[PATCH 4/6] powerpc: use common ptrace_syscall_enter hook to handle _TIF_SYSCALL_EMU

[Sudeep Holla]

Now that we have a new hook ptrace_syscall_enter that can be called from
syscall entry code and it handles PTRACE_SYSEMU in generic code, we
can do some cleanup using the same in do_syscall_trace_enter.

Cc: Oleg Nesterov <oleg at redhat.com>
Cc: Paul Mackerras <paulus at samba.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
---
 arch/powerpc/kernel/ptrace.c | 50 ++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index cb7e1439cafb..978cd2aac29e 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -3264,37 +3264,31 @@ long do_syscall_trace_enter(struct pt_regs *regs)
 {
 	u32 flags;
 
-	user_exit();
-
-	flags = READ_ONCE(current_thread_info()->flags) &
-		(_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
+	if (unlikely(ptrace_syscall_enter(regs))) {
+		/*
+		 * A nonzero return code from tracehook_report_syscall_entry()
+		 * tells us to prevent the syscall execution, but we are not
+		 * going to execute it anyway.
+		 *
+		 * Returning -1 will skip the syscall execution. We want to
+		 * avoid clobbering any registers, so we don't goto the skip
+		 * label below.
+		 */
+		return -1;
+	}
 
-	if (flags) {
-		int rc = tracehook_report_syscall_entry(regs);
+	user_exit();
 
-		if (unlikely(flags & _TIF_SYSCALL_EMU)) {
-			/*
-			 * A nonzero return code from
-			 * tracehook_report_syscall_entry() tells us to prevent
-			 * the syscall execution, but we are not going to
-			 * execute it anyway.
-			 *
-			 * Returning -1 will skip the syscall execution. We want
-			 * to avoid clobbering any registers, so we don't goto
-			 * the skip label below.
-			 */
-			return -1;
-		}
+	flags = READ_ONCE(current_thread_info()->flags) & _TIF_SYSCALL_TRACE;
 
-		if (rc) {
-			/*
-			 * The tracer decided to abort the syscall. Note that
-			 * the tracer may also just change regs->gpr[0] to an
-			 * invalid syscall number, that is handled below on the
-			 * exit path.
-			 */
-			goto skip;
-		}
+	if (flags && tracehook_report_syscall_entry(regs)) {
+		/*
+		 * The tracer decided to abort the syscall. Note that
+		 * the tracer may also just change regs->gpr[0] to an
+		 * invalid syscall number, that is handled below on the
+		 * exit path.
+		 */
+		goto skip;
 	}
 
 	/* Run seccomp after ptrace; allow it to set gpr[3]. */
-- 
2.17.1