From: Nicholas Piggin <npiggin@gmail.com>
To: Christophe Leroy <christophe.leroy@c-s.fr>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/4] powerpc/64: remove support for kernel-mode syscalls
Date: Tue, 27 Aug 2019 20:41:20 +1000 [thread overview]
Message-ID: <1566902428.f4rgy4icjs.astroid@bobo.none> (raw)
In-Reply-To: <1566900842.ttf5qhpflv.astroid@bobo.none>
Nicholas Piggin's on August 27, 2019 8:20 pm:
> Christophe Leroy's on August 27, 2019 4:13 pm:
>>
>>
>> Le 27/08/2019 à 05:30, Nicholas Piggin a écrit :
>>> There is support for the kernel to execute the 'sc 0' instruction and
>>> make a system call to itself. This is a relic that is unused in the
>>> tree, therefore untested. It's also highly questionable for modules to
>>> be doing this.
>>
>> I like it.
>>
>> I dropped support for that in PPC32 when I added fast-path syscalls.
>
> Good, then we'll match again.
>
>>> - beq 2f /* if from kernel mode */
>>> #ifdef CONFIG_PPC_FSL_BOOK3E
>>> START_BTB_FLUSH_SECTION
>>> BTB_FLUSH(r10)
>>> END_BTB_FLUSH_SECTION
>>> #endif
>>> ACCOUNT_CPU_USER_ENTRY(r13, r10, r11)
>>> -2: std r2,GPR2(r1)
>
> Btw. there is a hunk which restores this optimisation but it leaked
> into a later patch, I'll move it back here.
I'm wrong. Now I look at it again, the hunk should be removed
completely of course.
Thanks,
Nick
next prev parent reply other threads:[~2019-08-27 10:44 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 3:30 [PATCH 0/4] powerpc/64: syscalls in C Nicholas Piggin
2019-08-27 3:30 ` [PATCH 1/4] powerpc: convert to copy_thread_tls Nicholas Piggin
2019-08-27 6:07 ` Christophe Leroy
2019-08-27 10:13 ` Nicholas Piggin
2019-08-27 14:00 ` Christophe Leroy
2019-09-02 3:29 ` Michael Ellerman
2019-08-27 3:30 ` [PATCH 2/4] powerpc/64: remove support for kernel-mode syscalls Nicholas Piggin
2019-08-27 6:13 ` Christophe Leroy
2019-08-27 10:20 ` Nicholas Piggin
2019-08-27 10:41 ` Nicholas Piggin [this message]
2019-08-27 3:30 ` [PATCH 2/4] powerpc/64s: " Nicholas Piggin
2019-08-27 6:14 ` Christophe Leroy
2019-08-27 10:21 ` Nicholas Piggin
2019-08-27 3:30 ` [PATCH 3/4] powerpc/64: system call remove non-volatile GPR save optimisation Nicholas Piggin
2019-08-27 8:10 ` Segher Boessenkool
2019-08-27 3:30 ` [PATCH 4/4] powerpc/64: system call implement the bulk of the logic in C Nicholas Piggin
2019-08-27 6:46 ` Christophe Leroy
2019-08-27 10:30 ` Nicholas Piggin
2019-08-27 14:35 ` kbuild test robot
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