From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755994AbcEXMUh (ORCPT ); Tue, 24 May 2016 08:20:37 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:15325 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753895AbcEXMUg (ORCPT ); Tue, 24 May 2016 08:20:36 -0400 Subject: Re: [PATCH 1/1] arm64: fix flush_cache_range To: Mark Rutland References: <1464088597-8820-1-git-send-email-thunder.leizhen@huawei.com> <20160524113727.GD25374@leverpostej> CC: Catalin Marinas , Will Deacon , linux-arm-kernel , linux-kernel , Xinwei Hu , Zefan Li , Hanjun Guo , Tianhong Ding From: "Leizhen (ThunderTown)" Message-ID: <574446B9.8040105@huawei.com> Date: Tue, 24 May 2016 20:19:05 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20160524113727.GD25374@leverpostej> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.23.164] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A090205.574446C9.0088,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 2e67d4311fa47e3a3109076a332df783 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/5/24 19:37, Mark Rutland wrote: > On Tue, May 24, 2016 at 07:16:37PM +0800, Zhen Lei wrote: >> When we ran mprotect04(a test case in LTP) infinitely, it would always >> failed after a few seconds. The case can be described briefly that: copy >> a empty function from code area into a new memory area(created by mmap), >> then call mprotect to change the protection to PROT_EXEC. The syscall >> sys_mprotect will finally invoke flush_cache_range, but this function >> currently only invalid icache, the operation of flush dcache is missed. > > In the LTP code I see powerpc-specific D-cache / I-cache synchronisation > (i.e. d-cache cleaning followed by I-cache invalidation), so there > appears to be some expectation of userspace maintenance. Hoever, there > is no such ARM-specific I-cache maintenance. But I see some other platforms have D-cache maintenance, like: arch/nios2/mm/cacheflush.c And according to the name of flush_cache_range, it should do this, I judged. Otherwise, mprotect04 will be failed on more platforms, it's easy to discover. Only PPC have specific cache synchronization, maybe it meets some hardware limitation. It's impossible a programmer fixed a common bug on only one platform but leave others unchanged. > > It looks like the test may be missing I-cache maintenance regardless of > the semantics of mprotect in this case. > > I have not yet devled into flush_cache_range and how it is called. SYSCALL_DEFINE3(mprotect ---> mprotect_fixup ---> change_protection ---> change_protection_range --> flush_cache_range > > Thanks, > Mark. > >> Signed-off-by: Zhen Lei >> --- >> arch/arm64/mm/flush.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm64/mm/flush.c b/arch/arm64/mm/flush.c >> index dbd12ea..eda4124 100644 >> --- a/arch/arm64/mm/flush.c >> +++ b/arch/arm64/mm/flush.c >> @@ -31,7 +31,7 @@ void flush_cache_range(struct vm_area_struct *vma, unsigned long start, >> unsigned long end) >> { >> if (vma->vm_flags & VM_EXEC) >> - __flush_icache_all(); >> + flush_icache_range(start, end); >> } >> >> static void sync_icache_aliases(void *kaddr, unsigned long len) >> -- >> 2.5.0 >> >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >> > > . >