riscv64: add bionic assembler and string functions.
Pull the portable C string functions from FreeBSD, and do fairly literal
translations of our existing .S files for the bionic-specific stuff.
Test: treehugger
Change-Id: Id42e5b8a51ed73155be020d74edd7011a2103574
diff --git a/libc/arch-riscv64/bionic/vfork.S b/libc/arch-riscv64/bionic/vfork.S
new file mode 100644
index 0000000..0eff9e9
--- /dev/null
+++ b/libc/arch-riscv64/bionic/vfork.S
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <platform/bionic/tls_defines.h>
+#include <private/bionic_asm.h>
+#include <asm/signal.h>
+#include <linux/sched.h>
+
+ENTRY(vfork)
+ // t0 = __get_tls()[TLS_SLOT_THREAD_ID]
+ mv t0, tp
+ ld t0, TLS_SLOT_THREAD_ID * 8(t0)
+
+ // Set cached_pid_ to 0, vforked_ to 1, and stash the previous value.
+ li t1, 0x80000000
+ lw t2, 20(t0)
+ sw t1, 20(t0)
+
+ li a0, (CLONE_VM | CLONE_VFORK | SIGCHLD)
+ li a1, 0 //uses a duplicate of the parent's stack
+ li a2, 0
+ li a3, 0
+ li a4, 0
+
+ li a7, __NR_clone
+ ecall
+
+ // if (rc == 0) we're the child, and finished...
+ beqz a0, .L_success
+
+ // else if (rc != 0): reset cached_pid_ and vforked_...
+ sw t2, 20(t0)
+ // ...and work out whether we succeeded or failed.
+ bltz a0, .L_failure
+.L_success:
+ ret
+
+.L_failure:
+ neg a0, a0
+ j __set_errno_internal
+END(vfork)