[PATCH v12 11/13] arch/tile: enable task isolation functionality

From: Chris Metcalf
Date: Tue Apr 05 2016 - 13:39:47 EST

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We add the necessary call to task_isolation_enter() in the
prepare_exit_to_usermode() routine. We already unconditionally
call into this routine if TIF_NOHZ is set, since that's where
we do the user_enter() call.

We add calls to task_isolation_check_exception() in places
where exceptions may not generate signals to the application.

Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
---
arch/tile/Kconfig | 1 +
arch/tile/include/asm/thread_info.h | 4 +++-
arch/tile/kernel/process.c | 9 +++++++++
arch/tile/kernel/ptrace.c | 7 +++++++
arch/tile/kernel/single_step.c | 5 +++++
arch/tile/kernel/smp.c | 28 ++++++++++++++++------------
arch/tile/kernel/unaligned.c | 3 +++
arch/tile/mm/fault.c | 3 +++
arch/tile/mm/homecache.c | 2 ++
9 files changed, 49 insertions(+), 13 deletions(-)

diff --git a/arch/tile/Kconfig b/arch/tile/Kconfig
index 81719302b056..322ba76c8631 100644
--- a/arch/tile/Kconfig
+++ b/arch/tile/Kconfig
@@ -33,6 +33,7 @@ config TILE
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select HAVE_ARCH_SECCOMP_FILTER
+ select HAVE_ARCH_TASK_ISOLATION

# FIXME: investigate whether we need/want these options.
# select HAVE_IOREMAP_PROT
diff --git a/arch/tile/include/asm/thread_info.h b/arch/tile/include/asm/thread_info.h
index 4b7cef9e94e0..ea7fbd0d879d 100644
--- a/arch/tile/include/asm/thread_info.h
+++ b/arch/tile/include/asm/thread_info.h
@@ -126,6 +126,7 @@ extern void _cpu_idle(void);
#define TIF_SYSCALL_TRACEPOINT 9 /* syscall tracepoint instrumentation */
#define TIF_POLLING_NRFLAG 10 /* idle is polling for TIF_NEED_RESCHED */
#define TIF_NOHZ 11 /* in adaptive nohz mode */
+#define TIF_TASK_ISOLATION 12 /* in task isolation mode */

#define _TIF_SIGPENDING (1<<TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1<<TIF_NEED_RESCHED)
@@ -139,11 +140,12 @@ extern void _cpu_idle(void);
#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
#define _TIF_POLLING_NRFLAG (1<<TIF_POLLING_NRFLAG)
#define _TIF_NOHZ (1<<TIF_NOHZ)
+#define _TIF_TASK_ISOLATION (1<<TIF_TASK_ISOLATION)

/* Work to do as we loop to exit to user space. */
#define _TIF_WORK_MASK \
(_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
- _TIF_ASYNC_TLB | _TIF_NOTIFY_RESUME)
+ _TIF_ASYNC_TLB | _TIF_NOTIFY_RESUME | _TIF_TASK_ISOLATION)

/* Work to do on any return to user space. */
#define _TIF_ALLWORK_MASK \
diff --git a/arch/tile/kernel/process.c b/arch/tile/kernel/process.c
index b5f30d376ce1..e752f6c2b645 100644
--- a/arch/tile/kernel/process.c
+++ b/arch/tile/kernel/process.c
@@ -29,6 +29,7 @@
#include <linux/signal.h>
#include <linux/delay.h>
#include <linux/context_tracking.h>
+#include <linux/isolation.h>
#include <asm/stack.h>
#include <asm/switch_to.h>
#include <asm/homecache.h>
@@ -495,9 +496,17 @@ void prepare_exit_to_usermode(struct pt_regs *regs, u32 thread_info_flags)
tracehook_notify_resume(regs);
}

+ if (thread_info_flags & _TIF_TASK_ISOLATION)
+ task_isolation_enter();
+
local_irq_disable();
thread_info_flags = READ_ONCE(current_thread_info()->flags);

+ /* Clear task isolation from cached_flags manually. */
+ if ((thread_info_flags & _TIF_TASK_ISOLATION) &&
+ task_isolation_ready())
+ thread_info_flags &= ~_TIF_TASK_ISOLATION;
+
} while (thread_info_flags & _TIF_WORK_MASK);

if (thread_info_flags & _TIF_SINGLESTEP) {
diff --git a/arch/tile/kernel/ptrace.c b/arch/tile/kernel/ptrace.c
index 54e7b723db99..475a362415fb 100644
--- a/arch/tile/kernel/ptrace.c
+++ b/arch/tile/kernel/ptrace.c
@@ -23,6 +23,7 @@
#include <linux/elf.h>
#include <linux/tracehook.h>
#include <linux/context_tracking.h>
+#include <linux/isolation.h>
#include <asm/traps.h>
#include <arch/chip.h>

@@ -255,6 +256,12 @@ int do_syscall_trace_enter(struct pt_regs *regs)
{
u32 work = ACCESS_ONCE(current_thread_info()->flags);

+ /* In isolation mode, we may prevent the syscall from running. */
+ if (work & _TIF_TASK_ISOLATION) {
+ if (task_isolation_syscall(regs->regs[TREG_SYSCALL_NR]) == -1)
+ return -1;
+ }
+
if (secure_computing() == -1)
return -1;

diff --git a/arch/tile/kernel/single_step.c b/arch/tile/kernel/single_step.c
index 862973074bf9..3baa7230149e 100644
--- a/arch/tile/kernel/single_step.c
+++ b/arch/tile/kernel/single_step.c
@@ -23,6 +23,7 @@
#include <linux/types.h>
#include <linux/err.h>
#include <linux/prctl.h>
+#include <linux/isolation.h>
#include <asm/cacheflush.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
@@ -320,6 +321,8 @@ void single_step_once(struct pt_regs *regs)
int size = 0, sign_ext = 0; /* happy compiler */
int align_ctl;

+ task_isolation_exception("single step at %#lx", regs->pc);
+
align_ctl = unaligned_fixup;
switch (task_thread_info(current)->align_ctl) {
case PR_UNALIGN_NOPRINT:
@@ -767,6 +770,8 @@ void single_step_once(struct pt_regs *regs)
unsigned long *ss_pc = this_cpu_ptr(&ss_saved_pc);
unsigned long control = __insn_mfspr(SPR_SINGLE_STEP_CONTROL_K);

+ task_isolation_exception("single step at %#lx", regs->pc);
+
*ss_pc = regs->pc;
control |= SPR_SINGLE_STEP_CONTROL_1__CANCELED_MASK;
control |= SPR_SINGLE_STEP_CONTROL_1__INHIBIT_MASK;
diff --git a/arch/tile/kernel/smp.c b/arch/tile/kernel/smp.c
index 07e3ff5cc740..da1eb240fc57 100644
--- a/arch/tile/kernel/smp.c
+++ b/arch/tile/kernel/smp.c
@@ -20,6 +20,7 @@
#include <linux/irq.h>
#include <linux/irq_work.h>
#include <linux/module.h>
+#include <linux/isolation.h>
#include <asm/cacheflush.h>
#include <asm/homecache.h>

@@ -67,6 +68,7 @@ void send_IPI_single(int cpu, int tag)
.x = cpu % smp_width,
.state = HV_TO_BE_SENT
};
+ task_isolation_debug(cpu);
__send_IPI_many(&recip, 1, tag);
}

@@ -84,6 +86,7 @@ void send_IPI_many(const struct cpumask *mask, int tag)
r->x = cpu % smp_width;
r->state = HV_TO_BE_SENT;
}
+ task_isolation_debug_cpumask(mask);
__send_IPI_many(recip, nrecip, tag);
}

@@ -181,10 +184,11 @@ void flush_icache_range(unsigned long start, unsigned long end)
struct ipi_flush flush = { start, end };

/* If invoked with irqs disabled, we can not issue IPIs. */
- if (irqs_disabled())
+ if (irqs_disabled()) {
+ task_isolation_debug_cpumask(task_isolation_map);
flush_remote(0, HV_FLUSH_EVICT_L1I, NULL, 0, 0, 0,
NULL, NULL, 0);
- else {
+ } else {
preempt_disable();
on_each_cpu(ipi_flush_icache_range, &flush, 1);
preempt_enable();
@@ -258,10 +262,8 @@ void __init ipi_init(void)

#if CHIP_HAS_IPI()

-void smp_send_reschedule(int cpu)
+static void __smp_send_reschedule(int cpu)
{
- WARN_ON(cpu_is_offline(cpu));
-
/*
* We just want to do an MMIO store. The traditional writeq()
* functions aren't really correct here, since they're always
@@ -273,15 +275,17 @@ void smp_send_reschedule(int cpu)

#else

-void smp_send_reschedule(int cpu)
+static void __smp_send_reschedule(int cpu)
{
- HV_Coord coord;
-
- WARN_ON(cpu_is_offline(cpu));
-
- coord.y = cpu_y(cpu);
- coord.x = cpu_x(cpu);
+ HV_Coord coord = { .y = cpu_y(cpu), .x = cpu_x(cpu) };
hv_trigger_ipi(coord, IRQ_RESCHEDULE);
}

#endif /* CHIP_HAS_IPI() */
+
+void smp_send_reschedule(int cpu)
+{
+ WARN_ON(cpu_is_offline(cpu));
+ task_isolation_debug(cpu);
+ __smp_send_reschedule(cpu);
+}
diff --git a/arch/tile/kernel/unaligned.c b/arch/tile/kernel/unaligned.c
index 0db5f7c9d9e5..754204987532 100644
--- a/arch/tile/kernel/unaligned.c
+++ b/arch/tile/kernel/unaligned.c
@@ -25,6 +25,7 @@
#include <linux/module.h>
#include <linux/compat.h>
#include <linux/prctl.h>
+#include <linux/isolation.h>
#include <asm/cacheflush.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
@@ -1545,6 +1546,8 @@ void do_unaligned(struct pt_regs *regs, int vecnum)
return;
}

+ task_isolation_exception("unaligned JIT at %#lx", regs->pc);
+
if (!info->unalign_jit_base) {
void __user *user_page;

diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c
index 26734214818c..7f910e4061f1 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c
@@ -35,6 +35,7 @@
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/kdebug.h>
+#include <linux/isolation.h>

#include <asm/pgalloc.h>
#include <asm/sections.h>
@@ -844,6 +845,8 @@ static inline void __do_page_fault(struct pt_regs *regs, int fault_num,
void do_page_fault(struct pt_regs *regs, int fault_num,
unsigned long address, unsigned long write)
{
+ task_isolation_exception("page fault interrupt %d at %#lx (%#lx)",
+ fault_num, regs->pc, address);
__do_page_fault(regs, fault_num, address, write);
}

diff --git a/arch/tile/mm/homecache.c b/arch/tile/mm/homecache.c
index 40ca30a9fee3..e044e8dd8372 100644
--- a/arch/tile/mm/homecache.c
+++ b/arch/tile/mm/homecache.c
@@ -31,6 +31,7 @@
#include <linux/smp.h>
#include <linux/module.h>
#include <linux/hugetlb.h>
+#include <linux/isolation.h>

#include <asm/page.h>
#include <asm/sections.h>
@@ -83,6 +84,7 @@ static void hv_flush_update(const struct cpumask *cache_cpumask,
* Don't bother to update atomically; losing a count
* here is not that critical.
*/
+ task_isolation_debug_cpumask(&mask);
for_each_cpu(cpu, &mask)
++per_cpu(irq_stat, cpu).irq_hv_flush_count;
}
--
2.7.2

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