From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bjorn Helgaas Date: Fri, 12 Dec 2003 16:09:29 +0000 Subject: Re: [jakub@redhat.com: Re: [brian.j.vandecoevering@intel.com: RE: [Linux-ia64] problems with ppp/ppp Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org __put_user_check in both the 2.4 and 2.5 BK trees looks like the one quoted below, so evidently the problem has not been fixed. If you have a proposed fix, a patch and a test case would be useful. On Friday 12 December 2003 8:37 am, Bill Nottingham wrote: > Back long ago, I reported a problem with PPP on ia64: > > http://www.gelato.unsw.edu.au/linux-ia64/0105/1641.html > > We added the workaround in our tree for earlier releases, > and promptly forgot about it; however, someone reported that > RHEL 3 has the same issue (as we took the workaround out.) > > Jakub noticed the following - does this explain the problem? > > Bill > > ----- Forwarded message from Jakub Jelinek ----- > > From: Jakub Jelinek > To: notting@redhat.com > Subject: Re: [brian.j.vandecoevering@intel.com: RE: [Linux-ia64] problems with ppp/pppd: put_user/copy_to_user] > Reply-To: Jakub Jelinek > User-Agent: Mutt/1.4.1i > X-Reply-To: Jakub Jelinek > Date: Fri, 12 Dec 2003 07:32:59 -0500 > > On Thu, Dec 11, 2003 at 09:16:50PM -0800, David S. Miller wrote: > > On Thu, 11 Dec 2003 22:58:48 -0500 > > Bill Nottingham wrote: > > > > > According to Intel, this patch is *still* needed to fix ppp on > > > ia64 in RHEL3. We should probably verify this, although I'm > > > still at a loss as to why it works. > > > > Either a compiler problem or their put_user() implementation > > is busted. > > The latter I guess. > At least linux-2.4.22-1.2108.nptl I have unpacked on my box > has in asm-ia64/uaccess.h: > > #define put_user(x,ptr) __put_user_check((__typeof__(*(ptr)))(x),(ptr),sizeof(*(ptr)),get_fs()) > > #define __put_user_check(x,ptr,size,segment) \ > ({ \ > register long __pu_err asm ("r8") = -EFAULT; \ > __typeof__(*(ptr)) *__pu_addr = (ptr); \ > if (__access_ok((long)__pu_addr,size,segment)) { \ > __pu_err = 0; \ > switch (size) { \ > case 1: __put_user_8(x,__pu_addr); break; \ > case 2: __put_user_16(x,__pu_addr); break; \ > case 4: __put_user_32(x,__pu_addr); break; \ > case 8: __put_user_64(x,__pu_addr); break; \ > default: __put_user_unknown(); break; \ > } \ > } \ > __pu_err; \ > }) > > #define __put_user_32(x,addr) \ > asm volatile ( \ > "\n"_LL"\tst4 %1=%r2%P1\t// %0 gets overwritten by exception handler\n" \ > "\t.xdata4 \"__ex_table\", @gprel(1b), @gprel(1f)\n" \ > _LL \ > : "=r"(__pu_err) : "m"(__m(addr)), "rO"(x), "0"(__pu_err)) > > But, a function call clobbers r8. > Guess a > __typeof(x) __x = (x); > before __pu_err and > s/x/__x/ is needed. > Probably __pu_addr decl should be moved before __pu_err is initialized too, > otherwise > extern int *foo (); > put_user (0, foo ()); > might not work properly. > > Jakub > > > > ----- End forwarded message -----