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-rw-r--r--libc-top-half/musl/src/thread/s390x/clone.s54
1 files changed, 54 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/thread/s390x/clone.s b/libc-top-half/musl/src/thread/s390x/clone.s
new file mode 100644
index 0000000..2125f20
--- /dev/null
+++ b/libc-top-half/musl/src/thread/s390x/clone.s
@@ -0,0 +1,54 @@
+.text
+.global __clone
+.hidden __clone
+.type __clone, %function
+__clone:
+ # int clone(
+ # fn, a = r2
+ # stack, b = r3
+ # flags, c = r4
+ # arg, d = r5
+ # ptid, e = r6
+ # tls, f = *(r15+160)
+ # ctid) g = *(r15+168)
+ #
+ # pseudo C code:
+ # tid = syscall(SYS_clone,b,c,e,g,f);
+ # if (!tid) syscall(SYS_exit, a(d));
+ # return tid;
+
+ # preserve call-saved register used as syscall arg
+ stg %r6, 48(%r15)
+
+ # create initial stack frame for new thread
+ nill %r3, 0xfff8
+ aghi %r3, -160
+ lghi %r0, 0
+ stg %r0, 0(%r3)
+
+ # save fn and arg to child stack
+ stg %r2, 8(%r3)
+ stg %r5, 16(%r3)
+
+ # shuffle args into correct registers and call SYS_clone
+ lgr %r2, %r3
+ lgr %r3, %r4
+ lgr %r4, %r6
+ lg %r5, 168(%r15)
+ lg %r6, 160(%r15)
+ svc 120
+
+ # restore call-saved register
+ lg %r6, 48(%r15)
+
+ # if error or if we're the parent, return
+ ltgr %r2, %r2
+ bnzr %r14
+
+ # we're the child. call fn(arg)
+ lg %r1, 8(%r15)
+ lg %r2, 16(%r15)
+ basr %r14, %r1
+
+ # call SYS_exit. exit code is already in r2 from fn return value
+ svc 1