From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965178AbWD1CK1 (ORCPT ); Thu, 27 Apr 2006 22:10:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965180AbWD1CK1 (ORCPT ); Thu, 27 Apr 2006 22:10:27 -0400 Received: from ns1.suse.de ([195.135.220.2]:747 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S965178AbWD1CK0 (ORCPT ); Thu, 27 Apr 2006 22:10:26 -0400 From: NeilBrown To: Andrew Morton Date: Fri, 28 Apr 2006 12:10:21 +1000 Message-Id: <1060428021021.22243@suse.de> X-face: [Gw_3E*Gng}4rRrKRYotwlE?.2|**#s9D, linux-kernel@vger.kernel.org, andrea@suse.de Subject: [PATCH 002 of 2] Make copy_from_user_inatomic NOT zero the tail on i386 References: <20060428114321.21969.patches@notabene> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org As described in a previous patch and documented in mm/filemap.h, copy_from_user_inatomic* shouldn't zero out the tail of the buffer after an incomplete copy. This patch implements that change for i386. For the _nocache version, a new __copy_user_intel_nocache is defined similar to copy_user_zeroio_intel_nocache, and this is ultimately used for the copy. For the regular version, __copy_to_user_inatomic is used to implement __copy_from_user_inatomic as the only difference is that copy_to doesn't zero the tail, just as we want. Possibly this is a horrible hack. Comments welcome. Signed-off-by: Neil Brown ### Diffstat output ./arch/i386/lib/usercopy.c | 106 +++++++++++++++++++++++++++++++++++++++++++ ./include/asm-i386/uaccess.h | 31 +++++++----- 2 files changed, 125 insertions(+), 12 deletions(-) diff ./arch/i386/lib/usercopy.c~current~ ./arch/i386/lib/usercopy.c --- ./arch/i386/lib/usercopy.c~current~ 2006-04-28 10:31:13.000000000 +1000 +++ ./arch/i386/lib/usercopy.c 2006-04-28 10:36:34.000000000 +1000 @@ -528,6 +528,97 @@ static unsigned long __copy_user_zeroing return size; } +static unsigned long __copy_user_intel_nocache(void __user *to, + const void *from, unsigned long size) +{ + int d0, d1; + + __asm__ __volatile__( + " .align 2,0x90\n" + "0: movl 32(%4), %%eax\n" + " cmpl $67, %0\n" + " jbe 2f\n" + "1: movl 64(%4), %%eax\n" + " .align 2,0x90\n" + "2: movl 0(%4), %%eax\n" + "21: movl 4(%4), %%edx\n" + " movnti %%eax, 0(%3)\n" + " movnti %%edx, 4(%3)\n" + "3: movl 8(%4), %%eax\n" + "31: movl 12(%4),%%edx\n" + " movnti %%eax, 8(%3)\n" + " movnti %%edx, 12(%3)\n" + "4: movl 16(%4), %%eax\n" + "41: movl 20(%4), %%edx\n" + " movnti %%eax, 16(%3)\n" + " movnti %%edx, 20(%3)\n" + "10: movl 24(%4), %%eax\n" + "51: movl 28(%4), %%edx\n" + " movnti %%eax, 24(%3)\n" + " movnti %%edx, 28(%3)\n" + "11: movl 32(%4), %%eax\n" + "61: movl 36(%4), %%edx\n" + " movnti %%eax, 32(%3)\n" + " movnti %%edx, 36(%3)\n" + "12: movl 40(%4), %%eax\n" + "71: movl 44(%4), %%edx\n" + " movnti %%eax, 40(%3)\n" + " movnti %%edx, 44(%3)\n" + "13: movl 48(%4), %%eax\n" + "81: movl 52(%4), %%edx\n" + " movnti %%eax, 48(%3)\n" + " movnti %%edx, 52(%3)\n" + "14: movl 56(%4), %%eax\n" + "91: movl 60(%4), %%edx\n" + " movnti %%eax, 56(%3)\n" + " movnti %%edx, 60(%3)\n" + " addl $-64, %0\n" + " addl $64, %4\n" + " addl $64, %3\n" + " cmpl $63, %0\n" + " ja 0b\n" + " sfence \n" + "5: movl %0, %%eax\n" + " shrl $2, %0\n" + " andl $3, %%eax\n" + " cld\n" + "6: rep; movsl\n" + " movl %%eax,%0\n" + "7: rep; movsb\n" + "8:\n" + ".section .fixup,\"ax\"\n" + "9: lea 0(%%eax,%0,4),%0\n" + "16: jmp 8b\n" + ".previous\n" + ".section __ex_table,\"a\"\n" + " .align 4\n" + " .long 0b,16b\n" + " .long 1b,16b\n" + " .long 2b,16b\n" + " .long 21b,16b\n" + " .long 3b,16b\n" + " .long 31b,16b\n" + " .long 4b,16b\n" + " .long 41b,16b\n" + " .long 10b,16b\n" + " .long 51b,16b\n" + " .long 11b,16b\n" + " .long 61b,16b\n" + " .long 12b,16b\n" + " .long 71b,16b\n" + " .long 13b,16b\n" + " .long 81b,16b\n" + " .long 14b,16b\n" + " .long 91b,16b\n" + " .long 6b,9b\n" + " .long 7b,16b\n" + ".previous" + : "=&c"(size), "=&D" (d0), "=&S" (d1) + : "1"(to), "2"(from), "0"(size) + : "eax", "edx", "memory"); + return size; +} + #else /* @@ -709,6 +800,21 @@ unsigned long __copy_from_user_ll_nocach return n; } +unsigned long __copy_from_user_ll_nocache_nozero(void *to, const void __user *from, + unsigned long n) +{ + BUG_ON((long)n < 0); +#ifdef CONFIG_X86_INTEL_USERCOPY + if ( n > 64 && cpu_has_xmm2) + n = __copy_user_intel_nocache(to, from, n); + else + __copy_user(to, from, n); +#else + __copy_user(to, from, n); +#endif + return n; +} + /** * copy_to_user: - Copy a block of data into user space. * @to: Destination address, in user space. diff ./include/asm-i386/uaccess.h~current~ ./include/asm-i386/uaccess.h --- ./include/asm-i386/uaccess.h~current~ 2006-04-28 10:08:04.000000000 +1000 +++ ./include/asm-i386/uaccess.h 2006-04-28 10:37:12.000000000 +1000 @@ -393,6 +393,8 @@ unsigned long __must_check __copy_from_u const void __user *from, unsigned long n); unsigned long __must_check __copy_from_user_ll_nocache(void *to, const void __user *from, unsigned long n); +unsigned long __must_check __copy_from_user_ll_nocache_nozero(void __user *to, + const void *from, unsigned long n); /* * Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault @@ -464,11 +466,23 @@ __copy_to_user(void __user *to, const vo * atomic context and will fail rather than sleep. In this case the * uncopied bytes will *NOT* be padded with zeros. See fs/filemap.h * for explanation of why this is needed. - * FIXME this isn't implimented yet EMXIF */ static __always_inline unsigned long __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n) { + /* As the only difference between copy_from and copy_to is that + * copy_from zeros any tail that wasn't actually copied to, + * and as that is exactly what we want for inatomic copy_from, + * we use copy_to_user_inatomic to implement + * copy_from_user_inatomic. Ofcourse we need to lie about + * __user tags.... + */ + return __copy_to_user_inatomic((void __user*)to, (const void *)from, n); +} +static __always_inline unsigned long +__copy_from_user(void *to, const void __user *from, unsigned long n) +{ + might_sleep(); if (__builtin_constant_p(n)) { unsigned long ret; @@ -489,9 +503,10 @@ __copy_from_user_inatomic(void *to, cons #define ARCH_HAS_NOCACHE_UACCESS -static __always_inline unsigned long __copy_from_user_inatomic_nocache(void *to, +static __always_inline unsigned long __copy_from_user_nocache(void *to, const void __user *from, unsigned long n) { + might_sleep(); if (__builtin_constant_p(n)) { unsigned long ret; @@ -511,17 +526,9 @@ static __always_inline unsigned long __c } static __always_inline unsigned long -__copy_from_user(void *to, const void __user *from, unsigned long n) -{ - might_sleep(); - return __copy_from_user_inatomic(to, from, n); -} - -static __always_inline unsigned long -__copy_from_user_nocache(void *to, const void __user *from, unsigned long n) +__copy_from_user_inatomic_nocache(void *to, const void __user *from, unsigned long n) { - might_sleep(); - return __copy_from_user_inatomic_nocache(to, from, n); + return __copy_from_user_ll_nocache_nozero((void __user *)to, (const void *)from, n); } unsigned long __must_check copy_to_user(void __user *to,