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McKenney" , Boqun Feng , Andy Lutomirski , Dave Watson , linux-kernel , linux-api , Paul Turner , Andrew Morton , Russell King , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrew Hunter , Andi Kleen , Chris Lameter , Ben Maurer , rostedt , Josh Triplett , Linus Torvalds , Catalin Marinas , Will Deacon , Michael Kerrisk , Joel Fernandes , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linuxppc-dev Message-ID: <112970629.1913.1526501596485.JavaMail.zimbra@efficios.com> In-Reply-To: <20180516161837.GI12198@hirez.programming.kicks-ass.net> References: <20180430224433.17407-1-mathieu.desnoyers@efficios.com> <20180430224433.17407-8-mathieu.desnoyers@efficios.com> <20180516161837.GI12198@hirez.programming.kicks-ass.net> Subject: Re: [PATCH 07/14] powerpc: Add support for restartable sequences MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.142.138] X-Mailer: Zimbra 8.8.8_GA_2026 (ZimbraWebClient - FF52 (Linux)/8.8.8_GA_2031) Thread-Topic: powerpc: Add support for restartable sequences Thread-Index: PpuTAhPtg5HdKhcrUxmji33zT6zOXw== Sender: linux-api-owner@vger.kernel.org X-Mailing-List: linux-api@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: ----- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Desnoyers Subject: Re: [PATCH 07/14] powerpc: Add support for restartable sequences Date: Wed, 16 May 2018 16:13:16 -0400 (EDT) Message-ID: <112970629.1913.1526501596485.JavaMail.zimbra@efficios.com> References: <20180430224433.17407-1-mathieu.desnoyers@efficios.com> <20180430224433.17407-8-mathieu.desnoyers@efficios.com> <20180516161837.GI12198@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180516161837.GI12198@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org To: Peter Zijlstra Cc: "Paul E. McKenney" , Boqun Feng , Andy Lutomirski , Dave Watson , linux-kernel , linux-api , Paul Turner , Andrew Morton , Russell King , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andrew Hunter , Andi Kleen , Chris Lameter , Ben Maurer , rostedt , Josh Triplett , Linus Torvalds , Catalin Marinas , Will Deacon List-Id: linux-api@vger.kernel.org ----- 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