Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752626AbbDEABR (ORCPT ); Sat, 4 Apr 2015 20:01:17 -0400 Received: from mail-wg0-f41.google.com ([74.125.82.41]:36822 "EHLO mail-wg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752371AbbDEABQ (ORCPT ); Sat, 4 Apr 2015 20:01:16 -0400 MIME-Version: 1.0 In-Reply-To: <20150404141434.GC22756@gmail.com> References: <1428152303-17154-1-git-send-email-brgerst@gmail.com> <20150404141434.GC22756@gmail.com> Date: Sat, 4 Apr 2015 20:01:14 -0400 Message-ID: Subject: Re: [PATCH] x86/signal: Remove pax argument from restore_sigcontext From: Brian Gerst To: Ingo Molnar Cc: "H. Peter Anvin" , Andy Lutomirski , Denys Vlasenko , Linus Torvalds , Borislav Petkov , "the arch/x86 maintainers" , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3077 Lines: 76 On Sat, Apr 4, 2015 at 10:14 AM, Ingo Molnar wrote: > > * Brian Gerst wrote: > >> The pax argument is unnecesary. Instead, store the RAX value directly >> in regs. >> >> Signed-off-by: Brian Gerst >> Cc: Ingo Molnar >> Cc: "H. Peter Anvin" >> Cc: Andy Lutomirski >> Cc: Denys Vlasenko >> Cc: Linus Torvalds >> Cc: Borislav Petkov >> Cc: x86@kernel.org >> Cc: linux-kernel@vger.kernel.org >> --- >> arch/x86/ia32/ia32_signal.c | 17 ++++++----------- >> arch/x86/include/asm/sighandling.h | 4 +--- >> arch/x86/kernel/signal.c | 22 ++++++++-------------- >> 3 files changed, 15 insertions(+), 28 deletions(-) >> >> diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c >> index 1f5e2b0..c81d35e6 100644 >> --- a/arch/x86/ia32/ia32_signal.c >> +++ b/arch/x86/ia32/ia32_signal.c >> @@ -161,8 +161,7 @@ int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from) >> } >> >> static int ia32_restore_sigcontext(struct pt_regs *regs, >> - struct sigcontext_ia32 __user *sc, >> - unsigned int *pax) >> + struct sigcontext_ia32 __user *sc) >> { >> unsigned int tmpflags, err = 0; >> void __user *buf; >> @@ -184,7 +183,7 @@ static int ia32_restore_sigcontext(struct pt_regs *regs, >> RELOAD_SEG(es); >> >> COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); >> - COPY(dx); COPY(cx); COPY(ip); >> + COPY(dx); COPY(cx); COPY(ip); COPY(ax); >> /* Don't touch extended registers */ >> >> COPY_SEG_CPL3(cs); >> @@ -197,8 +196,6 @@ static int ia32_restore_sigcontext(struct pt_regs *regs, >> >> get_user_ex(tmp, &sc->fpstate); >> buf = compat_ptr(tmp); >> - >> - get_user_ex(*pax, &sc->ax); >> } get_user_catch(err); > > Note that arch/x86/kernel/signal.c appears to have a similar pattern - > and there it could be removed as well? > > I'm wondering what the original reason for adding the extra handling > of regs->ax was. Maybe something changed regs->ax - but I cannot find > such code path anymore. > > It would be nice to try to do a bit of Git archeology to figure out > the origins of this complication - maybe it's something subtle - or > it's something that has changed meanwhile. It goes all the way back to 2.1.106pre1, when restore_sigcontext() was changed to return an error code instead of EAX directly. https://git.kernel.org/cgit/linux/kernel/git/history/history.git/diff/arch/i386/kernel/signal.c?id=9a8f8b7ca3f319bd668298d447bdf32730e51174 -- Brian Gerst -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/