From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 65DC51D2F50 for ; Tue, 6 Aug 2024 14:38:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722955115; cv=none; b=AUBoy6dI6I7EAvEh6bJf2jxqUIxFfjvf8DJ/adlkfRsFm99VVbodqMVHYR3k3qTkRMQWwjaT6GGfMaIyC/6fCK2DaXlbUlfa1s1eghxaJ5sXUFtADXZ6qTlFmlMTlGcIRtEZV4oODU62GwsqEBFix0zGd9v4+HgYMBmMoMo5ZFw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722955115; c=relaxed/simple; bh=I7uuq+gz1aOnDED7ieqVh/OdYhRbOKEI+TyDsKUjMHg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hoW0aHao1Xn2Y52RNF60Eu/C1vVLgMFSVeKg2XEKDFsPADdRsxt0gimdWajPHYsCZ0g+SZTQzaS3f2bw+gqNoBZn+nNaxuw4nO/T7eIRk5SXJeUGZdUF0qrcO90isV+N/9sqOV/O4BGQhmnknqdoBmtYTsbVzyMsamsZXSSIjqw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7D3071063; Tue, 6 Aug 2024 07:38:58 -0700 (PDT) Received: from e133380.arm.com (e133380.arm.com [10.1.197.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 168703F6A8; Tue, 6 Aug 2024 07:38:28 -0700 (PDT) Date: Tue, 6 Aug 2024 15:38:26 +0100 From: Dave Martin To: Joey Gouly Cc: linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org, aneesh.kumar@kernel.org, aneesh.kumar@linux.ibm.com, bp@alien8.de, broonie@kernel.org, catalin.marinas@arm.com, christophe.leroy@csgroup.eu, dave.hansen@linux.intel.com, hpa@zytor.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, maz@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, naveen.n.rao@linux.ibm.com, npiggin@gmail.com, oliver.upton@linux.dev, shuah@kernel.org, szabolcs.nagy@arm.com, tglx@linutronix.de, will@kernel.org, x86@kernel.org, kvmarm@lists.linux.dev Subject: Re: [PATCH v4 15/29] arm64: handle PKEY/POE faults Message-ID: References: <20240503130147.1154804-1-joey.gouly@arm.com> <20240503130147.1154804-16-joey.gouly@arm.com> <20240801160110.GC841837@e124191.cambridge.arm.com> <20240806134357.GA2017741@e124191.cambridge.arm.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240806134357.GA2017741@e124191.cambridge.arm.com> Hi, On Tue, Aug 06, 2024 at 02:43:57PM +0100, Joey Gouly wrote: > On Tue, Aug 06, 2024 at 02:33:37PM +0100, Dave Martin wrote: > > Hi, > > > > On Thu, Aug 01, 2024 at 05:01:10PM +0100, Joey Gouly wrote: > > > On Thu, Jul 25, 2024 at 04:57:09PM +0100, Dave Martin wrote: > > > > On Fri, May 03, 2024 at 02:01:33PM +0100, Joey Gouly wrote: > > > > > If a memory fault occurs that is due to an overlay/pkey fault, report that to > > > > > userspace with a SEGV_PKUERR. > > > > > > > > > > Signed-off-by: Joey Gouly > > > > > Cc: Catalin Marinas > > > > > Cc: Will Deacon > > > > > --- > > > > > arch/arm64/include/asm/traps.h | 1 + > > > > > arch/arm64/kernel/traps.c | 12 ++++++-- > > > > > arch/arm64/mm/fault.c | 56 ++++++++++++++++++++++++++++++++-- > > > > > 3 files changed, 64 insertions(+), 5 deletions(-) [...] > > > > > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > > > > > index 215e6d7f2df8..1bac6c84d3f5 100644 > > > > > --- a/arch/arm64/kernel/traps.c > > > > > +++ b/arch/arm64/kernel/traps.c > > > > > @@ -263,16 +263,24 @@ static void arm64_show_signal(int signo, const char *str) > > > > > __show_regs(regs); > > > > > } > > > > > > > > > > -void arm64_force_sig_fault(int signo, int code, unsigned long far, > > > > > - const char *str) > > > > > +void arm64_force_sig_fault_pkey(int signo, int code, unsigned long far, > > > > > + const char *str, int pkey) > > > > > { > > > > > arm64_show_signal(signo, str); > > > > > if (signo == SIGKILL) > > > > > force_sig(SIGKILL); > > > > > + else if (code == SEGV_PKUERR) > > > > > + force_sig_pkuerr((void __user *)far, pkey); > > > > > > > > Is signo definitely SIGSEGV here? It looks to me like we can get in > > > > here for SIGBUS, SIGTRAP etc. > > > > > > > > si_codes are not unique between different signo here, so I'm wondering > > > > whether this should this be: > > > > > > > > else if (signo == SIGSEGV && code == SEGV_PKUERR) > > > > > > > > ...? > > > > > > > > > > > > > else > > > > > force_sig_fault(signo, code, (void __user *)far); > > > > > } > > > > > > > > > > +void arm64_force_sig_fault(int signo, int code, unsigned long far, > > > > > + const char *str) > > > > > +{ > > > > > + arm64_force_sig_fault_pkey(signo, code, far, str, 0); > > > > > > > > Is there a reason not to follow the same convention as elsewhere, where > > > > -1 is passed for "no pkey"? > > > > > > > > If we think this should never be called with signo == SIGSEGV && > > > > code == SEGV_PKUERR and no valid pkey but if it's messy to prove, then > > > > maybe a WARN_ON_ONCE() would be worth it here? > > > > > > > > > > Anshuman suggested to separate them out, which I did like below, I think that > > > addresses your comments too? > > > > > > diff --git arch/arm64/kernel/traps.c arch/arm64/kernel/traps.c > > > index 215e6d7f2df8..49bac9ae04c0 100644 > > > --- arch/arm64/kernel/traps.c > > > +++ arch/arm64/kernel/traps.c > > > @@ -273,6 +273,13 @@ void arm64_force_sig_fault(int signo, int code, unsigned long far, > > > force_sig_fault(signo, code, (void __user *)far); > > > } > > > > > > +void arm64_force_sig_fault_pkey(int signo, int code, unsigned long far, > > > + const char *str, int pkey) > > > +{ > > > + arm64_show_signal(signo, str); > > > + force_sig_pkuerr((void __user *)far, pkey); > > > +} > > > + > > > void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, > > > const char *str) > > > { > > > > > > diff --git arch/arm64/mm/fault.c arch/arm64/mm/fault.c > > > index 451ba7cbd5ad..1ddd46b97f88 100644 > > > --- arch/arm64/mm/fault.c > > > +++ arch/arm64/mm/fault.c > > > > (Guessing where this is means to apply, since there is no hunk header > > or context...) > > Sorry I had some other changes and just mashed the bits into a diff-looking-thing. Fair enough. There are a few similar bits of code, so including more lines of context would have been helpful. The change looked reasonable though. > > > > > > - arm64_force_sig_fault(SIGSEGV, si_code, far, inf->name); > > > + if (si_code == SEGV_PKUERR) > > > + arm64_force_sig_fault_pkey(SIGSEGV, si_code, far, inf->name, pkey); > > > > Maybe drop the the signo and si_code argument? This would mean that > > arm64_force_sig_fault_pkey() can't be called with a signo/si_code > > combination that makes no sense. > > > > I think pkey faults are always going to be SIGSEGV/SEGV_PKUERR, right? > > Or are there other combinations that can apply for these faults? > > Ah yes, I can simplify it even more, thanks. > > diff --git arch/arm64/kernel/traps.c arch/arm64/kernel/traps.c > index 49bac9ae04c0..d9abb8b390c0 100644 > --- arch/arm64/kernel/traps.c > +++ arch/arm64/kernel/traps.c > @@ -273,10 +273,9 @@ void arm64_force_sig_fault(int signo, int code, unsigned long far, > force_sig_fault(signo, code, (void __user *)far); > } > > -void arm64_force_sig_fault_pkey(int signo, int code, unsigned long far, > - const char *str, int pkey) > +void arm64_force_sig_fault_pkey(unsigned long far, const char *str, int pkey) > { > - arm64_show_signal(signo, str); > + arm64_show_signal(SIGSEGV, str); > force_sig_pkuerr((void __user *)far, pkey); > } Looks sensible. I see that force_sig_pkuerr() fills in the signo and si_code itself. Cheers ---Dave