From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57220) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1alZD6-0004sl-5O for qemu-devel@nongnu.org; Thu, 31 Mar 2016 05:48:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1alZD2-0004PA-TW for qemu-devel@nongnu.org; Thu, 31 Mar 2016 05:48:16 -0400 References: <1459355811-31155-1-git-send-email-laurent@vivier.eu> From: Thomas Huth Message-ID: <56FCF259.5000301@tuxfamily.org> Date: Thu, 31 Mar 2016 11:48:09 +0200 MIME-Version: 1.0 In-Reply-To: <1459355811-31155-1-git-send-email-laurent@vivier.eu> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] linux-user,target-ppc: fix use of MSR_LE List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laurent Vivier , Riku Voipio Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, Alexander Graf On 30.03.2016 18:36, Laurent Vivier wrote: > setup_frame()/setup_rt_frame()/restore_user_regs() are using > MSR_LE as the similar kernel functions do: as a bitmask. > > But in QEMU, MSR_LE is a bit position, so change this > accordingly. > > The previous code was doing nothing as MSR_LE is 0, > and "env->msr &= ~MSR_LE" doesn't change the value of msr. > > And yes, a user process can change its endianness, > see linux kernel commit: > > fab5db9 [PATCH] powerpc: Implement support for setting little-endian mode via prctl > > and prctl(2): PR_SET_ENDIAN, PR_GET_ENDIAN > > Signed-off-by: Laurent Vivier > --- > linux-user/signal.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/linux-user/signal.c b/linux-user/signal.c > index a233bab..f1b597b 100644 > --- a/linux-user/signal.c > +++ b/linux-user/signal.c > @@ -4588,7 +4588,7 @@ static void restore_user_regs(CPUPPCState *env, > > /* If doing signal return, restore the previous little-endian mode. */ > if (sig) > - env->msr = (env->msr & ~MSR_LE) | (msr & MSR_LE); > + env->msr = (env->msr & ~(1ull << MSR_LE)) | (msr & (1ull << MSR_LE)); > > /* Restore Altivec registers if necessary. */ > if (env->insns_flags & PPC_ALTIVEC) { > @@ -4703,7 +4703,7 @@ static void setup_frame(int sig, struct target_sigaction *ka, > #endif > > /* Signal handlers are entered in big-endian mode. */ > - env->msr &= ~MSR_LE; > + env->msr &= ~(1ull << MSR_LE); > > unlock_user_struct(frame, frame_addr, 1); > return; > @@ -4798,7 +4798,7 @@ static void setup_rt_frame(int sig, struct target_sigaction *ka, > #endif > > /* Signal handlers are entered in big-endian mode. */ > - env->msr &= ~MSR_LE; > + env->msr &= ~(1ull << MSR_LE); > > unlock_user_struct(rt_sf, rt_sf_addr, 1); > return; > Reviewed-by: Thomas Huth