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+/* $NetBSD: execsp.S,v 1.3 2025/06/04 19:25:45 christos Exp $ */
+
+/*-
+ * Copyright (c) 2025 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+#define _LOCORE
+
+#include <machine/asm.h>
+
+RCSID("$NetBSD: execsp.S,v 1.3 2025/06/04 19:25:45 christos Exp $")
+
+/*
+ * void execsp_start(void (*cleanup@x0)(void), void *obj_main@x1,
+ * struct ps_strings *ps_strings@x2)
+ *
+ * ELF entry point. Saves the stack pointer in startsp and defers
+ * to the usual csu __start routine.
+ */
+ENTRY(execsp_start)
+ mov x16, sp
+ adrp x17, _C_LABEL(startsp)
+ str x16, [x17, :lo12:_C_LABEL(startsp)]
+ b _C_LABEL(__start)
+END(execsp_start)
+
+/*
+ * void execsp_ctor(void)
+ *
+ * ELF constructor. Saves the stack pointer in ctorsp and
+ * returns.
+ */
+ENTRY(execsp_ctor)
+ mov x16, sp
+ adrp x17, _C_LABEL(ctorsp)
+ str x16, [x17, :lo12:_C_LABEL(ctorsp)]
+ ret
+END(execsp_ctor)
+
+ /* Make execsp_ctor a constructor. */
+ .section .init_array,"aw",%init_array
+ .p2align 3
+ .xword _C_LABEL(execsp_ctor)
+
+/*
+ * int main(int argc@x0, char **argv@x1, ...)
+ *
+ * Main function. Saves the stack pointer in mainsp and returns
+ * zero. We will call execsp_main in execsp_dtor once dtorsp has
+ * been initialized.
+ */
+ENTRY(main)
+ mov x16, sp
+ adrp x17, _C_LABEL(mainsp)
+ str x16, [x17, :lo12:_C_LABEL(mainsp)]
+ mov x0, #0
+ ret
+END(main)
+
+/*
+ * void execsp_dtor(void)
+ *
+ * ELF destructor. Saves the stack pointer in dtorsp and defers
+ * to the C execsp_main in h_execsp.c to report the stack pointers
+ * back to the t_signal_and_sp parent.
+ */
+ENTRY(execsp_dtor)
+ mov x16, sp
+ adrp x17, _C_LABEL(dtorsp)
+ str x16, [x17, :lo12:_C_LABEL(dtorsp)]
+ b _C_LABEL(execsp_main)
+END(execsp_dtor)
+
+ /* Make execsp_ctor a destructor. */
+ .section .fini_array,"aw",%fini_array
+ .p2align 3
+ .xword _C_LABEL(execsp_dtor)