From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rohit Seth Date: Sat, 28 Apr 2007 18:17:45 +0000 Subject: RE: Fw: [PATCH] ia64: race flushing icache in do_no_page path Message-Id: <200704281817.l3SIHu0P001764@smtp.corp.google.com> List-Id: In-Reply-To: References: <20070426001615.GA8908@ldl.fc.hp.com> In-Reply-To: <20070426001615.GA8908@ldl.fc.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: 'Hugh Dickins' Cc: 'Nick Piggin' , 'Mike Stroyan' , 'Andrew Morton' , "'Luck, Tony'" , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Hi Hugh, -----Original Message----- From: Hugh Dickins [mailto:hugh@veritas.com] Sent: Friday, April 27, 2007 10:34 PM To: Rohit Seth Cc: Nick Piggin; Mike Stroyan; Andrew Morton; Luck, Tony; linux-ia64@vger.kernel.org; linux-kernel@vger.kernel.org Subject: Re: Fw: [PATCH] ia64: race flushing icache in do_no_page path On Fri, 27 Apr 2007, Rohit Seth wrote: > lazy_mmu_prot_update was added specifically for notifying change in > protection. So, in a way it is closer to update_mmu_cache (Which is > for change in mappings itself). Though for ia64 implementation, this > ends up flushing the icaches when needed. >The ia64 implementation is the only one which has any use for it, Even Itanium didn't need it for almost 5 years :) Though I think archs that have incoherent I & D caches could be (theoritically) exposed to same (original) mprotect code path bug that triggered this API. >and >it's only interested when it's executable i.e. "lazy_mmu_prot_update" >is a name concealing some overdesign. You are right that ia64 is only interested in whne the execute permissions kick in (and FWIW ia64 used to use update_mmu_cache API to do what it is now doing lazy_mmu_prot_update). Though the idea was to design an API that any arch can use to know when ever there is change in protections on a mapping. Cheers, -rohit