libc: Import from TF-A

Based on arm-trusted-firware commit 873e394b3bf93214a441f9f98237b58fbbea55aa

Change-Id: I510e092f2b9ff333e9461bdde8d80ed1fab1460c
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>
diff --git a/lib/libc/aarch64/setjmp.S b/lib/libc/aarch64/setjmp.S
new file mode 100644
index 0000000..9d9eb49
--- /dev/null
+++ b/lib/libc/aarch64/setjmp.S
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <asm_macros.S>
+#include <assert_macros.S>
+#include <setjmp.h>
+
+	.globl	setjmp
+	.globl	longjmp
+
+/*
+ * int setjmp(jmp_buf env);
+ */
+func setjmp
+	mov	x7, sp
+
+	stp	x19, x20, [x0, #JMP_CTX_X19]
+	stp	x21, x22, [x0, #JMP_CTX_X21]
+	stp	x23, x24, [x0, #JMP_CTX_X23]
+	stp	x25, x26, [x0, #JMP_CTX_X25]
+	stp	x27, x28, [x0, #JMP_CTX_X27]
+	stp	x29, x30, [x0, #JMP_CTX_X29]
+	stp	x7, xzr, [x0, #JMP_CTX_SP]
+
+	mov	x0, #0
+	ret
+endfunc setjmp
+
+
+/*
+ * void longjmp(jmp_buf env, int val);
+ */
+func longjmp
+	ldp	x7, xzr, [x0, #JMP_CTX_SP]
+
+#if ENABLE_ASSERTIONS
+	/*
+	 * Since we're unwinding the stack, assert that the stack being reset to
+	 * is shallower.
+	 */
+	mov	x19, sp
+	cmp	x7, x19
+	ASM_ASSERT(ge)
+#endif
+
+	ldp	x19, x20, [x0, #JMP_CTX_X19]
+	ldp	x21, x22, [x0, #JMP_CTX_X21]
+	ldp	x23, x24, [x0, #JMP_CTX_X23]
+	ldp	x25, x26, [x0, #JMP_CTX_X25]
+	ldp	x27, x28, [x0, #JMP_CTX_X27]
+	ldp	x29, x30, [x0, #JMP_CTX_X29]
+
+	mov	sp, x7
+
+	ands	x0, x1, x1 /* Move val to x0 and set flags */
+	cinc	x0, x0, eq /* If val is 0, return 1 */
+	ret
+endfunc longjmp