG_ARC_HAS_LLSC preempt_disable(); /* to guarantee atomic r-m-w of futex op */ #endif - pagefault_disable(); switch (op) { case FUTEX_OP_SET: @@ -101,7 +103,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, ret = -ENOSYS; } - pagefault_enable(); #ifndef CONFIG_ARC_HAS_LLSC preempt_enable(); #endif diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 83c391b597d4..e133da303a98 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h @@ -134,10 +134,12 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret, tmp; + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; + #ifndef CONFIG_SMP preempt_disable(); #endif - pagefault_disable(); switch (op) { case FUTEX_OP_SET: @@ -159,7 +161,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); #ifndef CONFIG_SMP preempt_enable(); #endif diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h index 6cc26a127819..97f6a63810ec 100644 --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h @@ -48,7 +48,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr) int oldval = 0, ret, tmp; u32 __user *uaddr = __uaccess_mask_ptr(_uaddr); - pagefault_disable(); + if (!access_ok(_uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -75,8 +76,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/hexagon/include/asm/futex.h b/arch/hexagon/include/asm/futex.h index cb635216a732..8693dc5ae9ec 100644 --- a/arch/hexagon/include/asm/futex.h +++ b/arch/hexagon/include/asm/futex.h @@ -36,7 +36,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -62,8 +63,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/ia64/include/asm/futex.h b/arch/ia64/include/asm/futex.h index 2e106d462196..1db26b432d8c 100644 --- a/arch/ia64/include/asm/futex.h +++ b/arch/ia64/include/asm/futex.h @@ -50,7 +50,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -74,8 +75,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/microblaze/include/asm/futex.h b/arch/microblaze/include/asm/futex.h index 8c90357e5983..86131ed84c9a 100644 --- a/arch/microblaze/include/asm/futex.h +++ b/arch/microblaze/include/asm/futex.h @@ -34,7 +34,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -56,8 +57,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/mips/include/asm/futex.h b/arch/mips/include/asm/futex.h index b83b0397462d..86f224548651 100644 --- a/arch/mips/include/asm/futex.h +++ b/arch/mips/include/asm/futex.h @@ -88,7 +88,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -115,8 +116,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/nds32/include/asm/futex.h b/arch/nds32/include/asm/futex.h index 5213c65c2e0b..60b7ab74ed92 100644 --- a/arch/nds32/include/asm/futex.h +++ b/arch/nds32/include/asm/futex.h @@ -66,8 +66,9 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret; + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; - pagefault_disable(); switch (op) { case FUTEX_OP_SET: __futex_atomic_op("move %0, %3", ret, oldval, tmp, uaddr, @@ -93,8 +94,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/openrisc/include/asm/futex.h b/arch/openrisc/include/asm/futex.h index fe894e6331ae..865e9cd0d97b 100644 --- a/arch/openrisc/include/asm/futex.h +++ b/arch/openrisc/include/asm/futex.h @@ -35,7 +35,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -57,8 +58,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/parisc/include/asm/futex.h b/arch/parisc/include/asm/futex.h index 50662b6cb605..6e2e4d10e3c8 100644 --- a/arch/parisc/include/asm/futex.h +++ b/arch/parisc/include/asm/futex.h @@ -40,11 +40,10 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) u32 tmp; _futex_spin_lock_irqsave(uaddr, &flags); - pagefault_disable(); ret = -EFAULT; if (unlikely(get_user(oldval, uaddr) != 0)) - goto out_pagefault_enable; + goto out_unlock; ret = 0; tmp = oldval; @@ -72,8 +71,7 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) if (ret == 0 && unlikely(put_user(tmp, uaddr) != 0)) ret = -EFAULT; -out_pagefault_enable: - pagefault_enable(); +out_unlock: _futex_spin_unlock_irqrestore(uaddr, &flags); if (!ret) diff --git a/arch/powerpc/include/asm/futex.h b/arch/powerpc/include/asm/futex.h index eea28ca679db..d6e32b32f452 100644 --- a/arch/powerpc/include/asm/futex.h +++ b/arch/powerpc/include/asm/futex.h @@ -35,8 +35,9 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, { int oldval = 0, ret; + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; allow_write_to_user(uaddr, sizeof(*uaddr)); - pagefault_disable(); switch (op) { case FUTEX_OP_SET: @@ -58,8 +59,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, ret = -ENOSYS; } - pagefault_enable(); - *oval = oldval; prevent_write_to_user(uaddr, sizeof(*uaddr)); diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h index 4ad6409c4647..84574acfb927 100644 --- a/arch/riscv/include/asm/futex.h +++ b/arch/riscv/include/asm/futex.h @@ -40,7 +40,8 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { int oldval = 0, ret = 0; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -67,8 +68,6 @@ arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/s390/include/asm/futex.h b/arch/s390/include/asm/futex.h index 5e97a4353147..3c18a48baf44 100644 --- a/arch/s390/include/asm/futex.h +++ b/arch/s390/include/asm/futex.h @@ -28,8 +28,10 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, int oldval = 0, newval, ret; mm_segment_t old_fs; + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; + old_fs = enable_sacf_uaccess(); - pagefault_disable(); switch (op) { case FUTEX_OP_SET: __futex_atomic_op("lr %2,%5\n", @@ -54,7 +56,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, default: ret = -ENOSYS; } - pagefault_enable(); disable_sacf_uaccess(old_fs); if (!ret) diff --git a/arch/sh/include/asm/futex.h b/arch/sh/include/asm/futex.h index 3190ec89df81..b39cda09fb95 100644 --- a/arch/sh/include/asm/futex.h +++ b/arch/sh/include/asm/futex.h @@ -34,8 +34,6 @@ static inline int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 oldval, newval, prev; int ret; - pagefault_disable(); - do { ret = get_user(oldval, uaddr); @@ -67,8 +65,6 @@ static inline int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, ret = futex_atomic_cmpxchg_inatomic(&prev, uaddr, oldval, newval); } while (!ret && prev != oldval); - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/sparc/include/asm/futex_64.h b/arch/sparc/include/asm/futex_64.h index 0865ce77ec00..72de967318d7 100644 --- a/arch/sparc/include/asm/futex_64.h +++ b/arch/sparc/include/asm/futex_64.h @@ -38,8 +38,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, if (unlikely((((unsigned long) uaddr) & 0x3UL))) return -EINVAL; - pagefault_disable(); - switch (op) { case FUTEX_OP_SET: __futex_cas_op("mov\t%4, %1", ret, oldval, uaddr, oparg); @@ -60,8 +58,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/x86/include/asm/futex.h b/arch/x86/include/asm/futex.h index 13c83fe97988..6bcd1c1486d9 100644 --- a/arch/x86/include/asm/futex.h +++ b/arch/x86/include/asm/futex.h @@ -47,7 +47,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, { int oldval = 0, ret, tem; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -70,8 +71,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/arch/xtensa/include/asm/futex.h b/arch/xtensa/include/asm/futex.h index 0c4457ca0a85..271cfcf8a841 100644 --- a/arch/xtensa/include/asm/futex.h +++ b/arch/xtensa/include/asm/futex.h @@ -72,7 +72,8 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, #if XCHAL_HAVE_S32C1I || XCHAL_HAVE_EXCLUSIVE int oldval = 0, ret; - pagefault_disable(); + if (!access_ok(uaddr, sizeof(u32))) + return -EFAULT; switch (op) { case FUTEX_OP_SET: @@ -99,8 +100,6 @@ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, ret = -ENOSYS; } - pagefault_enable(); - if (!ret) *oval = oldval; diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index 02970b11f71f..f4c3470480c7 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -34,7 +34,6 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) u32 tmp; preempt_disable(); - pagefault_disable(); ret = -EFAULT; if (unlikely(get_user(oldval, uaddr) != 0)) @@ -67,7 +66,6 @@ arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr) ret = -EFAULT; out_pagefault_enable: - pagefault_enable(); preempt_enable(); if (ret == 0) diff --git a/kernel/futex.c b/kernel/futex.c index bd18f60e4c6c..2cc8a35109da 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1662,10 +1662,9 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr) oparg = 1 << oparg; } - if (!access_ok(uaddr, sizeof(u32))) - return -EFAULT; - + pagefault_disable(); ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr); + pagefault_enable(); if (ret) return ret;