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authorWaldemar Brodkorb <wbrodkorb@conet.de>2018-05-31 01:04:17 +0200
committerWaldemar Brodkorb <wbrodkorb@conet.de>2018-06-10 06:35:18 +0200
commit9595fb8cd595028bece5174e7eddf660ae3dcc10 (patch)
tree56ffac7a96d15a2a9c825a4f96c3f1bcea7c4fa0 /libc/sysdeps/linux/riscv64/clone.S
parentdf8caec1978cb5fe7d9a7e7ea9dd773605e89032 (diff)
risc-v: initial 64 bit port, static only (no TLS/NPTL)
Only a simple hello world is tested in qemu system emulation.
Diffstat (limited to 'libc/sysdeps/linux/riscv64/clone.S')
-rw-r--r--libc/sysdeps/linux/riscv64/clone.S80
1 files changed, 80 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/riscv64/clone.S b/libc/sysdeps/linux/riscv64/clone.S
new file mode 100644
index 000000000..f7684c88d
--- /dev/null
+++ b/libc/sysdeps/linux/riscv64/clone.S
@@ -0,0 +1,80 @@
+/* Wrapper around clone system call. RISC-V version.
+ Copyright (C) 1996-2018 Free Software Foundation, Inc.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* clone() is even more special than fork() as it mucks with stacks
+ and invokes a function in the right context after its all over. */
+
+#include <sys/asm.h>
+#include <sysdep.h>
+#define _ERRNO_H 1
+#include <bits/errno.h>
+
+/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
+ void *parent_tidptr, void *tls, void *child_tidptr) */
+
+ .text
+LEAF (clone)
+
+ /* Sanity check arguments. */
+ beqz a0,L (invalid) /* No NULL function pointers. */
+ beqz a1,L (invalid) /* No NULL stack pointers. */
+
+ addi a1,a1,-16 /* Reserve argument save space. */
+ REG_S a0,0(a1) /* Save function pointer. */
+ REG_S a3,SZREG(a1) /* Save argument pointer. */
+
+ /* The syscall expects the args to be in different slots. */
+ mv a0,a2
+ mv a2,a4
+ mv a3,a5
+ mv a4,a6
+
+ /* Do the system call. */
+ li a7,__NR_clone
+ scall
+
+ bltz a0,L (error)
+ beqz a0,L (thread_start)
+
+ /* Successful return from the parent. */
+ ret
+
+L (invalid):
+ li a0, -EINVAL
+ /* Something bad happened -- no child created. */
+L (error):
+ j __syscall_error
+ END (clone)
+
+/* Load up the arguments to the function. Put this block of code in
+ its own function so that we can terminate the stack trace with our
+ debug info. */
+
+ENTRY (__thread_start)
+L (thread_start):
+ /* Restore the arg for user's function. */
+ REG_L a1,0(sp) /* Function pointer. */
+ REG_L a0,SZREG(sp) /* Argument pointer. */
+
+ /* Call the user's function. */
+ jalr a1
+
+ /* Call exit with the function's return value. */
+ li a7, __NR_exit
+ scall
+
+ END (__thread_start)