From: Nicholas Piggin <npiggin@gmail•com>
To: Christophe Leroy <christophe.leroy@csgroup•eu>,
linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH 10/14] powerpc/64: use interrupt restart table to speed up return from interrupt
Date: Wed, 17 Mar 2021 09:46:01 +1000 [thread overview]
Message-ID: <1615938093.2fovnegcfp.astroid@bobo.none> (raw)
In-Reply-To: <f39dab9b-2f16-4c3d-9d7e-4fd2487c5c7d@csgroup.eu>
Excerpts from Christophe Leroy's message of March 17, 2021 5:34 am:
>
>
> Le 15/03/2021 à 23:03, Nicholas Piggin a écrit :
>> The restart table facility is used to return from interrupt without
>> disabling MSR EE or RI.
>
> What happens when an interrupt happens between the point you restore the user r1 and the rfi which
> returns to user ?
> If an interrupt happens there, the interrupt prolog sees it as an interrupt coming from kernel, so
> it uses r1 as is, but r1 points to user stack.
The interrupt is "soft-masked" because it arrives from kernel with an
address below __end_soft_masked. Masked interrupts never touch the
stack. It then checks the restart table and finds an entry, so it
returns to the restart which loads the previous r1 from paca.
Thanks,
Nick
next prev parent reply other threads:[~2021-03-16 23:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 22:03 [PATCH 00/14] powerpc/64: fast interrupt exits Nicholas Piggin
2021-03-15 22:03 ` [PATCH 01/14] powerpc: remove interrupt exit helpers unused argument Nicholas Piggin
2021-05-17 13:49 ` Christophe Leroy
2021-03-15 22:03 ` [PATCH 02/14] powerpc/64s: security fallback improvement Nicholas Piggin
2021-03-15 22:03 ` [PATCH 03/14] powerpc/64s: introduce different functions to return from SRR vs HSRR interrupts Nicholas Piggin
2021-03-15 22:03 ` [PATCH 04/14] powerpc/64s: avoid reloading (H)SRR registers if they are still valid Nicholas Piggin
2021-04-02 22:39 ` Michael Ellerman
2021-04-04 0:49 ` Nicholas Piggin
2021-04-03 2:28 ` Michael Ellerman
2021-04-04 0:51 ` Nicholas Piggin
2021-03-15 22:03 ` [PATCH 05/14] powerpc/64: move interrupt return asm to interrupt_64.S Nicholas Piggin
2021-03-15 22:03 ` [PATCH 06/14] powerpc/64s: save one more register in the masked interrupt handler Nicholas Piggin
2021-03-15 22:03 ` [PATCH 07/14] powerpc/64: allow alternate return locations for soft-masked interrupts Nicholas Piggin
2021-03-15 22:03 ` [PATCH 08/14] powerpc/64: interrupt soft-enable race fix Nicholas Piggin
2021-03-15 22:03 ` [PATCH 09/14] powerpc/64: treat low kernel text as irqs soft-masked Nicholas Piggin
2021-03-15 22:03 ` [PATCH 10/14] powerpc/64: use interrupt restart table to speed up return from interrupt Nicholas Piggin
2021-03-16 19:34 ` Christophe Leroy
2021-03-16 23:46 ` Nicholas Piggin [this message]
2021-03-15 22:03 ` [PATCH 11/14] powerpc/64e: Remove PPR from pt_regs Nicholas Piggin
2021-03-15 22:04 ` [PATCH 12/14] powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE] Nicholas Piggin
2021-03-16 7:21 ` Christophe Leroy
2021-03-16 8:13 ` Nicholas Piggin
2021-03-19 11:29 ` Michael Ellerman
2021-03-15 22:04 ` [PATCH 13/14] powerpc/64: handle MSR EE and RI in interrupt entry wrapper Nicholas Piggin
2021-03-15 22:04 ` [PATCH 14/14] powerpc/64s: use the same default PPR for user and kernel Nicholas Piggin
2021-05-17 14:09 ` Christophe Leroy
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