From: Martin Schwidefsky <schwidefsky@de.ibm.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>, Dave Hansen <dave@sr71.net>,
Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH] s390, sched: Fix thread_struct move fallout to __switch_to()
Date: Mon, 20 Jul 2015 10:33:47 +0200 [thread overview]
Message-ID: <20150720103347.38979f15@mschwide> (raw)
In-Reply-To: <20150720082004.GB12468@gmail.com>
On Mon, 20 Jul 2015 10:20:04 +0200
Ingo Molnar <mingo@kernel.org> wrote:
>
> * Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
>
> > Unfortunately not true. It breaks the build on s390 since a couple of
> > displacements used in asm code now get too large:
> >
> > arch/s390/kernel/entry.S:181: Error: operand out of range (0x00000000000018a8 is not between 0x0000000000000000 and 0x0000000000000fff)
> > arch/s390/kernel/entry.S:191: Error: operand out of range (0x00000000000018a8 is not between 0x0000000000000000 and 0x0000000000000fff)
> > arch/s390/kernel/entry.S:423: Error: operand out of range (0x0000000000001924 is not between 0x0000000000000000 and 0x0000000000000fff)
> > arch/s390/kernel/entry.S:437: Error: operand out of range (0x00000000000018e8 is not between 0x0000000000000000 and 0x0000000000000fff)
> > arch/s390/kernel/entry.S:438: Error: operand out of range (0x00000000000018e0 is not between 0x0000000000000000 and 0x0000000000000fff)
> > arch/s390/kernel/entry.S:439: Error: operand out of range (0x00000000000018f0 is not between 0x0000000000000000 and 0x0000000000000fff)
> > make[1]: *** [arch/s390/kernel/entry.o] Error 1
> >
> > Let's see how we can fix this.
>
> Sorry about this!
>
> So I looked at the __switch_to() assembly, and the main complication appears to be
> that we have two uses of 'prev':
>
> lg %r4,__THREAD_info(%r2) # get thread_info of prev
>
>
> stg %r15,__THREAD_ksp(%r2) # store kernel stack of prev
>
> the __THREAD_info offset is best expressed relative to task_struct - the
> __THREAD_ksp offset is best expressed relative to thread_struct.
>
> I.e. I think the best fix would be to extend the signature of s390's __switch_to()
> from (prev,next) to (prev,next,prev_thread,next_thread).
>
> Is the C parameter mapping r2,r3,r4,r5? If yes then the patch below should do the
> trick. (Utterly untested.)
>
> Note:
>
> - I renamed __THREAD_info to __TASK_thread_info, to better separate task_struct
> and thread_struct offsets syntactically and visually.
>
> - I removed __THREAD_mm_segment which is unused
>
> I also looked at fixing pgm_check_handler(), but my s390-fu gave up completely on
> that one: task_struct is in 'r14', but this is a hardware entry function it
> appears. So to fix it we'd have to pick a temporary register, put thread_struct
> pointer into it, and fix up these offsets:
>
> arch/s390/kernel/asm-offsets.c: DEFINE(__THREAD_per_address, offsetof(struct task_struct, thread.per_event.address));
> arch/s390/kernel/asm-offsets.c: DEFINE(__THREAD_per_paid, offsetof(struct task_struct, thread.per_event.paid));
> arch/s390/kernel/asm-offsets.c: DEFINE(__THREAD_trap_tdb, offsetof(struct task_struct, thread.trap_tdb));
>
> to be thread_struct relative.
Just use the patch I've sent. No worries :-)
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
next prev parent reply other threads:[~2015-07-20 8:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-18 3:18 [GIT PULL] x86 fixes Ingo Molnar
2015-07-20 7:20 ` Heiko Carstens
2015-07-20 8:00 ` [PATCH] sched, s390: Fix the fallout of increasing the offset of 'thread_struct' within 'task_struct' Ingo Molnar
2015-07-20 8:12 ` Martin Schwidefsky
2015-07-20 8:38 ` Ingo Molnar
2015-07-20 8:56 ` Martin Schwidefsky
2015-07-20 8:20 ` [PATCH] s390, sched: Fix thread_struct move fallout to __switch_to() Ingo Molnar
2015-07-20 8:33 ` Martin Schwidefsky [this message]
2015-07-20 8:34 ` Ingo Molnar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150720103347.38979f15@mschwide \
--to=schwidefsky@de.ibm.com \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=dave@sr71.net \
--cc=heiko.carstens@de.ibm.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).