[thirdparty/glibc.git] / sysdeps / or1k / start.S

/* start, OpenRISC version.
   Copyright (C) 2022-2023 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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.

   In addition to the permissions in the GNU Lesser General Public
   License, the Free Software Foundation gives you unlimited
   permission to link the compiled version of this file with other
   programs, and to distribute those programs without any restriction
   coming from the use of this file. (The GNU Lesser General Public
   License restrictions do apply in other respects; for example, they
   cover modification of the file, and distribution when not linked
   into another program.)

   Note that people who make modified versions of this file are not
   obligated to grant this special exception for their modified
   versions; it is their choice whether to do so. The GNU Lesser
   General Public License gives permission to release a modified
   version without this exception; this exception also makes it
   possible to release a modified version which carries forward this
   exception.

   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
   <https://www.gnu.org/licenses/>.  */

/* This is the canonical entry point, usually the first thing in the text
   segment.

   sp   The stack contains the arguments and environment:
    0(sp)     argc
    4(sp)     argv[0]
    ...
    (4*argc)(sp)    NULL
    (4*(argc+1))(sp)  envp[0]
    ...
    NULL
 */

#define __ASSEMBLY__
#include <sysdep.h>
#include <entry.h>

ENTRY (ENTRY_POINT)

	/* Setup Arguments to the __libc_start_main function.  */

	/* Take values for argc and argv off the stack.
	   These will be passed as arguments two and three to main
	   and thus go in registers r4 and r5, respectively.  */
	l.lwz	r4, 0(r1)
	l.addi	r5, r1, 4

	/* Pass in rtld_fini from dl-start.S.  */
	l.or	r8, r3, r3

#ifdef PIC
	/* Obtain a pointer to .got in r16 */
	l.jal	0x8
	 l.movhi r16, gotpchi(_GLOBAL_OFFSET_TABLE_-4)
	l.ori	r16, r16, gotpclo(_GLOBAL_OFFSET_TABLE_+0)
	l.add	r16, r16, r9

	/* Pass in the the main symbol.  */
	l.lwz	r3, got(main)(r16)
#else
	/* Pass in the the main symbol.  */
	l.movhi r3, hi(main)
	l.ori	r3, r3, lo(main)
#endif
	/* Used to be init and fini.  */
	l.movhi	r6, 0x0
	l.movhi	r7, 0x0

	/* Push stack limit onto the stack.
	   This provides the highest stack address to user code (as stack grows
	   downwards.
	   This is the seventh argument to __libc_start_main and thus needs to
	   be passed on the stack.  */
	l.sw	-4(r1), r1

	/* Adjust stack to account for a total of 7 args (i.e. the last one is
	   on the stack.  */
	l.addi	r1, r1, -4

	/* Clear the frame pointer and link register since this is the
	   outermost frame.  */
	l.movhi	r2, 0x0
	l.movhi	r9, 0x0

	/* Let the libc call main and exit with its return code.  */
#ifdef PIC
	l.j	plt(__libc_start_main)
#else
	l.j	__libc_start_main
#endif
	 l.nop
END (ENTRY_POINT)

	/* Define a symbol for the first piece of initialized data.  */
	.data
	.globl __data_start
__data_start:
	.long 0
	.weak data_start
	data_start = __data_start
Commit	Line	Data
de5c0edc	1	/* start, OpenRISC version.
6d7e8eda	2	Copyright (C) 2022-2023 Free Software Foundation, Inc.
de5c0edc SH	3	This file is part of the GNU C Library.
	4
	5	The GNU C Library is free software; you can redistribute it and/or
	6	modify it under the terms of the GNU Lesser General Public
	7	License as published by the Free Software Foundation; either
	8	version 2.1 of the License, or (at your option) any later version.
	9
06d4381d SN	10	In addition to the permissions in the GNU Lesser General Public
	11	License, the Free Software Foundation gives you unlimited
	12	permission to link the compiled version of this file with other
	13	programs, and to distribute those programs without any restriction
	14	coming from the use of this file. (The GNU Lesser General Public
	15	License restrictions do apply in other respects; for example, they
	16	cover modification of the file, and distribution when not linked
	17	into another program.)
	18
	19	Note that people who make modified versions of this file are not
	20	obligated to grant this special exception for their modified
	21	versions; it is their choice whether to do so. The GNU Lesser
	22	General Public License gives permission to release a modified
	23	version without this exception; this exception also makes it
	24	possible to release a modified version which carries forward this
	25	exception.
	26
de5c0edc SH	27	The GNU C Library is distributed in the hope that it will be useful,
	28	but WITHOUT ANY WARRANTY; without even the implied warranty of
	29	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	30	Lesser General Public License for more details.
	31
	32	You should have received a copy of the GNU Lesser General Public
06d4381d SN	33	License along with the GNU C Library; if not, see
06d4381d SN	34	<https://www.gnu.org/licenses/>. */
de5c0edc SH	35
	36	/* This is the canonical entry point, usually the first thing in the text
	37	segment.
	38
	39	sp The stack contains the arguments and environment:
	40	0(sp) argc
	41	4(sp) argv[0]
	42	...
	43	(4*argc)(sp) NULL
	44	(4*(argc+1))(sp) envp[0]
	45	...
	46	NULL
	47	*/
	48
	49	#define __ASSEMBLY__
	50	#include <sysdep.h>
	51	#include <entry.h>
	52
	53	ENTRY (ENTRY_POINT)
	54
	55	/* Setup Arguments to the __libc_start_main function. */
	56
	57	/* Take values for argc and argv off the stack.
	58	These will be passed as arguments two and three to main
	59	and thus go in registers r4 and r5, respectively. */
	60	l.lwz r4, 0(r1)
	61	l.addi r5, r1, 4
	62
	63	/* Pass in rtld_fini from dl-start.S. */
	64	l.or r8, r3, r3
	65
	66	#ifdef PIC
	67	/* Obtain a pointer to .got in r16 */
	68	l.jal 0x8
	69	l.movhi r16, gotpchi(_GLOBAL_OFFSET_TABLE_-4)
	70	l.ori r16, r16, gotpclo(_GLOBAL_OFFSET_TABLE_+0)
	71	l.add r16, r16, r9
	72
	73	/* Pass in the the main symbol. */
	74	l.lwz r3, got(main)(r16)
	75	#else
	76	/* Pass in the the main symbol. */
	77	l.movhi r3, hi(main)
	78	l.ori r3, r3, lo(main)
	79	#endif
	80	/* Used to be init and fini. */
	81	l.movhi r6, 0x0
	82	l.movhi r7, 0x0
	83
	84	/* Push stack limit onto the stack.
	85	This provides the highest stack address to user code (as stack grows
	86	downwards.
	87	This is the seventh argument to __libc_start_main and thus needs to
	88	be passed on the stack. */
	89	l.sw -4(r1), r1
	90
	91	/* Adjust stack to account for a total of 7 args (i.e. the last one is
	92	on the stack. */
	93	l.addi r1, r1, -4
	94
	95	/* Clear the frame pointer and link register since this is the
	96	outermost frame. */
	97	l.movhi r2, 0x0
	98	l.movhi r9, 0x0
99
100	/* Let the libc call main and exit with its return code. */
101	#ifdef PIC
102	l.j plt(__libc_start_main)
103	#else
104	l.j __libc_start_main
105	#endif
106	l.nop
107	END (ENTRY_POINT)
108
109	/* Define a symbol for the first piece of initialized data. */
110	.data
111	.globl __data_start
112	__data_start:
113	.long 0
114	.weak data_start
115	data_start = __data_start