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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-api <linux-api@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Dave Watson <davejwatson@fb.com>, Paul Turner <pjt@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Russell King <linux@arm.linux.org.uk>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>,
	Ben Maurer <bmaurer@fb.com>, rostedt <rostedt@goodmis.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>, Michael Kerrisk <mtk.ma>
Subject: Re: [PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user
Date: Mon, 9 Jul 2018 14:19:19 -0400 (EDT)	[thread overview]
Message-ID: <1519037424.2393.1531160359475.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <CA+55aFzpjA3r9HdfCU5LrEhSt6S=+RfKuJ2GVc8Wv5Hz-_Me8Q@mail.gmail.com>

----- On Jul 9, 2018, at 2:04 PM, Linus Torvalds torvalds@linux-foundation.org wrote:

> On Mon, Jul 9, 2018 at 10:28 AM Mathieu Desnoyers
> <mathieu.desnoyers@efficios.com> wrote:
>>
>> So, another twist to this story: ppc32 does not implement u64 get_user().
> 
> I was going to say that "that's not possible", since we actually have
> 64-bit arguments at least in the form of "loff_t __user *".
> 
> But when I started looking, it turns out that yeah, we do
> "copy_from_user()" on them, and instead made the x86 copy_from_user()
> have special cases for constant sizes.
> 
> So a 8-byte copy_from_user() is fine. It ends up being a "get_user()"
> on x86 anyway.

Given that this memory area has already been checked with access_ok()
on rseq registration, are you fine with leaving
__get_user/__put_user/__copy_{from,to}_user in place so we do the
minimal change at this stage of rc, or should I go ahead and replace
the lot with get_user/put_user/copy_{from,to}_user ?

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

WARNING: multiple messages have this Message-ID (diff)
From: mathieu.desnoyers@efficios.com (Mathieu Desnoyers)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user
Date: Mon, 9 Jul 2018 14:19:19 -0400 (EDT)	[thread overview]
Message-ID: <1519037424.2393.1531160359475.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <CA+55aFzpjA3r9HdfCU5LrEhSt6S=+RfKuJ2GVc8Wv5Hz-_Me8Q@mail.gmail.com>

----- On Jul 9, 2018, at 2:04 PM, Linus Torvalds torvalds at linux-foundation.org wrote:

> On Mon, Jul 9, 2018 at 10:28 AM Mathieu Desnoyers
> <mathieu.desnoyers@efficios.com> wrote:
>>
>> So, another twist to this story: ppc32 does not implement u64 get_user().
> 
> I was going to say that "that's not possible", since we actually have
> 64-bit arguments at least in the form of "loff_t __user *".
> 
> But when I started looking, it turns out that yeah, we do
> "copy_from_user()" on them, and instead made the x86 copy_from_user()
> have special cases for constant sizes.
> 
> So a 8-byte copy_from_user() is fine. It ends up being a "get_user()"
> on x86 anyway.

Given that this memory area has already been checked with access_ok()
on rseq registration, are you fine with leaving
__get_user/__put_user/__copy_{from,to}_user in place so we do the
minimal change at this stage of rc, or should I go ahead and replace
the lot with get_user/put_user/copy_{from,to}_user ?

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

WARNING: multiple messages have this Message-ID (diff)
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-api <linux-api@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Dave Watson <davejwatson@fb.com>, Paul Turner <pjt@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Russell King <linux@arm.linux.org.uk>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andi Kleen <andi@firstfloor.org>, Chris Lameter <cl@linux.com>,
	Ben Maurer <bmaurer@fb.com>, rostedt <rostedt@goodmis.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	Joel Fernandes <joelaf@google.com>,
	Andrew Hunter <ahh@google.com>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user
Date: Mon, 9 Jul 2018 14:19:19 -0400 (EDT)	[thread overview]
Message-ID: <1519037424.2393.1531160359475.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <CA+55aFzpjA3r9HdfCU5LrEhSt6S=+RfKuJ2GVc8Wv5Hz-_Me8Q@mail.gmail.com>

----- On Jul 9, 2018, at 2:04 PM, Linus Torvalds torvalds@linux-foundation.org wrote:

> On Mon, Jul 9, 2018 at 10:28 AM Mathieu Desnoyers
> <mathieu.desnoyers@efficios.com> wrote:
>>
>> So, another twist to this story: ppc32 does not implement u64 get_user().
> 
> I was going to say that "that's not possible", since we actually have
> 64-bit arguments at least in the form of "loff_t __user *".
> 
> But when I started looking, it turns out that yeah, we do
> "copy_from_user()" on them, and instead made the x86 copy_from_user()
> have special cases for constant sizes.
> 
> So a 8-byte copy_from_user() is fine. It ends up being a "get_user()"
> on x86 anyway.

Given that this memory area has already been checked with access_ok()
on rseq registration, are you fine with leaving
__get_user/__put_user/__copy_{from,to}_user in place so we do the
minimal change at this stage of rc, or should I go ahead and replace
the lot with get_user/put_user/copy_{from,to}_user ?

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com

  reply	other threads:[~2018-07-09 18:19 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-08 21:03 [PATCH for 4.18 0/6] Restartable Sequences updates Mathieu Desnoyers
2018-07-08 21:03 ` Mathieu Desnoyers
2018-07-08 21:03 ` [PATCH for 4.18 1/6] rseq: use __u64 for rseq_cs fields, validate user inputs Mathieu Desnoyers
2018-07-08 21:03   ` Mathieu Desnoyers
2018-07-08 21:03 ` [PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user Mathieu Desnoyers
2018-07-08 21:03   ` Mathieu Desnoyers
2018-07-08 21:03   ` Mathieu Desnoyers
2018-07-09 17:28   ` Mathieu Desnoyers
2018-07-09 17:28     ` Mathieu Desnoyers
2018-07-09 17:28     ` Mathieu Desnoyers
2018-07-09 18:04     ` Linus Torvalds
2018-07-09 18:04       ` Linus Torvalds
2018-07-09 18:04       ` Linus Torvalds
2018-07-09 18:19       ` Mathieu Desnoyers [this message]
2018-07-09 18:19         ` Mathieu Desnoyers
2018-07-09 18:19         ` Mathieu Desnoyers
2018-07-09 19:04         ` Linus Torvalds
2018-07-09 19:04           ` Linus Torvalds
2018-07-09 19:04           ` Linus Torvalds
2018-07-10  6:16     ` Michael Ellerman
2018-07-10  6:16       ` Michael Ellerman
2018-07-10  6:16       ` Michael Ellerman
2018-07-10 13:48       ` Mathieu Desnoyers
2018-07-10 13:48         ` Mathieu Desnoyers
2018-07-10 13:48         ` Mathieu Desnoyers
2018-07-08 21:03 ` [PATCH for 4.18 3/6] rseq: uapi: update uapi comments Mathieu Desnoyers
2018-07-08 21:03   ` Mathieu Desnoyers
2018-07-08 21:03 ` [PATCH for 4.18 4/6] rseq: uapi: declare rseq_cs field as union, update includes Mathieu Desnoyers
2018-07-08 21:03   ` Mathieu Desnoyers
2018-07-08 21:03 ` [PATCH for 4.18 5/6] rseq: remove unused types_32_64.h uapi header Mathieu Desnoyers
2018-07-08 21:03   ` Mathieu Desnoyers
2018-07-08 21:03 ` [PATCH for 4.18 6/6] rseq/selftests: cleanup: update comment above rseq_prepare_unload Mathieu Desnoyers
2018-07-08 21:03   ` Mathieu Desnoyers
2018-07-08 21:12 ` [PATCH for 4.18 0/6] Restartable Sequences updates Linus Torvalds
2018-07-08 21:12   ` Linus Torvalds
2018-07-09 18:04 ` Mathieu Desnoyers
2018-07-09 18:04   ` Mathieu Desnoyers
  -- strict thread matches above, loose matches on Subject: below --
2018-07-09 19:51 [PATCH v2 " Mathieu Desnoyers
2018-07-09 19:51 ` [PATCH for 4.18 2/6] rseq: use get_user/put_user rather than __get_user/__put_user Mathieu Desnoyers
2018-07-09 19:51   ` Mathieu Desnoyers
2018-07-09 19:51   ` Mathieu Desnoyers

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