xref: /illumos-gate/usr/src/cmd/sgs/rtld/amd64/_setup.c (revision 56726c7e)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 /*
27  * Copyright (c) 2018, Joyent, Inc.
28  * Copyright 2022 Oxide Computer Company
29  */
30 
31 /*
32  * amd64 specific setup routine  -  relocate ld.so's symbols, setup its
33  * environment, map in loadable sections of the executable.
34  *
35  * Takes base address ld.so was loaded at, address of ld.so's dynamic
36  * structure, address of process environment pointers, address of auxiliary
37  * vector and * argv[0] (process name).
38  * If errors occur, send process signal - otherwise
39  * return executable's entry point to the bootstrap routine.
40  */
41 
42 #include	<signal.h>
43 #include	<stdlib.h>
44 #include	<sys/auxv.h>
45 #include	<sys/types.h>
46 #include	<sys/stat.h>
47 #include	<link.h>
48 #include	<dlfcn.h>
49 #include	"_rtld.h"
50 #include	"_audit.h"
51 #include	"msg.h"
52 
53 /*
54  * Number of bytes to save for register usage.
55  */
56 uint_t _plt_save_size;
57 void (*_plt_fp_save)(void *);
58 void (*_plt_fp_restore)(void *);
59 
60 extern void _elf_rtbndr_fp_save_orig(void *);
61 extern void _elf_rtbndr_fp_restore_orig(void *);
62 extern void _elf_rtbndr_fp_fxsave(void *);
63 extern void _elf_rtbndr_fp_fxrestore(void *);
64 extern void _elf_rtbndr_fp_xsave(void *);
65 extern void _elf_rtbndr_fp_xrestore(void *);
66 
67 /*
68  * Based on what the kernel has told us, go through and set up the various
69  * pointers that we'll need for elf_rtbndr for the FPU.
70  */
71 static void
_setup_plt_fpu(int kind,size_t len)72 _setup_plt_fpu(int kind, size_t len)
73 {
74 	/*
75 	 * If we didn't get a length for some reason, fall back to the old
76 	 * implementation.
77 	 */
78 	if (len == 0)
79 		kind = -1;
80 
81 	switch (kind) {
82 	case AT_386_FPINFO_FXSAVE:
83 		_plt_fp_save = _elf_rtbndr_fp_fxsave;
84 		_plt_fp_restore = _elf_rtbndr_fp_fxrestore;
85 		_plt_save_size = len;
86 		break;
87 	/*
88 	 * We can treat processors that don't correctly handle the exception
89 	 * information in xsave the same way we do others. The information
90 	 * that may or may not be properly saved and restored should not be
91 	 * relevant to us because of the ABI.
92 	 */
93 	case AT_386_FPINFO_XSAVE:
94 	case AT_386_FPINFO_XSAVE_AMD:
95 		_plt_fp_save = _elf_rtbndr_fp_xsave;
96 		_plt_fp_restore = _elf_rtbndr_fp_xrestore;
97 		_plt_save_size = len;
98 		break;
99 	default:
100 		_plt_fp_save = _elf_rtbndr_fp_save_orig;
101 		_plt_fp_restore = _elf_rtbndr_fp_restore_orig;
102 		/*
103 		 * The ABI says that 8 floating point registers are used for
104 		 * passing arguments (%xmm0 through %xmm7). Because these
105 		 * registers on some platforms may shadow the %ymm and %zmm
106 		 * registers, we end up needing to size this for the maximally
107 		 * sized register we care about, a 512-bit (64-byte) zmm
108 		 * register.
109 		 */
110 		_plt_save_size = 64 * 8;
111 		break;
112 	}
113 }
114 
115 /* VARARGS */
116 unsigned long
_setup(Boot * ebp,Dyn * ld_dyn)117 _setup(Boot *ebp, Dyn *ld_dyn)
118 {
119 	ulong_t		reladdr, relacount, ld_base = 0;
120 	ulong_t		relaent = 0, pltrelsz = 0;
121 	ulong_t		strtab, soname, interp_base = 0;
122 	char		*_rt_name, **_envp, **_argv;
123 	int		_syspagsz = 0, fd = -1;
124 	uint_t		_flags = 0;
125 	uint_t		hwcap[3] = { 0, 0, 0 };
126 	Dyn		*dyn_ptr;
127 	Phdr		*phdr = NULL;
128 	Rt_map		*lmp;
129 	auxv_t		*auxv, *_auxv;
130 	uid_t		uid = (uid_t)-1, euid = (uid_t)-1;
131 	gid_t		gid = (gid_t)-1, egid = (gid_t)-1;
132 	char		*_platform = NULL, *_execname = NULL, *_emulator = NULL;
133 	int		auxflags = -1, fpkind = -1;
134 	size_t		fpsize = 0;
135 
136 	/*
137 	 * Scan the bootstrap structure to pick up the basics.
138 	 */
139 	for (; ebp->eb_tag != EB_NULL; ebp++)
140 		switch (ebp->eb_tag) {
141 		case EB_LDSO_BASE:
142 			ld_base = (unsigned long)ebp->eb_un.eb_val;
143 			break;
144 		case EB_ARGV:
145 			_argv = (char **)ebp->eb_un.eb_ptr;
146 			break;
147 		case EB_ENVP:
148 			_envp = (char **)ebp->eb_un.eb_ptr;
149 			break;
150 		case EB_AUXV:
151 			_auxv = (auxv_t *)ebp->eb_un.eb_ptr;
152 			break;
153 		case EB_PAGESIZE:
154 			_syspagsz = (int)ebp->eb_un.eb_val;
155 			break;
156 		}
157 
158 	/*
159 	 * Search the aux. vector for the information passed by exec.
160 	 */
161 	for (auxv = _auxv; auxv->a_type != AT_NULL; auxv++) {
162 		switch (auxv->a_type) {
163 		case AT_EXECFD:
164 			/* this is the old exec that passes a file descriptor */
165 			fd = (int)auxv->a_un.a_val;
166 			break;
167 		case AT_FLAGS:
168 			/* processor flags (MAU available, etc) */
169 			_flags = auxv->a_un.a_val;
170 			break;
171 		case AT_PAGESZ:
172 			/* system page size */
173 			_syspagsz = (int)auxv->a_un.a_val;
174 			break;
175 		case AT_PHDR:
176 			/* address of the segment table */
177 			phdr = (Phdr *)auxv->a_un.a_ptr;
178 			break;
179 		case AT_BASE:
180 			/* interpreter base address */
181 			if (ld_base == 0)
182 				ld_base = auxv->a_un.a_val;
183 			interp_base = auxv->a_un.a_val;
184 			break;
185 		case AT_SUN_UID:
186 			/* effective user id for the executable */
187 			euid = (uid_t)auxv->a_un.a_val;
188 			break;
189 		case AT_SUN_RUID:
190 			/* real user id for the executable */
191 			uid = (uid_t)auxv->a_un.a_val;
192 			break;
193 		case AT_SUN_GID:
194 			/* effective group id for the executable */
195 			egid = (gid_t)auxv->a_un.a_val;
196 			break;
197 		case AT_SUN_RGID:
198 			/* real group id for the executable */
199 			gid = (gid_t)auxv->a_un.a_val;
200 			break;
201 		case AT_SUN_PLATFORM:
202 			/* platform name */
203 			_platform = auxv->a_un.a_ptr;
204 			break;
205 		case AT_SUN_EXECNAME:
206 			/* full pathname of execed object */
207 			_execname = auxv->a_un.a_ptr;
208 			break;
209 		case AT_SUN_AUXFLAGS:
210 			/* auxiliary flags */
211 			auxflags = (int)auxv->a_un.a_val;
212 			break;
213 		case AT_SUN_HWCAP:
214 			/* hardware capabilities */
215 			hwcap[0] = (uint_t)auxv->a_un.a_val;
216 			break;
217 		case AT_SUN_HWCAP2:
218 			/* hardware capabilities */
219 			hwcap[1] = (uint_t)auxv->a_un.a_val;
220 			break;
221 		case AT_SUN_HWCAP3:
222 			/* hardware capabilities */
223 			hwcap[2] = (uint_t)auxv->a_un.a_val;
224 			break;
225 		case AT_SUN_EMULATOR:
226 			/* name of emulation library, if any */
227 			_emulator = auxv->a_un.a_ptr;
228 			break;
229 		case AT_SUN_FPTYPE:
230 			fpkind = (int)auxv->a_un.a_val;
231 			break;
232 		case AT_SUN_FPSIZE:
233 			fpsize = (size_t)auxv->a_un.a_val;
234 			break;
235 		}
236 	}
237 
238 	/*
239 	 * Get needed info from ld.so's dynamic structure.
240 	 */
241 	/* LINTED */
242 	dyn_ptr = (Dyn *)((char *)ld_dyn + ld_base);
243 	for (ld_dyn = dyn_ptr; ld_dyn->d_tag != DT_NULL; ld_dyn++) {
244 		switch (ld_dyn->d_tag) {
245 		case DT_RELA:
246 			reladdr = ld_dyn->d_un.d_ptr + ld_base;
247 			break;
248 		case DT_RELACOUNT:
249 			relacount = ld_dyn->d_un.d_val;
250 			break;
251 		case DT_RELAENT:
252 			relaent = ld_dyn->d_un.d_val;
253 			break;
254 		case DT_PLTRELSZ:
255 			pltrelsz = ld_dyn->d_un.d_val;
256 			break;
257 		case DT_STRTAB:
258 			strtab = ld_dyn->d_un.d_ptr + ld_base;
259 			break;
260 		case DT_SONAME:
261 			soname = ld_dyn->d_un.d_val;
262 			break;
263 		}
264 	}
265 	_rt_name = (char *)strtab + soname;
266 
267 	/*
268 	 * If we don't have a RELAENT, just assume the size.
269 	 */
270 	if (relaent == 0)
271 		relaent = sizeof (Rela);
272 
273 	/*
274 	 * As all global symbol references within ld.so.1 are protected
275 	 * (symbolic), only RELATIVE and JMPSLOT relocations should be left
276 	 * to process at runtime.  Process all relocations now.
277 	 */
278 	relacount += (pltrelsz / relaent);
279 	for (; relacount; relacount--) {
280 		ulong_t	roffset;
281 
282 		roffset = ((Rela *)reladdr)->r_offset + ld_base;
283 		*((ulong_t *)roffset) += ld_base +
284 		    ((Rela *)reladdr)->r_addend;
285 		reladdr += relaent;
286 	}
287 
288 	/*
289 	 * If an emulation library is being used, use that as the linker's
290 	 * effective executable name. The real executable is not linked by this
291 	 * linker.
292 	 */
293 	if (_emulator != NULL) {
294 		_execname = _emulator;
295 		rtld_flags2 |= RT_FL2_BRANDED;
296 	}
297 
298 	/*
299 	 * Initialize the dyn_plt_ent_size field.  It currently contains the
300 	 * size of the dyn_plt_template.  It still needs to be aligned and have
301 	 * space for the 'dyn_data' area added.
302 	 */
303 	dyn_plt_ent_size = ROUND(dyn_plt_ent_size, M_WORD_ALIGN) +
304 	    sizeof (uintptr_t) + sizeof (uintptr_t) + sizeof (ulong_t) +
305 	    sizeof (ulong_t) + sizeof (Sym);
306 
307 	/*
308 	 * Initialize the amd64 specific PLT relocation constants based on the
309 	 * FP information that we have.
310 	 */
311 	_setup_plt_fpu(fpkind, fpsize);
312 
313 	/*
314 	 * Continue with generic startup processing.
315 	 */
316 	if ((lmp = setup((char **)_envp, (auxv_t *)_auxv, _flags, _platform,
317 	    _syspagsz, _rt_name, ld_base, interp_base, fd, phdr,
318 	    _execname, _argv, uid, euid, gid, egid, auxflags,
319 	    hwcap)) == NULL) {
320 		rtldexit(&lml_main, 1);
321 	}
322 
323 	return (LM_ENTRY_PT(lmp)());
324 }
325