1 files changed, 15 insertions, 0 deletions
diff --git a/arch/tile/kernel/ptrace.c b/arch/tile/kernel/ptrace.c
index bac187498d61..de98c6ddf136 100644
--- a/arch/tile/kernel/ptrace.c
+++ b/arch/tile/kernel/ptrace.c
@@ -265,6 +265,21 @@ int do_syscall_trace_enter(struct pt_regs *regs)
 
 void do_syscall_trace_exit(struct pt_regs *regs)
 {
+	long errno;
+
+	/*
+	 * The standard tile calling convention returns the value (or negative
+	 * errno) in r0, and zero (or positive errno) in r1.
+	 * It saves a couple of cycles on the hot path to do this work in
+	 * registers only as we return, rather than updating the in-memory
+	 * struct ptregs.
+	 */
+	errno = (long) regs->regs[0];
+	if (errno < 0 && errno > -4096)
+		regs->regs[1] = -errno;
+	else
+		regs->regs[1] = 0;
+
 	if (test_thread_flag(TIF_SYSCALL_TRACE))
 		tracehook_report_syscall_exit(regs, 0);