From: Mathieu Desnoyers <mathieu.desnoyers@efficios•com>
To: Stephen Rothwell <sfr@canb•auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix•de>, Ingo Molnar <mingo@elte•hu>,
"H. Peter Anvin" <hpa@zytor•com>,
Peter Zijlstra <peterz@infradead•org>,
Linux-Next Mailing List <linux-next@vger•kernel.org>,
linux-kernel <linux-kernel@vger•kernel.org>,
Will Deacon <will.deacon@arm•com>
Subject: Re: linux-next: manual merge of the tip tree with Linus' tree
Date: Tue, 6 Feb 2018 12:52:34 +0000 (UTC) [thread overview]
Message-ID: <750091485.16756.1517921554396.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20180206114048.6c8ced1c@canb.auug.org.au>
----- On Feb 5, 2018, at 7:40 PM, Stephen Rothwell sfr@canb•auug.org.au wrote:
> Hi all,
>
> Today's linux-next merge of the tip tree got a conflict in:
>
> arch/arm64/kernel/entry.S
>
> between commit:
>
> 4bf3286d29f3 ("arm64: entry: Hook up entry trampoline to exception vectors")
>
> from Linus' tree and commit:
>
> f1e3a12b6543 ("membarrier/arm64: Provide core serializing command")
>
> from the tip tree.
>
> I fixed it up (probably not completely - see below) and can carry the
> fix as necessary. This is now fixed as far as linux-next is concerned,
> but any non trivial conflicts should be mentioned to your upstream
> maintainer when your tree is submitted for merging. You may also want
> to consider cooperating with the maintainer of the conflicting tree to
> minimise any particularly complex conflicts.
The change introduced by 4bf3286d29 "arm64: entry: Hook up entry trampoline
to exception vectors" adds a trampoline as mechanism for return:
- eret // return to kernel
+
+#ifndef CONFIG_UNMAP_KERNEL_AT_EL0
+ eret
+#else
+ .if \el == 0
+ bne 4f
+ msr far_el1, x30
+ tramp_alias x30, tramp_exit_native
+ br x30
+4:
+ tramp_alias x30, tramp_exit_compat
+ br x30
+ .else
+ eret
+ .endif
+#endif
Which means that with CONFIG_UNMAP_KERNEL_AT_EL0, for return to EL0,
the eret is in the trampoline:
.macro tramp_exit, regsize = 64
adr x30, tramp_vectors
msr vbar_el1, x30
tramp_unmap_kernel x30
.if \regsize == 64
mrs x30, far_el1
.endif
eret
.endm
ENTRY(tramp_exit_native)
tramp_exit
END(tramp_exit_native)
ENTRY(tramp_exit_compat)
tramp_exit 32
END(tramp_exit_compat)
One approach I would consider for this is to duplicate this
comment and add it just above the "eret" instruction within the
macro:
/*
* ARCH_HAS_MEMBARRIER_SYNC_CORE rely on eret context synchronization
* when returning from IPI handler, and when returning to user-space.
*/
Or perhaps Will has something else in mind ?
Thanks,
Mathieu
>
> --
> Cheers,
> Stephen Rothwell
>
> diff --cc arch/arm64/kernel/entry.S
> index b34e717d7597,5edde1c2e93e..000000000000
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@@ -324,21 -302,11 +324,25 @@@ alternative_else_nop_endi
> ldp x28, x29, [sp, #16 * 14]
> ldr lr, [sp, #S_LR]
> add sp, sp, #S_FRAME_SIZE // restore sp
> +
> + .if \el == 0
> +alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
> +#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
> + bne 4f
> + msr far_el1, x30
> + tramp_alias x30, tramp_exit_native
> + br x30
> +4:
> + tramp_alias x30, tramp_exit_compat
> + br x30
> +#endif
> + .else
> + /*
> + * ARCH_HAS_MEMBARRIER_SYNC_CORE rely on eret context synchronization
> + * when returning from IPI handler, and when returning to user-space.
> + */
> - eret // return to kernel
> + eret
> + .endif
> .endm
>
> .macro irq_stack_entry
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2018-02-06 12:51 UTC|newest]
Thread overview: 135+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-06 0:40 linux-next: manual merge of the tip tree with Linus' tree Stephen Rothwell
2018-02-06 12:52 ` Mathieu Desnoyers [this message]
2018-02-06 13:55 ` Will Deacon
2018-02-06 14:06 ` Mathieu Desnoyers
2018-02-06 14:11 ` Will Deacon
2018-02-06 17:05 ` Mathieu Desnoyers
2018-02-06 17:21 ` Will Deacon
2018-02-08 7:03 ` Ingo Molnar
2018-02-08 18:56 ` Will Deacon
2018-02-08 19:04 ` Mathieu Desnoyers
2018-02-09 18:25 ` Will Deacon
2018-02-09 20:35 ` Mathieu Desnoyers
-- strict thread matches above, loose matches on Subject: below --
2025-10-28 0:22 Stephen Rothwell
2025-10-28 1:10 ` Tejun Heo
2025-10-28 14:08 ` Peter Zijlstra
2025-05-13 6:54 Stephen Rothwell
2025-05-13 9:13 ` Ingo Molnar
2025-05-13 10:35 ` Stephen Rothwell
2025-05-13 6:52 Stephen Rothwell
2025-05-13 6:49 Stephen Rothwell
2025-05-13 6:45 Stephen Rothwell
2025-05-13 6:10 Stephen Rothwell
2025-05-13 6:00 Stephen Rothwell
2025-05-13 5:48 Stephen Rothwell
2025-05-13 23:09 ` Bagas Sanjaya
2024-02-08 1:30 Stephen Rothwell
2023-10-16 1:38 Stephen Rothwell
2023-08-09 2:15 Stephen Rothwell
2023-02-15 1:08 Stephen Rothwell
2023-02-15 11:15 ` Ingo Molnar
2022-07-13 5:08 Stephen Rothwell
2022-05-09 3:59 Stephen Rothwell
2022-01-04 2:45 Stephen Rothwell
2021-10-11 2:21 Stephen Rothwell
2021-10-11 20:48 ` Borislav Petkov
2020-11-06 2:39 Stephen Rothwell
2020-11-06 2:46 ` Steven Rostedt
2020-08-12 1:21 Stephen Rothwell
2020-06-11 1:00 Stephen Rothwell
2020-06-11 0:52 Stephen Rothwell
2020-06-11 10:43 ` Thomas Gleixner
2020-06-11 11:03 ` Stephen Rothwell
2020-06-10 1:49 Stephen Rothwell
2020-06-10 1:42 Stephen Rothwell
2020-05-18 5:10 Stephen Rothwell
2020-05-18 7:12 ` Borislav Petkov
2020-01-06 2:17 Stephen Rothwell
2020-01-06 6:53 ` Ingo Molnar
2019-12-20 1:53 Stephen Rothwell
2019-12-16 2:43 Stephen Rothwell
2019-12-03 2:10 Stephen Rothwell
2019-12-03 6:57 ` Ingo Molnar
2019-12-03 8:56 ` Stephen Rothwell
2019-09-02 7:31 Stephen Rothwell
2019-09-02 18:07 ` Ingo Molnar
2019-07-29 2:00 Stephen Rothwell
2019-03-06 5:53 Stephen Rothwell
2018-10-12 2:14 Stephen Rothwell
2018-10-12 2:18 ` Kees Cook
2018-10-12 10:47 ` Ingo Molnar
2018-10-12 18:56 ` Kees Cook
2018-06-07 1:53 Stephen Rothwell
2018-02-12 1:27 Stephen Rothwell
2018-02-12 7:19 ` Ingo Molnar
2018-02-06 0:54 Stephen Rothwell
2018-02-06 9:14 ` Peter Zijlstra
2018-02-06 0:44 Stephen Rothwell
2017-11-10 1:27 Stephen Rothwell
2017-05-22 3:27 Stephen Rothwell
2017-05-22 8:32 ` Mark Rutland
2017-05-22 21:44 ` Stephen Rothwell
2017-05-23 8:37 ` Mark Rutland
2016-02-03 0:09 Stephen Rothwell
2016-02-03 0:32 ` Toshi Kani
2015-09-18 1:12 Stephen Rothwell
2015-08-17 5:57 Stephen Rothwell
2015-07-06 0:08 Stephen Rothwell
2015-07-06 7:49 ` Paolo Bonzini
2015-07-06 21:34 ` Stephen Rothwell
2014-05-21 4:12 Stephen Rothwell
2014-05-21 4:24 ` H. Peter Anvin
2014-05-21 6:01 ` Ingo Molnar
2014-05-21 6:02 ` H. Peter Anvin
2014-05-21 6:05 ` Ingo Molnar
2014-05-21 6:10 ` Ingo Molnar
2014-05-21 4:12 Stephen Rothwell
2014-03-21 4:23 Stephen Rothwell
2014-03-21 8:47 ` Srivatsa S. Bhat
2014-02-18 3:09 Stephen Rothwell
2014-02-18 8:06 ` Hans-Christian Egtvedt
2014-02-18 14:15 ` Chen Gang
2014-01-30 1:42 Stephen Rothwell
2014-01-30 1:49 ` Andi Kleen
2014-01-30 1:58 ` Stephen Rothwell
2014-01-30 2:05 ` Andi Kleen
2014-01-28 0:43 Stephen Rothwell
2014-01-17 3:30 Stephen Rothwell
2014-01-17 17:27 ` Sören Brinkmann
2013-12-16 3:18 Stephen Rothwell
2013-09-04 4:24 Stephen Rothwell
2013-07-09 4:36 Stephen Rothwell
2012-12-03 4:19 Stephen Rothwell
2012-10-16 1:00 Stephen Rothwell
2012-10-21 16:29 ` Ingo Molnar
2012-10-15 0:32 Stephen Rothwell
2012-10-10 2:51 Stephen Rothwell
2012-10-10 2:45 Stephen Rothwell
2012-06-26 4:36 Stephen Rothwell
2012-06-22 5:01 Stephen Rothwell
2012-06-04 3:52 Stephen Rothwell
2012-05-22 5:44 Stephen Rothwell
2012-01-03 5:16 Stephen Rothwell
2012-01-03 5:08 Stephen Rothwell
2012-01-03 8:06 ` Ingo Molnar
2012-01-03 8:36 ` Stephen Rothwell
2011-04-14 3:14 Stephen Rothwell
2011-04-14 9:02 ` Peter Zijlstra
2011-04-14 9:25 ` Ingo Molnar
2011-04-08 5:02 Stephen Rothwell
2011-03-16 5:08 Stephen Rothwell
2011-03-16 8:50 ` Sebastian Andrzej Siewior
2011-03-16 11:02 ` Stephen Rothwell
2010-10-22 2:08 Stephen Rothwell
2010-10-06 2:47 Stephen Rothwell
2010-09-23 3:32 Stephen Rothwell
2010-07-26 3:39 Stephen Rothwell
2010-01-18 7:08 Stephen Rothwell
2010-01-18 7:50 ` Ingo Molnar
2010-01-18 8:59 ` Stephen Rothwell
2009-12-09 4:06 Stephen Rothwell
2009-09-24 4:07 Stephen Rothwell
2009-09-24 8:33 ` Ingo Molnar
2009-09-24 9:23 ` Stephen Rothwell
2009-08-19 6:07 Stephen Rothwell
2009-08-19 10:37 ` Ingo Molnar
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