From: Mathieu Desnoyers <mathieu.desnoyers@efficios•com>
To: Peter Zijlstra <peterz@infradead•org>
Cc: "Paul E. McKenney" <paulmck@linux•vnet.ibm.com>,
Boqun Feng <boqun.feng@gmail•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 <catalin.marinas@arm•com>,
Will Deacon <will.deacon@arm•com>,
Michael Kerrisk <mtk.manpages@gmail•com>,
Joel Fernandes <joelaf@google•com>,
Benjamin Herrenschmidt <benh@kernel•crashing.org>,
Paul Mackerras <paulus@samba•org>,
Michael Ellerman <mpe@ellerman•id.au>,
linuxppc-dev <linuxppc-dev@lists•ozlabs.org>
Subject: Re: [PATCH 07/14] powerpc: Add support for restartable sequences
Date: Wed, 16 May 2018 16:13:16 -0400 (EDT) [thread overview]
Message-ID: <112970629.1913.1526501596485.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20180516161837.GI12198@hirez.programming.kicks-ass.net>
----- On May 16, 2018, at 12:18 PM, Peter Zijlstra peterz@infradead•org wrote:
> On Mon, Apr 30, 2018 at 06:44:26PM -0400, Mathieu Desnoyers wrote:
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index c32a181a7cbb..ed21a777e8c6 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -223,6 +223,7 @@ config PPC
>> select HAVE_SYSCALL_TRACEPOINTS
>> select HAVE_VIRT_CPU_ACCOUNTING
>> select HAVE_IRQ_TIME_ACCOUNTING
>> + select HAVE_RSEQ
>> select IRQ_DOMAIN
>> select IRQ_FORCED_THREADING
>> select MODULES_USE_ELF_RELA
>> diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
>> index 61db86ecd318..d3bb3aaaf5ac 100644
>> --- a/arch/powerpc/kernel/signal.c
>> +++ b/arch/powerpc/kernel/signal.c
>> @@ -133,6 +133,8 @@ static void do_signal(struct task_struct *tsk)
>> /* Re-enable the breakpoints for the signal stack */
>> thread_change_pc(tsk, tsk->thread.regs);
>>
>> + rseq_signal_deliver(tsk->thread.regs);
>> +
>> if (is32) {
>> if (ksig.ka.sa.sa_flags & SA_SIGINFO)
>> ret = handle_rt_signal32(&ksig, oldset, tsk);
>> @@ -164,6 +166,7 @@ void do_notify_resume(struct pt_regs *regs, unsigned long
>> thread_info_flags)
>> if (thread_info_flags & _TIF_NOTIFY_RESUME) {
>> clear_thread_flag(TIF_NOTIFY_RESUME);
>> tracehook_notify_resume(regs);
>> + rseq_handle_notify_resume(regs);
>> }
>>
>> user_enter();
>
> Again no rseq_syscall().
Same question for PowerPC as for ARM:
Considering that rseq_syscall is implemented as follows:
+void rseq_syscall(struct pt_regs *regs)
+{
+ unsigned long ip = instruction_pointer(regs);
+ struct task_struct *t = current;
+ struct rseq_cs rseq_cs;
+
+ if (!t->rseq)
+ return;
+ if (!access_ok(VERIFY_READ, t->rseq, sizeof(*t->rseq)) ||
+ rseq_get_rseq_cs(t, &rseq_cs) || in_rseq_cs(ip, &rseq_cs))
+ force_sig(SIGSEGV, t);
+}
and that x86 calls it from syscall_return_slowpath() (which AFAIU is
now used in the fast-path since KPTI), I wonder where we should call
this on PowerPC ? I was under the impression that PowerPC return to
userspace fast-path was not calling C code unless work flags were set,
but I might be wrong.
Thoughts ?
Thanks!
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2018-05-16 20:20 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180430224433.17407-1-mathieu.desnoyers@efficios.com>
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 [this message]
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
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
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