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Message-Id: <1470774596-17341-7-git-send-email-cmetcalf@mellanox.com>
Date:	Tue,  9 Aug 2016 16:29:48 -0400
From:	Chris Metcalf <cmetcalf@...lanox.com>
To:	Gilad Ben Yossef <giladb@...lanox.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>, Tejun Heo <tj@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Andy Lutomirski <luto@...capital.net>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc:	Chris Metcalf <cmetcalf@...lanox.com>
Subject: [PATCH v14 06/14] arch/x86: enable task isolation functionality

In exit_to_usermode_loop(), call task_isolation_ready() for
TIF_TASK_ISOLATION tasks when we are checking the thread-info flags,
and after we've handled the other work, call task_isolation_enter()
for such tasks.

In syscall_trace_enter_phase1(), we add the necessary support for
reporting syscalls for task-isolation processes.

We add strict reporting for the kernel exception types that do
not result in signals, namely non-signalling page faults and
non-signalling MPX fixups.

Tested-by: Christoph Lameter <cl@...ux.com>
Signed-off-by: Chris Metcalf <cmetcalf@...lanox.com>
---
 arch/x86/Kconfig                   |  1 +
 arch/x86/entry/common.c            | 20 +++++++++++++++++++-
 arch/x86/include/asm/thread_info.h |  2 ++
 arch/x86/kernel/smp.c              |  2 ++
 arch/x86/kernel/traps.c            |  3 +++
 arch/x86/mm/fault.c                |  5 +++++
 6 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5c6e7471b732..10b2c0567dad 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -89,6 +89,7 @@ config X86
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_SOFT_DIRTY		if X86_64
+	select HAVE_ARCH_TASK_ISOLATION
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_EBPF_JIT			if X86_64
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 1433f6b4607d..5c1b9fc89bf2 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -21,6 +21,7 @@
 #include <linux/context_tracking.h>
 #include <linux/user-return-notifier.h>
 #include <linux/uprobes.h>
+#include <linux/isolation.h>
 
 #include <asm/desc.h>
 #include <asm/traps.h>
@@ -91,6 +92,15 @@ static long syscall_trace_enter(struct pt_regs *regs)
 	if (emulated)
 		return -1L;
 
+	/* In isolation mode, we may prevent the syscall from running. */
+	if (work & _TIF_TASK_ISOLATION) {
+		if (task_isolation_syscall(regs->orig_ax) == -1) {
+			regs->orig_ax = -1;
+			return 0;
+		}
+		work &= ~_TIF_TASK_ISOLATION;
+	}
+
 #ifdef CONFIG_SECCOMP
 	/*
 	 * Do seccomp after ptrace, to catch any tracer changes.
@@ -136,7 +146,7 @@ static long syscall_trace_enter(struct pt_regs *regs)
 
 #define EXIT_TO_USERMODE_LOOP_FLAGS				\
 	(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE |	\
-	 _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY)
+	 _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY | _TIF_TASK_ISOLATION)
 
 static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
 {
@@ -170,11 +180,19 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
 		if (cached_flags & _TIF_USER_RETURN_NOTIFY)
 			fire_user_return_notifiers();
 
+		if (cached_flags & _TIF_TASK_ISOLATION)
+			task_isolation_enter();
+
 		/* Disable IRQs and retry */
 		local_irq_disable();
 
 		cached_flags = READ_ONCE(pt_regs_to_thread_info(regs)->flags);
 
+		/* Clear task isolation from cached_flags manually. */
+		if ((cached_flags & _TIF_TASK_ISOLATION) &&
+		    task_isolation_ready())
+			cached_flags &= ~_TIF_TASK_ISOLATION;
+
 		if (!(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
 			break;
 
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 84b59846154a..eb3b648617c1 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -93,6 +93,7 @@ struct thread_info {
 #define TIF_SECCOMP		8	/* secure computing */
 #define TIF_USER_RETURN_NOTIFY	11	/* notify kernel of userspace return */
 #define TIF_UPROBE		12	/* breakpointed or singlestepping */
+#define TIF_TASK_ISOLATION	13	/* task isolation enabled for task */
 #define TIF_NOTSC		16	/* TSC is not accessible in userland */
 #define TIF_IA32		17	/* IA32 compatibility process */
 #define TIF_FORK		18	/* ret_from_fork */
@@ -117,6 +118,7 @@ struct thread_info {
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_USER_RETURN_NOTIFY	(1 << TIF_USER_RETURN_NOTIFY)
 #define _TIF_UPROBE		(1 << TIF_UPROBE)
+#define _TIF_TASK_ISOLATION	(1 << TIF_TASK_ISOLATION)
 #define _TIF_NOTSC		(1 << TIF_NOTSC)
 #define _TIF_IA32		(1 << TIF_IA32)
 #define _TIF_FORK		(1 << TIF_FORK)
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 658777cf3851..e4ffd9581cdb 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -23,6 +23,7 @@
 #include <linux/interrupt.h>
 #include <linux/cpu.h>
 #include <linux/gfp.h>
+#include <linux/isolation.h>
 
 #include <asm/mtrr.h>
 #include <asm/tlbflush.h>
@@ -125,6 +126,7 @@ static void native_smp_send_reschedule(int cpu)
 		WARN_ON(1);
 		return;
 	}
+	task_isolation_debug(cpu, "reschedule IPI");
 	apic->send_IPI(cpu, RESCHEDULE_VECTOR);
 }
 
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b70ca12dd389..eae51685c2b3 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -36,6 +36,7 @@
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/io.h>
+#include <linux/isolation.h>
 
 #ifdef CONFIG_EISA
 #include <linux/ioport.h>
@@ -383,6 +384,8 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 	case 2:	/* Bound directory has invalid entry. */
 		if (mpx_handle_bd_fault())
 			goto exit_trap;
+		/* No signal was generated, but notify task-isolation tasks. */
+		task_isolation_quiet_exception("bounds check");
 		break; /* Success, it was handled */
 	case 1: /* Bound violation. */
 		info = mpx_generate_siginfo(regs);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index dc8023060456..b1509876794c 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -14,6 +14,7 @@
 #include <linux/prefetch.h>		/* prefetchw			*/
 #include <linux/context_tracking.h>	/* exception_enter(), ...	*/
 #include <linux/uaccess.h>		/* faulthandler_disabled()	*/
+#include <linux/isolation.h>		/* task_isolation_quiet_exception */
 
 #include <asm/cpufeature.h>		/* boot_cpu_has, ...		*/
 #include <asm/traps.h>			/* dotraplinkage, ...		*/
@@ -1397,6 +1398,10 @@ good_area:
 		perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
 	}
 
+	/* No signal was generated, but notify task-isolation tasks. */
+	if (flags & PF_USER)
+		task_isolation_quiet_exception("page fault at %#lx", address);
+
 	check_v8086_mode(regs, address, tsk);
 }
 NOKPROBE_SYMBOL(__do_page_fault);
-- 
2.7.2

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