1/*	$OpenBSD: boot_md.c,v 1.6 2022/01/31 05:43:22 guenther Exp $ */
2
3/*
4 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 */
28
29/*
30 * IMPORTANT: any functions below are NOT protected by SSP.  Please
31 * do not add anything except what is required to reach GOT with
32 * an adjustment.
33 */
34
35#define	_DYN_LOADER
36
37#include <sys/exec_elf.h>
38
39#include "util.h"
40#include "archdep.h"		/* for RELOC_TAG */
41
42#include "../../lib/csu/os-note-elf.h"
43
44typedef	Elf_RelA	RELOC_TYPE;
45
46/*
47 * Local decls.
48 */
49void _dl_boot_bind(const long, long *, Elf_Dyn *) __boot;
50
51void
52_dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynp)
53{
54	AuxInfo			*auxstack;
55	long			*stack;
56	int			n, argc;
57	char			**argv, **envp;
58	long			loff;
59	const RELOC_TYPE	*rend;
60	const RELOC_TYPE	*dt_reloc;	/* DT_RELA */
61	Elf_Addr		dt_relocsz;	/* DT_RELASZ */
62	Elf_Addr		dt_pltgot;
63	Elf_Addr		dt_pltrelsz;
64	const Elf_Sym		*dt_symtab;
65	const RELOC_TYPE	*dt_jmprel;
66
67	/*
68	 * Scan argument and environment vectors. Find dynamic
69	 * data vector put after them.
70	 */
71	stack = (long *)sp;
72	argc = *stack++;
73	argv = (char **)stack;
74	envp = &argv[argc + 1];
75	stack = (long *)envp;
76	while (*stack++ != 0L)
77		;
78
79	/*
80	 * Zero out dl_data.
81	 */
82	for (n = 0; n <= AUX_entry; n++)
83		dl_data[n] = 0;
84
85	/*
86	 * Dig out auxiliary data set up by exec call. Move all known
87	 * tags to an indexed local table for easy access.
88	 */
89	for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null;
90	    auxstack++) {
91		if (auxstack->au_id > AUX_entry)
92			continue;
93		dl_data[auxstack->au_id] = auxstack->au_v;
94	}
95	loff = dl_data[AUX_base];	/* XXX assumes ld.so is linked at 0x0 */
96
97	/*
98	 * Scan the DYNAMIC section for the loader for the two items we need
99	 */
100	dt_pltrelsz = dt_relocsz = dt_pltgot = 0;
101	dt_jmprel = dt_reloc = NULL;
102	dt_symtab = NULL;
103	while (dynp->d_tag != DT_NULL) {
104		/* first the tags that are pointers to be relocated */
105		if (dynp->d_tag == DT_PLTGOT)
106			dt_pltgot = dynp->d_un.d_ptr + loff;
107		else if (dynp->d_tag == DT_SYMTAB)
108			dt_symtab = (void *)(dynp->d_un.d_ptr + loff);
109		else if (dynp->d_tag == RELOC_TAG)	/* DT_{RELA,REL} */
110			dt_reloc = (void *)(dynp->d_un.d_ptr + loff);
111		else if (dynp->d_tag == DT_JMPREL)
112			dt_jmprel = (void *)(dynp->d_un.d_ptr + loff);
113
114		/* Now for the tags that are just sizes or counts */
115		else if (dynp->d_tag == DT_PLTRELSZ)
116			dt_pltrelsz = dynp->d_un.d_val;
117		else if (dynp->d_tag == RELOC_TAG+1)	/* DT_{RELA,REL}SZ */
118			dt_relocsz = dynp->d_un.d_val;
119		dynp++;
120	}
121
122	rend = (RELOC_TYPE *)((char *)dt_jmprel + dt_pltrelsz);
123	for (; dt_jmprel < rend; dt_jmprel++) {
124		Elf_Addr *ra;
125		const Elf_Sym *sp;
126
127		sp = dt_symtab + ELF_R_SYM(dt_jmprel->r_info);
128		ra = (Elf_Addr *)(dt_jmprel->r_offset + loff);
129		ra[0] = loff + sp->st_value + dt_jmprel->r_addend;
130		ra[1] = dt_pltgot;
131	}
132
133	rend = (RELOC_TYPE *)((char *)dt_reloc + dt_relocsz);
134	for (; dt_reloc < rend; dt_reloc++) {
135		Elf_Addr *ra;
136		const Elf_Sym *sp;
137
138		sp = dt_symtab + ELF_R_SYM(dt_reloc->r_info);
139		ra = (Elf_Addr *)(dt_reloc->r_offset + loff);
140		*ra = loff + sp->st_value + dt_reloc->r_addend;
141	}
142}
143