4.8-stable patches

added patches:
	arm64-debug-avoid-resetting-stepping-state-machine-when-tif_singlestep.patch

diff --git a/queue-4.8/arm64-debug-avoid-resetting-stepping-state-machine-when-tif_singlestep.patch b/queue-4.8/arm64-debug-avoid-resetting-stepping-state-machine-when-tif_singlestep.patch
new file mode 100644 (file)
index 0000000..dcf2309
--- /dev/null
+++ b/queue-4.8/arm64-debug-avoid-resetting-stepping-state-machine-when-tif_singlestep.patch
@@ -0,0 +1,46 @@
+From 3a402a709500c5a3faca2111668c33d96555e35a Mon Sep 17 00:00:00 2001
+From: Will Deacon <will.deacon@arm.com>
+Date: Fri, 26 Aug 2016 11:36:39 +0100
+Subject: arm64: debug: avoid resetting stepping state machine when TIF_SINGLESTEP
+
+From: Will Deacon <will.deacon@arm.com>
+
+commit 3a402a709500c5a3faca2111668c33d96555e35a upstream.
+
+When TIF_SINGLESTEP is set for a task, the single-step state machine is
+enabled and we must take care not to reset it to the active-not-pending
+state if it is already in the active-pending state.
+
+Unfortunately, that's exactly what user_enable_single_step does, by
+unconditionally setting the SS bit in the SPSR for the current task.
+This causes failures in the GDB testsuite, where GDB ends up missing
+expected step traps if the instruction being stepped generates another
+trap, e.g. PTRACE_EVENT_FORK from an SVC instruction.
+
+This patch fixes the problem by preserving the current state of the
+stepping state machine when TIF_SINGLESTEP is set on the current thread.
+
+Cc: <stable@vger.kernel.org>
+Reported-by: Yao Qi <yao.qi@arm.com>
+Signed-off-by: Will Deacon <will.deacon@arm.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/arm64/kernel/debug-monitors.c |    6 ++++--
+ 1 file changed, 4 insertions(+), 2 deletions(-)
+
+--- a/arch/arm64/kernel/debug-monitors.c
++++ b/arch/arm64/kernel/debug-monitors.c
+@@ -435,8 +435,10 @@ NOKPROBE_SYMBOL(kernel_active_single_ste
+ /* ptrace API */
+ void user_enable_single_step(struct task_struct *task)
+ {
+-      set_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
+-      set_regs_spsr_ss(task_pt_regs(task));
++      struct thread_info *ti = task_thread_info(task);
++
++      if (!test_and_set_ti_thread_flag(ti, TIF_SINGLESTEP))
++              set_regs_spsr_ss(task_pt_regs(task));
+ }
+ NOKPROBE_SYMBOL(user_enable_single_step);
+ 

diff --git a/queue-4.8/series b/queue-4.8/series
new file mode 100644 (file)
index 0000000..b960d72
--- /dev/null
+++ b/queue-4.8/series
@@ -0,0 +1 @@
+arm64-debug-avoid-resetting-stepping-state-machine-when-tif_singlestep.patch