xref: /illumos-gate/usr/src/cmd/sgs/rtld/amd64/_setup.c (revision d0158222)
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  */
29 
30 /*
31  * amd64 specific setup routine  -  relocate ld.so's symbols, setup its
32  * environment, map in loadable sections of the executable.
33  *
34  * Takes base address ld.so was loaded at, address of ld.so's dynamic
35  * structure, address of process environment pointers, address of auxiliary
36  * vector and * argv[0] (process name).
37  * If errors occur, send process signal - otherwise
38  * return executable's entry point to the bootstrap routine.
39  */
40 
41 #include	<signal.h>
42 #include	<stdlib.h>
43 #include	<sys/auxv.h>
44 #include	<sys/types.h>
45 #include	<sys/stat.h>
46 #include	<link.h>
47 #include	<dlfcn.h>
48 #include	"_rtld.h"
49 #include	"_audit.h"
50 #include	"msg.h"
51 
52 /*
53  * Number of bytes to save for register usage.
54  */
55 uint_t _plt_save_size;
56 void (*_plt_fp_save)(void *);
57 void (*_plt_fp_restore)(void *);
58 
59 extern void _elf_rtbndr_fp_save_orig(void *);
60 extern void _elf_rtbndr_fp_restore_orig(void *);
61 extern void _elf_rtbndr_fp_fxsave(void *);
62 extern void _elf_rtbndr_fp_fxrestore(void *);
63 extern void _elf_rtbndr_fp_xsave(void *);
64 extern void _elf_rtbndr_fp_xrestore(void *);
65 
66 /*
67  * Based on what the kernel has told us, go through and set up the various
68  * pointers that we'll need for elf_rtbndr for the FPU.
69  */
70 static void
_setup_plt_fpu(int kind,size_t len)71 _setup_plt_fpu(int kind, size_t len)
72 {
73 	/*
74 	 * If we didn't get a length for some reason, fall back to the old
75 	 * implementation.
76 	 */
77 	if (len == 0)
78 		kind = -1;
79 
80 	switch (kind) {
81 	case AT_386_FPINFO_FXSAVE:
82 		_plt_fp_save = _elf_rtbndr_fp_fxsave;
83 		_plt_fp_restore = _elf_rtbndr_fp_fxrestore;
84 		_plt_save_size = len;
85 		break;
86 	/*
87 	 * We can treat processors that don't correctly handle the exception
88 	 * information in xsave the same way we do others. The information
89 	 * that may or may not be properly saved and restored should not be
90 	 * relevant to us because of the ABI.
91 	 */
92 	case AT_386_FPINFO_XSAVE:
93 	case AT_386_FPINFO_XSAVE_AMD:
94 		_plt_fp_save = _elf_rtbndr_fp_xsave;
95 		_plt_fp_restore = _elf_rtbndr_fp_xrestore;
96 		_plt_save_size = len;
97 		break;
98 	default:
99 		_plt_fp_save = _elf_rtbndr_fp_save_orig;
100 		_plt_fp_restore = _elf_rtbndr_fp_restore_orig;
101 		/*
102 		 * The ABI says that 8 floating point registers are used for
103 		 * passing arguments (%xmm0 through %xmm7). Because these
104 		 * registers on some platforms may shadow the %ymm and %zmm
105 		 * registers, we end up needing to size this for the maximally
106 		 * sized register we care about, a 512-bit (64-byte) zmm
107 		 * register.
108 		 */
109 		_plt_save_size = 64 * 8;
110 		break;
111 	}
112 }
113 
114 /* VARARGS */
115 unsigned long
_setup(Boot * ebp,Dyn * ld_dyn)116 _setup(Boot *ebp, Dyn *ld_dyn)
117 {
118 	ulong_t		reladdr, relacount, ld_base = 0;
119 	ulong_t		relaent = 0, pltrelsz = 0;
120 	ulong_t		strtab, soname, interp_base = 0;
121 	char		*_rt_name, **_envp, **_argv;
122 	int		_syspagsz = 0, fd = -1;
123 	uint_t		_flags = 0;
124 	uint_t		hwcap[2] = { 0, 0 };
125 	Dyn		*dyn_ptr;
126 	Phdr		*phdr = NULL;
127 	Rt_map		*lmp;
128 	auxv_t		*auxv, *_auxv;
129 	uid_t		uid = (uid_t)-1, euid = (uid_t)-1;
130 	gid_t		gid = (gid_t)-1, egid = (gid_t)-1;
131 	char		*_platform = NULL, *_execname = NULL, *_emulator = NULL;
132 	int		auxflags = -1, fpkind = -1;
133 	size_t		fpsize = 0;
134 
135 	/*
136 	 * Scan the bootstrap structure to pick up the basics.
137 	 */
138 	for (; ebp->eb_tag != EB_NULL; ebp++)
139 		switch (ebp->eb_tag) {
140 		case EB_LDSO_BASE:
141 			ld_base = (unsigned long)ebp->eb_un.eb_val;
142 			break;
143 		case EB_ARGV:
144 			_argv = (char **)ebp->eb_un.eb_ptr;
145 			break;
146 		case EB_ENVP:
147 			_envp = (char **)ebp->eb_un.eb_ptr;
148 			break;
149 		case EB_AUXV:
150 			_auxv = (auxv_t *)ebp->eb_un.eb_ptr;
151 			break;
152 		case EB_PAGESIZE:
153 			_syspagsz = (int)ebp->eb_un.eb_val;
154 			break;
155 		}
156 
157 	/*
158 	 * Search the aux. vector for the information passed by exec.
159 	 */
160 	for (auxv = _auxv; auxv->a_type != AT_NULL; auxv++) {
161 		switch (auxv->a_type) {
162 		case AT_EXECFD:
163 			/* this is the old exec that passes a file descriptor */
164 			fd = (int)auxv->a_un.a_val;
165 			break;
166 		case AT_FLAGS:
167 			/* processor flags (MAU available, etc) */
168 			_flags = auxv->a_un.a_val;
169 			break;
170 		case AT_PAGESZ:
171 			/* system page size */
172 			_syspagsz = (int)auxv->a_un.a_val;
173 			break;
174 		case AT_PHDR:
175 			/* address of the segment table */
176 			phdr = (Phdr *)auxv->a_un.a_ptr;
177 			break;
178 		case AT_BASE:
179 			/* interpreter base address */
180 			if (ld_base == 0)
181 				ld_base = auxv->a_un.a_val;
182 			interp_base = auxv->a_un.a_val;
183 			break;
184 		case AT_SUN_UID:
185 			/* effective user id for the executable */
186 			euid = (uid_t)auxv->a_un.a_val;
187 			break;
188 		case AT_SUN_RUID:
189 			/* real user id for the executable */
190 			uid = (uid_t)auxv->a_un.a_val;
191 			break;
192 		case AT_SUN_GID:
193 			/* effective group id for the executable */
194 			egid = (gid_t)auxv->a_un.a_val;
195 			break;
196 		case AT_SUN_RGID:
197 			/* real group id for the executable */
198 			gid = (gid_t)auxv->a_un.a_val;
199 			break;
200 		case AT_SUN_PLATFORM:
201 			/* platform name */
202 			_platform = auxv->a_un.a_ptr;
203 			break;
204 		case AT_SUN_EXECNAME:
205 			/* full pathname of execed object */
206 			_execname = auxv->a_un.a_ptr;
207 			break;
208 		case AT_SUN_AUXFLAGS:
209 			/* auxiliary flags */
210 			auxflags = (int)auxv->a_un.a_val;
211 			break;
212 		case AT_SUN_HWCAP:
213 			/* hardware capabilities */
214 			hwcap[0] = (uint_t)auxv->a_un.a_val;
215 			break;
216 		case AT_SUN_HWCAP2:
217 			/* hardware capabilities */
218 			hwcap[1] = (uint_t)auxv->a_un.a_val;
219 			break;
220 		case AT_SUN_EMULATOR:
221 			/* name of emulation library, if any */
222 			_emulator = auxv->a_un.a_ptr;
223 			break;
224 		case AT_SUN_FPTYPE:
225 			fpkind = (int)auxv->a_un.a_val;
226 			break;
227 		case AT_SUN_FPSIZE:
228 			fpsize = (size_t)auxv->a_un.a_val;
229 			break;
230 		}
231 	}
232 
233 	/*
234 	 * Get needed info from ld.so's dynamic structure.
235 	 */
236 	/* LINTED */
237 	dyn_ptr = (Dyn *)((char *)ld_dyn + ld_base);
238 	for (ld_dyn = dyn_ptr; ld_dyn->d_tag != DT_NULL; ld_dyn++) {
239 		switch (ld_dyn->d_tag) {
240 		case DT_RELA:
241 			reladdr = ld_dyn->d_un.d_ptr + ld_base;
242 			break;
243 		case DT_RELACOUNT:
244 			relacount = ld_dyn->d_un.d_val;
245 			break;
246 		case DT_RELAENT:
247 			relaent = ld_dyn->d_un.d_val;
248 			break;
249 		case DT_PLTRELSZ:
250 			pltrelsz = ld_dyn->d_un.d_val;
251 			break;
252 		case DT_STRTAB:
253 			strtab = ld_dyn->d_un.d_ptr + ld_base;
254 			break;
255 		case DT_SONAME:
256 			soname = ld_dyn->d_un.d_val;
257 			break;
258 		}
259 	}
260 	_rt_name = (char *)strtab + soname;
261 
262 	/*
263 	 * If we don't have a RELAENT, just assume the size.
264 	 */
265 	if (relaent == 0)
266 		relaent = sizeof (Rela);
267 
268 	/*
269 	 * As all global symbol references within ld.so.1 are protected
270 	 * (symbolic), only RELATIVE and JMPSLOT relocations should be left
271 	 * to process at runtime.  Process all relocations now.
272 	 */
273 	relacount += (pltrelsz / relaent);
274 	for (; relacount; relacount--) {
275 		ulong_t	roffset;
276 
277 		roffset = ((Rela *)reladdr)->r_offset + ld_base;
278 		*((ulong_t *)roffset) += ld_base +
279 		    ((Rela *)reladdr)->r_addend;
280 		reladdr += relaent;
281 	}
282 
283 	/*
284 	 * If an emulation library is being used, use that as the linker's
285 	 * effective executable name. The real executable is not linked by this
286 	 * linker.
287 	 */
288 	if (_emulator != NULL) {
289 		_execname = _emulator;
290 		rtld_flags2 |= RT_FL2_BRANDED;
291 	}
292 
293 	/*
294 	 * Initialize the dyn_plt_ent_size field.  It currently contains the
295 	 * size of the dyn_plt_template.  It still needs to be aligned and have
296 	 * space for the 'dyn_data' area added.
297 	 */
298 	dyn_plt_ent_size = ROUND(dyn_plt_ent_size, M_WORD_ALIGN) +
299 	    sizeof (uintptr_t) + sizeof (uintptr_t) + sizeof (ulong_t) +
300 	    sizeof (ulong_t) + sizeof (Sym);
301 
302 	/*
303 	 * Initialize the amd64 specific PLT relocation constants based on the
304 	 * FP information that we have.
305 	 */
306 	_setup_plt_fpu(fpkind, fpsize);
307 
308 	/*
309 	 * Continue with generic startup processing.
310 	 */
311 	if ((lmp = setup((char **)_envp, (auxv_t *)_auxv, _flags, _platform,
312 	    _syspagsz, _rt_name, ld_base, interp_base, fd, phdr,
313 	    _execname, _argv, uid, euid, gid, egid, NULL, auxflags,
314 	    hwcap)) == NULL) {
315 		rtldexit(&lml_main, 1);
316 	}
317 
318 	return (LM_ENTRY_PT(lmp)());
319 }
320