From: Will Deacon <will.deacon@arm.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Vineet Gupta <vgupta@synopsys.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Kuo <rkuo@codeaurora.org>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Michal Simek <monstr@monstr.eu>,
Ralf Baechle <ralf@linux-mips.org>,
Jonas Bonn <jonas@southpole.se>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Stafford Horne <shorne@gmail.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH 1/1] futex: remove duplicated code
Date: Mon, 15 May 2017 14:16:45 +0100 [thread overview]
Message-ID: <20170515131644.GA3605@arm.com> (raw)
In-Reply-To: <20170515130742.18357-1-jslaby@suse.cz>
Hi Jiri,
On Mon, May 15, 2017 at 03:07:42PM +0200, Jiri Slaby wrote:
> There is code duplicated over all architecture's headers for
> futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr,
> and comparison of the result.
>
> Remove this duplication and leave up to the arches only the needed
> assembly which is now in arch_futex_atomic_op_inuser.
>
> Note that s390 removed access_ok check in d12a29703 ("s390/uaccess:
> remove pointless access_ok() checks") as access_ok there returns true.
> We introduce it back to the helper for the sake of simplicity (it gets
> optimized away anyway).
Whilst I think this is a good idea, the code in question actually results
in undefined behaviour per the C spec and is reported by UBSAN. See my
patch fixing arm64 here (which I'd forgotten about):
https://www.spinics.net/lists/linux-arch/msg38564.html
But, as stated in the thread above, I think we should go a step further
and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
appear to be used by userspace, and this whole thing is a total mess.
Any thoughts?
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Vineet Gupta <vgupta@synopsys.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Kuo <rkuo@codeaurora.org>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Michal Simek <monstr@monstr.eu>,
Ralf Baechle <ralf@linux-mips.org>,
Jonas Bonn <jonas@southpole.se>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Stafford Horne <shorne@gmail.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
"David S. Miller" <davem@davemloft.net>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>, Arnd Bergmann <arnd@arndb.de>,
x86@kernel.org, linux-alpha@vger.kernel.org,
linux-snps-arc@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-mips@linux-mips.org, openrisc@lists.librecores.org,
linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org,
linux-arch@vger.kernel.org
Subject: Re: [PATCH 1/1] futex: remove duplicated code
Date: Mon, 15 May 2017 14:16:45 +0100 [thread overview]
Message-ID: <20170515131644.GA3605@arm.com> (raw)
Message-ID: <20170515131645.h5vxGl1SErUwWv1aMtsMiC_P31yW39kvY6SPw13kUVI@z> (raw)
In-Reply-To: <20170515130742.18357-1-jslaby@suse.cz>
Hi Jiri,
On Mon, May 15, 2017 at 03:07:42PM +0200, Jiri Slaby wrote:
> There is code duplicated over all architecture's headers for
> futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr,
> and comparison of the result.
>
> Remove this duplication and leave up to the arches only the needed
> assembly which is now in arch_futex_atomic_op_inuser.
>
> Note that s390 removed access_ok check in d12a29703 ("s390/uaccess:
> remove pointless access_ok() checks") as access_ok there returns true.
> We introduce it back to the helper for the sake of simplicity (it gets
> optimized away anyway).
Whilst I think this is a good idea, the code in question actually results
in undefined behaviour per the C spec and is reported by UBSAN. See my
patch fixing arm64 here (which I'd forgotten about):
https://www.spinics.net/lists/linux-arch/msg38564.html
But, as stated in the thread above, I think we should go a step further
and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
appear to be used by userspace, and this whole thing is a total mess.
Any thoughts?
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Vineet Gupta <vgupta@synopsys.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Kuo <rkuo@codeaurora.org>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Michal Simek <monstr@monstr.eu>,
Ralf Baechle <ralf@linux-mips.org>,
Jonas Bonn <jonas@southpole.se>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Stafford Horne <shorne@gmail.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH 1/1] futex: remove duplicated code
Date: Mon, 15 May 2017 13:16:45 +0000 [thread overview]
Message-ID: <20170515131644.GA3605@arm.com> (raw)
In-Reply-To: <20170515130742.18357-1-jslaby@suse.cz>
Hi Jiri,
On Mon, May 15, 2017 at 03:07:42PM +0200, Jiri Slaby wrote:
> There is code duplicated over all architecture's headers for
> futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr,
> and comparison of the result.
>
> Remove this duplication and leave up to the arches only the needed
> assembly which is now in arch_futex_atomic_op_inuser.
>
> Note that s390 removed access_ok check in d12a29703 ("s390/uaccess:
> remove pointless access_ok() checks") as access_ok there returns true.
> We introduce it back to the helper for the sake of simplicity (it gets
> optimized away anyway).
Whilst I think this is a good idea, the code in question actually results
in undefined behaviour per the C spec and is reported by UBSAN. See my
patch fixing arm64 here (which I'd forgotten about):
https://www.spinics.net/lists/linux-arch/msg38564.html
But, as stated in the thread above, I think we should go a step further
and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
appear to be used by userspace, and this whole thing is a total mess.
Any thoughts?
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: Jiri Slaby <jslaby@suse.cz>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Vineet Gupta <vgupta@synopsys.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Kuo <rkuo@codeaurora.org>,
Tony Luck <tony.luck@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Michal Simek <monstr@monstr.eu>,
Ralf Baechle <ralf@linux-mips.org>,
Jonas Bonn <jonas@southpole.se>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Stafford Horne <shorne@gmail.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Subject: Re: [PATCH 1/1] futex: remove duplicated code
Date: Mon, 15 May 2017 14:16:45 +0100 [thread overview]
Message-ID: <20170515131644.GA3605@arm.com> (raw)
In-Reply-To: <20170515130742.18357-1-jslaby@suse.cz>
Hi Jiri,
On Mon, May 15, 2017 at 03:07:42PM +0200, Jiri Slaby wrote:
> There is code duplicated over all architecture's headers for
> futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr,
> and comparison of the result.
>
> Remove this duplication and leave up to the arches only the needed
> assembly which is now in arch_futex_atomic_op_inuser.
>
> Note that s390 removed access_ok check in d12a29703 ("s390/uaccess:
> remove pointless access_ok() checks") as access_ok there returns true.
> We introduce it back to the helper for the sake of simplicity (it gets
> optimized away anyway).
Whilst I think this is a good idea, the code in question actually results
in undefined behaviour per the C spec and is reported by UBSAN. See my
patch fixing arm64 here (which I'd forgotten about):
https://www.spinics.net/lists/linux-arch/msg38564.html
But, as stated in the thread above, I think we should go a step further
and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
appear to be used by userspace, and this whole thing is a total mess.
Any thoughts?
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-snps-arc@lists.infradead.org
Subject: [PATCH 1/1] futex: remove duplicated code
Date: Mon, 15 May 2017 14:16:45 +0100 [thread overview]
Message-ID: <20170515131644.GA3605@arm.com> (raw)
In-Reply-To: <20170515130742.18357-1-jslaby@suse.cz>
Hi Jiri,
On Mon, May 15, 2017@03:07:42PM +0200, Jiri Slaby wrote:
> There is code duplicated over all architecture's headers for
> futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr,
> and comparison of the result.
>
> Remove this duplication and leave up to the arches only the needed
> assembly which is now in arch_futex_atomic_op_inuser.
>
> Note that s390 removed access_ok check in d12a29703 ("s390/uaccess:
> remove pointless access_ok() checks") as access_ok there returns true.
> We introduce it back to the helper for the sake of simplicity (it gets
> optimized away anyway).
Whilst I think this is a good idea, the code in question actually results
in undefined behaviour per the C spec and is reported by UBSAN. See my
patch fixing arm64 here (which I'd forgotten about):
https://www.spinics.net/lists/linux-arch/msg38564.html
But, as stated in the thread above, I think we should go a step further
and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
appear to be used by userspace, and this whole thing is a total mess.
Any thoughts?
Will
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon@arm.com>
To: openrisc@lists.librecores.org
Subject: [OpenRISC] [PATCH 1/1] futex: remove duplicated code
Date: Mon, 15 May 2017 14:16:45 +0100 [thread overview]
Message-ID: <20170515131644.GA3605@arm.com> (raw)
In-Reply-To: <20170515130742.18357-1-jslaby@suse.cz>
Hi Jiri,
On Mon, May 15, 2017 at 03:07:42PM +0200, Jiri Slaby wrote:
> There is code duplicated over all architecture's headers for
> futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr,
> and comparison of the result.
>
> Remove this duplication and leave up to the arches only the needed
> assembly which is now in arch_futex_atomic_op_inuser.
>
> Note that s390 removed access_ok check in d12a29703 ("s390/uaccess:
> remove pointless access_ok() checks") as access_ok there returns true.
> We introduce it back to the helper for the sake of simplicity (it gets
> optimized away anyway).
Whilst I think this is a good idea, the code in question actually results
in undefined behaviour per the C spec and is reported by UBSAN. See my
patch fixing arm64 here (which I'd forgotten about):
https://www.spinics.net/lists/linux-arch/msg38564.html
But, as stated in the thread above, I think we should go a step further
and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
appear to be used by userspace, and this whole thing is a total mess.
Any thoughts?
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/1] futex: remove duplicated code
Date: Mon, 15 May 2017 14:16:45 +0100 [thread overview]
Message-ID: <20170515131644.GA3605@arm.com> (raw)
In-Reply-To: <20170515130742.18357-1-jslaby@suse.cz>
Hi Jiri,
On Mon, May 15, 2017 at 03:07:42PM +0200, Jiri Slaby wrote:
> There is code duplicated over all architecture's headers for
> futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr,
> and comparison of the result.
>
> Remove this duplication and leave up to the arches only the needed
> assembly which is now in arch_futex_atomic_op_inuser.
>
> Note that s390 removed access_ok check in d12a29703 ("s390/uaccess:
> remove pointless access_ok() checks") as access_ok there returns true.
> We introduce it back to the helper for the sake of simplicity (it gets
> optimized away anyway).
Whilst I think this is a good idea, the code in question actually results
in undefined behaviour per the C spec and is reported by UBSAN. See my
patch fixing arm64 here (which I'd forgotten about):
https://www.spinics.net/lists/linux-arch/msg38564.html
But, as stated in the thread above, I think we should go a step further
and remove FUTEX_OP_{OR,ANDN,XOR,OPARG_SHIFT} altogether. They don't
appear to be used by userspace, and this whole thing is a total mess.
Any thoughts?
Will
next prev parent reply other threads:[~2017-05-15 13:16 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-15 13:07 [PATCH 1/1] futex: remove duplicated code Jiri Slaby
2017-05-15 13:07 ` Jiri Slaby
2017-05-15 13:07 ` [OpenRISC] " Jiri Slaby
2017-05-15 13:07 ` Jiri Slaby
2017-05-15 13:07 ` Jiri Slaby
2017-05-15 13:07 ` Jiri Slaby
2017-05-15 13:07 ` Jiri Slaby
2017-05-15 13:16 ` Will Deacon [this message]
2017-05-15 13:16 ` Will Deacon
2017-05-15 13:16 ` [OpenRISC] " Will Deacon
2017-05-15 13:16 ` Will Deacon
2017-05-15 13:16 ` Will Deacon
2017-05-15 13:16 ` Will Deacon
2017-05-15 13:16 ` Will Deacon
2017-05-17 8:01 ` Jiri Slaby
2017-05-17 8:01 ` Jiri Slaby
2017-05-17 8:01 ` [OpenRISC] " Jiri Slaby
2017-05-17 8:01 ` Jiri Slaby
2017-05-17 8:01 ` Jiri Slaby
2017-05-17 8:01 ` Jiri Slaby
2017-05-17 8:01 ` Jiri Slaby
2017-05-18 17:30 ` Will Deacon
2017-05-18 17:30 ` Will Deacon
2017-05-18 17:30 ` [OpenRISC] " Will Deacon
2017-05-18 17:30 ` Will Deacon
2017-05-18 17:30 ` Will Deacon
2017-05-18 17:30 ` Will Deacon
2017-05-18 17:30 ` Will Deacon
2017-05-22 21:11 ` Thomas Gleixner
2017-05-22 21:11 ` Thomas Gleixner
2017-05-22 21:11 ` [OpenRISC] " Thomas Gleixner
2017-05-22 21:11 ` Thomas Gleixner
2017-05-22 21:11 ` Thomas Gleixner
2017-05-22 21:11 ` Thomas Gleixner
2017-05-22 21:11 ` Thomas Gleixner
2017-05-25 14:28 ` Will Deacon
2017-05-25 14:28 ` Will Deacon
2017-05-25 14:28 ` [OpenRISC] " Will Deacon
2017-05-25 14:28 ` Will Deacon
2017-05-25 14:28 ` Will Deacon
2017-05-25 14:28 ` Will Deacon
2017-05-25 14:28 ` Will Deacon
2017-05-26 6:54 ` Thomas Gleixner
2017-05-26 6:54 ` Thomas Gleixner
2017-05-26 6:54 ` [OpenRISC] " Thomas Gleixner
2017-05-26 6:54 ` Thomas Gleixner
2017-05-26 6:54 ` Thomas Gleixner
2017-05-26 6:54 ` Thomas Gleixner
2017-05-26 6:54 ` Thomas Gleixner
-- strict thread matches above, loose matches on Subject: below --
2017-06-21 11:53 [PATCH 1/1] futex: remove duplicated code and fix UB Jiri Slaby
2017-06-21 11:53 ` Jiri Slaby
2017-06-21 11:53 ` Jiri Slaby
2017-06-21 11:53 ` Jiri Slaby
2017-06-21 11:53 ` Jiri Slaby
2017-06-21 11:53 ` Jiri Slaby
2017-06-22 3:53 ` Darren Hart
2017-06-22 3:53 ` Darren Hart
2017-06-22 3:53 ` Darren Hart
2017-06-22 3:53 ` Darren Hart
2017-06-22 3:53 ` Darren Hart
2017-06-22 3:53 ` Darren Hart
2017-06-23 7:51 ` Thomas Gleixner
2017-06-23 7:51 ` Thomas Gleixner
2017-06-23 7:51 ` Thomas Gleixner
2017-06-23 7:51 ` Thomas Gleixner
2017-06-23 7:51 ` Thomas Gleixner
2017-06-23 7:51 ` Thomas Gleixner
2017-06-23 7:51 ` Thomas Gleixner
2017-06-26 12:02 ` Jiri Slaby
2017-06-26 12:02 ` Jiri Slaby
2017-06-26 12:02 ` Jiri Slaby
2017-06-26 12:02 ` Jiri Slaby
2017-06-26 12:02 ` Jiri Slaby
2017-06-26 12:08 ` Will Deacon
2017-06-26 12:08 ` Will Deacon
2017-06-26 12:08 ` Will Deacon
2017-06-26 12:08 ` Will Deacon
2017-06-26 12:08 ` Will Deacon
2017-07-03 10:18 ` Thomas Gleixner
2017-07-03 10:18 ` Thomas Gleixner
2017-07-03 10:18 ` Thomas Gleixner
2017-07-03 10:18 ` Thomas Gleixner
2017-07-03 10:18 ` Thomas Gleixner
2017-07-03 10:18 ` Thomas Gleixner
2017-07-03 10:18 ` Thomas Gleixner
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