From f3bc9ef92a8bcd012c9eea30676eca19f567f0f7 Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Sun, 9 Sep 2018 18:57:12 +0200
Subject: [PATCH] Call proper Linux system calls proper-like.

---
 plat/linuxmips/libsys/_syscall.s | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/plat/linuxmips/libsys/_syscall.s b/plat/linuxmips/libsys/_syscall.s
index 75c551d20..8d5ecde90 100644
--- a/plat/linuxmips/libsys/_syscall.s
+++ b/plat/linuxmips/libsys/_syscall.s
@@ -14,5 +14,21 @@
 
 .define __syscall
 __syscall:
+	lw r2, 0(sp)        ! syscall number
+	addiu r2, r2, 4000  ! MIPS uses non-standard numbers
+	lw r4, 4(sp)
+	lw r5, 8(sp)
+	lw r6, 12(sp)
 	syscall 0
 
+	beq r7, zero, exit  ! branch on success
+	nop
+
+	/* The result (in r2) is the errno. */
+	lui at, ha16[_errno]
+	sw r2, lo16[_errno] (at)
+	li r2, -1
+exit:
+	jr ra
+	nop
+