From: Boqun Feng <boqun.feng@gmail.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.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 <catalin.marinas@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: Sun, 20 May 2018 22:08:11 +0800 [thread overview]
Message-ID: <20180520140811.GB1121@tardis> (raw)
In-Reply-To: <418003803.516.1526667437396.JavaMail.zimbra@efficios.com>
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.
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
next prev parent reply other threads:[~2018-05-20 14:03 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 [this message]
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
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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