From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f69.google.com (mail-pg0-f69.google.com [74.125.83.69]) by kanga.kvack.org (Postfix) with ESMTP id 92C676B0033 for ; Tue, 17 Jan 2017 14:33:08 -0500 (EST) Received: by mail-pg0-f69.google.com with SMTP id z67so135502540pgb.0 for ; Tue, 17 Jan 2017 11:33:08 -0800 (PST) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id b84si16094939pfl.88.2017.01.17.11.33.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Jan 2017 11:33:07 -0800 (PST) Subject: Re: [PATCH v4 4/4] sparc64: Add support for ADI (Application Data Integrity) References: <0c08eb00e5a9735d7d0bcbeaadeacaa761011aab.1483999591.git.khalid.aziz@oracle.com> <20170116.233924.374841184595409216.davem@davemloft.net> From: Khalid Aziz Message-ID: <767310a9-d3bd-9721-2d20-ce2c60cddd06@oracle.com> Date: Tue, 17 Jan 2017 12:32:46 -0700 MIME-Version: 1.0 In-Reply-To: <20170116.233924.374841184595409216.davem@davemloft.net> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: David Miller Cc: corbet@lwn.net, viro@zeniv.linux.org.uk, nitin.m.gupta@oracle.com, mike.kravetz@oracle.com, akpm@linux-foundation.org, mingo@kernel.org, kirill.shutemov@linux.intel.com, adam.buchbinder@gmail.com, hughd@google.com, minchan@kernel.org, keescook@chromium.org, chris.hyser@oracle.com, atish.patra@oracle.com, cmetcalf@mellanox.com, atomlin@redhat.com, jslaby@suse.cz, joe@perches.com, paul.gortmaker@windriver.com, mhocko@suse.com, lstoakes@gmail.com, jack@suse.cz, dave.hansen@linux.intel.com, vbabka@suse.cz, dan.j.williams@intel.com, iamjoonsoo.kim@lge.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, khalid@gonehiking.org On 01/16/2017 09:39 PM, David Miller wrote: > From: Khalid Aziz > Date: Wed, 11 Jan 2017 09:12:54 -0700 > >> + __asm__ __volatile__( >> + ".word 0xa1438000\n\t" /* rd %mcdper, %l0 */ > > Just use "rd %%asr14, %0" this way you don't have to play all of these > fixed register games which kill the code generated by gcc. If you > forcefully clobber a windowed register like %l0 it means the function > being emitted can never be a leaf function, tail calls are no longer > allowed, etc. Hi David, "rd %%asr14, %0" should work but does not due to bugs in assembler - , and . These bugs were fixed in binutils 2.27 but older assemblers will cause kernel build to fail. Using byte coded equivalent is the safest option. > >> + ".word 0x9d800011\n\t" /* wr %g0, %l1, %mcdper */ > > Likewise use "wr %%g0, %0, %%asr14" > >> + ".word 0xaf900001\n\t" /* wrpr %g0, %g1, %pmcdper */ > > Hmmm, which %asr encodes %pmcdper? %pmcdper is not an asr, rather a privileged register (pr23). Thanks, Khalid > >> diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c >> index 8a6982d..68b03bf 100644 >> --- a/arch/sparc/kernel/mdesc.c >> +++ b/arch/sparc/kernel/mdesc.c >> @@ -20,6 +20,7 @@ >> #include >> #include >> #include >> +#include >> >> /* Unlike the OBP device tree, the machine description is a full-on >> * DAG. An arbitrary number of ARCs are possible from one >> @@ -1104,5 +1105,8 @@ void __init sun4v_mdesc_init(void) >> >> cur_mdesc = hp; >> >> +#ifdef CONFIG_SPARC64 > > mdesc.c is only built on sparc64, this ifdef is superfluous. > >> +/* Update the state of MCDPER register in current task's mm context before >> + * dup so the dup'd task will inherit flags in this register correctly. >> + * Current task may have updated flags since it started running. >> + */ >> +int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) >> +{ >> + if (adi_capable() && src->mm) { >> + register unsigned long tmp_mcdper; >> + >> + __asm__ __volatile__( >> + ".word 0x83438000\n\t" /* rd %mcdper, %g1 */ >> + "mov %%g1, %0\n\t" >> + : "=r" (tmp_mcdper) >> + : >> + : "g1"); >> + src->mm->context.mcdper = tmp_mcdper; > > I don't like the idea of duplicating 'mm' state using the task struct > copy. Why do not the MM handling interfaces handle this properly? > > Maybe it means you've abstracted the ADI register handling in the > wrong place. Maybe it's a thread property which is "pushed" from > the MM context. > -- > To unsubscribe from this list: send the line "unsubscribe sparclinux" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org