From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Andy Lutomirski <luto@amacapital.net>,
Dave Watson <davejwatson@fb.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-api <linux-api@vger.kernel.org>,
Paul Turner <pjt@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Russell King <linux@arm.linux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
Andrew Hunter <ahh@google.com>, Andi Kleen <andi@firstfloor.org>,
Chris Lameter <cl@linux.com>, Ben Maurer <bmaurer@fb.com>,
rostedt <rostedt@goodmis.org>,
Josh Triplett <josh@joshtriplett.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Catalin Marinas <cata>
Subject: Re: [PATCH 07/14] powerpc: Add support for restartable sequences
Date: Wed, 23 May 2018 17:29:45 -0400 (EDT) [thread overview]
Message-ID: <37442352.1577.1527110985175.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <1928158599.1541.1527106479862.JavaMail.zimbra@efficios.com>
----- On May 23, 2018, at 4:14 PM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
> ----- On May 20, 2018, at 10:08 AM, Boqun Feng boqun.feng@gmail.com wrote:
>
>> On Fri, May 18, 2018 at 02:17:17PM -0400, Mathieu Desnoyers wrote:
>>> ----- On May 17, 2018, at 7:50 PM, Boqun Feng boqun.feng@gmail.com wrote:
>>> [...]
>>> >> > I think you're right. So we have to introduce callsite to rseq_syscall()
>>> >> > in syscall path, something like:
>>> >> >
>>> >> > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
>>> >> > index 51695608c68b..a25734a96640 100644
>>> >> > --- a/arch/powerpc/kernel/entry_64.S
>>> >> > +++ b/arch/powerpc/kernel/entry_64.S
>>> >> > @@ -222,6 +222,9 @@ system_call_exit:
>>> >> > mtmsrd r11,1
>>> >> > #endif /* CONFIG_PPC_BOOK3E */
>>> >> >
>>> >> > + addi r3,r1,STACK_FRAME_OVERHEAD
>>> >> > + bl rseq_syscall
>>> >> > +
>>> >> > ld r9,TI_FLAGS(r12)
>>> >> > li r11,-MAX_ERRNO
>>> >> > andi.
>>> >> > r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
>>> >> >
>>>
>>> By the way, I think this is not the right spot to call rseq_syscall, because
>>> interrupts are disabled. I think we should move this hunk right after
>>> system_call_exit.
>>>
>>
>> Good point.
>>
>>> Would you like to implement and test an updated patch adding those calls for ppc
>>> 32 and 64 ?
>>>
>>
>> I'd like to help, but I don't have a handy ppc environment for test...
>> So I made the below patch which has only been build-tested, hope it
>> could be somewhat helpful.
>
> Hi Boqun,
>
> I tried your patch in a ppc64 le environment, and it does not survive boot
> with CONFIG_DEBUG_RSEQ=y. init gets killed right away.
The following fixup gets ppc64 to work:
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -208,6 +208,7 @@ system_call_exit:
/* Check whether the syscall is issued inside a restartable sequence */
addi r3,r1,STACK_FRAME_OVERHEAD
bl rseq_syscall
+ ld r3,RESULT(r1)
#endif
/*
* Disable interrupts so current_thread_info()->flags can't change,
> Moreover, I'm not sure that the r3 register don't contain something worth
> saving before the call on ppc32. Just after there is a "mr" instruction
> which AFAIU takes r3 as input register.
I'll start testing on ppc32 now.
Thanks,
Mathieu
>
> Can you look into it ?
>
> Thanks,
>
> Mathieu
>
>>
>> Regards,
>> Boqun
>>
>> --------------------------------->8
>> Subject: [PATCH] powerpc: Add syscall detection for restartable sequences
>>
>> Syscalls are not allowed inside restartable sequences, so add a call to
>> rseq_syscall() at the very beginning of system call exiting path for
>> CONFIG_DEBUG_RSEQ=y kernel. This could help us to detect whether there
>> is a syscall issued inside restartable sequences.
>>
>> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
>> ---
>> arch/powerpc/kernel/entry_32.S | 5 +++++
>> arch/powerpc/kernel/entry_64.S | 5 +++++
>> 2 files changed, 10 insertions(+)
>>
>> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
>> index eb8d01bae8c6..2f134eebe7ed 100644
>> --- a/arch/powerpc/kernel/entry_32.S
>> +++ b/arch/powerpc/kernel/entry_32.S
>> @@ -365,6 +365,11 @@ syscall_dotrace_cont:
>> blrl /* Call handler */
>> .globl ret_from_syscall
>> ret_from_syscall:
>> +#ifdef CONFIG_DEBUG_RSEQ
>> + /* Check whether the syscall is issued inside a restartable sequence */
>> + addi r3,r1,STACK_FRAME_OVERHEAD
>> + bl rseq_syscall
>> +#endif
>> mr r6,r3
>> CURRENT_THREAD_INFO(r12, r1)
>> /* disable interrupts so current_thread_info()->flags can't change */
>> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
>> index 2cb5109a7ea3..2e2d59bb45d0 100644
>> --- a/arch/powerpc/kernel/entry_64.S
>> +++ b/arch/powerpc/kernel/entry_64.S
>> @@ -204,6 +204,11 @@ system_call: /* label this so stack traces look sane */
>> * This is blacklisted from kprobes further below with _ASM_NOKPROBE_SYMBOL().
>> */
>> system_call_exit:
>> +#ifdef CONFIG_DEBUG_RSEQ
>> + /* Check whether the syscall is issued inside a restartable sequence */
>> + addi r3,r1,STACK_FRAME_OVERHEAD
>> + bl rseq_syscall
>> +#endif
>> /*
>> * Disable interrupts so current_thread_info()->flags can't change,
>> * and so that we don't get interrupted after loading SRR0/1.
>> --
>> 2.16.2
>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2018-05-23 21:29 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-30 22:44 [RFC PATCH for 4.18 00/14] Restartable Sequences Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 01/14] uapi headers: Provide types_32_64.h (v2) Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 02/14] rseq: Introduce restartable sequences system call (v13) Mathieu Desnoyers
2018-05-16 16:24 ` Peter Zijlstra
2018-05-16 20:18 ` Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 03/14] arm: Add restartable sequences support Mathieu Desnoyers
2018-05-16 16:18 ` Peter Zijlstra
2018-05-16 20:13 ` Mathieu Desnoyers
2018-05-17 13:32 ` Will Deacon
2018-05-17 15:30 ` Mathieu Desnoyers
2018-05-22 18:19 ` Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 04/14] arm: Wire up restartable sequences system call Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 05/14] x86: Add support for restartable sequences (v2) Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 06/14] x86: Wire up restartable sequence system call Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 07/14] powerpc: Add support for restartable sequences Mathieu Desnoyers
2018-05-16 16:18 ` Peter Zijlstra
2018-05-16 20:13 ` Mathieu Desnoyers
2018-05-17 1:19 ` Boqun Feng
2018-05-17 7:43 ` Peter Zijlstra
2018-05-17 15:28 ` Mathieu Desnoyers
2018-05-17 23:50 ` Boqun Feng
2018-05-18 18:17 ` Mathieu Desnoyers
2018-05-20 14:08 ` Boqun Feng
2018-05-23 20:14 ` Mathieu Desnoyers
2018-05-23 20:46 ` Paul E. McKenney
2018-05-23 21:29 ` Mathieu Desnoyers [this message]
2018-05-24 1:03 ` Michael Ellerman
2018-05-28 7:00 ` Mathieu Desnoyers
2018-05-18 12:38 ` Michael Ellerman
2018-04-30 22:44 ` [PATCH 08/14] powerpc: Wire up restartable sequences system call Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 09/14] selftests: lib.mk: Introduce OVERRIDE_TARGETS Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 10/14] rseq: selftests: Provide rseq library (v5) Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 11/14] rseq: selftests: Provide basic test Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 12/14] rseq: selftests: Provide basic percpu ops test (v2) Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 13/14] rseq: selftests: Provide parametrized tests (v2) Mathieu Desnoyers
2018-04-30 22:44 ` [PATCH 14/14] rseq: selftests: Provide Makefile, scripts, gitignore (v2) Mathieu Desnoyers
2018-05-02 3:53 ` [RFC PATCH for 4.18 00/14] Restartable Sequences Daniel Colascione
2018-05-02 8:43 ` Peter Zijlstra
2018-05-02 16:03 ` Mathieu Desnoyers
2018-05-02 16:07 ` Daniel Colascione
2018-05-02 16:42 ` Steven Rostedt
2018-05-02 16:55 ` Daniel Colascione
2018-05-03 16:12 ` Mathieu Desnoyers
2018-05-03 16:22 ` Daniel Colascione
2018-05-03 18:04 ` Mathieu Desnoyers
2018-05-03 16:48 ` Joel Fernandes
2018-05-03 17:18 ` Daniel Colascione
2018-05-03 17:46 ` Joel Fernandes
2018-05-04 22:17 ` Ben Maurer
2018-05-02 17:22 ` Peter Zijlstra
2018-05-02 18:27 ` Daniel Colascione
2018-05-02 20:22 ` Peter Zijlstra
2018-05-02 20:37 ` Daniel Colascione
2018-05-03 1:15 ` Steven Rostedt
2018-05-03 8:49 ` Peter Zijlstra
2018-05-06 10:03 ` Thomas Gleixner
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