From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Paul McKenney <paulmck@kernel.org>,
"Joel Fernandes (Google)" <joel@joelfernandes.org>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Frederic Weisbecker <frederic@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
Alexandre Chartre <alexandre.chartre@oracle.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org
Subject: Re: [RESEND][patch V3 06/23] bug: Annotate WARN/BUG/stackfail as noinstr safe
Date: Thu, 2 Apr 2020 16:43:18 -0500 [thread overview]
Message-ID: <20200402214318.v54a34rvvo2svtoh@treble> (raw)
In-Reply-To: <20200402213431.GK2452@worktop.programming.kicks-ass.net>
On Thu, Apr 02, 2020 at 11:34:31PM +0200, Peter Zijlstra wrote:
> On Thu, Apr 02, 2020 at 04:01:15PM -0500, Josh Poimboeuf wrote:
> > On Fri, Mar 20, 2020 at 07:00:02PM +0100, Thomas Gleixner wrote:
> > > Warnings, bugs and stack protection fails from noinstr sections, e.g. low
> > > level and early entry code, are likely to be fatal.
> > >
> > > Mark them as "safe" to be invoked from noinstr protected code to avoid
> > > annotating all usage sites. Getting the information out is important.
> > >
> > > Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> > > ---
> > > arch/x86/include/asm/bug.h | 3 +++
> > > include/asm-generic/bug.h | 9 +++++++--
> > > kernel/panic.c | 4 +++-
> > > 3 files changed, 13 insertions(+), 3 deletions(-)
> > >
> > > --- a/arch/x86/include/asm/bug.h
> > > +++ b/arch/x86/include/asm/bug.h
> > > @@ -70,13 +70,16 @@ do { \
> > > #define HAVE_ARCH_BUG
> > > #define BUG() \
> > > do { \
> > > + instr_begin(); \
> > > _BUG_FLAGS(ASM_UD2, 0); \
> > > unreachable(); \
> > > } while (0)
> >
> > For visual symmetry at least, it seems like this wants an instr_end()
> > before the unreachable(). Does objtool not like that?
>
> Can't remember, but I think it's weird to put something after you know
> it unreachable.
Yeah, I guess... but my lizard brain likes to see closure :-)
--
Josh
next prev parent reply other threads:[~2020-04-02 21:43 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-20 17:59 [RESEND][patch V3 00/23] x86/entry: Consolidation part II (syscalls) Thomas Gleixner
2020-03-20 17:59 ` [RESEND][patch V3 01/23] rcu: Dont acquire lock in NMI handler in rcu_nmi_enter_common() Thomas Gleixner
2020-03-24 15:37 ` [patch " Frederic Weisbecker
2020-03-20 17:59 ` [RESEND][patch V3 02/23] rcu: Add comments marking transitions between RCU watching and not Thomas Gleixner
2020-03-24 15:38 ` [patch " Frederic Weisbecker
2020-03-20 17:59 ` [RESEND][patch V3 03/23] vmlinux.lds.h: Create section for protection against instrumentation Thomas Gleixner
2020-03-24 12:26 ` Borislav Petkov
2020-04-03 8:08 ` Alexandre Chartre
2020-03-20 18:00 ` [RESEND][patch V3 04/23] kprobes: Prevent probes in .noinstr.text section Thomas Gleixner
2020-03-23 14:00 ` [patch " Masami Hiramatsu
2020-03-23 16:03 ` Thomas Gleixner
2020-03-24 5:49 ` Masami Hiramatsu
2020-03-24 9:47 ` Thomas Gleixner
2020-03-25 13:39 ` Masami Hiramatsu
2020-03-20 18:00 ` [RESEND][patch V3 05/23] tracing: Provide lockdep less trace_hardirqs_on/off() variants Thomas Gleixner
2020-04-03 8:34 ` Alexandre Chartre
2020-03-20 18:00 ` [RESEND][patch V3 06/23] bug: Annotate WARN/BUG/stackfail as noinstr safe Thomas Gleixner
2020-04-02 21:01 ` Josh Poimboeuf
2020-04-02 21:34 ` Peter Zijlstra
2020-04-02 21:43 ` Josh Poimboeuf [this message]
2020-04-02 21:49 ` Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 07/23] lockdep: Prepare for noinstr sections Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 08/23] x86/entry: Mark enter_from_user_mode() noinstr Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 09/23] x86/entry/common: Protect against instrumentation Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 10/23] x86/entry: Move irq tracing on syscall entry to C-code Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 11/23] x86/entry: Move irq flags tracing to prepare_exit_to_usermode() Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 12/23] context_tracking: Ensure that the critical path cannot be instrumented Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 13/23] lib/smp_processor_id: Move it into noinstr section Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 14/23] x86/speculation/mds: Mark mds_user_clear_cpu_buffers() __always_inline Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 15/23] x86/entry/64: Check IF in __preempt_enable_notrace() thunk Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 16/23] x86/entry/64: Mark ___preempt_schedule_notrace() thunk noinstr Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 17/23] rcu/tree: Mark the idle relevant functions noinstr Thomas Gleixner
2020-03-24 16:09 ` Paul E. McKenney
2020-03-24 19:28 ` Thomas Gleixner
2020-03-24 19:58 ` Paul E. McKenney
2020-03-20 18:00 ` [RESEND][patch V3 18/23] x86/kvm: Move context tracking where it belongs Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 19/23] x86/kvm/vmx: Add hardirq tracing to guest enter/exit Thomas Gleixner
2020-03-24 23:03 ` Peter Zijlstra
2020-03-24 23:21 ` Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 20/23] x86/kvm/svm: Handle hardirqs proper on " Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 21/23] context_tracking: Make guest_enter/exit_irqoff() .noinstr ready Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 22/23] x86/kvm/vmx: Move guest enter/exit into .noinstr.text Thomas Gleixner
2020-03-20 18:00 ` [RESEND][patch V3 23/23] x86/kvm/svm: " Thomas Gleixner
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