From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/9911 Path: news.gmane.org!not-for-mail From: Bobby Bingham Newsgroups: gmane.linux.lib.musl.general Subject: Re: [PATCH v2] add powerpc64 port Date: Thu, 14 Apr 2016 19:55:51 -0500 Message-ID: <20160415005551.GA24404@dora.lan> References: <1459747571-9123-1-git-send-email-koorogi@koorogi.info> <20160413230506.GE22574@port70.net> <20160414080138.GA23694@dora.lan> <20160414191400.GZ21636@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 X-Trace: ger.gmane.org 1460681769 31199 80.91.229.3 (15 Apr 2016 00:56:09 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 15 Apr 2016 00:56:09 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-9924-gllmg-musl=m.gmane.org@lists.openwall.com Fri Apr 15 02:56:09 2016 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1aqs3M-0001jk-Ly for gllmg-musl@m.gmane.org; Fri, 15 Apr 2016 02:56:08 +0200 Original-Received: (qmail 5389 invoked by uid 550); 15 Apr 2016 00:56:06 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 5365 invoked from network); 15 Apr 2016 00:56:05 -0000 Content-Disposition: inline In-Reply-To: <20160414191400.GZ21636@brightrain.aerifal.cx> X-Operating-System: Linux dora 4.3.3 User-Agent: Mutt/1.5.24 (2015-08-30) Xref: news.gmane.org gmane.linux.lib.musl.general:9911 Archived-At: On Thu, Apr 14, 2016 at 03:14:00PM -0400, Rich Felker wrote: > On Thu, Apr 14, 2016 at 03:01:38AM -0500, Bobby Bingham wrote: > > On Thu, Apr 14, 2016 at 01:05:07AM +0200, Szabolcs Nagy wrote: > > > * Bobby Bingham [2016-04-04 00:26:11 -0500]: > > > > +++ b/arch/powerpc64/bits/setjmp.h > > > > @@ -0,0 +1 @@ > > > > +typedef unsigned long long __jmp_buf[66]; > > > > > > hm glibc seems to use long[64] with 16byte alignment, > > > is the size diff because of alignment? > > > > Yes. Though apparently the glibc setjmp asm has code to detect a > > misaligned jmp_buf, but its handling of that case ends up overflowing > > the jmp_buf. > > > > I can make some changes to get our jmp_buf down to 65, but the only ways > > to get it down to 64 are either with 16 byte alignment, or to have setjmp > > spill vector registers to the stack first so it can copy them from there > > to the jmp_buf through a gpr. > > > > How important is it to match glibc here? > > I think you could avoid the need for alignment or increased buffer > size by positioning the vector registers at > jmp_buf_end-vector_save_size rounded _down_ to alignment, then > positioning the grps around them (so, putting the last gpr at the end > rather than before the vectors if the buffer as a whole is > misaligned). Is it valid to do the following? jmp_buf a, b; if (!setjmp(a)) { memcpy(b, a, sizeof a); longjmp(b, 1); } If that's valid, and the two jmp_bufs might be aligned differently, then this wouldn't work. > > But it might be preferable to have the alignment match ABI too. Is > there any way it can be achieved with just things guaranteed to exist > by the psABI (is __int128 required by the psABI?) or does it require > C11 and/or GNUC attributes to get 16-byte alignment? The ABI does specify __int128. I can switch jmp_buf to this. > > Rich