From: David Laight <David.Laight@ACULAB.COM>
To: "'Michal Suchánek'" <msuchanek@suse.de>,
"Petr Mladek" <pmladek@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Michal Hocko <mhocko@suse.cz>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Stephen Rothwell <sfr@ozlabs.org>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"Martin Schwidefsky" <schwidefsky@de.ibm.com>,
"Tobin C . Harding" <me@tobin.cc>
Subject: RE: [PATCH] vsprintf: Do not break early boot with probing addresses
Date: Thu, 9 May 2019 13:46:59 +0000 [thread overview]
Message-ID: <8ad8bb83b7034f7e92df12040fb8c2c2@AcuMS.aculab.com> (raw)
In-Reply-To: <20190509153829.06319d0c@kitsune.suse.cz>
From: Michal Suchánek
> Sent: 09 May 2019 14:38
...
> > The problem is the combination of some new code called via printk(),
> > check_pointer() which calls probe_kernel_read(). That then calls
> > allow_user_access() (PPC_KUAP) and that uses mmu_has_feature() too early
> > (before we've patched features).
>
> There is early_mmu_has_feature for this case. mmu_has_feature does not
> work before patching so parts of kernel that can run before patching
> must use the early_ variant which actually runs code reading the
> feature bitmap to determine the answer.
Does the early_ variant get patched so the it is reasonably
efficient after the 'patching' is done?
Or should there be a third version which gets patched across?
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
WARNING: multiple messages have this Message-ID (diff)
From: David Laight <David.Laight@ACULAB.COM>
To: "'Michal Suchánek'" <msuchanek@suse.de>,
"Petr Mladek" <pmladek@suse.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Michal Hocko <mhocko@suse.cz>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Stephen Rothwell <sfr@ozlabs.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
"Tobin C . Harding" <me@tobin.cc>
Subject: RE: [PATCH] vsprintf: Do not break early boot with probing addresses
Date: Thu, 9 May 2019 13:46:59 +0000 [thread overview]
Message-ID: <8ad8bb83b7034f7e92df12040fb8c2c2@AcuMS.aculab.com> (raw)
In-Reply-To: <20190509153829.06319d0c@kitsune.suse.cz>
From: Michal Suchánek
> Sent: 09 May 2019 14:38
...
> > The problem is the combination of some new code called via printk(),
> > check_pointer() which calls probe_kernel_read(). That then calls
> > allow_user_access() (PPC_KUAP) and that uses mmu_has_feature() too early
> > (before we've patched features).
>
> There is early_mmu_has_feature for this case. mmu_has_feature does not
> work before patching so parts of kernel that can run before patching
> must use the early_ variant which actually runs code reading the
> feature bitmap to determine the answer.
Does the early_ variant get patched so the it is reasonably
efficient after the 'patching' is done?
Or should there be a third version which gets patched across?
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2019-05-09 13:47 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-09 12:19 [PATCH] vsprintf: Do not break early boot with probing addresses Petr Mladek
2019-05-09 12:19 ` Petr Mladek
2019-05-09 13:05 ` Andy Shevchenko
2019-05-09 13:05 ` Andy Shevchenko
2019-05-09 13:13 ` Steven Rostedt
2019-05-09 13:13 ` Steven Rostedt
2019-05-09 14:06 ` Petr Mladek
2019-05-09 14:06 ` Petr Mladek
2019-05-09 13:38 ` Michal Suchánek
2019-05-09 13:38 ` Michal Suchánek
2019-05-09 13:46 ` David Laight [this message]
2019-05-09 13:46 ` David Laight
2019-05-10 10:21 ` Michael Ellerman
2019-05-10 10:21 ` Michael Ellerman
2019-05-10 10:21 ` Michael Ellerman
2019-05-10 4:32 ` Sergey Senozhatsky
2019-05-10 4:32 ` Sergey Senozhatsky
2019-05-10 4:47 ` Linus Torvalds
2019-05-10 5:07 ` Sergey Senozhatsky
2019-05-10 5:07 ` Sergey Senozhatsky
2019-05-10 6:41 ` Michael Ellerman
2019-05-10 6:41 ` Michael Ellerman
2019-05-10 6:41 ` Michael Ellerman
2019-05-10 6:41 ` Michael Ellerman
2019-05-10 8:06 ` Petr Mladek
2019-05-10 8:06 ` Petr Mladek
2019-05-10 8:16 ` Sergey Senozhatsky
2019-05-10 8:16 ` Sergey Senozhatsky
2019-05-10 8:42 ` Petr Mladek
2019-05-10 8:42 ` Petr Mladek
2019-05-10 8:51 ` Sergey Senozhatsky
2019-05-10 8:51 ` Sergey Senozhatsky
2019-05-10 14:49 ` Petr Mladek
2019-05-10 14:49 ` Petr Mladek
2019-05-10 16:24 ` Steven Rostedt
2019-05-10 16:24 ` Steven Rostedt
2019-05-10 16:32 ` Martin Schwidefsky
2019-05-10 16:32 ` Martin Schwidefsky
2019-05-10 16:40 ` Steven Rostedt
2019-05-10 16:40 ` Steven Rostedt
2019-05-10 16:45 ` Martin Schwidefsky
2019-05-10 16:45 ` Martin Schwidefsky
2019-05-13 12:24 ` Petr Mladek
2019-05-13 12:24 ` Petr Mladek
2019-05-10 16:41 ` Andy Shevchenko
2019-05-10 16:41 ` Andy Shevchenko
2019-05-10 17:35 ` christophe leroy
2019-05-10 17:35 ` christophe leroy
2019-05-13 8:52 ` David Laight
2019-05-13 8:52 ` David Laight
2019-05-13 9:13 ` Andy Shevchenko
2019-05-13 9:13 ` Andy Shevchenko
2019-05-13 9:13 ` Andy Shevchenko
2019-05-13 12:42 ` Petr Mladek
2019-05-13 12:42 ` Petr Mladek
2019-05-13 12:42 ` Petr Mladek
2019-05-13 14:15 ` Steven Rostedt
2019-05-13 14:15 ` Steven Rostedt
2019-05-13 14:15 ` Steven Rostedt
2019-05-14 2:07 ` Sergey Senozhatsky
2019-05-14 2:07 ` Sergey Senozhatsky
2019-05-14 2:07 ` Sergey Senozhatsky
2019-05-14 2:25 ` Sergey Senozhatsky
2019-05-14 2:25 ` Sergey Senozhatsky
2019-05-14 2:25 ` Sergey Senozhatsky
2019-05-14 8:28 ` David Laight
2019-05-14 8:28 ` David Laight
2019-05-14 8:28 ` David Laight
2019-05-14 9:02 ` Geert Uytterhoeven
2019-05-14 9:02 ` Geert Uytterhoeven
2019-05-14 9:02 ` Geert Uytterhoeven
2019-05-14 18:37 ` Steven Rostedt
2019-05-14 18:37 ` Steven Rostedt
2019-05-14 18:37 ` Steven Rostedt
2019-05-14 19:13 ` Geert Uytterhoeven
2019-05-14 19:13 ` Geert Uytterhoeven
2019-05-14 19:13 ` Geert Uytterhoeven
2019-05-14 19:35 ` Steven Rostedt
2019-05-14 19:35 ` Steven Rostedt
2019-05-14 19:35 ` Steven Rostedt
2019-05-15 7:23 ` Geert Uytterhoeven
2019-05-15 7:23 ` Geert Uytterhoeven
2019-05-15 7:23 ` Geert Uytterhoeven
2019-05-15 7:53 ` Petr Mladek
2019-05-15 7:53 ` Petr Mladek
2019-05-15 7:53 ` Petr Mladek
2019-05-15 6:21 ` Sergey Senozhatsky
2019-05-15 6:21 ` Sergey Senozhatsky
2019-05-15 6:21 ` Sergey Senozhatsky
2019-05-15 7:35 ` Petr Mladek
2019-05-15 7:35 ` Petr Mladek
2019-05-15 7:35 ` Petr Mladek
2019-05-15 9:00 ` David Laight
2019-05-15 9:00 ` David Laight
2019-05-15 9:00 ` David Laight
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