From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 8E6201007D1 for ; Fri, 27 Nov 2009 22:02:03 +1100 (EST) Subject: Re: [PATCH] fix PPC floating point debug From: Benjamin Herrenschmidt To: Stefani Seibold In-Reply-To: <1259312340.9648.6.camel@wall-e> References: <1259312340.9648.6.camel@wall-e> Content-Type: text/plain; charset="UTF-8" Date: Fri, 27 Nov 2009 22:01:56 +1100 Message-ID: <1259319716.2076.3.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2009-11-27 at 09:59 +0100, Stefani Seibold wrote: > The PPC architecture is unable to debug applications using hardware > floating point, because it would not save the floating point registers. > > After returning from the debugger, the contents of register was > modified. This patch fix this bug. I'm not sure what problem you are trying to fix... debugging FP apps works just fine afaik. You don't need to flush the FP state into the thread when delivering the SIGTRAP. If you have a signal handler, that will be done for you by the signal code before laying out the signal frame. If you are using ptrace, you should be using the appropriate ptrace calls to retrieve the FP state and they should do the right thing to. Do you have a precise example that doesn't work and which is fixed by your patch ? Cheers, Ben. > Signed-off-by: Stefani Seibold > --- > traps.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > --- linux-2.6.32-rc5/arch/powerpc/kernel/traps.c.orig 2009-11-27 09:47:37.989943124 +0100 > +++ linux-2.6.32-rc5/arch/powerpc/kernel/traps.c 2009-11-27 09:47:41.088330825 +0100 > @@ -559,6 +559,8 @@ void instruction_breakpoint_exception(st > return; > if (debugger_iabr_match(regs)) > return; > + if (regs->msr & MSR_FP) > + giveup_fpu(current); > _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip); > } > > @@ -577,6 +579,8 @@ void __kprobes single_step_exception(str > if (debugger_sstep(regs)) > return; > > + if (regs->msr & MSR_FP) > + giveup_fpu(current); > _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip); > } > > @@ -834,6 +838,8 @@ void __kprobes program_check_exception(s > regs->nip += 4; > return; > } > + if (regs->msr & MSR_FP) > + giveup_fpu(current); > _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip); > return; > } > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev