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From: Al Viro <viro@zeniv.linux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Vineet Gupta <Vineet.Gupta1@synopsys.com>,
	Khalid Aziz <khalid.aziz@oracle.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Kees Cook <keescook@chromium.org>, Ingo Molnar <mingo@kernel.org>,
	Aleksa Sarai <cyphar@cyphar.com>,
	"open list:SYNOPSYS ARC ARCHITECTURE"
	<linux-snps-arc@lists.infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [RFC 1/4] asm-generic/uaccess: don't define inline functions if noinline lib/* in use
Date: Wed, 15 Jan 2020 14:12:24 +0000	[thread overview]
Message-ID: <20200115141224.GH8904@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CAK8P3a2ao=xBuy3XHBkdo03KEjpMHGe9ahwj-uogtkZBXsMkGw@mail.gmail.com>

On Wed, Jan 15, 2020 at 10:08:31AM +0100, Arnd Bergmann wrote:

> > I would suggest that anybody who uses asm-generic/uaccess.h needs to
> > simply use the generic library version.
> 
> Or possibly just everybody altogether: the remaining architectures that
> have a custom implementation don't seem to be doing any better either.

No go for s390.  There you really want to access userland memory in
larger chunks - it's oriented for block transfers.  IIRC, the insn
they are using has a costly setup phase, independent of the amount
to copy, followed by reasonably fast transfer more or less linear
by the size.

WARNING: multiple messages have this Message-ID (diff)
From: Al Viro <viro@zeniv.linux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arch <linux-arch@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Andrey Konovalov <andreyknvl@google.com>,
	Vineet Gupta <Vineet.Gupta1@synopsys.com>,
	Aleksa Sarai <cyphar@cyphar.com>, Ingo Molnar <mingo@kernel.org>,
	Khalid Aziz <khalid.aziz@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	"open list:SYNOPSYS ARC ARCHITECTURE"
	<linux-snps-arc@lists.infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC 1/4] asm-generic/uaccess: don't define inline functions if noinline lib/* in use
Date: Wed, 15 Jan 2020 14:12:24 +0000	[thread overview]
Message-ID: <20200115141224.GH8904@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CAK8P3a2ao=xBuy3XHBkdo03KEjpMHGe9ahwj-uogtkZBXsMkGw@mail.gmail.com>

On Wed, Jan 15, 2020 at 10:08:31AM +0100, Arnd Bergmann wrote:

> > I would suggest that anybody who uses asm-generic/uaccess.h needs to
> > simply use the generic library version.
> 
> Or possibly just everybody altogether: the remaining architectures that
> have a custom implementation don't seem to be doing any better either.

No go for s390.  There you really want to access userland memory in
larger chunks - it's oriented for block transfers.  IIRC, the insn
they are using has a costly setup phase, independent of the amount
to copy, followed by reasonably fast transfer more or less linear
by the size.

_______________________________________________
linux-snps-arc mailing list
linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc

  reply	other threads:[~2020-01-15 14:12 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-14 20:08 [RFC 0/4] Switching ARC to optimized generic strncpy_from_user Vineet Gupta
2020-01-14 20:08 ` Vineet Gupta
2020-01-14 20:08 ` Vineet Gupta
2020-01-14 20:08 ` [RFC 1/4] asm-generic/uaccess: don't define inline functions if noinline lib/* in use Vineet Gupta
2020-01-14 20:08   ` Vineet Gupta
2020-01-14 20:57   ` Arnd Bergmann
2020-01-14 20:57     ` Arnd Bergmann
2020-01-15 23:01     ` Vineet Gupta
2020-01-15 23:01       ` Vineet Gupta
2020-01-16 11:43       ` Arnd Bergmann
2020-01-16 11:43         ` Arnd Bergmann
2020-01-14 21:32   ` Linus Torvalds
2020-01-14 21:32     ` Linus Torvalds
2020-01-15  9:08     ` Arnd Bergmann
2020-01-15  9:08       ` Arnd Bergmann
2020-01-15 14:12       ` Al Viro [this message]
2020-01-15 14:12         ` Al Viro
2020-01-15 14:21         ` Arnd Bergmann
2020-01-15 14:21           ` Arnd Bergmann
2020-01-14 20:08 ` [RFC 2/4] lib/strncpy_from_user: Remove redundant user space pointer range check Vineet Gupta
2020-01-14 20:08   ` Vineet Gupta
2020-01-14 21:22   ` Linus Torvalds
2020-01-14 21:22     ` Linus Torvalds
2020-01-14 21:52     ` Vineet Gupta
2020-01-14 21:52       ` Vineet Gupta
2020-01-14 23:46     ` Al Viro
2020-01-14 23:46       ` Al Viro
2020-01-15 14:42   ` Andrey Konovalov
2020-01-15 14:42     ` Andrey Konovalov
2020-01-15 14:42     ` Andrey Konovalov
2020-01-15 23:00     ` Vineet Gupta
2020-01-15 23:00       ` Vineet Gupta
2020-01-14 20:08 ` [RFC 3/4] ARC: uaccess: remove noinline variants of __strncpy_from_user() and friends Vineet Gupta
2020-01-14 20:08   ` Vineet Gupta
2020-01-14 20:08 ` [RFC 4/4] ARC: uaccess: use optimized generic __strnlen_user/__strncpy_from_user Vineet Gupta
2020-01-14 20:08   ` Vineet Gupta
2020-01-14 20:42   ` Arnd Bergmann
2020-01-14 20:42     ` Arnd Bergmann
2020-01-14 21:36     ` Vineet Gupta
2020-01-14 21:36       ` Vineet Gupta
2020-01-14 21:49       ` Linus Torvalds
2020-01-14 21:49         ` Linus Torvalds
2020-01-14 22:14         ` Vineet Gupta
2020-01-14 22:14           ` Vineet Gupta

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