powerpc: Syscall hooks for context tracking subsystem

This is the syscall slow path hooks for context tracking subsystem,
corresponding to
[PATCH] x86: Syscall hooks for userspace RCU extended QS
  commit bf5a3c13b939813d28ce26c01425054c740d6731

TIF_MEMDIE is moved to the second 16-bits (with value 17), as it seems there
is no asm code using it. TIF_NOHZ is added to _TIF_SYCALL_T_OR_A, so it is
better for it to be in the same 16 bits with others in the group, so in the
asm code, andi. with this group could work.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 10 insertions, 2 deletions

diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h
index 8ceea14d6fe4..ba7b1973866e 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -97,7 +97,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_PERFMON_CTXSW       6       /* perfmon needs ctxsw calls */
 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
 #define TIF_SINGLESTEP          8       /* singlestepping active */
-#define TIF_MEMDIE              9       /* is terminating due to OOM killer */
+#define TIF_NOHZ                9       /* in adaptive nohz mode */
 #define TIF_SECCOMP             10      /* secure computing */
 #define TIF_RESTOREALL          11      /* Restore all regs (implies NOERROR) */
 #define TIF_NOERROR             12      /* Force successful syscall return */
@@ -106,6 +106,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_TRACEPOINT  15      /* syscall tracepoint instrumentation */
 #define TIF_EMULATE_STACK_STORE 16      /* Is an instruction emulation
                                                 for stack store? */
+#define TIF_MEMDIE              17      /* is terminating due to OOM killer */
 
 /* as above, but as bit values */
 #define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
@@ -124,8 +125,10 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_UPROBE             (1<<TIF_UPROBE)
 #define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
 #define _TIF_EMULATE_STACK_STORE        (1<<TIF_EMULATE_STACK_STORE)
+#define _TIF_NOHZ               (1<<TIF_NOHZ)
 #define _TIF_SYSCALL_T_OR_A     (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
-                                 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)
+                                 _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
+                                 _TIF_NOHZ)
 
 #define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
                                  _TIF_NOTIFY_RESUME | _TIF_UPROBE)
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 3b14d320e69f..98c2fc198712 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -32,6 +32,7 @@
 #include <trace/syscall.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/perf_event.h>
+#include <linux/context_tracking.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
@@ -1788,6 +1789,8 @@ long do_syscall_trace_enter(struct pt_regs *regs)
 {
         long ret = 0;
 
+        user_exit();
+
         secure_computing_strict(regs->gpr[0]);
 
         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
@@ -1832,4 +1835,6 @@ void do_syscall_trace_leave(struct pt_regs *regs)
         step = test_thread_flag(TIF_SINGLESTEP);
         if (step || test_thread_flag(TIF_SYSCALL_TRACE))
                 tracehook_report_syscall_exit(regs, step);
+
+        user_enter();
 }