/*      $NetBSD: rtld_start.S,v 1.6 2023/05/07 12:41:48 skrll Exp $     */

/*-
 * Copyright (c) 2014 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Thomas of 3am Software Foundry.
 *
 * 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.
 */

#include <machine/asm.h>

        .globl _C_LABEL(_rtld_relocate_nonplt_self)
        .globl _C_LABEL(_rtld)

#define PTRSZ   __SIZEOF_POINTER__

/*
 * void
 * ___start(
 *     void (*cleanup)(void),
 *     struct ps_strings *ps_strings
 * )
 */

ENTRY(_rtld_start)
        mv      s0, sp                  # save stack pointer
        addi    sp, sp, -4 * PTRSZ      # adjust stack pointer
                                        # -> 2 * PTR_SIZE(sp) for atexit
                                        # -> 3 * PTR_SIZE(sp) for obj_main
        mv      s1, a1                  # save ps_strings pointer

.L0:    auipc   gp, %pcrel_hi(_GLOBAL_OFFSET_TABLE_)
        PTR_L   t0, %pcrel_lo(.L0)(gp) # &_DYNAMIC
.L1:    auipc   a0, %pcrel_hi(_DYNAMIC)
        addi    a0, a0, %pcrel_lo(.L1)
        sub     s2, a0, t0              # save for _rtld
        mv      a1, s2
        call    _C_LABEL(_rtld_relocate_nonplt_self)

        mv      a1, s2                  # relocbase
        addi    a0, sp, 2 * PTRSZ       # sp
        call    _C_LABEL(_rtld)         # a0 = _rtld(sp, relocbase)
        mv      t0, a0

        PTR_L   a0, 2 * PTRSZ(sp)       # cleanup function
//      PTR_L   a1, 3 * PTRSZ(sp)       # obj_main pointer (not used)
        mv      a1, s1                  # restore ps_strings
        mv      sp, s0                  # restore stack pointer
        mv      s0, zero                # break stack chain
        jr      t0                      # _start(cleanup, ps_strings);
END(_rtld_start)

/*
 * Needs to be 12 so that stack alignment is preserved on both RV32 and RV64.
 */

#define XCALLFRAME_SIZ          (12 * SZREG)
#define XCALLFRAME_RA           ( 8 * SZREG)
#define XCALLFRAME_A7           ( 7 * SZREG)
#define XCALLFRAME_A6           ( 6 * SZREG)
#define XCALLFRAME_A5           ( 5 * SZREG)
#define XCALLFRAME_A4           ( 4 * SZREG)
#define XCALLFRAME_A3           ( 3 * SZREG)
#define XCALLFRAME_A2           ( 2 * SZREG)
#define XCALLFRAME_A1           ( 1 * SZREG)
#define XCALLFRAME_A0           ( 0 * SZREG)

/*
 * t0 = obj pointer
 * t1 = reloc offset
 */
ENTRY_NP(_rtld_bind_start)
        addi    sp, sp, -XCALLFRAME_SIZ // save arguments on stack
        REG_S   a0,  XCALLFRAME_A0(sp)
        REG_S   a1,  XCALLFRAME_A1(sp)
        REG_S   a2,  XCALLFRAME_A2(sp)
        REG_S   a3,  XCALLFRAME_A3(sp)
        REG_S   a4,  XCALLFRAME_A4(sp)
        REG_S   a5,  XCALLFRAME_A5(sp)
        REG_S   a6,  XCALLFRAME_A6(sp)
        REG_S   a7,  XCALLFRAME_A7(sp)
        REG_S   ra,  XCALLFRAME_RA(sp)

        mv      a0, t0                  /* object from got.plt[1] */
        mv      a1, t1                  /* reloc offset */

        call    _C_LABEL(_rtld_bind)
        mv      t0, a0                  /* save function pointer */

        REG_L   a0, XCALLFRAME_A0(sp)
        REG_L   a1, XCALLFRAME_A1(sp)
        REG_L   a2, XCALLFRAME_A2(sp)
        REG_L   a3, XCALLFRAME_A3(sp)
        REG_L   a4, XCALLFRAME_A4(sp)
        REG_L   a5, XCALLFRAME_A5(sp)
        REG_L   a6, XCALLFRAME_A6(sp)
        REG_L   a7, XCALLFRAME_A7(sp)
        REG_L   ra, XCALLFRAME_RA(sp)
        addi    sp, sp, XCALLFRAME_SIZ
        jr      t0
END(_rtld_bind_start)