From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Kosina <jikos@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
"Woodhouse, David" <dwmw@amazon.co.uk>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Oleg Nesterov <oleg@redhat.com>,
Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak
Date: Mon, 3 Sep 2018 15:47:51 +0200 [thread overview]
Message-ID: <20180903134751.GV24124@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <nycvar.YFH.7.76.1809031443540.25787@cbobk.fhfr.pm>
On Mon, Sep 03, 2018 at 02:45:25PM +0200, Jiri Kosina wrote:
> if (tsk && tsk->mm &&
> tsk->mm->context.ctx_id != last_ctx_id &&
> - get_dumpable(tsk->mm) != SUID_DUMP_USER)
> + ___ptrace_may_access(tsk, current, PTRACE_MODE_IBPB))
> indirect_branch_prediction_barrier();
So the question posed here is: can @next ptrace @prev?
Which confuses me greatly; it is @prev doing the BTB poisoning for
@next, so we want to know if @prev can ptrace @next, no?
next prev parent reply other threads:[~2018-09-03 13:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-03 12:45 [PATCH v2 2/3] x86/speculation: Apply IBPB more strictly to avoid cross-process spectre v2 leak Jiri Kosina
2018-09-03 13:47 ` Peter Zijlstra [this message]
2018-09-03 13:57 ` Jiri Kosina
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